Comparing and optimizing the potential advantages of a salinity-gradient solar pond for either absorption-based or ejector-based refrigeration cycles combined with thermoelectric generators

Abstract

This study compares the applicability of two popular refrigeration cycles for air-conditioning, i.e., absorption-based (Model 1) and ejector-based (Model 2), combined with a salinity-gradient solar pond. Indeed, there exists a gap in comparing the performance of solar pond-based refrigeration cycles to which this study intends to respond. In addition, utilizing zeotropic mixtures in an ejector refrigeration cycle integrated with a solar pond and selecting the most suitable zeotropic for such a framework has not been regarded in the literature. Both models are boosted using thermoelectric generators for low-temperature waste heat recovery and electricity generation. Energy, exergy, economic, and environmental investigations with a net present value analysis are implemented, and multi-objective optimization using non-dominated sorting genetic algorithm-II is conducted. As another principal point, this paper performs a case study to illustrate the performance of models regarding an actual climate condition. Results show that using Butane-R143a zeotropic increases the advantages of Model 1; however, Model 2 is the most suitable selection for the solar pond. According to the optimum state, Model 1 possesses exergy efficiency and Levelized cost of products of 17.93% and 0.12 $/kWh, which are 0.84 percentage points and 83% better than Model 2. But Model 2 has a better environmental performance by mitigating 22% further carbon dioxide than Model 1.