Optimization of Organic Rankine Cycle with different working fluids using Taguchi method

Abstract

In the scenario of growing population, it is known that the dependance on non renewable energy is increasing exponentially. In any IC engine only 40% of the energy given by the fuel is utilized. The remaining goes as heat in exhaust gas and coolant. In this context a waste recovery system using Organic Rankine Cycle (ORC) has been developed to increase the percentage of energy conversion of burnt fuel in the engine. Further, in practical situations a vehicle may be subjected to different load and speed conditions due to which the exhaust gas temperature may also vary slightly. In the present research work a methodology is proposed to optimize the ORC using Taguchi method to meet the varying load conditions of an IC engine. For this purpose different working fluids are considered for the ORC. Engine load, specific fuel consumption, turbine inlet temperature, degree of superheat, condenser temperature, condenser pressure and coolant temperature are considered as the influencing parameters for the optimization procedure using L27 orthogonal array. The efficiency, work done and specific fluid consumption are selected as the objective parameters. In this way optimization is carried out for three working fluids namely R236fa, R124 and R245. It was found that R124 has the maximum thermal efficiency with a value of 15.32% followed by R236fa. Though R 124 has the highest efficiency, R236fa was concluded as the best working fluid considering fluid consumption and environmental factors.