Comprehensive study on waste heat recovery from gas turbine exhaust using combined steam Rankine and organic Rankine cycles
Tanatip Kittijungjit, Thepparat Klamrassamee, Yossapong Laoonual, Yanin Sukjai
Abstract
• The study focused on a comprehensive assessment of waste heat recovery systems based on thermodynamic performance, economic viability, carbon emission reduction, and exergy destruction. An open-source process modeling software, DWSIM, has been utilized to develop, process modeling, and analyze the waste heat recovery cycles. • The SRC + S-ORC + C-ORC configuration emerged as the most favorable across thermodynamics, economics, and carbon emission reduction criteria • Exergy Analysis: The evaporator has been identified as the component with the highest exergy destruction, indicating key areas for performance improvements. Waste heat recovery technology has proven to be an effective approach for enhancing energy efficiency, reducing greenhouse gas emissions, and lowering energy costs. This study assesses the performance of different waste heat recovery systems from thermodynamic, exergy destruction, economic, and environmental perspectives. Using the DWSIM software, the study simulated a waste heat recovery cycle powered by a high-temperature heat source (508.99 °C) to maximize recovery power and determine the optimal system configuration, including standalone Organic Rankine Cycle (ORC), standalone Steam Rankine Cycle (SRC), and combined systems like SRC with series ORC (SRC + S-ORC), cascade ORC (SRC + C-ORC), and a combination of both (SRC + S-ORC + C-ORC). Among these configurations, the SRC + S-ORC + C-ORC configuration delivered the best performance, achieving a net power output of 3,532.14 kW and a thermal efficiency of 17.09 %. Economically, it demonstrated strong results with a net present value of €1.478 million, a payback period of 8.01 years, and a benefit-cost ratio of 1.32. This configuration also had the highest environmental impact, reducing CO2 emissions by 12,452.48 metric tons per year, equivalent to annual earnings of approximately €999,933.85 through carbon credits trading. The study also found that the evaporator experienced the most significant exergy destruction, suggesting opportunities for improving the highest exergy destruction area, leading to an increase in overall system efficiency. In conclusion, the SRC + S-ORC + C-ORC configuration offers the most promising combination of thermodynamic, economic, and environmental benefits for waste heat recovery systems.