Investigation of low-cost eutectic salts to ensure food products during power outages. (July 2023)

• Record Type: Journal Article
• Authors: Radebe, T.B.; Ndanduleni, A.U.C.; Huan, Z.
• Is Part Of: Journal of energy storage. Volume 63(2023)
• Publication Date: 2023-07
• Subjects: Phase change material -- Eutectic water-salt -- Domestic refrigerator -- Thermal energy storage -- Load shedding; Energy storage -- Periodicals; Energy storage -- Research -- Periodicals; 621.3126
• DOI: 10.1016/j.est.2023.106960
• Languages: English
• ISSNs: 2352-152X

Abstract

Abstract: Temperature-sensitive food products such as fruits and vegetables require refrigeration to minimise spoilage and prolong product shelf life for later consumption. To reduce food spoilage during power outages, a Phase Change Material (PCM) can be integrated into a domestic refrigerator to maintain the inside temperature constant. This study investigated three inexpensive eutectic water-salt solutions, KCl, MgCl2 and NaCl with a phase change temperature of −10 °C, −19 °C and −21 °C, because of their high latent heat and relatively low price. Transmission and air infiltration loads were used to determine the amount of PCM required to maintain the inside temperature of a KIC KBF 525/1 ME Refrigerator below 4 °C during an average 2.5-hour power outage in South Africa. From the heat loads inquired, 1.5 and 5 l were required. For both 1.5 l of KCl and NaCl the temperature of the refrigerated compartment exceeded 5 °C after 2.5 h. For the 5 l of KCl, however, the temperature of the refrigerated compartment took 20 h before exceeding 5 °C. For 5 l of NaCl, it was able to pull down the temperature and maintain 0 °C in the refrigerated compartment for close to 10 h. It took 1.5 l of KCl and NaCl 1 day and 3 days to fully solidify and 5 l of KCl and NaCl 2 days and 6 days. It was noted that to increase the heat transfer inside the refrigerator, it is advisable to use a PCM with the lowest phase change temperature, however, the PCM might not fully freeze if the freezer temperature is not drastically below the phase change temperature. Highlights: The prepared PCM maintained the inside temperature of a refrigerator below 4 °C during an average 2.5-hour power outage. This study investigated three inexpensive, eutectic saltwater PCM with different melting temperature and high latent heat. For both 1.5 litres of KCl and NaCl the temperature of the refrigerated compartment exceeded 5 °C after 2.5 hours. For the 5 litres of KCl, the refrigerated compartment exceeded 5 °C after 20 hours. It took 1.5 litres of KCl and NaCl 1 day and 3 days to fully solidify and 5 litres of KCl and NaCl 2 days and 6 days.