Patent GB-968490-A (GB)
Title: Air-conditioning apparatus
IPC: F24F3/10
Filed: 1963-07-02
Abstract: 968,490. Air conditioning. SULZER BROS. Ltd. July 2, 1963 [July 2, 1962], No. 26284/63. Heading F4V. In an air conditioning system of the induction type including means for heating and means for cooling the primary air and a heating and a cooling device for the fluid of a circuit supplying heat exchangers for the secondary air in the induction units, a by-pass is provided for bypassing return fluid around the cooling device and through a heater for primary air. As shown in Fig. 1, the induction units 14 are located in two zones N and S and are fed by pumps 30 either with hot water from the heating device 16 or with cold water from the cooling device 17 according to the setting of three-way shut-off valves 35 in the supply pipes to the units actuated simultaneously with three-way valves 40 in the return pipes by temperature detectors 57 sensing atmospheric temperature. Water may be recirculated through the units via branch return lines 43 according to the setting of mixing valves 36 controlled by temperature detectors 63 and 64 responsive to water temperature in the supply pipes 33 and to atmospheric temperature, their signals being compared in controlling units 65. The heating device 16 is supplied with steam through a pipe 19, the rate of supply being controlled by a valve 19 in response to a temperature-senser 26 in the water pipe 31 leading from the heating device. The cooling device 17 is cooled by a compression refrigeration circuit including a throttling valve (in addition to the expansion valve) controlled by a comparison of atmospheric temperature and temperature in the cold water supply line, Fig. 2 (not shown). Primary air is supplied to the induction units via a filter 3, electrostatic precipitator 4, preheater 5, humidifier 6, water droplet remover 7, cooler 8, after heaters 9 and 11, blower 1 and a silencer 12. If during cold weather operation when hot water is passed to the units 14 and the cooling device is normally inoperative, there is a temporary demand for cold water supply to the units 14, the valves 35 and 40 will cause water to flow to the units from the cooling circuit and atmospheric temperature sensers 51 and 55 will open valves 52 and 54 to cause return water to by-pass the cooling device 17 and flow through the after-heater 9 to cool the water. The valves 52 and 54 may also operate in response to a thermostat 62 in the primary air flow which also controls a valve 47 regulating hot water flow to the preheater 5 to keep the dew point of the primary air constant. Hot water flow to the afterheater 11 is controlled by a valve 46 in response to a temperature senser 61 in the primary air supply duct 13. Cold water may flow in variable proportions through the cooler 8 and a by-pass according to the position of a valve 48 controlled by a comparison of primary air temperature sensed at 58 and atmospheric temperature sensed at 59. In summer the humidifier 6 is inoperative and in winter it is operative. In a modification, Fig. 2 (not shown), separate heating and cooling devices 16 and 17 are provided for each zone N and S and a three pipe water supply system is adopted enabling the units 14 to be individually controlled; two by-passing after-heaters are provided, one for each of the cooling circuits; and the valves 52 and 54 for by-passing the cooler are manually controlled. In further modifications (not shown) a separate after-heater may be provided for each zone of a two-pipe system, or a common after-heater may be provided for a three pipe system. A two pipe system may have a single heat exchanger through which either a heating or a cooling medium flows in which case one zone may be cooled by return water while the heat-exchanger heats water for the other zone.