Benefits of closed display cabinets for food preservation
Closed refrigerated display cabinets are increasingly used in retail stores because of their many advantages, particularly a significant reduction in warm and humid air infiltration, compared with open cabinets. Several researchers have demonstrated through experimentation that closed display cabinets achieve several favourable outcomes including energy savings of 20–70%, reductions in internal temperature heterogeneity, and improved food quality. Moreover, doors can also provide better thermal comfort in retail stores due to less cold air spillage from the display cabinet. Given these benefits, doors have been installed to an increasing extent in various countries. Thus, an agreement reached between the French authorities and the major supermarket stakeholders aims to replace open display cabinets by closed display cabinets, and to ensure that by 2020, 75% of all display cabinets in use will be closed models.
In a recent article1 published in the International Journal of Refrigeration, researchers from France (IRSTEA and AgroParisTech) and Thailand (KMIT Ladkrabang) investigated the influence of operating conditions, i.e. the frequency of door openings, ambient temperature and percentage of occupied volumes, on the thermal performance of a closed refrigerated display cabinet.
They showed that the product position in the cabinet is a determining factor of its temperature: a high temperature was observed at the front, particularly at the top of the cabinet, and a low temperature was observed at the back. Air infiltration due to door openings caused a product temperature increase at the front and a temperature decrease at the back. At a higher door opening frequency (more than 60 openings per hour per door), the product temperature at the level of the front middle shelf was the most affected. Both the ambient temperature and occupied volume also affected product temperature variations in the closed display cabinet.
However, in comparison to an open display cabinet, a closed display cabinet achieves lower product temperature and better temperature homogeneity, even with a high door-opening frequency. These findings indicate that the use of closed refrigerated display cabinets is strongly recommended to achieve better food preservation.
1 Chaomuang N., Flick D., Denis A., Laguerre O. Influence of operating conditions on the temperature performance of a closed refrigerated display cabinet [in] International Journal of Refrigeration, Vol. 103, July 2019, p. 32-41
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