Desiccant Enhanced Evaporative Air-Conditioning (DEVAP)

This online engineering PDH interactive presentation focuses on the novel concept of a desiccant enhanced evaporative air conditioner (DEVap) with the objective of combining the benefits of liquid desiccant and evaporative cooling technologies into an innovative “cooling core”, developed by National Renewable Energy Laboratory (NREL).

The course describes the desiccant enhanced evaporative air conditioner (DEVap A/C) concept. Today’s advanced indirect evaporative coolers provide powerful and efficient cooling sinks but are fundamentally limited by the moisture content in the air. Alone, these coolers can achieve temperatures that approach the dew point of the ambient air without adding humidity; however, they cannot dehumidify. Use of stand-alone indirect evaporative coolers is thus relegated to arid or semiarid geographical areas.

Simply combining desiccant-based dehumidification and indirect evaporative cooling technologies is feasible but has not shown promise because the equipment is too large and complex. Attempts have been made to apply liquid desiccant cooling to an indirect evaporative cooler core, but no viable design has been introduced to the market. DEVap attempts to clear this hurdle and combine, in a single cooling core, evaporative and desiccant cooling. DEVap’s crucial advantage is the intimate thermal contact between the dehumidification and the cooling heat sink, which makes dehumidification many times more potent. This leads to distinct optimization advantages, including cheaper desiccant materials and a small cooling core. The novel design uses membrane technology to contain liquid desiccant and water. Additionally, DEVap’s thermodynamic potential overcomes many shortcomings of standard refrigeration-based direct expansion cooling. DEVap decouples cooling and dehumidification performance, which results in independent temperature and humidity control. The energy input is largely switched away from electricity to low-grade thermal energy that can be sourced from fuels such as natural gas, waste heat, solar, or biofuels. Furthermore, DEVap is novel and disruptive, so bringing it into the entrenched conventional air conditioner market will create some market risk. Designing and installing a new DEVap system requires retraining. DEVap has unknown longevity and reliability compared to standard A/C. If these risks can be properly addressed, the DEVap air conditioner concept has strong potential to significantly reduce U.S. energy consumption and provide value to energy companies by reducing summertime electric power demand and resulting grid strain.

This 2 PDH online interactive presentation is designed for mechanical engineers, HVAC engineers responsible for air conditioning operations, and professionals involved in heating, ventilating, and air-conditioning (HVAC) technologies and analysis.