Exergy assessment of an Organic Rankine Cycle for waste heat recovery from a refrigeration system: a review

Abstract

The increased use of fossil fuels in the industry has resulted in severe environmental issues, such as ozone depletion, air pollution, and climate change, among others. Due to diverse resources, such as biomass, solar radiation, and so on, approximately half of the energy produced worldwide is discarded as heat. Utilizing this waste energy as heat reduces fuel usage, reduces carbon dioxide (CO2) emissions, and improves overall system performance. The Organic Rankine Cycle (ORC) is the most efficient and reliable method of converting waste heat from low and medium temperatures into usable power. Exergy refers to the maximum amount of work a system can perform in any state and any environment. Engineers are employing exergy analysis to optimize every system, according to recent research. It comprises assessing and improving system performance utilizing exergy basics, equation balance, and exergy efficiencies. It also facilitates identifying critical sources of exergy loss, which may subsequently be targeted for reduction. This study provides an overview of the exergetic assessment of vapor compression refrigeration systems (VCRS) utilizing ORC. The thermodynamic, environmental, and selection features of 29 different organic fluids, as well as their selection corresponding to the heat source temperatures, are all discussed in this article. The findings of this research include a comparison of these refrigerants under various operating conditions. The primary purpose of this research is to provide a full ORC review for discarded heat retrieval from a refrigeration system, which includes benchmarks for working fluid selection and the impact of operating limits.