Experimental study on the temperature management behaviours of a controllable loop thermosyphon

The loop thermosyphon with active heat transfer control capability is a promising solution for the temperature management of the fresh food compartment of cool-storage refrigerators or other precise temperature control devices. However, the frequently start-stop operating mode of the loop thermosyphon has not received enough attention, its active temperature management behaviours still requires further investigation. In this study, a controllable loop thermosyphon used in the temperature control of a fresh food compartment is developed and its start-stop is controlled by the temperature controller with the assistance of two magnetic valves. The performances of the controllable loop thermosyphon in long-term and start-stop operating modes are tested. The controllable loop thermosyphon with 35% filling ratio present highest heat transfer rate, reliable heat transfer capability, and good stability for the varying temperatures in the fresh food compartment. Based on this filling ratio, the heat transfer rate remains higher than 40 W during the long-term operating test. When the controllable loop thermosyphon operates in the start-stop mode, the start-stop cycle decreases from 39.4 min to 27.2 min and the operating ratio increases from 12.6% to 53.7% as the temperature of the fresh food compartment rises. Particularly, when the start-stop cycle reduces from 42.6 min to 18.1 min, the temperature control accuracy is improved from 2.0 °C to 0.4 °C. The results demonstrate that the controllable loop thermosyphon is promising as a novel precise temperature management device and is qualified for the use in cool-storage refrigerators.