To do this Kozubal developed a counterflow indirect design wherein a small amount of supply air is bled off and fed through evaporative channels adjacent to the supply air channels. In this way the supply air is cooled via conduction to the evaporative channels, without adding any moisture to the supply air.
To complete the cycle, the liquid desiccant must be regenerated to remove the water it absorbed. To accomplish this, heat is added to the desiccant to raise the absorbed water’s vapor pressure. Blow air past this hot desiccant and water vapor is carried away, which is done in another specially designed heat and mass exchanger.
“This air conditioner works by adding heat,” Eric said, “We can use natural gas, solar heat or waste heat from many industrial processes to drive an air conditioner.”
“I can foresee a time when this approach replaces most air conditioning in the world,” said Judkoff.
Kozubal points out that aside from large energy savings, DEVAP has several other advantages over conventional cooling including:
- No need for environmentally damaging working fluids used in vapor compression systems.
- The working fluids in DEVAP are environmentally benign — water and a strong salt solution for the desiccant.
- DEVAP allows independent control of temperature and humidity, something that is not possible with conventional air conditioning unless an expensive overcooling and re-heating process is employed.
- No need for a compressor, and large amounts of expensive copper coils.
- DEVAP contains fewer moving parts in the form of simple low pressure pumps and fans.
- As efficient as DEVAP already is, there is lots of “thermodynamic room” for cost effective efficiency improvements.
Next page: Cooling in any climate