Indirect evaporative cooler using membrane-contained, liquid desiccant for dehumidification

Abstract

An indirect evaporative cooler for cooling inlet supply air from a first temperature to a second, lower temperature using a stream of liquid coolant and a stream of exhaust or purge air. The cooler includes a first flow channel for inlet supply air and a second flow channel adjacent the first for exhaust air. The first and second flow channels are defined in part by sheets of a membrane permeable to water vapor such that mass is transferred as a vapor through the membrane from the inlet supply air to a contained liquid desiccant for dehumidification and also to the exhaust air as heat is transferred from the inlet supply air to the liquid coolant. A separation wall divides the liquid desiccant and the coolant but allows heat to be transferred from the supply air to the coolant which releases water vapor to the counter or cross flowing exhaust air.

Description

[0001] contract source [0002] The US Government has rights in this invention under Contract No. DE-AC36-99GO10337 between the US Department of Energy and the National Renewable Energy Laboratory, a division of the Midwest Research Institute. Background technique [0003] Air conditioning is used all over the world to provide a comfortable and healthy indoor environment that is properly ventilated, cool and has adequate humidity control. While beneficial for conditioning the supplied air, conventional air conditioning systems are expensive to operate due to the large amount of energy used, such as electricity. As the demand for energy continues to grow, the cost of air conditioning is also expected to increase, and there is a growing demand for more efficient air conditioning methods and technologies. Also, increasing is the need for cooling technologies that do not use chemicals and materials such as many traditional refrigerants that could be environmentally damaging if re...

AI Technical Summary

Problems solved by technology

Therefore, air conditioning systems may need to include refrigerated air conditioning to cool the air from the evaporative cooler, making such systems more expensive to purchase, operate, and maintain

[0006] Also, traditional evaporative coolers cannot dehumidify the air, and in fact often output air with 80% to 90% relative humidity, which is only acceptable in some very dry environments due to the very humid air Reduces evaporation rates for building occupants (e.g., reduces comfort levels) and may cause condensation, which can lead to corrosion or other problems

Dehumidification is provided as a second or subsequent stage in some evaporative coolers, for example by wicking a liquid desiccant into the walls of the air flow channels or chambers, but such systems are not widely available, This is due to increased operating and maintenance costs and considerations for desiccant exhaust with conditioned air

Images