Improvements in and relating to heat interchangers and refrigeration or cooling systems

723,702. Refrigerating. DOLE REFRIGERTING CO. Aug. 18, 1952 [July 23, 1952], No. 20724/52. Class 29. A heat-exchange plate for evaporating liquid refrigerant formed in an evaporator during defrosting, comprises a sealed evacuated housing containing heat storage material and two conduits, one a heating conduit and the other for the passage of refrigerant, each having an inlet and an outlet to the housing exterior. As shown in Fig. 3, the housing comprises two walls 1, 10 sealed together around their peripheries and the refrigerant conduit AI is defined by the wall 1 and an embossed intermediate wall 2. The space BI between the wall 2 and the wall 10 is filled with the heat storage material such as glycerine or alcohol and water, or an eutectic. The heating conduit comprises a tube 50 containing insulation 52 and an electric resistance heater 51. As shown in Fig. 5, the lower wall 20 is not in contact with the wall 2 but is in heat exchange relation therewith by means of partitions 22 held together by rods 23 and apertured at 26. The heating conduit 115b passes through the apertures 26. As shown in Fig. 7, the refrigerant conduit comprises a pipe 73 and the heating conduit comprises a pipe 74 for fluid located around the periphery of the plate. According to Fig. 8 (not shown), the refrigerant conduit is a pipe held between the two walls of the housing and the heating conduit is an electric heater within a tube of the same diameter as the refrigerant conduit. As shown in Fig. 9, an evaporator 107 is defrosted by hot gas flowing through pipe 103a and liquid refrigerant is re-evaporated in the conduit 116 of the plate A by heat from the heating conduit 115. Between the plate A and the compressor 100 is located a refrigerant trap 117 from which a lubricant return 117a leads to the suction pipe 118. The defrosting is initiated by a timing device B which opens valve 120 in pipe 103a, energises a fan 123 adjacent evaporator 107 and energises the heating conduit 115. A refrigerant dryer 109 and a flow indicator 108 are included in the circuit. Specification 707,102 is referred to.