蒸気圧縮式冷凍機と低温潜熱蓄熱器を組み合わせた冷熱の高効率生成

Abstract

To level the electric load and increase the efficiency of cold heat production, a new cold heat storage-heat utilization air conditioning system incorporating PCM(phase-change material with a melting temperature of 13℃) in conventional VCRM(vapor compression refrigerating machine) was proposed. In this system, the cold heat is stored in PCM13 during the VCRM operation in the night-time. Subsequently, the cold heat stored in PCM13 is rleased for use as a coolant in the VCPM condenser in the case of high COP(coefficient of performance) during daytime. Energy savings of the proposed system were compared with the conventional cold heat production system with ice in terms of the cooling load of a standard office and a residence in summer in Tokyo. This comparison was based on estimation of COP of VCRM from p-h diagram of hydrofluorocarbon refrigerant, R134a. As a result, the energy saving of the proposed system, compared with the ice thermal storage in terms of power input of cold heat of 5℃, was 13% and 11% for a standard office and a residence, respectively. The higher energy saving obtained for a standard office was attributed to the fact that the cooling load is distributed over day-time in the office, while in the residence, it is highest at night-time. Finally, when ice was replaced with PCM13 in a conventional ice thermal storage, the energy consumption was reduced by 47% and 49% for a standard office and a residence, respectively. However, the temperature of cold heat supplied was 18℃ which was too high to dehumidify the air in the air-conditioning process.