GB1085126A - Three-pipe air conditioning systems - Google Patents

Abstract

1,085,126. Heating and cooling buildings; air conditioning. SULZER BROS. Ltd. Nov. 16, 1964 [Nov. 19, 1963], No. 46604/64. Headings F4U and F4V. A three-pipe air conditioning system having hot and cold water supply lines to room unit heat exchangers includes by-passes leading water from the hot and cold lines downstream of the units to the water heater and cooler respectively. As illustrated, pumps 20 pass water from the heater and cooler 9 and 10 to hot and cold headers 21 and 22 and thence via hot water lines 40 and cold water lines 41 to room units 8 of various building zones N, E, S, W, the supply of water to the individual units being controlled by three-way valves 53. Return lines 46 pass water into hot or cold water return lines 63, 64 according to the setting of three-way valves 66 controlled by temperature sensors 65 in the return lines 46. By-passes 55 and 56 lead hot and cold water from the lines 40 and 41 downstream of the units 8 to headers 57 and 58 connected to the hot and cold return lines 63 and 64. The by-passes have throttle elements 59 and 60 allowing adjustment to compensate for different flow resistances in the buildings. In each zone a pressure difference controller 44 acting through a relay 47 adjusts a hot water line valve 42 to maintain a constant pressure difference between that line and the return line 46, and a pressure difference controller 45 acting through a relay 48 adjusts a cold water line valve 43 to maintain the pressure difference between that line and the return line 46 at a set value determined by external sensors 49 and 50 responsive to solar radiation and external air temperature respectively. The heater 9 is heated by a heat exchanger connected by lines 23 and 24 to a boiler, and heat is extracted from the cooler 10 by an intermediate water circuit having a pump 36 and given up to the evaporator 30 of a refrigeration circuit. The intermediate water circuit temperature is maintained constant by means of a cooler by-pass 37 operated by a valve 35. Heat is removed from the refrigeration condenser 28 by a circuit including lines 31 and 33 which are shunted by heat exchangers 68 and 69 in the hot and cold water return lines 63 and 64. Air treatment.-The room units 8 are of induction type having secondary air heat exchangers fed by the three - pipe system, primary air being supplied by a blower 2 from a central station 1. The latter includes mechanical and/or electrical dust filters 3, a preheater 4, a scrubber and humidifier 5, a cooler 6 and a heater 7, each of which may be wholly or partly by-passed. The air heaters and cooler derive heat from the heater 9 and give heat up to the cooler 10 respectively, and a thermostat (not shown) maintains the air temperature immediately downstream of the preheater 4 at at least 2‹ C. Water for the humidifier 5 is heated by a heat exchanger 70 connected in the return line 63 to the heater 9.