Gold paint ≠ gold reflectivity Silver paint ≠ silver reflectivity At least outside of the visible spectrum. Paint just looks the part -it's optical properties are totally different to precious metals and also different to whatever coating is on your plastic mirrors.
Yep. In general, even with the reflective film, that will usually still have plastic surrounding the colored pigments or film layer. Either stuff is suface-coated with a metal film or not. So electroplating, true chrome either without a coat or with an IR transparent coating and sputtering are probably the most common ways to get this done. But it doesn't really make sense to use semi-gloss chrome paints or these films where the properties are unknown for these comparisons :/
Golds chemical properties allow it to be polished to such a fine degree, that it can refract the wavelength of infrared light. The color itself doesn't matter.
@@hondacivc93 Why talk about things you know nothing about? 1. It is not polished, it is deposited on a previously polished surface. The same way any other first surface mirror with silver is made. 2. Pretty much anything can be polished, as that is only a measure of surface roughness. There is nothing inherently preventing a perfectly flat surface. 3. Flatness has nothing to do with how good this flat surface reflects a specific wavelength. That is inherently a property of the material. You can polish coal as much as you want, it will always be black. Gold is always gold colored, no matter how rough you make the surface. 4. The color is said inherent material property and is all that matters for what is reflected. The flat surface just makes sure that the reflection ends up where you want it to, instead of going somewhere else. That is all the flatness is needed for.
Since you're trying to catch the light on the big plate, the parabolic shape on your primary mirrors is unnecessary. Each petal or mirror segment can be flat and the secondary mirror can be flat; the parabolic effect will come from how each segment is focused on the secondary. Rather than throw a tiny hot spot onto the receiver, let it be bigger and heat the whole thing more-or-less evenly. Lower deltas are less lossy. Also: you really want a dark receiver. Shiny silver will reflect a lot of the incident energy, shiny black will absorb it without re-radiating it so readily. Your ideal surface should be black chrome.
If he wants to achieve a real focus, each mirror should be a section of a paraboloid. Mirrors at the same radius can have the same shape, but the mirrors should be different shapes at different radius values.
I did something like this with a 1.2m satellite dish and aluminium foil, and then a mylar sheet over the dish and partially evacuated the volume behind - it was scary efficient! I used candle soot to coat the bottom of a pan to absorb the energy. At night, I could point it to a clear sky and use it to freeze things!
Agreed. Given that each mirror is similar (or smaller) than the collector-plate, there's no need to concentrate the sunlight, simply reflecting it with a pile of small individually flat mirrors will be sufficient. So he spent a LOT of time and effort doing something of no practical value here.
If you want to concentrate the light back to the back you need a Ritchey Chretien formula so hyperboloid mirrors on the primary mirror and a correspondant hyperboloid secondary mirror. But it's complicated and overkill. I would have use paraboloid mirrors on the primary but would have place the heat plate on the focal point instead of a secondary mirror. It makes the formula way easier to colimate and you get rid of difficult to build optics. As others mention, darkening the hot plate ensure light coming from the primary mirror isn't reflected so lost.
The heated aluminium disc should be dark, black (but not catch fire) to use enough of the light that is focused on it (as it's well known, the darker the object, the better it heats up). And, I'm sure you've considered this, but just in case: of course each segment must be the shape of the corresponding part of a parabola, not of the parabola's centre.
If the focus point will be few centimetres above aluminium disk, trap for light could be made: second disk with small hole that will be few centimetres above main disk and aluminium wall between two disks. that way almost all light will get through the hole in the first disk and then rereflect many times inside our trap, heating everything up. This also will stop wind from cooling main disk. And of course all walls inside trap should be black - main disk heat resistant paint and other walls of the trap could be painted with black 3.0 to really boost performance.
Not necessarily, if all parabolic mirrors (and their respective focal points) are equidistant to the secondary mirror/heater plate. It's way cheaper and faster to have one mold for all mirrors.
3d Printing 6 different forms (as it's rotationally symmetrical, you should be able to reuse them) probbably isn't too much overhead, but I'm not certain it's worth it. In case of remoulding, a vacuum attatched to the negative mold might pull the plates into shape without damaging the mirrors finish by compressing them from the top. A more expensive option might be to get copper-clad plexiglass for the panels, form them and then electroplate them silver. The upside is you should be able to get a very eaven coat by placing the opposite electrode at the focal point of the mirror, so it's fairly equidistant from all points (minus the spherical/parabolic deviation) That would hopefully remove some of the waviness you have in your formed sections from the adhesive releasing and/or the film buckling.
Also needless to say, make sure if you paint the plate black, you use temeperature-resistant paint like the stuff the make to paint mufflers or barbecues. Probably need some sort of primer with it as well, although the more different layers you have the worse the thermal conductivity could possibly be.
One glaring thing that may be a problem... the heat collector is currently reflective. Spray it matt black with heat resistant (stove paint) paint as it will absorb heat much better than the shiny surface.
@@ConceptCraftedCreationsThe fact you're using aluminum gives you an option for making it black: There was research done stating that a simple candle's soot actually forms carbon nanotubes onto the aluminium surface. Simply put, just soot the aluminium disc with a candle and gently have something transparent to protect it from the elements. Used this for my solar space heater, works well, however haven't tested if simply painting it black has any difference. But theoretically the nanotubes would be perfect light capturers.
@@ConceptCraftedCreations it might be hard to find paint that can resist such high temps, but i hope you do. In either case sand down the surface with a medium grit to make sure there is no reflectiveness, either on the black paint or the bare aluminum.
Color isn't really a good indicator for reflectance of infrared light. Actual gold like the stuff used on the telescope would reflect much more light, because the spray paint uses stuff that looks like gold, but isn't, it probably reflects much less light.
Lasers (IR CO2) use gold mirrors, they work well enough up to about 50W. The coating is rather fragile. They're reasonably cheap but small, only 20mm. Telescope dudes will sputter silver onto glass (say 300mm) easily enough, could probably point you towards someone who could do gold. These would have the coating on the front.
Building all of this just to be hit with the reality that you live in the Netherlands is very relatable. It's like when me and me dad installed solar panel lights on our house and forgot we get an absurd amount of clouds, so we originally thought we bought defective lights XD
Send me a version for testing in SEA. I already have a neighbor with a similar set up who sells solar roasted chicken on the highway. I will send back a cut of the profits for further R&D.
Do you remember if they were the blue crystalline looking ones or the black ones with stripes? The blue ones have like 4 times the Amp output in relation to surface area but only in direct sunlight. The black ones will output under 4 inches of snow and clouds.
i think it was 2004 the CSIRO in Australia built a large molten/solid salt solar reflector system that reached higher turbine steam temperature than has ever been achieved in a fossil fuel turbine. California put up a system around the same time but little has been done with it considering its potential to generate power for hrs after the sun is off reflectors thanks to molten salts high thermal capacity as for panel systems there's a NUMBER of factors that influence the sun levels needed for power the more line impedance/material to length to diameter to amps the less efficient the cable panel interface and panel cell interface the more resistance in inverter and battery's the less of the 22-24% (average panels ppl use these days efficiency) we manage to capture actually makes it to the destination reflector systems actualy do away with a lot of resistance because your heating a central rod that then boils and turns a steam turbine like a regular coal or gas plant and even in low light u just need a larger mirror footprint and u can get same heat but on a regular PV you can be getting double or triple the power depending on those factors from a system that is technically the same if your just looking at panels rated output tested at a cell level
yep this is why my new design for a multiple power source green power system will provide for 24/7 365 power production with a scalable design that can be produced for both commercial General grid distribution to a private at point of use (no grid tie in needed, thus reducing demands on a frail public utility system) Also providing a system deigned for very remote points of use. This system's use of several proven green power technologies provides a level of reliability in proper power production that few if any other green power systems can provide ( excluding systems that are anything but naturally occurring that use exotic elements & or fuel sources. { I.E. atomic, oil gas, coal } All of which can cause very harmful byproducts & waist. NONE OF WHICH ARE TRULY NEEDED to obtain large volumes of energy. ) I have the design but do not work for free.
JWST needs parabolic mirrors to create an image, you do not have the same requirement: you just need all the light from a mirror to reflect on the collector. A plane mirror illuminated by the sun creates a reflection of the same size at most, so the only requirement is to have a collector of the same size of the mirror.
This is a good point, I think a solid compromise that would be especially effective here, is set a reasonable focal goal for the curvatures, small enough to splash the majority of the target for good transfer.
Partially true, but one thing to consider is that the efficiency of a solar heat collector is proportional to the temperature difference you can achieve, and you can get a larger temperature difference for the same size collector by concentrating the light using parabolic mirrors.
Yes, focusing to a point is unnecessary unless you want to melt things - key is to collect energy as heat more efficiently, not concentrate it more than is necessary. The same energy can make a high temperature over a small area, or lower temperature over a larger area, and the latter may be more efficient by maximising heat transfer time to heat the fluid medium by the desired amount. There are a lot of things to consider. Coating the collector with soot from a candle will also increase absorption.
@ No, flat mirrors only fine if the collector is where all the reflections impinge on it on the end of the boom. There is no shape that can then reflect them all to the collector in the centre of the dish as they would all miss except one. In this case they would need to be partially focused to land on a parabolic convex reflector to then land on the collector in the dish, with a suitable radius to provide a temperature enough to heat the water to the desired temperature.
xD (I'm not American) My salary is less than $100 a month, however I recently allowed myself a set of 200 springs for $5 for the sake of 4 springs :) But the springs can really be replaced with alternatives, and the bearing is specific and very important, I guess it's just the man was choosing what to spend money on and what is not worth it
@@broniusale5987 Yeah, I don't understand what that was about either. Just looked at temu, searched for springs: springs galore for 10 to 20 ct a piece.
Awesome 👍 I'm doing an experiment with lunar simulant, sintering sublmation, and deposition. One of the ideas is to use a solar furnace on the moon exploiting the vacuum environment to create eutectic alloys. Excellent video 👍
Instead of allowing the water to flow through the collection plate under acrylic, I would of put copper tubing and soldered it into place to make better contact. Better contact allows for more efficient transfer of thermal energy. Also, the water will get very hot and start to build up pressure which can cause the acrylic to start to flex under the pressure, plus the heat making it softer. On my single solar thermal collector I had on a 2ftx4ft panel, the water would start boiling before exiting the system, which led to a lot of a air locking keeping the water from flowing smoothly. The system *had* to run under pressure to keep the water from boiling so easily.
Yeah, that acrylic backplate is just begging for leaks. The mirror tests already show it can significantly flex at 100C, and there's going to be a lot of water/steam pressure in there.
