Experimental investigation on the characteristics of a controllable separate heat pipe-based cold storage temperature control system

Abstract

PCM cold storage systems have been widely employed in household refrigerators due to their economy and efficiency. However, the PCM heat transfer process is out of effective control, limiting the accurate temperature control ability of the system. Herein, a controllable separated heat pipe that can regulate heat transfer is introduced into the PCM cold storage system to resolve its issues. A novel controllable separate heat pipe-based cold storage temperature control system is proposed. The dynamic temperature control ability and cold storage characteristics of the system under various operating conditions are revealed through experiments. As a result, the spatial inhomogeneity of the temperature field of the PCM is discovered which is related to the unsteady heat transfer between the PCMs in different regions and to the on–off state of the controllable separate heat pipe. In the discharging mode, the stable temperature control time of the compartment decreases by 53% when the temperature decreases from 7 °C to 1 °C. In addition, a lower inlet temperature of the ethylene glycol solution results in faster cold storage rates and greater temperature differences of the PCMs in different regions (the maximum temperature difference is 3.47 °C when the inlet temperature is −26 °C). Moreover, the results of door opening experiments show that the temperature can be controlled within an accuracy of 2.5 °C when the door opening time is 60 s, demonstrating the temperature regulation ability of the system. The results verify the feasibility of the technical route and provide a valuable reference for the optimization of precise temperature control systems.