Advanced Exergy and Exergoeconomic Analysis of Cascade Absorption Refrigeration System Driven by Low-Grade Waste Heat

A cascade absorption refrigeration system, which utilizes low-grade waste heat, was investigated by an advanced exergy analysis and an exergoeconomic analysis that are compared with a conventional method. In the advanced analysis, the exergy destruction rate, exergy destruction cost rate, and investment cost rate of each component in the system are divided into endogenous/exogenous parts and avoidable/unavoidable parts. The results show that 24.44% of the exergy destruction rate, 23.80% of the exergy destruction cost rate, and 17.68% of the investment cost rate can be avoided by system optimization. The LiBr heat exchanger has the highest exergy destruction rate (437.447 kW) and highest exergy destruction cost rate (7.257 $/h), while the NH3 generator has the highest avoidable exergy destruction rate (95.309 kW) and highest investment cost rate (7.502 $/h). Most exergy destruction rates and corresponding exergy destruction cost rates are endogenous; thus, optimizing the components is necessary. In addition, the results of the exergoeconomic factor show that the investment cost rate of most components needs to be optimized. The sensitivity of parameters has a significant impact on the system. An advanced exergy analysis and an exergoeconomic analysis provide valuable information for optimizing the irreversibility and inefficiency of the system.