Yeah, I thought there was no way you could finish the whole project in only a 13 and a half minute video. Well, you are almost done. Can't wait for part two!
Very good project. 1. Place the heat receiver on the rods, and not reflect the light twice, which only leads to double losses due to light reflection. 2. Paint it black or smoke it with soot. 3. It is possible to apply a reflective coating after forming the bend of the mirror, in order to avoid cracks when heated. 4. Add a protective layer on top of the reflective one, since it is difficult to maintain the integrity of the coating in the sun, wind and rain. Plus, the second layer can be polished with a car polishing machine. 5. Replace tracking by lighting level with a simple table of the sun's location by time of day (but then you need to add potentiometers or decoders to the rotary axes). 6. If you want to leave the installation outside for a long time, you need to add a protective function to avoid strong winds, add a wind sensor or simply take information from the local weather forecast (mirrors are just a big sail)
Won’t that table shift by time of year, requiring either manual adjustment or additional complexity? I personally think this method of tracking is super elegant and quite simple overall.
Engineer here with a few suggestions - Your aluminum plate should have been copper for a couple of reasons - first, aluminum is reflective in the visible spectrum. A copper plate can be treated with a liquid known as "liver of sulfur" which creates a strongly-absorbing black surface, dramatically increasing the amount of energy that can actually be absorbed. Second, copper has a thermal conductivity roughly twice that of aluminum, meaning your total thermal resistance is lower. The net effect is that significantly more heat can flow from the absorbing surface into the water. Another consideration - choose the flow of the water carefully so that you are in the turbulent regime - this will increase your Nusselt number and further improve your efficiency. As others have also pointed out, each mirror segment can be flat as you are trying to focus onto a large area. This is also preferable as a uniform temperature distribution in your collector will also serve to boost your efficiency. I suggest you look into non-imaging optics, and specifically into something called a compound parabolic concentrator or CPC. Another more advanced improvement that can be made is to place the front side of your collector under vacuum, or at least under partial vacuum. This reduces convective losses from your collector. You may also find after having made these improvements that there will exist an ideal operating point where you have the collector operating at a sufficiently-low temperature so as to reduce radiative losses. The blackbody radiative losses from your collector scale as temperature to the 4th power, so while faster water flow will help you get into the turbulent regime it will also lower your operating temperature which serves to reduce radiative losses. This is a cool project with a lot of room for exploration! keep up the good work!
As someone who builds solar cookers I've never seen anyone at that level of engineering (except industrial projects). Very impressive and I also like the design👍Looking forward to part 2
The mirrors away from the center have to continue the parabola, aka, you CAN'T use the same mold for all of the mirrors, the light will be coming at an angle and not go to the focal point, you need 3 different molds for the ones nearest to furthest from the center (also molds will be directional)
Also do note, if you want to focus all light onto a single point the secondary mirror will have to be an ellipsoid one, with one focal point matching the one of the large mirrors, if you want the heat to be more evenly distributed a parabolic mirror will do the trick
Every other cut a new piece is printed or a new graphic designed. It is absolutly incredible how much time you spend on this project and its documentation while making it look like a walk in the park right here.
I think you should create a solar tracker that only requires grid coordinates and a calendar to operate. With those two pieces of information, one should be able to create a platform for solar collectors that is 100% accurate without worrying about it being exposed to the sun.
Wow, I love the way you cover major engineering challenges and even your design mistakes and why they failed and how they possibly could have been avoided. So many good lessons on the process of design and the use of hobbyist tools to achieve complex designs. I am an instant fan. Can't wait for part 2.
Great project! Some thoughts: 1. Probably the best, cheapest mirrors you can find are the aluminium discs in mechanical hard drives, which are regularly used as front-surface mirrors for laser builds. Sure, that means a *LOT* more mounting points, but the better efficiency should make it worthwhile. For mounting, you could cut some discs into washers, which will reduce mounting to a single screw. Also, as aluminium is fairly soft they should be easy to form into a parabolic shape. 2. As the amount of screw adjustment needed for focusing each mirror will be relatively small, slices of PVC pipe would be sturdy enough and provide enough spring while being _dirt_ cheap. Alternatively, as you should only need to worry about tilting towards/away from the center, you could 3d print a mount with built-in compliant joint and just use a screwed wedge to set the angle. That would make printing and assembly *MUCH* faster and easier. 3. Rather than depending solely on light to determine where the sun is, just use one of the many Arduino solar tracking libraries to ballpark the position using lat/long/time/date. It can not only always aim your mirrors directly at the sun, but can automatically reset the array for morning. You'll need an IMU to feed back the array's direction and inclination, as well as an RTC, but those are cheap and easy to incorporate. 4. That vertical mount is... sketchy, at best. I would pivot the array around its center of gravity in the center of the platform, then tilt it using a tight non-elastic cord/belt/chain that is anchored to the top and bottom edges of the array and travels around a gear in the middle if using toothed belt or chain or wrapped around a powered drum in the middle if not. Cheers!
Really interesting project. My thoughts. Gold paint and gold are obviously different but that’s not important as cost is a factor. You could try using aluminium foil or even “speed tape” (aluminium tape). I don’t think using parabolic mirrors is important if the overall shape is parabolic. You’re just trying to focus the light onto the central mirror and then onto the heat collector. The central mirror may need to be parabolic to focus the energy roughly onto the collector. Why not just stick small mirrors onto a TV dish and try that. Much cheaper especially if you get a scrap one. The dish and mounts are also designed to work in high winds but the weight will mean larger motors and you may need to use a counterbalance to help lessen the load on any motors.
I'm guessing the JWST used a gold coating because it is good at reflecting IR, because imagining in the IR spectrum is what the JWST's main mission is.
Ok.. 4 minutes in.. I just want to take a minute to compliment how hard core bad ass this is. I mean wow… just wow. So killer. You’re just skimming past the 3D modeling and printing for the right alignments and all that. Incredible work good sir.
Great Idea! For the Parabolic Curve. . . You could just Keep the Mirrors Flat Since they already Follow a parabolic curve. Otherwise Each Mirror would have to Have the Individual Corresponding Curve for that Segment of the Overall Parabola of the Dish. Without that Exact Arrangement you will loose Light Density, I personally believe Flat Mirrors Arranged along the Parabolic Curve would Give an Overall Higher Density of Reflected Light though not 100 percent.
That's what I was thinking. I'm sure there are quite a few scientific journals on what's best. there's no need to reinvent the wheel with how much effort is being put into it.
Gorgeous overall design. As some others have stated, the primary mirrors do not need to be parabolic. Therefore, you could simply use polished stainless or aluminum. I have seen similar designs, but your hexagonal shapes are even more appealing. Want to try it myself!
Amazing project, choosing foil on Plexiglas with foil as reflectors....well its cost effective. The bigger problem i see is with using Plexiglas as the back cover for the heat collector. Years ago i tryed to build watercooling blocks from Plexiglas and found out it gets very soft around 60C already, making the seals leak because the skews loose pressure cuz they sink into the plexi.
I enjoyed watching this very much. Many other comments have addressed my thought that each of your segments needed to be a different section of the parabolic curve (like on the JWST), but as many have said, this is only necessary to focus a sharp image. Looking forward to seeing video #2
The only thing I would have done differently is just make one huge parabolic instead of segmented ones. I also would like to see how it's going to be used because I'm having trouble understanding how other than just heating water what use is it? granted heating water is pretty useful too.
Easier to replace a single failed mirror from an array, rather than having to replace the whole thing. Also easier to make small mirrors than big ones Also easier to correct for flaws etc with small mirrors than one big one. There are some advantages to a solid mirror. There are some advantages to a mirror array. 🤷♂️
If you point it at a solar panel you can get a lot of power out of it. Most aren't rated for that level of power though so for consumers a heat based generator might be more plausible
I have wanted to try this for a hot tub or something remote. I have an idea… instead of making parabolic mirrors (and the inaccuracy’s/power losses) what about… 1) using flat hexagonal actual mirrors (or cheap transparent glass you coat with aluminium sputtering) 2) moving the heat sink to where the flat mirrors converge. I know it’s heavy and will need metal support AND it’s harder to move to follow the sun, but… the flat mirrors only need to reflect somewhere on to the heat sink it doesn’t need to be perfectly focused. I think you might get much more energy this way? Also obviously the heat sink needs to be black if possible. Lovely project. Thanks!
Paint the heat collector black, as silver reflects...no need for individual curved mirrors, as the current setup uses low reflectivity film. Rather user real flat mirrors and get all reflections from the flat mirrors to overlap on the heat collector. More smaller real mirrors may be the way to go.
Aside from using flat mirrors to make it easier and painting the disk black: The heatdisk should also have some sort of transparent casing as to trap more heat. A large hot metal disk also is good at giving off heat to the surrounding air. And the cover would also protect whatever dark coating you use.
Did you apply the paint at the front of the acrylic panes? It wasn't clear to me, it would be best to apply it at the back like with any mirror. Then the aluminium core plate must be painted matte black of course, you do not want that to act as a mirror too. I expect some issues with boiling, tubes may burst or come off. You may need to control the water flow based on the plate's temperature, making sure it won't exceed 90 degrees Celcius or so. And using astronomical data tables for your date and location seems more effective than trying to figure out where the sun is in real time. This is how all trackers for solar panels work. Overall I am impressed once again.
Yeah, he's going to need a lot of water pumping through that block to keep the sink below boiling temperature, which means needing a constant use for the hot water. Recycling got water will also make it boil. Honeslty, being able to form the plexiglass mirrors at 100C means getting any where close to boiling will cause the seals around the plexiglass backplate to pop. The tempreature and constant water/steam pressure will warp it.
A common mirrors is backed to use the main clear material(glass) as a means to protect the thin coating that produces the mirror finish. Typical acrylic mirrors(makeup mirrors and the like) put the mirrored surface a the front to prevent double images. I ideally the lenses should be coated in metal foil as paint looks like metal but it doesn’t have the same properties. When using a mirrored backing the acrylic will absorb some energy reducing efficiency of the mirror and generating unwanted heat. Given the mirror is acrylic that additional heat would likely deform the shape of the mirror. Putting the mirror on the outside will reflect more of the incoming light and reduce the temperature of the acrylic.
@@MartinMaat I rewrote my response. I reread it and I disliked the tone and content so I changed the direction of my response to promote better discourse. btw, I said “high energy” not in a technical but relative sense. The suns 1000 w/m² load is not insignificant to a design that uses sheet acrylic. Typical use case for an acrylic mirrors is indoors and notably less than 100w/m².
