How to DESIGN and ANALYSE a refrigeration system

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  • Опубліковано 23 гру 2024

КОМЕНТАРІ • 135

  • @EngineeringMindset
    @EngineeringMindset  7 років тому +12

    ⚠️ *Found this video super useful?* Buy Paul a coffee to say thanks: ☕
    PayPal: www.paypal.me/TheEngineerinMindset

  • @shhagley
    @shhagley 4 роки тому +5

    So much simpler and concise than all the other videos,Kudos Paul

  • @shaukathayat749
    @shaukathayat749 7 років тому +5

    dear uploader, God bless u for helping engineers with such precious videos.

  • @w5cdt
    @w5cdt 4 роки тому +6

    It’s been 40 years since I took thermodynamics....thanks for the tutorial.

  • @dhruvrajsinhgohil4892
    @dhruvrajsinhgohil4892 3 роки тому +10

    Do you know how to calculate length of tube required in Evoprator and condenser?

    • @blackburnmichelson6189
      @blackburnmichelson6189 2 роки тому +1

      good question

    • @tshepipowerhouse9004
      @tshepipowerhouse9004 2 роки тому

      ever got the answer?

    • @stephendinoboy
      @stephendinoboy 2 роки тому

      I think it is based on your facilities (how far your evap and condenser areas are). And then you compute the corresponding piping pressure losses to adjust your respectiv capacities.

    • @lauderdalechad
      @lauderdalechad 3 місяці тому

      There are charts online for this. Heatcraft is a good source.

  • @movax20h
    @movax20h 5 років тому +6

    Just a minor correction, in your slides and in tables you use, the Enthalpy and Entropy, should be labelled Specific enthalpy and Specific entropy. Sure, it is a sortcut, but still, it is nice to be more .... specific :) Distinction is useful when then anlyzing enthalpy and mass flow and work required. Also thanks god you are using metric units.

    • @dhruvrajsinhgohil4892
      @dhruvrajsinhgohil4892 3 роки тому +1

      Do you know how to calculate length of tube required in Evoprator and condenser?

  • @strikerchooo
    @strikerchooo Рік тому

    Great video, thanks! Just a note - if its W or kW it is power, if it is in Jaules - then it is work. Since the evap, condens and compressors are in kW all should be power.

  • @mzs9262
    @mzs9262 7 років тому +8

    hey Paul !! we love you all God bless You and Your TEAM . we are proud of you.
    .. Dear Paul i want to ask a Question that why we need such kind of calculations ? or after finding all these unknown parameter what will be our next step ???

    • @michaelmolter6180
      @michaelmolter6180 3 роки тому

      I imagine these calculations are more important when designing commercial or industrial scale refrigeration where its not just an off the shelf condensor and evaporator. You'd need to be able to select or size individual components, estimate system performance, and get an idea of cost.

  • @74womack
    @74womack 6 років тому +1

    So glad I found this channel.Thanks for the great work mate.

  • @miken1574
    @miken1574 2 роки тому

    Love this channel and love Paul. Watched several videos on this channel on various topics and learned so much. Starting this series, however, I can't help but notice the way he pronounces the letter "h". It sounds like he's saying "Heych-VAC". So weird, haha.

  • @волковдмитрий-ц2ш
    @волковдмитрий-ц2ш 5 років тому

    The best video I've seen so far. My question is: For other gas like propane, methane and Neon? Where should I look? Tank you, I will definitely watch your other videos

    • @EngineeringMindset
      @EngineeringMindset  5 років тому

      Scroll to the bottom of this page for data sheets on all refrigerants theengineeringmindset.com/refrigerant-properties/

  • @VencaZajicek
    @VencaZajicek 3 роки тому +1

    Thank you for this video. May i ask you? How is possible to calculate dimension (ID and lenght) of capillary tube? ..when I use very stron vent on condenser, how can I calculate its effect on the system?

  • @AngelRodriguez-qg5zq
    @AngelRodriguez-qg5zq Рік тому

    Thanks Paul! At minute 4:42, what path would you have taken if you had started knowing the cooling load you are looking for?

    • @rholanddelamerced
      @rholanddelamerced 11 місяців тому +1

      Same question here... I am having a difficulty starting at the cooling load. I'm starting to wonder if I am going to use the average COP of ref systems to know the power of the compressor that I would be using.

