Thermoeconomic optimization of LiBr/H2O-R134a compression-absorption cascade refrigeration cycle

• Thermoeconomic analysis was made first time for compression-absorption cascade cycle.
• This cascade cycle has potential to reduce electric energy consumption about 50%.
• (COPcyclegen) of the cascade cycle are improved about 7%.
• The exergetic efficiency of the cascade cycle are improved about 3.1%.
• The minimum cost flow rate is determined as 4.05 ($/h) for optimum case.

This study presents the thermoeconomic optimization of LiBr/H2O-R134a compression-absorption cascade refrigeration cycle. The detailed exergy-based thermoeconomic analyses, thermoeconomic evaluation with exergoeconomic variables, and thermoeconomic optimization by using non-linear simplex direct search method have been performed for the cascade refrigeration cycle. In the sample application, the thermoeconomic optimization reveals the optimum generator temperature, condenser temperature, absorber temperature, condenser temperature of vapour compression section, effectiveness of solution heat exchanger and compressor isentropic efficiency. This analysis points out that the evaporator equipage and solution heat exchanger should be designed carefully according to the exergoeconomic factor values. The exergetic efficiency and minimum cost of objective function are determined as 7.30% and 4.05 ($/h) for the optimum case of sample application. The minimum cost of objective function is reduced about 3.3%, the coefficient of performance (COPcyclegen) and exergetic efficiency of cascade cycle are improved about 7% and 3.1% respectively, according to the base case.