@jacobs8718 I still don't see how direct sunlight is going to heat up an acrylic pane. Do you have a source for that? The stuff is used all over the place as cheap double glazing, mounted on window frames, facing the sun. It does absolutely nothing. We had one such pane at home when I was young to save energy. I just looked it up, it only gets somewhat soft over 85 degrees Celcius. It never significantly goes over room temperature. Granted, with a back coated mirror light passes twice but so what? It is a clear material. Even if it would absorb some frequencies, those would already be absorbed on the way in and thus will not be absorbed again on the way out.
This is a cassegrain antenna design. The formulas are all over the antenna design websites. It is very critical though. and actually you usually want to focus in a single point but for this you should try for a focal point past the plate just where the cone of light would evenly cover the plate.
Great ideas, fabrication, and explanation of your thought process! Having recently completed 13 years in the large-scale solar power industry, here are some comments to digest. For those hoping to home brew concentrated solar generation for home or small business, the many problems to overcome are mulit-year durability, degradation due to falling reflectivity, wind survival, and reduced output due to high temperatures caused by concentrating solar energy. Solving these problems greatly increases cost. The reason less efficient flat solar panels dominate the market is, considering positive and neagative tradeoffs, they're far superior to concentrated solar technologies on a cost vs production basis. Single axis tracking improves production with only a small increase in cost. But 2 axis tracking greatly increases cost, complexity, maintenance, and reduces longevity of the equipment.
Have you ever tried to put window tint/film on a curved surface like that? Tint does fine when curved in one direction, but sucks getting it to lay down flat in two.. without a LOT of heat from a heat gun you'll never get it to lay down flat on a parabolic shape.
Cool video love the fact that you showed your mistakes as well as your successes. Innovation is all about trying something and then trying something better good job thanks for the work of putting this video together
Very good quality of video overall, no junk or filler. As for tilting mechanism, consider redesigning it. Main problem with current iteration is that it is relatively weak. It may hold light frame with reflectors, but then it'll need to be strong enough to withstand the winds. And winds will potentially double or tripple the loads.
@@ConceptCraftedCreations since it's pretty much pure carbon, it shouldn't burn, but should increase the amount of light energy being absorbed into the aluminum. You could also just hold the sun facing side of the aluminum over a campfire until it collects a good coating of soot.
I love the graphic projections on the table, very creative! The 3D printed springs losing some of their strength after just a few hours has got me worried, I don't believe they're going to hold up beyond a few weeks and start shifting the mirrors out of alignment.
Anything I would have done? Not use gold and silver paint for one. When it comes to energy, paint is not the same as the actual materials; it's a case of pigment versus metallic elements. Sure, I get that neither one is cheap, but you can only go so far with just substitutes.
@@ConceptCraftedCreations Seemed accurate enough to me, so kudos on that. Seriously though, real silver mirrors will beat just about any substitute in this kind of situation.
@@ConceptCraftedCreations Gold paint, isnt the same color, nor reflectivity, of high purity Gold. For that test, you should use Gold-Leaf. Gold Leaf, is real gold.. just incredibly thin... making it semi-affordable, for coating things like Picture Frames.
I have to say, it looks amazing :) I'm curious how effective it would be, but it seems like a great project and would want one for myself, so I think I'm going to steal your design when you're done :D Also, being a neighbor from the south, I feel your pain trying to test solar panels in the rain. much love from Belgium! you have my subscription
For the sun tracking I'd seriously consider an equatorial aligned single axis drive, just like a German Equatorial telescope mount, it will allow for counter weight balancing to lessen strain on motors. There's a market for second hand mounts with some sophisticated tracking software more than capable of following the sun even over multiple days. You don't need your primary reflector segments to be curved either, they can be flat as you are not trying to cast the image of the sun on a focal plane, you just need the maximum of light from each reflector to reach a common surface area which will be your collector. If you could position your collector in front of the reflectors instead of needing a secondary reflector to send the light back down again then you avoid losing energy to a second reflector which will itself also be getting quite hot as it is nor reflecting 100% of the light/heat.
I thoroughly enjoyed watching this project, and I look forward to seeing more of it. Your mount appears more complicated than necessary. An equatorial mount similar to that used by many telescopes seems more practical. If you tilt the rotation axis so that axis points to Polaris you can rotate the mirror structure to track the sun, while north-south adjustment can remain constant (nearly) through the day.
I really enjoy your videos and creative projects. My mind is still obsessed with the tree wind generator. I see a potential problem with your heat collector plate. Let's assume you solve all the other issues and create the perfect solar energy collector/concentrator. In that situation you will have a very hot plate with water trapped into a VERY small diameter channel. That water will turn to steam very quickly and you won't be able pump water in fast enough (or with enough pressure) to stop the steam forming process. Once it starts you will not be able to stop it without removing the heat. I have seen the same thing happen when people attempt to heat water using 1/4 or 1/2 inch copper tubing with rocket stoves. After it gets warmed up to a specific point the steam creates back pressure and water doesn't flow through the system anymore. To solve this on the rocket stoves they use 3/4 inch (or larger) copper tubing. Then they can collect more heat with a slower flow of water. I would suggest you consider creating a new heat collector with a wider (or deeper) water channel so you can get a larger volume of water in contact with the heat. This will enable you to use slower moving water at lower pressures. Keep up the great work.
Consider adding an axle perpendicular to the back of the mirror, with an adjustable weight for counterbalance to take the strain off the motors and positioning mechanism. Also consider wind loading. The big wind that hits while you're away and can't reposition it into safe mode position.
awesome project. it's on my list for years now. 1. what if you molded the acrylic first and then put the silver foil on it? and did you check other foils, such as a rescue "blanket" or using real silver like they do for DIY telescope lenses? 2. the liquid for heating, I would have used oil as it goes easily to 300C without damaging or boiling. 3. what about a heat storage? a highly insulated barrel that stores all the energy and used when needed? 4. the solar tracking sensor: great! how did you solve that at the end of the day it goes back to the morning position? (otherwise it's impossible to find the sun when in evening position) 5. the aluminum disk you can easily ANODIZE in black. at home. that should last forever.
On your motor controller, add standard tracking/motion for the solar calendar (xyz angle and speed) and only allow a certain % deviation from photorestors so random clouds and over cast days it still tracks as it should. that way photoresistors are never totally out of scope and can correct the last few degrees and won't go crazy scanning everywhere for the sun if it loses track due to environmental reasons and or freezes because everywhere is the same brightness. The pan/tilt should be almost 100% predictable on a calendar basis but id imagine there is some deviation based on location and local weather witch could be problematic (especially being so far in the far north). And if your looking to go real fine grain, testing photoresistors to to find common resistance for a given light emittance. then adding small resistance so it doesn't have a bias to one quadrant would help with accuracy and balance (apologize in advance if wording is out of place or slurred, having a few beers finishing another mechatronics problem for the night and love projects like this...thank god for spellllll check) love what your doing and want to do some similar stuff here in warm Florida. my comments are not supposed to be "HEY THIS IS WHAT YOUR DOING WRONG " but what id love to add if and or when i do the same thing i appreciate showing your pitfalls in MFG because id do all of those to otherwise :)
I would put the collector at the 1st focus and make it a sphere with a hole in the side to let the light in and stop any reflections from leaving. Imagine machining channels into a hollow sphere with a hole in the side, then coat the inside with candle soot. This way, you won't have to worry about machining a secondary mirror. The parabolic segments reflect just once through the hole in the sphere and everything is captured. I made a solar tracker using an Arduino, GPS module and two servos, (later two steppers) and some code to translate time of day and lat/long location into elevation and azimuth in degrees. Works even when overcast. Add an anemometer then set to elevation to 90° if wind exceeds a limit. Use a linear actuator for elevation - this can take a lot of load. Raise the dish and add a counterweight to reduce static torque. Servos are a pain - they want to slew suddenly to another position at power-on, and that can break things if they don't have a clutch mechanism!
I'd make the aluminum plate black to reflect less light. I personally would make more parts out of metal, but what you are doing seems right for the prototype stages. I'd replace the acrylic on back of the aluminum plate with something more heat resistant. I've see smaller mirrors melt metal and stone in short order. I would think that amount of heat might outrun that pump. Maybe add a temperature monitor to the system and program the tracker to take a break if needed in the current config. Paint can be polished to a real good surface finish giving it more reflectivity. I'm not sure how well 2k or epoxy paint works on acrylic, but that would be a more durable paint. Cool project.
The center should be as dark/non-reflective as possible if you want to absorb the most amount of heat. Consider either: a black anodized coating; a cast iron attachment; or really scuffing the surface (easiest but least effective option).
It might be worth looking into Tollens Reagent for making your mirrors. Just be careful when working with the chemicals. And while that tilt mechanism works inside, this thing is made to be outside in the elements, the big one here being wind. Before using that as your final design, stress test it with increasing amounts of weight until failure or your confident it can survive wind gusts. You could also go with something a little more like what you used for the base but on a cam at the top of a support beam. Plus as others have said, making that heat plate dark or black to absorb more heat is a must, as keeping it silver will reflect a ton of energy that your looking to save. Overall I love the project though, its an very interesting concept for collecting solar power.
Really interesting project. Back in BEAM robotics days, we would build sun trackers with LDRs that way. The solar panel powers the circuit, so you build the circuit to move motors so that the panel is always pointed at the brightest light source. I always imagined using one to control a large dish like this, so it's super cool to see! You're using plexiglass for the mirrors, which allows visible, IR, and I'm pretty sure most UV to pass through, right? What about pressing the plexi first, and silvering the back instead? That would give a much smoother finish, but who knows... people do this with aluminum foil, so maybe that much precision isn't worth the effort.
So much great feedback in these comments, so excited for the next part! Hopefully they’ll work great, but maybe check how well the 3d printed springs maintain their elasticity after being under compression and also at heat? They might just deform being in the sun all day.
id reccomend applying the reflective film after shaping if possible, a heat gun may help with this like applying a wrap to a car maybe? i would also recomend making the centre plate black so that absorbs the light energy rather than reflectibg it away, if you could give it a black anodising that could work great. Good luck!
Some suggestions for improvement: Shape the mirrors before applying the reflective film, that way the heat doesn't affect them. This does have the downside that you'd need to use a rubber or other flexible squidger in order to apply the film individually parabolic hexes don't add up to a parabolic array, you should have forms to shape them to make the full array of mirrors parabolic. Based on your design, you would probably only need three forms: one for the inner 6, one for the 6 outer corners, and one for the 6 outer middle hexes. If it isn't clear, it's similar to making a giant poster by printing it out on multiple sheets of standard printer paper and then taping them together
This is the concept I needed for my design and I know the algorithm brought me here for a reason lol. We are working on different light spectrum's though lol. I need less heat and a more solar panel friendly spectrum. The telescope concentrates the light and sends it indoors over photonic or fibre optic lines and spreads the light out to a server rack full of stack-able solar panels, mirrors, and diffusers. Not built yet but I would like to see just how far a system like that could be pushed. We should share notes lol.
