Experimental studies on combined cooling and power system driven by low-grade heat sources

An experimental investigation was undertaken to study the actual useful output and performance of a combined power and cooling system that uses low-grade energy. The cycle used was a combination of NH3-H2O absorption refrigeration cycle and Kalina extraction turbine cycle. The expected performance characteristics of the dual output system were first evaluated using an energetic and exergetic approach based on the quality of useful outputs; in the experimental confirmation. It was evaluated in Cooling Alone mode (CA mode) and Combined Cooling-Power mode (CCP mode), for the same operating conditions. The weak solution flow rate and generator temperature were maintained constant at 0.237 kg/s and 133 °C respectively throughout the experimental run. The maximum cooling load of 34.26 kW was achieved with a COP's of 0.57 in CA mode. In CCP mode, the system was operated at a split ratio of 0.5 with the useful cooling load of 15.26 kW and estimated expander load of 2.21 kW respectively, with power to cooling ratio of 0.14. The corresponding effective first-law and exergetic efficiencies were 13% and 48%. This study provides a feasible and flexible way to meet the desired combination of power/cooling ratio to generate varying demand profiles using available low-grade heat sources.