GB773721A - Improvements in refrigerating systems of the continuous cycle absorption-type - Google Patents

Abstract

773,721. Refrigerating. BORSIG, AKT.- GES. June 7, 1955, No. 16355/55. Class 29 In a continuous cycle absorption system the evaporator and absorber of which are at a lower pressure than the generator and condenser, strong solution is supplied from the absorber to the generator by two differential piston pumps 12, 14, connected in parallel and actuated respectively by high pressure refrigerant vapour and by weak solution flowing from the generator to the absorber. Refrigerant vapour flows from generator 1 through rectifier 4, pipe 5 and diphlegmator 8 to condenser 11. Liquid refrigerant flows from condenser 11 to receiver 16 and then through expansion valve 17 to evaporators 18, 20 connected in series, valve 17 being controlled in accordance with evaporator pressure. Weak solution flows from generator 1 through standpipe 2, liquid heat exchanger 13, the driving cylinder of pump 14 and float valve 24 to an absorber vessel 23. Strong solution is withdrawn from vessel 23 through standpipe 32 by pumps 12, 14 which force it through pipe 33, a liquid heat exchanger 26, a pipe 33a, the main liquid heat exchanger 13 and pipe 34 to the generator. High pressure refrigerant vapour from the outlet chamber 7 of diphlegmator 8 flows through pipe 28 to the driving cylinder of pump 12. The spent vapour from this cylinder and vapour from the evaporators flow through pipes 35, 21 respectively to an injector 27 which withdraws absorbent from vessel 23 through pipe 22. Absorption takes place just downstream of the injector and the strong solution is cooled in liquid heat exchanger 26 and a cooling coil 25 before reentering vessel 23. Condenser 11 has an inlet valve 10 which prevents flow of vapour to the condenser until a predetermined pressure difference exists betwen the generator and the absorber, this difference being adequate to operate pump 12. Refrigerant vapour flowing through pipe 28 to the pump 12 is throttled by a valve 29' responsive to the generator temperature and further throttles can be provided upstream and/or downstream of the driving cylinder of pump 12. The heat supply to the generator is controlled by a valve 36 actuated in response to the pressure of the generator and/or the absorber communicated through pipes 38, 37. Diphlegmator 8, condenser 10, vessel 23 and coil 25 may be air-cooled but, as shown, are all located in a water tank 39 and a valve 9 allows water flow when the condenser pressure exceeds a predetermined value. If tank 39 is the heat output of a heat-pump then the temperature of the water can control valve 9. To prevent condensation in the driving cylinder of pump 12, that cylinder or the driving vapour can be heated. The float valve 24 controlling the supply of weak solution may be omitted and a valve, placed in the weak solution pipe, is closed whenever the liquid level in generator 1 falls below the top of stand-pipe 2. In a modified evaporator construction, Fig. 2, liquid is fed through a float valve 7a to flooded evaporator 18 the outlet of which has a valve 19a progressively closed if the refrigerant concentration in the absorber, and thus the absorber pressure, falls. This closing causes the pressure difference between evaporator 18 and the absorber to rise and liquid refrigerant, and any extraneous absorbent, is forced through pipe 19b and the second evaporator 20 to the absorber to increase the concentration therein. The Specification describes in detail the construction of the pumps 12, 14.