1. You can apply film with heat gun and soapy water. Just like car window film applications. 2. You do not need parabolic fancy mirror for heat collection. Especially if your heat receptor is as big as individual mirrors. You can even use flat mirror. 3. Paint your heat receptor black.
-I'd redesign this to have the collector plate be smaller and mounted at the focal point of the parabola and not try to reflect it back to the center as you are introducing unnecessary inefficiency with the extra reflection. -like many other people have pointed out, the collector plate should be black as you want to trap as much heat as possible, not reflect it away -I think it would have made more sense to 3d-print the segments of the dish then electro-plate them as that would reflect a lot better than any paint would and it would mean you could print each segment with the correct curve instead of trying to bend it afterwards and having to create molds which would be inaccurate as you would need to create a different molds to have the correct curvature in each segment. The segments could also be designed to interlock with each other to reduce their size(to allow to fit in your 3d-printer) and reduce the mounting points. Either that or bend the plastic before applying the reflective film -the angles of the mounts for the dish segments didn't really need to be adjustable. The shape of the parabola isn't variable. It should have been designed in CAD first then each mount printed at the correct angle. It would have saved you complexity and weight and cost. You could have even designed a spine right into the segments of the parabola and avoided mounts altogether. s of the parabola and avoided mounts altogether. Domes are fairly sturdy structures on their own so a spine might not even be necessary. -since this device is meant to be used outdoor and presumably in the elements, considerations need to be made for wind and rain. The joints need to be sturdy enough to take a strong gust given the surface area and shape and the device needs to have proper drainage
I don't know what CAD software you are using. In Solid Edge, if you use the material properties correctly, the software can identify the center of gravity (CoG) of both a part and an assembly. If you place the CoG of the upper mirror assembly directly above the central point of your turntable and are able to figure out a method for pivoting the mirror assembly up and down on an axis which passes through this CoG, there will be no moment arm to contend with. The motors required for motion will only be fighting friction and inertia. They won't be battling many newton meters of torque.
Tip. Have a look at a polar aligned equatorial wedge. You will find tracking easier as all the tracking for the day can be done with one motor running at 1/24 revolution per hour.(the earth is rotating not the sun moving) Why is the disk in the middle silver it will reflect heat & light, it should be the darkest matt black you could find.
If you paint the aluminium heat sink with an ultra black paint like vanta black, or even just regular black itll absorb more of the light as heat, the water you pump through the sink could be salt water as well since salt water is more conductive and reaches boiling point easier. Those are my suggestions, great video!
For the stability of the array, perhaps a light compression shock absorber on the top side of the array to assist and stabalize the threaded rod erector.
You should get a light gray projection sheet or paper to put down on your table when you're using your projector like this, it'll increase contrast and color, as well as reducing reflectivity from the surface as it stands.
Great project man. One improvement I would make would be to simplify the tracking system. If you use an equatorial mount then you only need to move the whole assembly in azimuth (on the lazy susan axis) at 15 degrees per hour- a lot easier :)
First of all I would like to commend the meticulous work you have done. It's just fantastic problem solving ! I have few observations 1) the spherical mirrors should have been ok too because you are aiming for heating and non imaging application. The only requirement was that reflected sun rays must fall on aluminium collector and not miss it. 2) you need to apply some black absorbing material on aluminium having water pipes, which I guess you would be doing. 3) As I understand the acrylic mirrors have to direct and focus on some mirror which will reflect back that light to aluminum collector having water channel. Designing that will be more challenging as it is duplicate of your acrylic mirror design but with constraint of smaller dimension and more temperature capacity. 3) finally you need to keep appropriate flow rate in water channel to avoid steam formation. Goodluck to you However you must calculate the photo to thermal efficiency of your system and the benefit associated with it.
When you move your parabolic mirror away from the center axis and tilt them the focus point shifts and all of your mirrors won't be fully effective ... The whole assembly needs to be in a parabolic shape.
A few observational guesses... Once you put a black finish on your heat plate to make it more absorbent, I believe you will run into two other problems. 1, the plexiglass backing that you have screwed to the back will become very soft from the heat and allow the screw heads to sink in and lose all their clamping force which will cause the water to leak out. You need a second plate as a mirror image of the first to create the water channels without warping from the heat. it STILL may warp too much though, so some sort of high temp gasket material will be needed. 2, the supporting 3d printed structure to the heat plate will also be in danger of heating up beyond it's ability to remain solid. You should very easily surpass the melting point of any 3d printable filament, and that would cause some issues too. Maybe I'm missing totally on these things, but I don't think so. good luck and I'll be watching for sure! cool project!
Really like the presentation with the beamer onto the desk! :-) I would probably consider adding a counter-weigh of sort to the mirror if you want it to be more stable. But then you'd have to redesign the base section as that is not fit for an opening in the middle.
very interesting! use one of the car wrap foils. They stretch and you can apply them after bending the plexiglass. And they are highly reflective! Cant wait for your followup video!
What an awesome project! Very impressive. I think you're right to be concerned about the veritcal adjustment mechanism though. I'm sure it works great inside but I would assume that any amount of breeze outside would cause a failure, the mirrors will act like a huge sail. That same motor might work but I think if the reflector frame was mounted to a trunion, not unlike a bandsaws table, it would be a lot more stable and robust.
I would definitely pivot the reflector assembly around it's centre of gravity, rather than at the bottom. Make three A-frames - two with bearings supporting the weight of the assembly and the third off to the side for the motor to tilt the array.
Use soda lime glass for superior surface roughness and coat electrolessly which is used for creating mirrors. Soda lime will soften at lower temps arong 570 C
Around 30 years ago, I was involved in a project doing low-budget energy solutions in Belize, using recycled materials. One project was a solar collector, much like the one here. An old satellite dish was used with hundreds of small square mirrors, cut from common bathroom mirrors. The focal point, however, was not reflected but suspended from the edges of the parabolic dish. The result was so successful that it proved to be downright dangerous in the hands of the inexperienced users it was intended for.
Really cool project, I'd use mylar blankets though. You can shape that to acrylic or even ASA structure basically using vacuum wrapping. It's far more reflective and reflects heat better
a suggestion for building the mirrors: 1) 3d print a parabolic plate in plastic 2.a) spray it with a reflective paint 2.b) or tape aluminium length wise to cover the parabolic plate 3) cover it in epoxy resin to make it more durable a suggestion for the design: -instead of moving a huge and heavy mirror, focus smaller sized mirrors. (for example if the motor is reliable for 50 kg, instead of using a 75 kg mirror, use 4 smaller 40 kg mirrors) good luck and I hope this was useful
Some suggestions: Rather than try and bend the mirrors into shape, you could try Mylar and a vacuum to form a perfect parabola and focal point - no screws or heavy mirrors required. You could also make the mirrors a LOT larger. Mylar only reflects about 90% of light but making them larger (maybe to to the same weight) you''ll get a lot more overall energy. I presume the secondary mirror you mentioned (not shown) will be at the focal point and it's to reflect the light back to the heat exchanger. But that secondary mirror will need to handle about 7kw of energy - the same amount as the heat exchanger - it's going to get very hot, very quickly. A single reflector (array of articulated mirrors) will be easier to build and won't melt. So if you created an array of vacuum drum mylar mirrors each with 2 axis articulation and an adjustable vacuum - with some programming to relocate the focal point you will have a death ray.
I think for the mirrors they could be bent as the plexiglass glass and then spray painted to avoid the cracking in the first place. Also microwaving silver paint could lead to a ☠️ or 💥
Apply the reflective film after shaping the plastic....
Hard to apply flat sheet cleanly to a curved surface without creasing
@@taureviews if it's reflective tint, use a heat gun and soapy water, I promise it works.
Dido
@@taureviews People do it every day wrapping cars.
Its not you are wrong @taureviews
Gold paint ≠ gold reflectivity
Silver paint ≠ silver reflectivity
At least outside of the visible spectrum. Paint just looks the part -it's optical properties are totally different to precious metals and also different to whatever coating is on your plastic mirrors.
Yep. In general, even with the reflective film, that will usually still have plastic surrounding the colored pigments or film layer.
Either stuff is suface-coated with a metal film or not. So electroplating, true chrome either without a coat or with an IR transparent coating and sputtering are probably the most common ways to get this done.
But it doesn't really make sense to use semi-gloss chrome paints or these films where the properties are unknown for these comparisons :/
I was thinking the same thing.
This was really strange to watch.
Golds chemical properties allow it to be polished to such a fine degree, that it can refract the wavelength of infrared light. The color itself doesn't matter.
@@hondacivc93 Why talk about things you know nothing about?
1. It is not polished, it is deposited on a previously polished surface. The same way any other first surface mirror with silver is made.
2. Pretty much anything can be polished, as that is only a measure of surface roughness. There is nothing inherently preventing a perfectly flat surface.
3. Flatness has nothing to do with how good this flat surface reflects a specific wavelength. That is inherently a property of the material. You can polish coal as much as you want, it will always be black. Gold is always gold colored, no matter how rough you make the surface.
4. The color is said inherent material property and is all that matters for what is reflected. The flat surface just makes sure that the reflection ends up where you want it to, instead of going somewhere else. That is all the flatness is needed for.
Since you're trying to catch the light on the big plate, the parabolic shape on your primary mirrors is unnecessary. Each petal or mirror segment can be flat and the secondary mirror can be flat; the parabolic effect will come from how each segment is focused on the secondary. Rather than throw a tiny hot spot onto the receiver, let it be bigger and heat the whole thing more-or-less evenly. Lower deltas are less lossy.
Also: you really want a dark receiver. Shiny silver will reflect a lot of the incident energy, shiny black will absorb it without re-radiating it so readily. Your ideal surface should be black chrome.
If he wants to achieve a real focus, each mirror should be a section of a paraboloid. Mirrors at the same radius can have the same shape, but the mirrors should be different shapes at different radius values.
I did something like this with a 1.2m satellite dish and aluminium foil, and then a mylar sheet over the dish and partially evacuated the volume behind - it was scary efficient!
I used candle soot to coat the bottom of a pan to absorb the energy.
At night, I could point it to a clear sky and use it to freeze things!
Yeah! The aluminum plate needs to be as black as possible. And not gloss black. Matte black
Agreed. Given that each mirror is similar (or smaller) than the collector-plate, there's no need to concentrate the sunlight, simply reflecting it with a pile of small individually flat mirrors will be sufficient. So he spent a LOT of time and effort doing something of no practical value here.
