Solar Air Heater/ Night Radiative Cooling "Double Play" System?

menaus2 · 01-20-20, 06:35 PM

I've been mulling over a large air based solar heater recently, but the question I've been asking myself is if there is any way to utilize it during the summer for cooling purposes. The idea is to run it at night and use the "white plate" temperature of the night sky to cool the air in the panel, possibly condensate out some of the humidity at the same time. I live in the Midwest US where summer nights can be muggy, and the ability to flush the hot air at night without reintroducing humidity from fresh air would be nice. Some sort of automatic greenhouse type vent would be necessary to prevent stagnation during the day as well as getting rid of the condensation from the night cycle.

From my limited research, there's a guy on the Simply Solar forum who does this with his solar air heater in the Southwest US Desert climate with good results. It also seems like the radiative cooling potential of the night sky is highly dependent on cloudiness, and research papers I've skimmed suggest maybe 30-60 btu/ sqft cooling. Sooo...

-Has anyone tried this?
-Would a higher CFM or lower CFM be more efficient?
-Is this even practical outside a desert-like climate?
-And the obligatory "why not just use a ASHP?"

01-20-20, 06:35 PM	#1
menaus2 Apprentice EcoRenovator Join Date: Feb 2011 Location: Driftless Region, North America, Earth, Solar System, Orion Arm, Milky Way Galaxy,Virgo Supercluster Posts: 116 Thanks: 13 Thanked 35 Times in 25 Posts	Solar Air Heater/ Night Radiative Cooling "Double Play" System? I've been mulling over a large air based solar heater recently, but the question I've been asking myself is if there is any way to utilize it during the summer for cooling purposes. The idea is to run it at night and use the "white plate" temperature of the night sky to cool the air in the panel, possibly condensate out some of the humidity at the same time. I live in the Midwest US where summer nights can be muggy, and the ability to flush the hot air at night without reintroducing humidity from fresh air would be nice. Some sort of automatic greenhouse type vent would be necessary to prevent stagnation during the day as well as getting rid of the condensation from the night cycle. From my limited research, there's a guy on the Simply Solar forum who does this with his solar air heater in the Southwest US Desert climate with good results. It also seems like the radiative cooling potential of the night sky is highly dependent on cloudiness, and research papers I've skimmed suggest maybe 30-60 btu/ sqft cooling. Sooo... -Has anyone tried this? -Would a higher CFM or lower CFM be more efficient? -Is this even practical outside a desert-like climate? -And the obligatory "why not just use a ASHP?"