Investigation of thermal architectures for flue-gas assisted organic rankine cycle systems: An assessment for thermodynamics and environmental performance indicators

Abstract

In calculations of future energy demand and environmental pollution problems in which waste-heat recovery play a significant role, efficiency often is the primary factor. The organic Rankine cycle (ORC) continues to attract the widespread interest of researchers and/or manufacturer due to technical compatibility, feasibility, and reliability for low to medium grade waste-heat sources. This paper presents thermo-economic analysis on flue-gas assisted organic Rankine cycles (FGA-ORCs) based on both energy and exergy concepts. The heat source of the FGA-ORC system is the exhaust flue-gas of a stenter-frame which is highly used in the textile finishing process. In this study, to convert thermal energy into electrical and/or mechanical energy, an optimization study is performed using three different cycle architectures which have two turbines. Performance indicators such as thermal efficiency, exergetic efficiency, economic profit, performance ratio, and carbon footprint index were examined for the different operating conditions of three investigated thermal architectures. Finally, under the specified operating conditions, the thermal architecture with the best thermo-economic performance was determined by the reduced exergy destruction and increased economic profit due to increased net-work output.