If you want to concentrate the light back to the back you need a Ritchey Chretien formula so hyperboloid mirrors on the primary mirror and a correspondant hyperboloid secondary mirror. But it's complicated and overkill.
I would have use paraboloid mirrors on the primary but would have place the heat plate on the focal point instead of a secondary mirror. It makes the formula way easier to colimate and you get rid of difficult to build optics.
As others mention, darkening the hot plate ensure light coming from the primary mirror isn't reflected so lost.
The heated aluminium disc should be dark, black (but not catch fire) to use enough of the light that is focused on it (as it's well known, the darker the object, the better it heats up).
And, I'm sure you've considered this, but just in case: of course each segment must be the shape of the corresponding part of a parabola, not of the parabola's centre.
If the focus point will be few centimetres above aluminium disk, trap for light could be made: second disk with small hole that will be few centimetres above main disk and aluminium wall between two disks. that way almost all light will get through the hole in the first disk and then rereflect many times inside our trap, heating everything up. This also will stop wind from cooling main disk. And of course all walls inside trap should be black - main disk heat resistant paint and other walls of the trap could be painted with black 3.0 to really boost performance.
@@MrMpakobec Поддерживаю
Not necessarily, if all parabolic mirrors (and their respective focal points) are equidistant to the secondary mirror/heater plate. It's way cheaper and faster to have one mold for all mirrors.
3d Printing 6 different forms (as it's rotationally symmetrical, you should be able to reuse them) probbably isn't too much overhead, but I'm not certain it's worth it. In case of remoulding, a vacuum attatched to the negative mold might pull the plates into shape without damaging the mirrors finish by compressing them from the top.
A more expensive option might be to get copper-clad plexiglass for the panels, form them and then electroplate them silver. The upside is you should be able to get a very eaven coat by placing the opposite electrode at the focal point of the mirror, so it's fairly equidistant from all points (minus the spherical/parabolic deviation) That would hopefully remove some of the waviness you have in your formed sections from the adhesive releasing and/or the film buckling.
Also needless to say, make sure if you paint the plate black, you use temeperature-resistant paint like the stuff the make to paint mufflers or barbecues. Probably need some sort of primer with it as well, although the more different layers you have the worse the thermal conductivity could possibly be.
One glaring thing that may be a problem... the heat collector is currently reflective. Spray it matt black with heat resistant (stove paint) paint as it will absorb heat much better than the shiny surface.
Good one!👌
@@ConceptCraftedCreations dimple the surface like a golf ball before you paint it for more surface area.
@@ConceptCraftedCreationsThe fact you're using aluminum gives you an option for making it black:
There was research done stating that a simple candle's soot actually forms carbon nanotubes onto the aluminium surface.
Simply put, just soot the aluminium disc with a candle and gently have something transparent to protect it from the elements.
Used this for my solar space heater, works well, however haven't tested if simply painting it black has any difference. But theoretically the nanotubes would be perfect light capturers.
@@ConceptCraftedCreations it might be hard to find paint that can resist such high temps, but i hope you do. In either case sand down the surface with a medium grit to make sure there is no reflectiveness, either on the black paint or the bare aluminum.
@@IvanSpaceBiker that would do absolutely nothing.
Color isn't really a good indicator for reflectance of infrared light. Actual gold like the stuff used on the telescope would reflect much more light, because the spray paint uses stuff that looks like gold, but isn't, it probably reflects much less light.
Lasers (IR CO2) use gold mirrors, they work well enough up to about 50W. The coating is rather fragile. They're reasonably cheap but small, only 20mm.
Telescope dudes will sputter silver onto glass (say 300mm) easily enough, could probably point you towards someone who could do gold. These would have the coating on the front.
@@j.f.christ8421the silver would be oxidized very fast in the heat. In this case aluminum is probably best
@@ralanham76 Yeah, good point. Aluminium might even be better, it performs only slightly worse in visible (5-10%) but reflects more IR than silver.
EU TENTARIA ESPELHO FLEXIVEL A SER COLADO NO FINAL COM TODOS EM SUAS POSIÇÕES;DISCO DEVERIA SER NO PONTO FOCAL E NÃO NO CENTRO DO REFLETOR.
It would be polite to begin your comment with "Great vid" or "Cool project"
But I know politeness is not a thing in some cultures
Building all of this just to be hit with the reality that you live in the Netherlands is very relatable. It's like when me and me dad installed solar panel lights on our house and forgot we get an absurd amount of clouds, so we originally thought we bought defective lights XD
Send me a version for testing in SEA. I already have a neighbor with a similar set up who sells solar roasted chicken on the highway. I will send back a cut of the profits for further R&D.
Do you remember if they were the blue crystalline looking ones or the black ones with stripes? The blue ones have like 4 times the Amp output in relation to surface area but only in direct sunlight. The black ones will output under 4 inches of snow and clouds.
You need an optimisation for diffuse Licht ut would help
i think it was 2004 the CSIRO in Australia built a large molten/solid salt solar reflector system that reached higher turbine steam temperature than has ever been achieved in a fossil fuel turbine. California put up a system around the same time but little has been done with it considering its potential to generate power for hrs after the sun is off reflectors thanks to molten salts high thermal capacity
as for panel systems there's a NUMBER of factors that influence the sun levels needed for power the more line impedance/material to length to diameter to amps the less efficient the cable panel interface and panel cell interface the more resistance in inverter and battery's the less of the 22-24% (average panels ppl use these days efficiency) we manage to capture actually makes it to the destination
reflector systems actualy do away with a lot of resistance because your heating a central rod that then boils and turns a steam turbine like a regular coal or gas plant and even in low light u just need a larger mirror footprint and u can get same heat
but on a regular PV you can be getting double or triple the power depending on those factors from a system that is technically the same if your just looking at panels rated output tested at a cell level
yep this is why my new design for a multiple power source green power system will provide for 24/7 365 power production with a scalable design that can be produced for both commercial General grid distribution to a private at point of use (no grid tie in needed, thus reducing demands on a frail public utility system) Also providing a system deigned for very remote points of use. This system's use of several proven green power technologies provides a level of reliability in proper power production that few if any other green power systems can provide ( excluding systems that are anything but naturally occurring that use exotic elements & or fuel sources. { I.E. atomic, oil gas, coal } All of which can cause very harmful byproducts & waist. NONE OF WHICH ARE TRULY NEEDED to obtain large volumes of energy. ) I have the design but do not work for free.
JWST needs parabolic mirrors to create an image, you do not have the same requirement: you just need all the light from a mirror to reflect on the collector. A plane mirror illuminated by the sun creates a reflection of the same size at most, so the only requirement is to have a collector of the same size of the mirror.
This is a good point, I think a solid compromise that would be especially effective here, is set a reasonable focal goal for the curvatures, small enough to splash the majority of the target for good transfer.
Partially true, but one thing to consider is that the efficiency of a solar heat collector is proportional to the temperature difference you can achieve, and you can get a larger temperature difference for the same size collector by concentrating the light using parabolic mirrors.
Yes, focusing to a point is unnecessary unless you want to melt things - key is to collect energy as heat more efficiently, not concentrate it more than is necessary.
The same energy can make a high temperature over a small area, or lower temperature over a larger area, and the latter may be more efficient by maximising heat transfer time to heat the fluid medium by the desired amount. There are a lot of things to consider.
Coating the collector with soot from a candle will also increase absorption.
I agree, I think for a V1 flat mirrors are fine. Parabolic mirrors should be an improvement as an upgrade for more efficiency.
@ No, flat mirrors only fine if the collector is where all the reflections impinge on it on the end of the boom.
There is no shape that can then reflect them all to the collector in the centre of the dish as they would all miss except one.
In this case they would need to be partially focused to land on a parabolic convex reflector to then land on the collector in the dish, with a suitable radius to provide a temperature enough to heat the water to the desired temperature.
slewing bearing ok, but springs expensive?
xD
(I'm not American) My salary is less than $100 a month, however I recently allowed myself a set of 200 springs for $5 for the sake of 4 springs :)
But the springs can really be replaced with alternatives, and the bearing is specific and very important, I guess it's just the man was choosing what to spend money on and what is not worth it
@@broniusale5987 Yeah, I don't understand what that was about either. Just looked at temu, searched for springs: springs galore for 10 to 20 ct a piece.
@@MartinMaat don't promote cancer temu. it's a bloatware to the economics and healthy market.
You can probably buy springs by weight, 200g should be enough
Awesome 👍 I'm doing an experiment with lunar simulant, sintering sublmation, and deposition. One of the ideas is to use a solar furnace on the moon exploiting the vacuum environment to create eutectic alloys. Excellent video 👍
What is the energy loss of having a 2 mirror system vs having the alumnium plate take the direct reflection of the first mirrors?
More complicated piping I assume
@@p529. same piping. just put the plate into the focus point and its done.
@@jpjay1584 I'm assuming it's more about the weight of the heat plate versus a mirror than anything else.
Yeah, the ‘heat plate’ really should be at the focal point of the mirror array, instead of a double mirror.
The weight of the heating plate might be the main reason for the design choices here.
Instead of allowing the water to flow through the collection plate under acrylic, I would of put copper tubing and soldered it into place to make better contact. Better contact allows for more efficient transfer of thermal energy. Also, the water will get very hot and start to build up pressure which can cause the acrylic to start to flex under the pressure, plus the heat making it softer.
On my single solar thermal collector I had on a 2ftx4ft panel, the water would start boiling before exiting the system, which led to a lot of a air locking keeping the water from flowing smoothly. The system *had* to run under pressure to keep the water from boiling so easily.
Yeah, that acrylic backplate is just begging for leaks. The mirror tests already show it can significantly flex at 100C, and there's going to be a lot of water/steam pressure in there.
I suggested in another comment that a car radiator would be a better collector.
I'm also wondering if freezing will be a problem. Overnight there is gonna be a bit chilly
Maybe consider painting the collector plate black?
Yeah, I thought there was no way you could finish the whole project in only a 13 and a half minute video. Well, you are almost done. Can't wait for part two!
Glad you enjoyed it! Part 2 coming soon🤓
Very good project.
1. Place the heat receiver on the rods, and not reflect the light twice, which only leads to double losses due to light reflection.
2. Paint it black or smoke it with soot. 3. It is possible to apply a reflective coating after forming the bend of the mirror, in order to avoid cracks when heated.
4. Add a protective layer on top of the reflective one, since it is difficult to maintain the integrity of the coating in the sun, wind and rain. Plus, the second layer can be polished with a car polishing machine.
5. Replace tracking by lighting level with a simple table of the sun's location by time of day (but then you need to add potentiometers or decoders to the rotary axes).
