Exergy analysis of organic Rankine cycle for waste heat recovery using low GWP refrigerants

Abstract

The use of exergy analysis in thermodynamic systems, as well as energy analysis, is quickly increasing. Exergy analysis is useful for identifying processes that cause exergy destruction and losses, and it may be used in conjunction with energy analysis. Due to environmental concerns, the use of waste heat has received a lot of attention in recent years. The Organic Rankine Cycle (ORC) is a promising method for converting waste heat into usable work at low temperatures. In this research, both the Basic Organic Rankine Cycle and the Regenerative Organic Rankine Cycle are considered for the analysis. Python is used for the simulation process. This investigation shows that the regenerative ORC has higher thermal and second law efficiency and a lower exergy destruction rate compared to the basic ORC. The Global Warming Potential (GWP) and Ozone Depletion Potential (ODP) of R1233zd(E), R1234ze(Z), R1234ze(E), and R1234yf are considered low. R1233zd(E) had a 1–5.66% and a maximum of 4.17% lower second law efficiency than R113 in regenerative ORC and basic ORC, respectively. On the other hand, R113 is not an eco-friendly fluid. As a result, R1233zd(E) can be used in place of R113 to assure better environmental quality by sacrificing a small portion of efficiency. The fluids which have a higher critical temperature showed better results compared to the fluids which have a lower critical temperature. Throughout the study, R1233zd(E) performed better than the rest of the three fluids. In both basic and regenerative ORC, R1233zd(E) has higher thermal and second law efficiency.

Keywords

• Organic Rankine cycle
• Global warming potential
• Ozone depletion potential (ODP)
• Exergy and waste heat