  • @ishika562
    @ishika562 4 місяці тому +1

    Hey,, will you please guide how the lg compressor Dkt208mah which is producing 23100 btu is used in o general hot and cold model 2.5 ton.,which have a capacity of 28000 btu.. How these btu difference compensate cooling efficiency..

  • @anantagarwal5569
    @anantagarwal5569 5 років тому +2

    How can the temperature at state 1 and state 4 be the same?(Even in an ideal scenario)
    The refrigerant after leaving the evaporator will absorb heat and there will be a rise in it's temperature.

  • @DanielSanchez-it1ki
    @DanielSanchez-it1ki 3 роки тому

    Now, THIS is a lovely and very useful video. Great work!

  • @bireshroy4656
    @bireshroy4656 Рік тому

    the great teacher, best of the best

  • @garyrogers425
    @garyrogers425 6 років тому +7

    Fantastic video but there seems to be an error. The gas flow rate of 3kg/s is far to high for the picture in the video. Data sheets normally give this as kg/h. So I assume your data sheet said 180kg/h and you only converted to minutes instead of seconds, giving extreme kW values. The compressor looks more like a 1.3kW rather than an 82kW. (i.e. 82/60)

  • @davidcruz4611
    @davidcruz4611 4 роки тому +1

    Can you explain why the entropy does not change before and after the compressor. Thanks.

  • @EngineeringMindset
    @EngineeringMindset  5 років тому

    ⚠️Learn how *REFRIGERANT WORK* here: ua-cam.com/video/lMqoKLli0Y4/v-deo.html ⚠️

  • @herambgadgil1185
    @herambgadgil1185 3 роки тому +1

    On what basis have you selected the compressor?

  • @tusharkumar733
    @tusharkumar733 3 роки тому

    Very useful and in easy way explanation.

  • @garypoplin4599
    @garypoplin4599 5 місяців тому

    1:37 - This is a beautifully crafted video on the explanation of the refrigeration cycle using maths! I look forward to being able to work through your amazing excel workbook on my own. he only thing you got backwards here in this diagram is the metering device flashes the refrigerant into the bottom of the evaporator and boils back to a vapor out the top. (I am _not_ a troll. I just noticed the error.)
    Well done, Paul! I didn’t see a link to your excel workbook on the website or in this video. Can you point us to a link?

  • @agrup69
    @agrup69 7 років тому +3

    Hi! Thanks your sharing your knowledge! Can you tell how can I calculate the amount of refrigerate? Regards!

  • @dickyrock1
    @dickyrock1 4 місяці тому

    Thanks a mil for these videos

  • @andypag1071
    @andypag1071 7 днів тому

    Id like to build a solar assisted heat pump to wam water and uses thermodynamic panels and butane as a refrigerant. What videos do you suggest i watch to calculate the pump power needed and size heat exchanger coil size.

  • @amanofconstantsorrow1040
    @amanofconstantsorrow1040 6 років тому +1

    Man you are a legend .. thank you

  • @swarupgulalkari866
    @swarupgulalkari866 2 роки тому +1

    Please make se video on R290 as propane. As it has no superheated vapour chart.so how to solve it.please help.

  • @hoctin1875
    @hoctin1875 3 місяці тому

    Hello The Engineering Mindset, Do you have any video about calculating and designing for length and diameter of copper tube in a refrigeration system. Thanks you.

  • @CoCFFGamer
    @CoCFFGamer 3 роки тому

    If we have a cooling load then how do we start the design of the Refrigerator? Also, how to fix the evaporator pressure if we are designing a system to cool at around -70 to -80 degrees celcius?
    Thank You!!

  • @md.azadhossain6940
    @md.azadhossain6940 7 років тому

    A lot of thanks... we are always with you!

  • @cessromer7078
    @cessromer7078 3 місяці тому

    I implemented a simulation to modeling a close real life scenario however how can I add a function that simulate losses in the system either to any component to see the change in quality, enthalpy and entropy or a total loss function to watch for COP, performance of system among them ? thanks

  • @billdempsey7477
    @billdempsey7477 4 роки тому

    Ahhh...takes me back to Thermo except presented much better. Well done!

    • @3gkevh53
      @3gkevh53 3 роки тому

      You should get into the refrigeration design industry

  • @saifali2196
    @saifali2196 7 місяців тому

    Sir...can you elaborate the how you have taken the pressure for compressor from the manufacturer and along with it mass for the compressor also.

