Study of the flow and heat transfers in a wall jet carrying droplets mist-flow in refrigerated display cabinets
Etude de l'écoulement et des transferts thermiques dans un jet pariétal chargé de gouttelettes - Utilisation de la brumisation dans les meubles de vente
Résumé
From production to consumption, throughout the so-called cold chain, food requires strict temperature control. Display cabinets play an essential role in food conservation as they are considered as one of the weakest links of this chain. Most of the refrigerated cabinets are forced-air open display cabinets. An air curtain separates frozen-food from the ambient air. Nevertheless, changes of the ambient conditions can cause dramatic differences on the temperature of the load. The temperature of the warmest products can be higher than the maximal authorised temperature by European standard. This study takes part of a project concerning the use of mist injection to improve performances of refrigerated display cabinets. In a first step, flow simulations give a global view of the flow inside the cabinet. Then, temperatures that can be reached in the products without injection of mist, are calculated solving the energy equation. The introduction of a discrete phase model enables the prediction of the droplets deposition rate along the products surface. Three different approaches are considered in order to take into account the heat transfer due to droplets evaporation on this surface. Mesures realized on a cabinet permit, on the one hand, to draw a velocity map of the air curtain, and, on the other hand, to estimate the heat transfer coefficient evolution along the products surface.