Patent GB-911316-A (GB)
Title: Vapour cycle refrigeration system
Inventor: LEECH DONALD JOHN
IPC: F24F5/00
Filed: 1960-01-30
Abstract: 911,316. Refrigerating. NORMALAIR Ltd. Jan. 13, 1961 [Jan. 30, 1960], No. 3389/60. Class 29. [Also in Group XXIX] In an aircraft the cabin air of which is cooled and dried by the evaporator of a compression refrigerating system, the compressor and condenser fan are driven by turbines supplied with air from the aircraft engines and the compressor speed is regulated in accordance with the cooling load. Refrigerant circuit.-From compressor 1 refrigerant flows through pipe 7, 6 to condenser 5 feeding receiver 9. Liquid refrigerant then flows through pipe 12, 13 to expansion valve 240 supplying evaporator 11 whence gaseous refrigerant returns to the compressor through suction pipe 18, 19. Downstream of the evaporator in the air circuit is a moisture separator 15. The suction and liquid supply pipes include disconnectable units 17, 16, including automatically closing check valves. The expansion valve maintains a constant superheat by means of pipes 249, 250 connected to opposite sides of valve diaphragm 245 and detecting respectively the suction pressure and temperature. Should the compressor surge at light loads, a valve 180 allows compressed gas to flow from discharge pipe 7 through pipes 181, 182 to the compressor inlet pipe 19. Some liquid refrigerant from the condenser outlet flows through pipe 212 to pipe 181 to cool the recirculated gaseous refrigerant. Pipe 212 includes a dryer 214 through which all the refrigerant alternately passes. Compressor 1 and condenser fan 100 are driven by turbines 2, 101 supplied with compressed air through pipes 3, 102, including control valves 86, 109. Condenser cooling air louvres 120 operated by a control device 140 are provided. Regulation of speed of turbine 2 and the compressor.-Valve 86 in the air supply pipe 3 to turbine 2 is moved to closed position by spring 85 acting on diaphragm 82 but normally held open by air-pressure supplied to chamber 83 through pipes 92, 93, 94 by closure of manual switches 90, 114, this high pressure can be cut-off due to closure of solenoid valve 89 to stop the compressor. The chamber 83 can be bled to close valve 86 by venting pipe 88 through valves 281 responsive to racing of the compressor and 97 responsive to excessive compressor discharge pressure. Pipe 88 is also connected to venting valve 60 which is opened in responsive to lowered suction pressure conveyed to valve control chamber 57 through pipe 59. The control point of valve 60 is varied by a modulating unit 50 operated by a thermal element in the cabin so that the temperature of the latter is kept constant. Surge control valve 180.-Normally a valve 195 is held closed by the diaphragm 189 responsive to the difference between the dynamic and static discharge pressures conveyed to the valve chambers by pipes 210, 211. This allows a spring 192 to act on diaphragm 191 to hold closed valve 198 between by-pass pipes 181, 182. When the refrigerant flow drops, the pressure difference drops and valve 195 is opened so that high-pressure refrigerant is supplied therethrough to chamber 186 and overcomes spring 192 to open by-pass valve 198. Condenser fan turbine control.-Valve 109 in high pressure air supply pipe 102 to turbine 101 is normally held closed by spring 108 acting on diaphragm 105 but is maintained open by high-pressure air supplied to chamber 106 through pipes 116, 115, 93, 94. When a switch 114, which can be hand-operated or operated by retraction of the under-carriage, is closed a solenoid valve 113 in pipe 116 is closed and valve 109 is shut. Thus, when the aircraft is in flight, fan 100 does not operate and the condenser is cooled only by ram air. The chamber 106 is also vented to close valve 109 when a valve 111 is opened in response to low condenser pressures. Condenser louvre control.-The louvres 120 are normally held open by high pressure air supplied to diaphragm chamber 143 through air pipes 151, 115, 93, 94. At low condenser pressures, however, this pressure is vented through valve 152 to close the louvres.