AN AMMONIA-WATER ABSORPTION REFRIGERATOR WITH A LARGE TEMPERATURE LIFT FOR COMBINED HEATING AND COOLING

The COP (Coefficient of Performance) of an ammonia-water absorption re frigerator can be significantly improved by incorporating a mixing col umn and a second absorber which is combined with a two-stage refrigera nt expansion. At an internal temperature lift of 85 K (-20 degrees C t o + 65 degrees C), these modifications result in a 50% higher COP for cooling-assuming ideal components. With real components, a 40% improve ment may be achieved. The proposed cycle was realised in a laboratory test plant with a refrigeration capacity of 10 kW at -20 degrees C eva porator temperature. This machine was operated at a solution temperatu re up to 225 degrees C and a condenser temperature of 65 degrees C cor responding to a pressure up to 3.0 MPa. COP versus temperature lift an d load behaviour was tested. A COP of 0.38 was achieved at a temperatu re lift of 85 K. An efficient high-temperature lift cycle like that de scribed in this paper may find applications for deep freezing, as a to pping cycle to achieve triple-effect performance, or as a device to pr oduce simultaneous heating and cooling. (C) 1998 Elsevier Science Ltd and IIR. All rights reserved.