Development of a thermo-gravity pumping mechanism for circulating the working fluids in a novel LiBr–H2O vapour absorption refrigeration (VAR) system

VAR systems are heat powered refrigeration or air conditioning systems that can be operated without the use of mechanical or electrical energy. However, inefficiencies due to the high operating temperatures and/or additional electrical energy for operating mechanical pumps as well as high capital cost hinder the extensive use of these systems. The development of a novel VAR system incorporating a thermo-gravity pump and with reduced cost is the subject of this paper. An experimental apparatus consisting of a single stage LiBr–H2O VAR system is described. The apparatus incorporates two novel thermally activated valves for aiding circulation of system working fluids and a novel regenerative heat exchanger for improving the generator's and absorber's effectiveness. This paper describes the design and operation of a thermo-gravity pump also referred to as thermally activated pumping mechanism for circulating the refrigerant H2O(l), water vapour H2O(v), weak and strong LiBr–H2O(l) inside a novel VAR system.

► We have demonstrated that VAR system can do away with use of electromechanical pump.
► We have shown how VAR system uses low-grade temperatures of the order of 75–85 °C.
► The system is efficient and compact than other DAR cycles of the same cooling rate.
► Since the system uses LiBr–H2O, it poses no risks of hazardous refrigerant leakage.
► Costs were estimated to be less than other DAR cycles of the same cooling rate.