What determines which fluid cools and warms on an evaporation process? Is it possible for both the air and the water to cool? The reason I ask is that in another lecture it was stated that when the liquid evaporates it draws the heat from the liquid and the ambient air itself. However in a cooling tower it is shown that the air warms and the water cools. What explains this?
It depends on what direction the heat transfer is taking place. Don't forget that evaporation isn't the only type of heat transfer taking place. If there was a thin layer of plastic between the air and water, preventing any evaporation, then there is still heat transfer from the warmer to the cooler body through the media. Evaporation is the process of energy being added to water, after so much energy the liquid water goes through a phase change into water vapor. Water vapor takes slightly more energy with it and leaves behind slightly cooler liquid water. A sealed bottle of water will settle out at room temperature. An open bottle of water, depending on the rate of air passing over it's surface, will approach the wet bulb temperature. In this case, if the water was 40 degrees F and the room temperature was 80 F and the wet bulb temperature is 68F, the open bottle of water will go up. Likewise, if the water temperature starts at 80 F then its temperature would go down. Remember, the water in the open bottle is cooled by evaporation on it's surface touching air and is heated on it's surface touching the bottle. Does this answer your question? Please correct me if I accidentally reversed something.
Ex if i have air initially at 42 dec C and 37% RH. Can we achieved air at 11 Deg C by spraying 7 degree Celsius chilled water through evaporatorive cooler. Can you provide the calculation?
I honestly don't know why students don't show up to such lectures, I would kill to have such a professor honestly
Great lecture!!
What determines which fluid cools and warms on an evaporation process? Is it possible for both the air and the water to cool? The reason I ask is that in another lecture it was stated that when the liquid evaporates it draws the heat from the liquid and the ambient air itself. However in a cooling tower it is shown that the air warms and the water cools. What explains this?
It depends on what direction the heat transfer is taking place. Don't forget that evaporation isn't the only type of heat transfer taking place. If there was a thin layer of plastic between the air and water, preventing any evaporation, then there is still heat transfer from the warmer to the cooler body through the media.
Evaporation is the process of energy being added to water, after so much energy the liquid water goes through a phase change into water vapor. Water vapor takes slightly more energy with it and leaves behind slightly cooler liquid water.
A sealed bottle of water will settle out at room temperature. An open bottle of water, depending on the rate of air passing over it's surface, will approach the wet bulb temperature. In this case, if the water was 40 degrees F and the room temperature was 80 F and the wet bulb temperature is 68F, the open bottle of water will go up.
Likewise, if the water temperature starts at 80 F then its temperature would go down.
Remember, the water in the open bottle is cooled by evaporation on it's surface touching air and is heated on it's surface touching the bottle.
Does this answer your question? Please correct me if I accidentally reversed something.
37:47, captions are pretty great
Ex if i have air initially at 42 dec C and 37% RH.
Can we achieved air at 11 Deg C by spraying 7 degree Celsius chilled water through evaporatorive cooler.
Can you provide the calculation?
very bad handwriting
okay and ? what's your point
hallmark of a great engineer 😎