GB1000343A - Defrost means for refrigerated cabinets - Google Patents

Abstract

1,000,343. Refrigerators; defrosting. DUAL JET REFRIGERATION CO. May 25, 1964, No. 21447/64. Heading F4H. The evaporator of an open-fronted display case is defrosted by hot gas from the compressor the flow of hot gas being arranged to induce a flow of liquid refrigerant from an auxiliary refrigerant supply and the flow of liquid refrigerant being heated to produce refrigerant vapour which augments the hot gas flow to the evaporator. As shown in Fig. 1, the display case 10 has an open port 22 across which panels 58, 60 of air are circulated, and passages 38 and 40 for recirculating air from the inlets 64, 62 to the outlets 56, 54, evaporators 42 and 48 being positioned in the respective passages 38, 40. As shown in Fig. 4, evaporators 42, 48 are connected in parallel in a refrigeration system including a compressor 104, condenser 106, receiver 108 and a hot gas line 132 having a heater 134 and valve 138. A container 136 is arranged in receiver 108 to receive liquid refrigerant from the condenser, the end 130 of which depends into the container so that when valve 138 is opened the flow of hot gas through line 132 induces liquid refrigerant from the container 136 to flow through the condenser and into line 132. The liquid refrigerant is converted into vapour by heater 134 and forwarded to evaporator 42 together with the hot gas from the compressor. Valves 122 upstream of the evaporators and a valve 137 downstream of evaporator 42 are closed during defrosting, valve 137 being by-passed by a capillary tube 140 through which refrigerant returns to the compressor. Frost accumulation on the evaporator 42 is distributed more evenly by forming the passage 40 upstream of the evaporator of a greater cross-sectional area than the evaporator, the walls of the passage being converged to engage the evaporator at a point intermediate its ends so that air can enter at the sides of the evaporator as well as at its leading end (Fig. 5, not shown). In modifications (Figs. 2 and 3, not shown), the air circulates across opening 22 from top to bottom and an additional air panel with an associated recirculatory passage is provided. The heater 134 is arranged to operate during the time intervals between defrost cycles to preheat line 132. Specification 997,240 is referred to.