Portable chiller performance

[Diabolico]

I understand that portable air cooled chillers loose cooling capacity at higher ambient temperatures. My question is, how does high humidity affect the cooling capacity? is humid hot air worst than dry hot air?

Thanks

 

[35454]

normally, the higher the amount of humidity the better for cooling. Dry air is a very good insulator. Think about windows with double glass... the air between the glasses is dry for insulation. The more humide air is, the better conduction for transporting energy...

 

[35454]

hot air has a higher relative humidity and the cooling unit can produce condensation... maybe this affects the performance of your device...

 

[dcasto]

The higher ambient temperatures means that the condensor will operate at a higher temperature, which means the refrigerant is at a higher condensing pressure which means the compressor uses more energy AND it's capacity is reduced so net less cooling avaiable with more energy input.

Now, humid air, it that the ambient air or the air being cooled? If it's the ambient air, then the higher humity air has a lower density than dry air at the same temperature and pressure (humity air is lighter not heavier!!!). So the condensing fan blows the same volume, but less mass. There is an offset in that the humid air will have a higher heat capcity, so the net is that 90% humidy air can condense 1% more refrigerant than dry air.

If you are talking about the humid air you are cooling, then the humid air as it cools requires more cooling because you must condese at 1000 BTU/lb the water as you cool the air.