  • @jasonhewitt7614
    @jasonhewitt7614 2 роки тому

    Do you have any videos on capillary tube systems

  • @JaykeSapalaran-iq3qs
    @JaykeSapalaran-iq3qs 10 місяців тому

    Great video information ❤,
    Please make a video tutorial how to read enthalpy diagram

  • @IM-br1eb
    @IM-br1eb 4 роки тому

    12:30 How can the temperature at state 4 (refrigerant entering the evaporator) equal temperature at state 1 (refrigerant exiting the evaporator)?

    • @arturzych138
      @arturzych138 4 роки тому +1

      if something is going through a phase change it's temperature remains the same. As in the evaporator from liquid to vapor. This is also a rough calculation (ideal case)

  • @kdmq
    @kdmq 6 років тому +3

    9:45 *Enthalpy and Temperature

  • @gooddeedsleadto7499
    @gooddeedsleadto7499 7 місяців тому

    Line ( dome line) represents saturated liquid or saturated vapor?
    and
    everything within the dome is also saturated liquid or saturated vapor?
    And
    Left & right of the dome is sub cooled liquid and super heated vapor respectively?
    Please verify?
    Thank u

  • @wildbill4680
    @wildbill4680 5 місяців тому

    Hi Paul, when moving from stage 4 to stage 1 we assume the same temperature. But how do we account for superheat on the evaporator please?
    Would that be the “non idea” cycle? And if so is there a resource for this calculation anywhere please?
    Or is this accounted for in the suction and discharge input valves for the chosen compressor (ie 10k SH 5k SC)?
    Thanks

    • @EngineeringMindset
      @EngineeringMindset  5 місяців тому +1

      I'd say use the danfoss coolselector 2 app, it's free and will do all the calculations for you. I even narrated the tutorial videos for them.

  • @balakrishnabhat9977
    @balakrishnabhat9977 6 років тому +1

    Very well explained. Video is good but sound is low.

  • @mahmoudkobbara9838
    @mahmoudkobbara9838 3 роки тому

    thank u so much for ur efforts but can u please upload how to calculate refregiation system using out and TEC peltier with water cooled system

  • @TritonChannelTV
    @TritonChannelTV 2 роки тому

    Where did you get that 50.9 temp..? Pls explaine

  • @elhamasgary791
    @elhamasgary791 4 роки тому

    thanks for your video and useful information . how can we design a refrigeration system according to the heat that we want to rejected from building??

  • @Razlazy227
    @Razlazy227 4 роки тому

    How can I do heat balancing of water cooled condenser?
    Choice of refregeriant is 134A

  • @FoTeLulz
    @FoTeLulz 5 років тому +1

    Hello, I'm looking to design my own small scale refrigeration system for educational purposes, and was wondering if there is a specific type of compressor recommended? Thanks!

    • @satibel
      @satibel 3 роки тому

      I'recommen recycling a compressor from an old fridge/freezer/whatever as it's the cheapest if you want to work at those temps.

  • @abhinavverma279
    @abhinavverma279 7 років тому

    Hey Paul, thanks a lot for all your videos they are very resourceful. Can you please make a video for the safety devices installed in the chiller as it is a necessary devices to save chiller.
    Thanks.

  • @ShopperPlug
    @ShopperPlug 3 роки тому

    I want to build a deep freezer from scratch, what kind of expansion valve do I need using your calculation? Like what should I look for in data charts of expansion valve after doing calculations?

    • @EngineeringMindset
      @EngineeringMindset  3 роки тому +2

      Use coolselector by Danfoss. It'll do it all and the components

    • @ShopperPlug
      @ShopperPlug 3 роки тому

      @@EngineeringMindset thank you. Is there any other kind of calculator or rule book for generic compressors and expansion valves?

  • @mohdirfan-xy3ny
    @mohdirfan-xy3ny 7 років тому +4

    hey paul i have watched your all videos thanks for the great knowledge man.
    can u suggest me any book so that i can understand steb by step about hvac and get more knowledge

  • @ChrisBattle-t3h
    @ChrisBattle-t3h Рік тому

    Is there a book that you could recommend?

