Experimental investigation on a vertical display cabinet with central air supply

The frosting and defrosting of air cooler in a display cabinet usually lead to a large temperature fluctuation, thus increase the energy consumption of the display cabinet. In this paper, a vertical display cabinet with central air supply (VDCCAS) is established, experimented and compared with a conventional vertical display cabinet (CVDC). The refrigeration system of the VDCCAS consisting of a compressor, a condenser, a thermostatic expansion valve (TEV) and an evaporator is independent of the cabinet in a VDCCAS, and the cold air cooled by the evaporator is supplied through the air duct to the cabinet to realize refrigeration. Comparing to the CVDC, the VDCCAS can easily control the air curtain velocity, decrease the frost magnitude, increase the defrost cycle from 6 h to 9 h, and reduce the maximum product temperature rise in the defrost cycle from 3.0 °C to 2.0 °C. To reach the lowest temperature distribution in the cabinet, the optimum velocity of the air curtain is 0.7–0.8 m/s and the optimum Reynolds number is 4350–5000. When two cabinets work together, the airflow ratio of the two cabinets should be 1.1–1.2 in order to keep the temperature balance between the two cabinets.