Simulation-assisted performance improvement of a refrigerated vending machine for high-temperature application

Vending machines are popular worldwide due to their convenience. Compared with indoor applications, the refrigeration system in vending machines at an elevated outdoor temperature introduced inevitable additional power consumption. In this paper, aiming at reducing energy consumption in high-temperature environments, the refrigeration system of a baseline vending machine was modified by two improvement designs. First, changing from the baseline single-fan configuration to the double-fan configuration could theoretically increase airflow uniformity by 7.8%, which directly translated to a measured reduction in system power consumption by 6.9%. Second, heat recuperation via the capillary tube suction line heat exchanger demonstrated 12% theoretical specific refrigeration capacity improvement potential at high ambient temperatures, and therefore, increasing the length of the heat recuperation section resulted in a 4.3% reduction in power consumption. The system-level integration of these two component-level modifications successfully achieved energy savings of more than 11.2%, serving as a role model for future refrigeration systems operated at high ambient temperatures.