  • @JohnnyJr396
    @JohnnyJr396 2 роки тому

    Can someone help me out with entropy ? What is it and what does it mean when it’s increasing and decreasing in the refrigerant cycle.
    Thanks

  • @ercumentinal2311
    @ercumentinal2311 7 років тому +1

    Hi Paul. Thank you so much for your videos. I'm learning a lot from your videos because I'm new at "cooling world". Do you want to make a video about "Pump Down Cycle" of a chiller? If you do, I would be grateful to you. Best regards...

  • @meesreemst9308
    @meesreemst9308 2 роки тому

    If i know how much cooling capacity i need. How do i start this calculation process? Thanks

  • @sunil06sit143
    @sunil06sit143 Рік тому

    p=1200 kpa 2nd stage how you have choosed please explain thank you

  • @takiyasamsama
    @takiyasamsama 5 років тому

    This might be not so smart question, but may I know what chemical modelling is usually used for the saturation table? What I mean, is it Peng-Robinson, or etc.?

  • @lucky-gh5ox
    @lucky-gh5ox 3 роки тому

    How would be the design of system, but 2 independent evaporator?

  • @johnrichards4877
    @johnrichards4877 4 роки тому

    Really helpful video. What effect would a superheating and subcooling heat exchanger have?

  • @ghostridergr8259
    @ghostridergr8259 2 роки тому

    i have one dryer air..
    works 3 to 40 c temp
    i change filter and capillary tube but i haft to resize it...
    so now i have
    -7.5c entry to evaporator and exit 2.5c
    after to the accumulator i have - 3.5 and entry to compressor 9c is that normal.... how much must be the Δτ to the evaporator? and with the temp room so the dryer ro works good??
    thanks

  • @troubledsole9104
    @troubledsole9104 5 років тому

    Paul, I am buying you a coffee after I get paid for my next gig. Thank you so much!

  • @bevarasantoshkumar8636
    @bevarasantoshkumar8636 6 років тому

    Sir, I think according to consumer cooling load we select the evaporator to reject the heat load developed by system, in that video evaporator rejected heat load is around 408kw and compressor needs 85kw(work done on the compressor) to generate the that much capacity, what is refrigeration capacity of that compressor

  • @bucurrazvan1316
    @bucurrazvan1316 7 років тому +1

    Hello , those video are great, i've learn alots of intresthing things. Can u do a video about refrigertant quantity For example : i have a condensing unit X and one evaporator N length of pipes please .

  • @blackburnmichelson6189
    @blackburnmichelson6189 2 роки тому

    hi fried very good explanation. can you calculate comperessor electrical power?

  • @movax20h
    @movax20h 5 років тому

    Is it possible that the exit of the evaporator (1), is further than saturation line (x=1)? I.e. I understand it would create pressure extra at 1, higher than at 4, but is it possible in practice (with sufficiently thin pipes or something?)
    I also heard of some systems that operate above the critical pressure, could you cover these systems in separate video?

  • @sumeetmakwana4800
    @sumeetmakwana4800 6 років тому +2

    Sir, how to Design condenser ?

  • @MICRO.Elektroteknik
    @MICRO.Elektroteknik 2 роки тому

    Hello, I want to make 3kw and 3.5 kw evaporators and condensers, but I can't find the formulas. Can you help me please.

  • @vrichmarketingrenewableene9418
    @vrichmarketingrenewableene9418 6 років тому +1

    I want to ask something. I am repairing refrigerators for some time now, but I didn't solve this problem I encounter sometimes. After I recoil the evaporator of the refrigerator, I test the unit and it works fine, the pressure on both sides are normal. after 5-15 minutes the pressure in the low side begins to drop to negative and also in the high side lower to about 120 psi. I turn it off and the pressures take some time to normalize. Sometime, I just change the filter drier to solve the problem, but sometimes the problem continues even I change the filter drier. what causes the pressure to drop?

    • @ivanilarionov1893
      @ivanilarionov1893 2 роки тому

      Hi, I want to rebuild a 120 L refrigerator into something else. I need to change both the evaporator and condenser with copper pipes that are much more compact. I suppose that with the condenser is easy - I need to measure the length and the diameter of the original condenser and coil another one, just more dense and to compensate the worsened airflow with a fan. But what about the evaporator? The fabric evaporators are aluminum plates with unknown tube diameter and sometimes there are even splits in the line (i don't know for what purpose). And I don't want to cool air, but a volume of water down to 2-4 degrees. Will this change the refrigeration cycle somehow? Thanks!

