Performance evaluation for thermal architectures of flue-gas assisted organic rankine cycle systems

Abstract

Effective use of waste heat at low and medium temperatures is considered as one of the solutions to alleviate energy shortages and environmental pollution problems. Due to its feasibility and reliability, the organic Rankine cycle is continued to attract widespread interest from researchers and/or manufacturers. This paper presents thermodynamic and economic analyses 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 textile finishing process. In this study, to convert thermal energy into electrical and/or mechanical energy on a small scale, an optimization study was performed using five different cycle architectures. Parametric studies were also carried out to investigate the effect of operating parameters on performance indicators such as efficiency, economical profit and performance ratio. Finally, under specified operating conditions, the thermal architecture was identified that reduces exergy destruction and increases economic profit due to increased net-work output. For analyzed cases in this study, Scenario-4 (i.e., thermal architecture 4) shows the best system performance with 69% exergetic efficiency within the thermodynamic and practical limits.