6. If you want to leave the installation outside for a long time, you need to add a protective function to avoid strong winds, add a wind sensor or simply take information from the local weather forecast (mirrors are just a big sail)
I agree with all but #5
Won’t that table shift by time of year, requiring either manual adjustment or additional complexity?
I personally think this method of tracking is super elegant and quite simple overall.
Engineer here with a few suggestions -
Your aluminum plate should have been copper for a couple of reasons - first, aluminum is reflective in the visible spectrum. A copper plate can be treated with a liquid known as "liver of sulfur" which creates a strongly-absorbing black surface, dramatically increasing the amount of energy that can actually be absorbed. Second, copper has a thermal conductivity roughly twice that of aluminum, meaning your total thermal resistance is lower. The net effect is that significantly more heat can flow from the absorbing surface into the water.
Another consideration - choose the flow of the water carefully so that you are in the turbulent regime - this will increase your Nusselt number and further improve your efficiency.
As others have also pointed out, each mirror segment can be flat as you are trying to focus onto a large area. This is also preferable as a uniform temperature distribution in your collector will also serve to boost your efficiency. I suggest you look into non-imaging optics, and specifically into something called a compound parabolic concentrator or CPC.
Another more advanced improvement that can be made is to place the front side of your collector under vacuum, or at least under partial vacuum. This reduces convective losses from your collector.
You may also find after having made these improvements that there will exist an ideal operating point where you have the collector operating at a sufficiently-low temperature so as to reduce radiative losses. The blackbody radiative losses from your collector scale as temperature to the 4th power, so while faster water flow will help you get into the turbulent regime it will also lower your operating temperature which serves to reduce radiative losses.
This is a cool project with a lot of room for exploration! keep up the good work!
As someone who builds solar cookers I've never seen anyone at that level of engineering (except industrial projects). Very impressive and I also like the design👍Looking forward to part 2
Nah, he overcomplicates it. Keep it simple, that's the recipe of a good solar cooker :D
@@Sekir80 I agree, but it's always nice to see a different approach.
The mirrors away from the center have to continue the parabola, aka, you CAN'T use the same mold for all of the mirrors, the light will be coming at an angle and not go to the focal point, you need 3 different molds for the ones nearest to furthest from the center (also molds will be directional)
Also do note, if you want to focus all light onto a single point the secondary mirror will have to be an ellipsoid one, with one focal point matching the one of the large mirrors, if you want the heat to be more evenly distributed a parabolic mirror will do the trick
If the mirror puts a large strain on the tilt motor, could you add a counterweight to balance it?
Theoretically that would be possible yeah!👌
great comment! all gimbals are balanced.
Every other cut a new piece is printed or a new graphic designed. It is absolutly incredible how much time you spend on this project and its documentation while making it look like a walk in the park right here.
I think you should create a solar tracker that only requires grid coordinates and a calendar to operate. With those two pieces of information, one should be able to create a platform for solar collectors that is 100% accurate without worrying about it being exposed to the sun.
for me it would be more of a hassle because you would have to code for it. his solution is pretty straight forward easy
Wow, I love the way you cover major engineering challenges and even your design mistakes and why they failed and how they possibly could have been avoided. So many good lessons on the process of design and the use of hobbyist tools to achieve complex designs. I am an instant fan. Can't wait for part 2.
Great project! Some thoughts:
1. Probably the best, cheapest mirrors you can find are the aluminium discs in mechanical hard drives, which are regularly used as front-surface mirrors for laser builds. Sure, that means a *LOT* more mounting points, but the better efficiency should make it worthwhile. For mounting, you could cut some discs into washers, which will reduce mounting to a single screw. Also, as aluminium is fairly soft they should be easy to form into a parabolic shape.
2. As the amount of screw adjustment needed for focusing each mirror will be relatively small, slices of PVC pipe would be sturdy enough and provide enough spring while being _dirt_ cheap. Alternatively, as you should only need to worry about tilting towards/away from the center, you could 3d print a mount with built-in compliant joint and just use a screwed wedge to set the angle. That would make printing and assembly *MUCH* faster and easier.
3. Rather than depending solely on light to determine where the sun is, just use one of the many Arduino solar tracking libraries to ballpark the position using lat/long/time/date. It can not only always aim your mirrors directly at the sun, but can automatically reset the array for morning. You'll need an IMU to feed back the array's direction and inclination, as well as an RTC, but those are cheap and easy to incorporate.
4. That vertical mount is... sketchy, at best. I would pivot the array around its center of gravity in the center of the platform, then tilt it using a tight non-elastic cord/belt/chain that is anchored to the top and bottom edges of the array and travels around a gear in the middle if using toothed belt or chain or wrapped around a powered drum in the middle if not.
Cheers!
Brilliant design! I also love the use of a video projector pointed at the desk to add that [chef's kiss] to the presentation. Great work!
I like the mirror segmented, easy to replace if any damaged, allowed fine tuning, and cheap compared to a giant curved mirror. Nicely done
Really interesting project. My thoughts. Gold paint and gold are obviously different but that’s not important as cost is a factor. You could try using aluminium foil or even “speed tape” (aluminium tape). I don’t think using parabolic mirrors is important if the overall shape is parabolic. You’re just trying to focus the light onto the central mirror and then onto the heat collector. The central mirror may need to be parabolic to focus the energy roughly onto the collector.
Why not just stick small mirrors onto a TV dish and try that. Much cheaper especially if you get a scrap one. The dish and mounts are also designed to work in high winds but the weight will mean larger motors and you may need to use a counterbalance to help lessen the load on any motors.
I'm guessing the JWST used a gold coating because it is good at reflecting IR, because imagining in the IR spectrum is what the JWST's main mission is.
test the springs at different temps, cause they might lose their strength when hot from the mirrors
Actually the back of the mirrors will be cool as their purposes is to reflect
Ok.. 4 minutes in.. I just want to take a minute to compliment how hard core bad ass this is. I mean wow… just wow. So killer. You’re just skimming past the 3D modeling and printing for the right alignments and all that. Incredible work good sir.
there is spray paint that makes a mirror, better than the film.
Rust-Oleum Mirror Effect Finish Spray
I boggled by how you have the time and energy to do this, even more so by how you take the time to make such a great video about it! Well done, sir!
Great Idea! For the Parabolic Curve. . . You could just Keep the Mirrors Flat Since they already Follow a parabolic curve. Otherwise Each Mirror would have to Have the Individual Corresponding Curve for that Segment of the Overall Parabola of the Dish. Without that Exact Arrangement you will loose Light Density, I personally believe Flat Mirrors Arranged along the Parabolic Curve would Give an Overall Higher Density of Reflected Light though not 100 percent.
That's what I was thinking. I'm sure there are quite a few scientific journals on what's best. there's no need to reinvent the wheel with how much effort is being put into it.
the focus points would be too big but yes its easier to do.
wow, this is an amazing project and your demonstrations were superb. I can tell that you put a lot of effort into this video
6:58 missed opportunity to give a gold medal to silver and a silver medal to gold.
Gorgeous overall design. As some others have stated, the primary mirrors do not need to be parabolic. Therefore, you could simply use polished stainless or aluminum. I have seen similar designs, but your hexagonal shapes are even more appealing. Want to try it myself!
9:58 so many simple mistakes made. Why not apply the film after shaping the panels?
Thank you!!!!!!
This project is really interesting. The tracking system, using four LDR's, was excellent.
Amazing project, choosing foil on Plexiglas with foil as reflectors....well its cost effective.
The bigger problem i see is with using Plexiglas as the back cover for the heat collector.
Years ago i tryed to build watercooling blocks from Plexiglas and found out it gets very soft around 60C already, making the seals leak because the skews loose pressure cuz they sink into the plexi.
I enjoyed watching this very much. Many other comments have addressed my thought that each of your segments needed to be a different section of the parabolic curve (like on the JWST), but as many have said, this is only necessary to focus a sharp image. Looking forward to seeing video #2
The only thing I would have done differently is just make one huge parabolic instead of segmented ones. I also would like to see how it's going to be used because I'm having trouble understanding how other than just heating water what use is it? granted heating water is pretty useful too.
Humanities scientific advancement is pretty much measured by how complicated a way we can devise to boil water.
home made solar water heater powered by a fresnel lense
ua-cam.com/video/rrGMidc_P7s/v-deo.html
One huge mirror is more difficult to make. That's why the Webb uses that hexagons. Of course, individual mirror segments have their own issues....
Easier to replace a single failed mirror from an array, rather than having to replace the whole thing.
Also easier to make small mirrors than big ones
Also easier to correct for flaws etc with small mirrors than one big one.
There are some advantages to a solid mirror. There are some advantages to a mirror array. 🤷♂️
If you point it at a solar panel you can get a lot of power out of it. Most aren't rated for that level of power though so for consumers a heat based generator might be more plausible
I have wanted to try this for a hot tub or something remote. I have an idea… instead of making parabolic mirrors (and the inaccuracy’s/power losses) what about… 1) using flat hexagonal actual mirrors (or cheap transparent glass you coat with aluminium sputtering) 2) moving the heat sink to where the flat mirrors converge.
I know it’s heavy and will need metal support AND it’s harder to move to follow the sun, but… the flat mirrors only need to reflect somewhere on to the heat sink it doesn’t need to be perfectly focused. I think you might get much more energy this way? Also obviously the heat sink needs to be black if possible. Lovely project. Thanks!
Paint the heat collector black, as silver reflects...no need for individual curved mirrors, as the current setup uses low reflectivity film. Rather user real flat mirrors and get all reflections from the flat mirrors to overlap on the heat collector. More smaller real mirrors may be the way to go.
Aside from using flat mirrors to make it easier and painting the disk black: The heatdisk should also have some sort of transparent casing as to trap more heat. A large hot metal disk also is good at giving off heat to the surrounding air. And the cover would also protect whatever dark coating you use.
Did you apply the paint at the front of the acrylic panes? It wasn't clear to me, it would be best to apply it at the back like with any mirror. Then the aluminium core plate must be painted matte black of course, you do not want that to act as a mirror too. I expect some issues with boiling, tubes may burst or come off. You may need to control the water flow based on the plate's temperature, making sure it won't exceed 90 degrees Celcius or so. And using astronomical data tables for your date and location seems more effective than trying to figure out where the sun is in real time. This is how all trackers for solar panels work. Overall I am impressed once again.
Yeah, he's going to need a lot of water pumping through that block to keep the sink below boiling temperature, which means needing a constant use for the hot water. Recycling got water will also make it boil.
Honeslty, being able to form the plexiglass mirrors at 100C means getting any where close to boiling will cause the seals around the plexiglass backplate to pop. The tempreature and constant water/steam pressure will warp it.