  • @sto2779
    @sto2779 5 років тому +3

    compressor on the video shows m: 3kg/s and not 7kg/s as you mentioned. I can't find any compressor that show's its mass flow rate specifications.

  • @3dprintwiz378
    @3dprintwiz378 4 роки тому

    Just wanted to ask, I am using a different table and chart that comes from a book, which has quite different values than yours. When I read the preface, it says the tables and chart are based on a 0 *C where values of hf = 200 kj/kg and Sf = 1 kj/kg K. Is there a correction that I should do to get the same values that you get if I use my book. Thank you.

    • @jankracik4635
      @jankracik4635 2 роки тому

      There is no need for correction as you calculate with differences most of the time. It the difference between 2 points that matters.

    • @carlomabinibayo1284
      @carlomabinibayo1284 2 роки тому

      I am using a software called computer aided thermodynamic tables and it shows hf = 200 kj/kg and Sf = 1 kj/kg K same with yours. The table does not match with software for U,H and S.

  • @babsy11
    @babsy11 3 роки тому

    Thank you for this useful video, I thoroughly enjoyed watching it. There is a one thing though: on the evaporator load: it's written as m*(h1-h4) but calculated as m*(h1-h3). I presume is the latter. Am I correct?

    • @olabamijiafeez1071
      @olabamijiafeez1071 3 роки тому +1

      H3 = H4 isentropic process

    • @jankracik4635
      @jankracik4635 2 роки тому

      It is not isentropic. You probably meant isenthalpic, but it is not either of them. In reality, to be more precise it should be said that the enthalpy at 3 is the same as the enthalpy at 4. Between 3 and 4, enthalpy may be slightly varying. Hope it helps.

  • @RahulGawade123
    @RahulGawade123 6 років тому +1

    how to design according to the application?
    For example I want to design 50 ltr water cooler which cools water from 20 degree Celsius to 10 degree Celsius.

  • @kairodelvis
    @kairodelvis 7 років тому +1

    Excelentes videos, gracias

  • @Bursadesain
    @Bursadesain 7 років тому +1

    nice content, Thanks!

  • @llupllup
    @llupllup 6 років тому

    Hi Paul, i am interested on condenser. I want to know how to calculate cooling capacity in watts or kw on a condenser?

    • @EngineeringMindset
      @EngineeringMindset  6 років тому

      Himo Rexhepi it's explained in the video, don't skip through.

    • @llupllup
      @llupllup 6 років тому +1

      The Engineering Mindset Thank you for replay, i am going to watch again the video. Have a nice day.

  • @MuhammadJunaidJD
    @MuhammadJunaidJD 6 років тому

    thank you bro... this really helped...

  • @arturzych138
    @arturzych138 4 роки тому

    Question: How do you know the pressure required for the low and high side? Is it just the pressures the compressor can generate and need for the suction side?
    Also, if that's given or you find out, how do you know the mass needed in your system just use the ideal gas law at that point?
    Anyone can answer, I'm just curious

    • @felixstg1
      @felixstg1 2 роки тому

      Hi Artur, the system pressure is determined by the type of system you need. The high side pressure is relative to the location of the installation. If you are in Mexico, the high side pressure will be higher than if you are in Canada juste because the high side temperature needs to be higher than the outdoor temperature. The low side pressure is determined with the kind of product you need to refrigerate. If it's a freezer, you need to be lower temperature, therefore lower pressure. To determine the mass of the system, you need the piping size and the density of the fluid at each part of the system. This can be quite the task so we usually apoximate until the installation in complete and the technician can tell you what is the final mass the he put in the system.

    • @ivanilarionov1893
      @ivanilarionov1893 2 роки тому

      ​@@felixstg1 Hi, I want to rebuild a 120 L refrigerator into something else. I need to change both the evaporator and condenser with copper pipes that are much more compact. I suppose that with the condenser is easy - I need to measure the length and the diameter of the original condenser and coil another one, just more dense and to compensate the worsened airflow with a fan. But what about the evaporator? The fabric evaporators are aluminum plates with unknown tube diameter and sometimes there are even splits in the line (i don't know for what purpose). And I don't want to cool air, but a volume of water down to 2-4 degrees. Will this change the refrigeration cycle somehow? Thanks!

