PRELIMINARY STUDY ON ENERGY-SAVING PERFORMANCE OF A TRANSCRITICAL CO2 HEAT PUMP FOR FOOD PROCESSING INDUSTRY

摘要

In food processing, there are significant simultaneous demands of cooling (range: 0℃-15℃), warm water (range: 25℃-70℃) and hot water (range: 75℃-100℃) for washing, blanching, pasteurization, CIP (Cleaning-in-Place), and other processes. Most of the heated water is used only once rather than recycled. The water to be heated usually comes from environment and its temperature will vary as ambient temperature changes. In order to reduce energy consumption and greenhouse gases emission, a transcritical CO_2 heat pump system is proposed that can supply not only cooling, but also warm water and hot water simultaneously to meet the thermal demands of food processing. Simulation results showed that the potential primary energy saving rate of the proposed CO_2 heat pump is from 50% to 60% when inlet water temperature ranges from 5℃ to 30℃ during a year.