[geoffcampbell64]

I wonder how long it’ll be until someone figures out how to utilize this effect to create a heat pump! I would guess that this “photomolecular heat pump” might be easier to miniaturize since it has no need for a compressor. I wonder if other solvents or refrigerant might also be more efficient working fluids than water. Very exciting!!

[elil17]

You'd definitely still need a compressor - otherwise there'd be no change in pressure driving a change in temperature. I guess you're suggesting that the photomolecular effect could be used to boil the refrigerant at the heat pump's evaporator. Boiling is a bulk process caused when the temperature of the fluid rises so much that all it's intermolecular bonds start to get broken. Evaporation is a surface process where a few molecules randomly break free of their intermolecular bonds and mix with surrounding air. Boiling, not evaporation, occurs in a heat pump's evaporator (despite the name). The photomolecular effect doesn't cause boiling, only evaporation. You wouldn't really want evaporation to happen in an evaporator because you'd need to have air around and then you'd be compressing a bunch of air along with your refrigerant, which would waste a lot of energy.

My first thought was some sort of cooling tower application. Cooling towers use evaporating water to cool various process fluids. But, when building a cooling tower, you want to pull down the temperature of the water by having evaporation absorb the heat in the water. This evaporation process actually reduces the amount of heat that gets absorbed from the water because it uses energy from light and heat from the air instead.

If this has engineering applications, it will likely be in places where the end goal is the evaporation of the water itself, such as a drying process or passive desalination.