A common mirrors is backed to use the main clear material(glass) as a means to protect the thin coating that produces the mirror finish. Typical acrylic mirrors(makeup mirrors and the like) put the mirrored surface a the front to prevent double images. I ideally the lenses should be coated in metal foil as paint looks like metal but it doesn’t have the same properties.
When using a mirrored backing the acrylic will absorb some energy reducing efficiency of the mirror and generating unwanted heat. Given the mirror is acrylic that additional heat would likely deform the shape of the mirror. Putting the mirror on the outside will reflect more of the incoming light and reduce the temperature of the acrylic.
@@jacobs8718 That's nonsense, we're dealing with direct sunlight, not lasers or already concentrated "high energy" light beams.
@@MartinMaat I rewrote my response. I reread it and I disliked the tone and content so I changed the direction of my response to promote better discourse.
btw, I said “high energy” not in a technical but relative sense. The suns 1000 w/m² load is not insignificant to a design that uses sheet acrylic. Typical use case for an acrylic mirrors is indoors and notably less than 100w/m².
@jacobs8718 I still don't see how direct sunlight is going to heat up an acrylic pane. Do you have a source for that? The stuff is used all over the place as cheap double glazing, mounted on window frames, facing the sun. It does absolutely nothing. We had one such pane at home when I was young to save energy. I just looked it up, it only gets somewhat soft over 85 degrees Celcius. It never significantly goes over room temperature. Granted, with a back coated mirror light passes twice but so what? It is a clear material. Even if it would absorb some frequencies, those would already be absorbed on the way in and thus will not be absorbed again on the way out.
Bend / form the plexi glass, then apply reflective film. Cool project!
That's so cool. I think that the segments should be offset paraboloids. Also i wonder what geometry does the secondary mirror has
This is a cassegrain antenna design. The formulas are all over the antenna design websites. It is very critical though. and actually you usually want to focus in a single point but for this you should try for a focal point past the plate just where the cone of light would evenly cover the plate.
Great ideas, fabrication, and explanation of your thought process! Having recently completed 13 years in the large-scale solar power industry, here are some comments to digest. For those hoping to home brew concentrated solar generation for home or small business, the many problems to overcome are mulit-year durability, degradation due to falling reflectivity, wind survival, and reduced output due to high temperatures caused by concentrating solar energy. Solving these problems greatly increases cost. The reason less efficient flat solar panels dominate the market is, considering positive and neagative tradeoffs, they're far superior to concentrated solar technologies on a cost vs production basis. Single axis tracking improves production with only a small increase in cost. But 2 axis tracking greatly increases cost, complexity, maintenance, and reduces longevity of the equipment.
Shape the mirror before you coat it.
I was thinking the exact same thing.
Have you ever tried to put window tint/film on a curved surface like that? Tint does fine when curved in one direction, but sucks getting it to lay down flat in two.. without a LOT of heat from a heat gun you'll never get it to lay down flat on a parabolic shape.
4:00 It kinda looks like the Lesser Ark from Halo 3.
Thought the same thing
Cool video love the fact that you showed your mistakes as well as your successes. Innovation is all about trying something and then trying something better good job thanks for the work of putting this video together
Springs aren't cheep?!? Wft!?!
Yeah wtf, I am confused 😕
Addicted to 3D printing.
Here in the states you can buy a bag of 100 springs, depending on size and material, for well under $100(probably
Why you chose paint insted of space blanket? I think second can be more effective
But anyway project looks cool
Very good quality of video overall, no junk or filler.
As for tilting mechanism, consider redesigning it. Main problem with current iteration is that it is relatively weak. It may hold light frame with reflectors, but then it'll need to be strong enough to withstand the winds. And winds will potentially double or tripple the loads.
rub the aluminum disk with really fine grit sandpaper and then rub some artist charcoal all over it.
Is that also heat resistant that you know of?
@@ConceptCraftedCreations I'm sure that because the charcoal is carbon it would combust easily especially as a powder.
@@ConceptCraftedCreations since it's pretty much pure carbon, it shouldn't burn, but should increase the amount of light energy being absorbed into the aluminum. You could also just hold the sun facing side of the aluminum over a campfire until it collects a good coating of soot.
@@ConceptCraftedCreations anodize it. DONE!
I love the graphic projections on the table, very creative! The 3D printed springs losing some of their strength after just a few hours has got me worried, I don't believe they're going to hold up beyond a few weeks and start shifting the mirrors out of alignment.
Anything I would have done? Not use gold and silver paint for one. When it comes to energy, paint is not the same as the actual materials; it's a case of pigment versus metallic elements. Sure, I get that neither one is cheap, but you can only go so far with just substitutes.
I get what you mean! What's your opinion on the test with the laser to test reflectivity if i may ask?
@@ConceptCraftedCreations Seemed accurate enough to me, so kudos on that. Seriously though, real silver mirrors will beat just about any substitute in this kind of situation.
@@ConceptCraftedCreations Gold paint, isnt the same color, nor reflectivity, of high purity Gold. For that test, you should use Gold-Leaf. Gold Leaf, is real gold.. just incredibly thin... making it semi-affordable, for coating things like Picture Frames.
I have to say, it looks amazing :) I'm curious how effective it would be, but it seems like a great project and would want one for myself, so I think I'm going to steal your design when you're done :D Also, being a neighbor from the south, I feel your pain trying to test solar panels in the rain. much love from Belgium! you have my subscription
This is insane, can you please include project development and experiment timelines in your videos?
For the sun tracking I'd seriously consider an equatorial aligned single axis drive, just like a German Equatorial telescope mount, it will allow for counter weight balancing to lessen strain on motors. There's a market for second hand mounts with some sophisticated tracking software more than capable of following the sun even over multiple days.
You don't need your primary reflector segments to be curved either, they can be flat as you are not trying to cast the image of the sun on a focal plane, you just need the maximum of light from each reflector to reach a common surface area which will be your collector. If you could position your collector in front of the reflectors instead of needing a secondary reflector to send the light back down again then you avoid losing energy to a second reflector which will itself also be getting quite hot as it is nor reflecting 100% of the light/heat.
Two Russian youtubers made sun tracking based on math, location and date. They decided that tracking on light resistors was not a good fit
You may wanna try applying the reflective film after shaping the plastic. You can also use a heat gun and soapy water to make it easier. Good luck!
I thoroughly enjoyed watching this project, and I look forward to seeing more of it. Your mount appears more complicated than necessary. An equatorial mount similar to that used by many telescopes seems more practical. If you tilt the rotation axis so that axis points to Polaris you can rotate the mirror structure to track the sun, while north-south adjustment can remain constant (nearly) through the day.
I really enjoy your videos and creative projects. My mind is still obsessed with the tree wind generator. I see a potential problem with your heat collector plate. Let's assume you solve all the other issues and create the perfect solar energy collector/concentrator. In that situation you will have a very hot plate with water trapped into a VERY small diameter channel. That water will turn to steam very quickly and you won't be able pump water in fast enough (or with enough pressure) to stop the steam forming process. Once it starts you will not be able to stop it without removing the heat. I have seen the same thing happen when people attempt to heat water using 1/4 or 1/2 inch copper tubing with rocket stoves. After it gets warmed up to a specific point the steam creates back pressure and water doesn't flow through the system anymore. To solve this on the rocket stoves they use 3/4 inch (or larger) copper tubing. Then they can collect more heat with a slower flow of water. I would suggest you consider creating a new heat collector with a wider (or deeper) water channel so you can get a larger volume of water in contact with the heat. This will enable you to use slower moving water at lower pressures. Keep up the great work.
Consider adding an axle perpendicular to the back of the mirror, with an adjustable weight for counterbalance to take the strain off the motors and positioning mechanism. Also consider wind loading. The big wind that hits while you're away and can't reposition it into safe mode position.
awesome project. it's on my list for years now.
1. what if you molded the acrylic first and then put the silver foil on it?
and did you check other foils, such as a rescue "blanket" or using real silver like they do for DIY telescope lenses?
2. the liquid for heating, I would have used oil as it goes easily to 300C without damaging or boiling.
3. what about a heat storage? a highly insulated barrel that stores all the energy and used when needed?
4. the solar tracking sensor: great! how did you solve that at the end of the day it goes back to the morning position? (otherwise it's impossible to find the sun when in evening position)
5. the aluminum disk you can easily ANODIZE in black. at home. that should last forever.
On your motor controller, add standard tracking/motion for the solar calendar (xyz angle and speed) and only allow a certain % deviation from photorestors so random clouds and over cast days it still tracks as it should. that way photoresistors are never totally out of scope and can correct the last few degrees and won't go crazy scanning everywhere for the sun if it loses track due to environmental reasons and or freezes because everywhere is the same brightness. The pan/tilt should be almost 100% predictable on a calendar basis but id imagine there is some deviation based on location and local weather witch could be problematic (especially being so far in the far north). And if your looking to go real fine grain, testing photoresistors to to find common resistance for a given light emittance. then adding small resistance so it doesn't have a bias to one quadrant would help with accuracy and balance (apologize in advance if wording is out of place or slurred, having a few beers finishing another mechatronics problem for the night and love projects like this...thank god for spellllll check) love what your doing and want to do some similar stuff here in warm Florida. my comments are not supposed to be "HEY THIS IS WHAT YOUR DOING WRONG " but what id love to add if and or when i do the same thing i appreciate showing your pitfalls in MFG because id do all of those to otherwise :)
I would put the collector at the 1st focus and make it a sphere with a hole in the side to let the light in and stop any reflections from leaving.
Imagine machining channels into a hollow sphere with a hole in the side, then coat the inside with candle soot.
This way, you won't have to worry about machining a secondary mirror. The parabolic segments reflect just once through the hole in the sphere and everything is captured.
I made a solar tracker using an Arduino, GPS module and two servos, (later two steppers) and some code to translate time of day and lat/long location into elevation and azimuth in degrees.
Works even when overcast. Add an anemometer then set to elevation to 90° if wind exceeds a limit.
Use a linear actuator for elevation - this can take a lot of load. Raise the dish and add a counterweight to reduce static torque.
Servos are a pain - they want to slew suddenly to another position at power-on, and that can break things if they don't have a clutch mechanism!
I'd make the aluminum plate black to reflect less light. I personally would make more parts out of metal, but what you are doing seems right for the prototype stages. I'd replace the acrylic on back of the aluminum plate with something more heat resistant. I've see smaller mirrors melt metal and stone in short order. I would think that amount of heat might outrun that pump. Maybe add a temperature monitor to the system and program the tracker to take a break if needed in the current config. Paint can be polished to a real good surface finish giving it more reflectivity. I'm not sure how well 2k or epoxy paint works on acrylic, but that would be a more durable paint.
