This is a report by Applied Research Associates, Inc. (ARA), under contract to the US Department of Defense Environmental Security Technology Certification Program (ESTCP) (see http://www.dtic.mil/get-tr-doc/pdf?AD=AD1022577). A hybrid Environmental Control Unit (HECU) technology was demonstrated in which the integrated heat exchangers, filled with Phase Change Material (PCM), were fitted into a facility’s air conditioning system at the Tyndall Air Force Base, Florida. The PCM acts as a thermal battery storing cold energy to supplement the facility’s ECU operations reducing operational energy consumption, peak demand, and cost. After extensive pre-demonstrationtesting at ARA facilities, two methods of integrating PCM into a facility’s air conditioning system emerged: 1) PCM-filled coils suspended under ceiling air registers, a simple retrofit, this method targeted continuous PCM use by ensuring the coils were always in the path of air flow. 2) Peak Load Shaving (PLS) using a large PCM-filled coil. This PLS method used PCM module with large thermalstorage capacity to absorb heat and maintain room temperature during the peak demand period of the day. The air conditioner then regenerated the PCM during early morning hours, when the air conditioners ran more efficiently and the price of electricity is lower. The ceiling PCM-filled coils demonstration showed a 19% reduction in air conditioning energy use compared to the baseline. While, the PLS demonstration, using storage capacity for 1/3 of the peak period, showed 1.47% energy savings and based on Tyndall AFB
electricity pricing reduced the air conditioning energy cost by 6.2%.
(Image courtesy of Applied Research Associates, Inc.)