Transient simulation of carbon dioxide booster refrigeration system with mechanical subcooler in demand response operation

Abstract

Transcritical carbon dioxide refrigeration systems are becoming more common as refrigerant regulations increasingly require the use of refrigerants with low global warming potential. The use of carbon dioxide in the booster cycle is one path toward near-zero global warming potential, but improvements to the cycle performance particularly at hot ambient conditions are needed to match the efficiency of incumbent technology. Also, as connectivity and grid flexibility become increasingly important considerations, the ability to use supermarket refrigeration equipment to provide load shedding and shifting is a topic of growing interest. The current article examines a transcritical booster system with mechanical subcooling, using transient models validated against laboratory test results. The model is used to examine the relative reduction in power for a shed of refrigerating capacity at either the medium-temperature or low-temperature evaporator level.