Cool project.
The center should be as dark/non-reflective as possible if you want to absorb the most amount of heat. Consider either: a black anodized coating; a cast iron attachment; or really scuffing the surface (easiest but least effective option).
It might be worth looking into Tollens Reagent for making your mirrors. Just be careful when working with the chemicals. And while that tilt mechanism works inside, this thing is made to be outside in the elements, the big one here being wind. Before using that as your final design, stress test it with increasing amounts of weight until failure or your confident it can survive wind gusts. You could also go with something a little more like what you used for the base but on a cam at the top of a support beam. Plus as others have said, making that heat plate dark or black to absorb more heat is a must, as keeping it silver will reflect a ton of energy that your looking to save.
Overall I love the project though, its an very interesting concept for collecting solar power.
Apply reflective coat after shape, Stem vs base movement, adjustment of replace detection from bottom to top.
Really interesting project. Back in BEAM robotics days, we would build sun trackers with LDRs that way. The solar panel powers the circuit, so you build the circuit to move motors so that the panel is always pointed at the brightest light source. I always imagined using one to control a large dish like this, so it's super cool to see!
You're using plexiglass for the mirrors, which allows visible, IR, and I'm pretty sure most UV to pass through, right? What about pressing the plexi first, and silvering the back instead? That would give a much smoother finish, but who knows... people do this with aluminum foil, so maybe that much precision isn't worth the effort.
So much great feedback in these comments, so excited for the next part!
Hopefully they’ll work great, but maybe check how well the 3d printed springs maintain their elasticity after being under compression and also at heat? They might just deform being in the sun all day.
id reccomend applying the reflective film after shaping if possible, a heat gun may help with this like applying a wrap to a car maybe? i would also recomend making the centre plate black so that absorbs the light energy rather than reflectibg it away, if you could give it a black anodising that could work great. Good luck!
Some suggestions for improvement:
Shape the mirrors before applying the reflective film, that way the heat doesn't affect them. This does have the downside that you'd need to use a rubber or other flexible squidger in order to apply the film
individually parabolic hexes don't add up to a parabolic array, you should have forms to shape them to make the full array of mirrors parabolic. Based on your design, you would probably only need three forms: one for the inner 6, one for the 6 outer corners, and one for the 6 outer middle hexes. If it isn't clear, it's similar to making a giant poster by printing it out on multiple sheets of standard printer paper and then taping them together
This is the concept I needed for my design and I know the algorithm brought me here for a reason lol. We are working on different light spectrum's though lol. I need less heat and a more solar panel friendly spectrum. The telescope concentrates the light and sends it indoors over photonic or fibre optic lines and spreads the light out to a server rack full of stack-able solar panels, mirrors, and diffusers. Not built yet but I would like to see just how far a system like that could be pushed. We should share notes lol.
1. You can apply film with heat gun and soapy water. Just like car window film applications.
2. You do not need parabolic fancy mirror for heat collection. Especially if your heat receptor is as big as individual mirrors. You can even use flat mirror.
3. Paint your heat receptor black.
-I'd redesign this to have the collector plate be smaller and mounted at the focal point of the parabola and not try to reflect it back to the center as you are introducing unnecessary inefficiency with the extra reflection.
-like many other people have pointed out, the collector plate should be black as you want to trap as much heat as possible, not reflect it away
-I think it would have made more sense to 3d-print the segments of the dish then electro-plate them as that would reflect a lot better than any paint would and it would mean you could print each segment with the correct curve instead of trying to bend it afterwards and having to create molds which would be inaccurate as you would need to create a different molds to have the correct curvature in each segment. The segments could also be designed to interlock with each other to reduce their size(to allow to fit in your 3d-printer) and reduce the mounting points. Either that or bend the plastic before applying the reflective film
-the angles of the mounts for the dish segments didn't really need to be adjustable. The shape of the parabola isn't variable. It should have been designed in CAD first then each mount printed at the correct angle. It would have saved you complexity and weight and cost. You could have even designed a spine right into the segments of the parabola and avoided mounts altogether. s of the parabola and avoided mounts altogether. Domes are fairly sturdy structures on their own so a spine might not even be necessary.
-since this device is meant to be used outdoor and presumably in the elements, considerations need to be made for wind and rain. The joints need to be sturdy enough to take a strong gust given the surface area and shape and the device needs to have proper drainage
I don't know what CAD software you are using. In Solid Edge, if you use the material properties correctly, the software can identify the center of gravity (CoG) of both a part and an assembly. If you place the CoG of the upper mirror assembly directly above the central point of your turntable and are able to figure out a method for pivoting the mirror assembly up and down on an axis which passes through this CoG, there will be no moment arm to contend with. The motors required for motion will only be fighting friction and inertia. They won't be battling many newton meters of torque.
Tip. Have a look at a polar aligned equatorial wedge.
You will find tracking easier as all the tracking for the day can be done with one motor running at 1/24 revolution per hour.(the earth is rotating not the sun moving)
Why is the disk in the middle silver it will reflect heat & light, it should be the darkest matt black you could find.
If you paint the aluminium heat sink with an ultra black paint like vanta black, or even just regular black itll absorb more of the light as heat, the water you pump through the sink could be salt water as well since salt water is more conductive and reaches boiling point easier. Those are my suggestions, great video!
For the stability of the array, perhaps a light compression shock absorber on the top side of the array to assist and stabalize the threaded rod erector.
You should get a light gray projection sheet or paper to put down on your table when you're using your projector like this, it'll increase contrast and color, as well as reducing reflectivity from the surface as it stands.
Great project man. One improvement I would make would be to simplify the tracking system. If you use an equatorial mount then you only need to move the whole assembly in azimuth (on the lazy susan axis) at 15 degrees per hour- a lot easier :)
First of all I would like to commend the meticulous work you have done. It's just fantastic problem solving ! I have few observations
1) the spherical mirrors should have been ok too because you are aiming for heating and non imaging application. The only requirement was that reflected sun rays must fall on aluminium collector and not miss it.
2) you need to apply some black absorbing material on aluminium having water pipes, which I guess you would be doing.
3) As I understand the acrylic mirrors have to direct and focus on some mirror which will reflect back that light to aluminum collector having water channel. Designing that will be more challenging as it is duplicate of your acrylic mirror design but with constraint of smaller dimension and more temperature capacity.
3) finally you need to keep appropriate flow rate in water channel to avoid steam formation.
Goodluck to you
However you must calculate the photo to thermal efficiency of your system and the benefit associated with it.
When you move your parabolic mirror away from the center axis and tilt them the focus point shifts and all of your mirrors won't be fully effective ... The whole assembly needs to be in a parabolic shape.
The necessity for a parabolic mirror shape instead of a spherical shape was unexpected. I learned something today!
A few observational guesses... Once you put a black finish on your heat plate to make it more absorbent, I believe you will run into two other problems. 1, the plexiglass backing that you have screwed to the back will become very soft from the heat and allow the screw heads to sink in and lose all their clamping force which will cause the water to leak out. You need a second plate as a mirror image of the first to create the water channels without warping from the heat. it STILL may warp too much though, so some sort of high temp gasket material will be needed. 2, the supporting 3d printed structure to the heat plate will also be in danger of heating up beyond it's ability to remain solid. You should very easily surpass the melting point of any 3d printable filament, and that would cause some issues too. Maybe I'm missing totally on these things, but I don't think so. good luck and I'll be watching for sure! cool project!
Really like the presentation with the beamer onto the desk! :-)
I would probably consider adding a counter-weigh of sort to the mirror if you want it to be more stable. But then you'd have to redesign the base section as that is not fit for an opening in the middle.
very interesting! use one of the car wrap foils. They stretch and you can apply them after bending the plexiglass. And they are highly reflective! Cant wait for your followup video!
What an awesome project! Very impressive. I think you're right to be concerned about the veritcal adjustment mechanism though. I'm sure it works great inside but I would assume that any amount of breeze outside would cause a failure, the mirrors will act like a huge sail. That same motor might work but I think if the reflector frame was mounted to a trunion, not unlike a bandsaws table, it would be a lot more stable and robust.
I would definitely pivot the reflector assembly around it's centre of gravity, rather than at the bottom. Make three A-frames - two with bearings supporting the weight of the assembly and the third off to the side for the motor to tilt the array.
Use soda lime glass for superior surface roughness and coat electrolessly which is used for creating mirrors. Soda lime will soften at lower temps arong 570 C
Around 30 years ago, I was involved in a project doing low-budget energy solutions in Belize, using recycled materials. One project was a solar collector, much like the one here.
An old satellite dish was used with hundreds of small square mirrors, cut from common bathroom mirrors. The focal point, however, was not reflected but suspended from the edges of the parabolic dish. The result was so successful that it proved to be downright dangerous in the hands of the inexperienced users it was intended for.
Really cool project, I'd use mylar blankets though. You can shape that to acrylic or even ASA structure basically using vacuum wrapping. It's far more reflective and reflects heat better
Excellent ! I love your solar ground tracker! and the hexagonal tiling of the parabola!!!
a suggestion for building the mirrors:
1) 3d print a parabolic plate in plastic
2.a) spray it with a reflective paint
2.b) or tape aluminium length wise to cover the parabolic plate
3) cover it in epoxy resin to make it more durable
a suggestion for the design:
-instead of moving a huge and heavy mirror, focus smaller sized mirrors.
(for example if the motor is reliable for 50 kg, instead of using a 75 kg mirror, use 4 smaller 40 kg mirrors)
good luck and I hope this was useful
Some suggestions: Rather than try and bend the mirrors into shape, you could try Mylar and a vacuum to form a perfect parabola and focal point - no screws or heavy mirrors required. You could also make the mirrors a LOT larger. Mylar only reflects about 90% of light but making them larger (maybe to to the same weight) you''ll get a lot more overall energy.
I presume the secondary mirror you mentioned (not shown) will be at the focal point and it's to reflect the light back to the heat exchanger. But that secondary mirror will need to handle about 7kw of energy - the same amount as the heat exchanger - it's going to get very hot, very quickly. A single reflector (array of articulated mirrors) will be easier to build and won't melt.
So if you created an array of vacuum drum mylar mirrors each with 2 axis articulation and an adjustable vacuum - with some programming to relocate the focal point you will have a death ray.
mylar on it's own is already more reflective than the mirror tint he's using, so this is a good suggestion.
I think for the mirrors they could be bent as the plexiglass glass and then spray painted to avoid the cracking in the first place. Also microwaving silver paint could lead to a ☠️ or 💥
That frame you made is a work of art