Performance Simulation Model of a Radiation-Enhanced Thermal Diode Tank-Assisted Refrigeration and Air-Conditioning (RTDT-RAC) System: A Novel Cooling System

This paper presents a novel technology to improve the energy efficiency of refrigeration and air-conditioning (RAC) systems by applying a condenser cooling approach. The approach is based on the integration of an innovative radiation-enhanced thermal diode tank (RTDT) with a RAC system. The thermal diode tank (TDT), consisting of heat pipes and an insulated water tank, is a passive device to generate cooling water at a minimum night ambient temperature. When the radiation-enhanced heat pipe (RHP) is equipped with the TDT, it becomes an RTDT, which could theoretically lower the water temperature below the ambient temperature. In this study, a radiation-enhanced thermal diode tank (RTDT) is proposed to supply cooling water to the RAC system. Simulation models for the proposed RTDT-assisted RAC (RTDT-RAC) system are developed in order to investigate the impacts of the tank size to cooling capacity (TS/Qc) ratio, day/night ambient temperature fluctuations on the system's coefficient of performance (COP) and the energy saving percentage (ESP). The results show that a greater day/night ambient temperature difference and a larger TS/Qc value can both enhance the COP and ESP of the RTDT-RAC system. The optimal and threshold TS/Qc values were 1 m3/kW and 0.18 m3/kW, respectively. These findings demonstrate the potential of the RTDT-RAC system to achieve significant energy savings and provide valuable insights for the design and optimization of an RTDT-RAC system.