Dynamic modelling and performance prediction of a novel direct-expansion ice thermal storage system based multichannel flat tube evaporator plus micro heat pipe arrays storage module

Direct-expansion ice thermal storage (DX-ITS) system can improve the energy efficiency ratio (EER) by integrating the evaporator and the storage module. In this paper, a dynamic model for a DX-ITS system is developed to predict system behavior. This system consists of multichannel flat tube evaporator plus micro heat pipe arrays storage module, a 4-HP compressor using R134a, an air-cooled condenser with 40 m2 area and an electronic expansion valve. On this basis, the influences of the condenser's cooled-air temperature, cooled-air flow rate, and compressor speed on the system energy and thermodynamics performance are studied. Results show that the EER and the charging power could reach 2.24 and 5.41 kW, respectively, under cooled-air temperature, cooled-air flow rate, and compressor speed of 28.5 °C, 4660 m3/h, and 1450 rpm. The exergy efficiency is more sensitive to cooled-air temperature, which decreases by 22.48% from 11.52% to 8.93% as the cooled-air temperature increases from 18 °C to 35.5 °C. Moreover, the compressor has the highest exergy destruction ratio of 40%–55% in the exergy analysis of the system component, while the condenser has the lowest exergy destruction ratio of 7%–15%, indicating that optimizing the compressor is the key to improving the system's performance.