The use of closed refrigerated display cabinets in supermarkets is in progression because of the potential energy saving compared to the open ones with an air infiltration at the front. However, the influence of the presence of doors on product temperatures (determining factor of product quality) is much less studied. For better understanding the interest of the use of closed display cabinets, this chapter presents the state of the art of field studies, the airflow and temperature profile in the closed display cabinet, the influence of the presence of doors/the frequency of door openings and the room temperature. Finally, a literature review of studies on food quality in the closed display cabinet is presented.
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About 66-77% of heat input in an open refrigerated display cabinet come from the infiltration of warm and humid ambient air in a supermarket (Gaspar, Carrilho Gonçalves, & Pitarma, 2011; Tassou, Ge, Hadawey, & Marriott, 2011) which is one of the main causes of internal temperature heterogeneity. Temperature differences of more than 5°C can be found on cabinet shelves (Willocx, Hendrick, & Tobback, 1994) where the highest temperature is regularly located at the front of the cases (Evans, Scarcelli, & Swain, 2007; Laguerre, Hoang, Osswald, & Flick, 2012). To overcome this major drawback, installation of doors becomes an alternative and attracts more and more attention, and it will account for 75% of all display cabinets in retail stores by the end of 2020 in France (RPF, 2016). Closed refrigerated display cabinets have been increasingly used because of their potential energy savings of between 20-70% (Fricke & Becker, 2010; Lindberg, Axell, & Fahlén, 2010; Rhiemeier, Harnisch, Ters, Kauffeld, & Leisewitz, 2009; Rolfsman & Borgqvist, 2014). Such savings were mainly achieved through a reduction in the entrainment of ambient warm and moist air into the shelves-space storage, thus, less frost is deposited on cooling coils and compressor energy demand becomes less (Faramarzi, Coburn, & Sarhadian, 2002). The difference in the energy consumption from these studies depends on a number of factors, for example, the number of door openings, the door itself, the door seals/gaskets and the level of air infiltration during door openings (Evans, 2014). Among these influencing factors, the frequency, duration of door openings and air gaps between the doors are important which can result in higher energy consumption (Li, Zhu, Wang, & Zeng, 2007). The refrigeration energy consumption of closed display cabinets during stable night condition was approximately 10% lower than that of the display cabinet operated under periodically door openings (Vallée, 2015). Despite these findings, the energy consumption between these two cabinet types may not significantly different when the estimation of the mean total energy consumption is based on a unit display area because of the difference of cabinet design (Evans & Swain, 2010). Further research is required to access additional data.