Performance Analysis of Low-Capacity Water-LiBr Absorption-Cooling Systems Using Geothermal Heat-Sinks in Hot Climates

This paper addresses the use of a geothermal heat-sink to remove the heat released in domestic-sized single and double-effect water-LiBr absorption chillers operating in hot climates. This study is the continuation of a previous work, which demonstrated the operational constraints of these absorption chillers working in hot Algerian climate-zones. After localizing the non-operation zones for both systems, the thermo-physical properties of the soil at several depths are investigated for the implementation of the underground heat-exchanger. This heat-exchanger is connected to the condenser and the absorber of both systems, to supply cooling water at inlet temperatures of 33 degrees C in hot climate conditions, with ambient temperatures varying from 38 degrees C to 42 degrees C. The results show a steady operation for both absorption chillers in climate conditions which had not previously allowed the two systems to operate in water or air-cooled modes. A maximum coefficient of performance of 0.76 and 1.25 is obtained for single- and double-effect absorption cycles, respectively, with chilled water at 7 degrees C. The underground-tube length required is between 4.5 and 18 m, depending on the absorption-cycle configuration and the temperature of the chilled water.

Automated summary

This study investigates the use of a geothermal heat-sink for removing heat from single and double-effect water-LiBr absorption chillers in hot climates. The results show that both absorption chillers can operate steadily with the implementation of an underground heat-exchanger, providing cooling at inlet temperatures of 33 degrees C. The maximum coefficient of performance achieved is 0.76 and 1.25 for single- and double-effect absorption cycles, respectively, with chilled water at 7 degrees C. The required length of the underground-tube ranges from 4.5 to 18 m, depending on the system configuration and chilled water temperature.