GB988874A - Heating and cooling system - Google Patents

Abstract

988,874. Refrigerating; defrosting. M. W. BRAINARD. Jan. 9, 1962, No. 845/62. Heading F4H. A compression refrigerating system comprises a plurality of evaporators, one of which is associated with a heating coil, and valve means operable to bypass the condenser and supply hot refrigerant vapour to the heating coil. As shown, the system comprises two evaporators 30, 35 located respectively in the freezing and cooling compartments of a refrigerated truck (Fig. 1, not shown). A unit A comprising a compressor 20, condenser 21 and liquid receiver 22 is mounted externally of the truck and refrigerant is supplied from the receiver 22 through liquid lines 27, 28 to the evaporators 30, 35 respectively, the evaporators being connected to the compressor by suction lines 23 and 24. A heating coil 40 associated with the evaporator 35 is connected to the compressor discharge line by a line 41 containing a normally closed valve 43 and to the receiver 22 by a line 42 containing a one-way valve 46. When the temperature of the cooling compartment becomes too low a thermostatic switch 48 adjacent the evaporator 35 closes valves 45 and 44 positioned respectively between the condenser and receiver and in the liquid line 28, and opens valve 43, thus supplying hot refrigerant vapour to the heating coil 40 which then functions as the system condenser. This serves to raise the cooling compartment temperature and to defrost the evaporator 35. A by-pass line containing a pressure relief valve 47 is provided for the valve 45. When the evaporator 30 requires defrosting a switch 54 is operated to open a valve 51 in a line 50 connecting the compressor discharge line to the inlet of evaporator 30, and to close a valve 52 in the liquid line 27. Means 55 are provided to prevent valves 43 and 51 from being operated at the same time.