Patent GB-729709-A (GB)
Title: Improvements in or relating to air conditioning systems
IPC: F16D55/2255
Filed: 1953-08-24
Abstract: 729,709. Refrigerating; heat pumps. CARRIER ENGINEERING CO., Ltd. Aug. 24, 1953 [Nov. 28, 1952], No. 23348/53. Class 29. Relates to means for conditioning as to temperature and humidity the atmosphere in several compartments by means of the heat absorbing and emitting parts of a heat pump and to an automatic control system therefor. At least one compartment, e.g., the pump room 12 of a submarine, generally requires continuous cooling and therefore acts as the heat source of the system and does not require heating means. Heat pump (Fig. 1). As shown, two compartments 10, 11 each have a heating coil 45 and a cooling coil or evaporator 17, and the compartment 12 has only a cooling coil 17. Evaporators 17 are connected in parallel in a refrigerant circuit comprising a compressor 14, a condenser 15, a heat exchanger 16 and, for each evaporator, an expansion value 52 controlled by the superheat. The condenser may be air cooled but, as shown, water is circulated therethrough by a pump 35, the flow being regulated by a valve 38. The refrigerant flow to each evaporator is controlled by a valve 51 the solenoid of which is energized to open the valve upon a predetermined rise in either the humidity or temperature of the respective compartment. When the temperature of any compartment is below the prescribed minimum, the thermostat in that compartment acts : to vary the flow of cooling water through valve 38 to increase the discharge pressure and so cause condensation to take place in an auxiliary condenser 23 ; to energize a pump 42 which circulates water through the condenser 23 and through the cooling coils 45 ; and to control a mixing valve 48 which passes the heated water through the coil 45 and a by-pass 46 in such proportion as to supply the required amount of heat. Evaporators 17 may cool the compartments indirectly. Electric or other heaters may be provided for use if the heat pump is shut down. The condenser cooling water may be sea-water or, in a land installation, may be recirculated through a cooling tower. Control system. A fluid pressure control system is described, the air source being denoted at 63. Each compartment has a humidostat 59 and a thermostat 60 each acting to vent the air pressure upon decrease of the variable. The pressure is transmitted from these controls to the control 56 of refrigerant valve 51 through lines 61, 64 and a device 67 which causes the control 56 to be influenced by the line 61, 64, which has the higher pressure. Thus if either the humidity or temperature of the compartment, or both, is too high the valve 51 will be opened for the supply of refrigerant. When the temperature falls too low, the low pressure in line 64 causes the mixing valve 48 to open to supply hot water to coil 45 in the required degree. The low pressure is also transmitted to a relay 65 which has two actions. Firstly it operates the starter 73 for the motor 74 driving the hot-water circulating pump 42. Secondly, it operates a change-over relay 77 to alter the discharge pressure of the compressor in pipe 21. When no heating is required, the cooling water valve 38 is controlled by pressure device 89 responsive to the discharge pressure in pipe 21, the lines 78, 79 being connected by relay 77. When heating is required, relay 77 connects lines 78, 80 so that valve 38 is controlled by pressure device 90 responsive to pressure in pipe 21. Device 90 is set to maintain a higher pressure in pipe 21 than does device 89 and therefore acts to maintain a lower rate of flow of condenser cooling water.