  • @ateaturd
    @ateaturd 6 років тому +1

    Where is the Capillary Tube sizing video?

  • @jorgeramirez7406
    @jorgeramirez7406 6 років тому +1

    137/5000
    Hello Paul. Your videos are great. I'm just curious to know in which part of the system is located the plate heat exchanger? Thank you.

    • @EngineeringMindset
      @EngineeringMindset  6 років тому +1

      Well a plate heat exchanger is just a compact heat exchanger where two fluids exchange thermal energy. The condenser and evaporator are the two points of heat transfer in the a/c system so you'll often find phx on these parts.

  • @zaccomusic
    @zaccomusic 4 роки тому

    good video
    I hope you keep update :)

  • @salehshati1902
    @salehshati1902 4 роки тому

    thanks for you

  • @neelpunghera2639
    @neelpunghera2639 5 років тому

    Hey man, can we find cooling capacity in kw by enthalpy or entropy?

  • @vivekmohite9219
    @vivekmohite9219 7 років тому +1

    how can i design a refrigeration system for 10 degree output temperature and one tr

  • @EXPLORINGPIPING
    @EXPLORINGPIPING 7 років тому +1

    awesome sir

  • @mehulkhiloshiya8248
    @mehulkhiloshiya8248 5 років тому

    can i get compressor specifications of 1.5 ton for R134a

  • @liveinpeace7653
    @liveinpeace7653 3 роки тому

    How to know the amount of mass m

  • @kreatordeshmukh4900
    @kreatordeshmukh4900 7 років тому +1

    KINDLY UPDATE WITH SCREW,SCROLL & RECIPROCATING AIR COMPRESSOR

  • @NeriahNn
    @NeriahNn 2 місяці тому

    Can I have the excel file for this?

  • @sevenmaster7820
    @sevenmaster7820 8 місяців тому

    Can i have that excel sheet?

  • @superoxidedismutor
    @superoxidedismutor 6 років тому +3

    Why so low subcooling?
    Subcooling is love subcooling is life...

  • @intellectracoon
    @intellectracoon 5 років тому

    I have a question please,
    In our country we get ambient temperatures that reach 55 centigrade and the air temperature over the asphalt can reach 60 and inside the car if you increase the fan speed you will not get any cold air in the cabin. We use R134A refrigerant in our ac system. I was wondering if the gas will not condensate at these ambient temperatures.. ? Can you help please.
    Thanks a lot.

  • @mohammedegyptian2527
    @mohammedegyptian2527 7 місяців тому

    bravo

  • @TritonChannelTV
    @TritonChannelTV 3 роки тому

    You say 7 kg/S but you put 3kg/S which is correct? Pls reply

  • @carlomabinibayo1284
    @carlomabinibayo1284 2 роки тому

    I am using a software and it shows hf = 200 kj/kg , hg = 400kj/kg and Sf = 1 kj/kg K , Sg = 1.72 kj/kg. The table that you have does not match with software for U,H and S.

  • @davidcruz4611
    @davidcruz4611 4 роки тому

    Also please also use US standard units for us yanks. Thanks.

  • @ranahammad6338
    @ranahammad6338 11 місяців тому

    good Boy

  • @niro1722
    @niro1722 10 місяців тому

    ❤❤

  • @ysnkhll
    @ysnkhll 4 роки тому

    Who's here after watching Adam Savage's One Day Builds video? 😂🤷🏼‍♂️

  • @akilagayan6533
    @akilagayan6533 Рік тому

    🇱🇰 thanks

  • @honestman276
    @honestman276 Рік тому

    We can make industries but the citizens, politicians and bureaucrats are utterly corrupted in Bangladesh. So I don't dare to make and to run the business on it. Thanks from Bangladesh.

  • @jackmclane1826
    @jackmclane1826 7 місяців тому

    This is a bit too reduced to be useful. Stage 1 is not a saturated vapor. There is something called "superheat". Compressing into stage 2 also adds entropy. Stage 3 is not a saturated liquid at boiling temps. There is something called "subcooling".
    These simple 4 step diagrams don't cut it.

  • @rizky-ee2nv
    @rizky-ee2nv 5 років тому

    your formula for cooling load in evaporator not match with your explanation