Experimental investigation of the effect of phase change material on backup time and equivalent energy consumption of domestic refrigerator

Load shedding is a significant problem in rural areas. During a power outage, the cabin temperature of a refrigerator increases owing to the heat gain. In practice, a door should be opened to load and unload refrigerator products, particularly when the power failure period is longer. The use of a phase-change material (PCM) in the refrigerator cabin restricts the increase in temperature and provides a backup time that reduces energy consumption. Door-opening tests are essential during a power cut-off time to investigate the reduction in backup time owing to door openings. This article presents an experimental investigation on the influence of PCM masses of potassium chloride (KCl), sodium chloride (NaCl), and sodium fluoride (NaF) dissolved in water on the backup time and equivalent energy consumption of a domestic refrigerator for closed and open doors according to the standards IS 1476 and IEC 62552:2015. The backup time of closed-door tests was significantly increased by the PCM for all masses, i.e., between 15 and 200 min in absolute terms and between 14% and 182% in relative terms. The backup time for the closed-door tests was 1.8–1.03 times longer than that for the door-opening tests. The backup time of door-opening tests decreased significantly owing to heat entering the cabin for all masses, i.e., between 50 and 10 min in absolute terms and between 45.45% and 3.23% in relative terms. The equivalent energy consumption of a refrigerator decreased with an increase in PCM mass. In closed-door tests, it varied from 0.55 to 0.41 kWh.6-1 h for the 0–1.75 kg mass of all tested PCMs. In the door-opening tests, the equivalent energy consumption increased owing to door opening. The equivalent energy consumption for the door-opening tests was 1.12–1.02 times larger than that for the closed-door tests.