Comparing the profitability of waste heat electricity generation of internal combustion engines: An exergoeconomic analysis through optimization of two different organic Rankine cycle scenarios

The increasing consumption of fossil fuels has caused the emission of an enormous amount of greenhouse gases it has led to the problem of global warming and other damages to the environment. Therefore, heat recovery has become very important in recent years. In this paper, two different scenarios of the Organic Rankine cycle (ORC) are proposed to heat recovery of an internal combustion engine with two heat loss levels (stack and jacket water). The novelty of this paper is the comparison of the application of two different scenarios for the use of two available heat sources that have not been studied in previous research. Three different types of organic fluids including dry (n-butane and R245fa), wet (R134a) and isentropic (R123) were studied by energy, exergy and economic analysis. In addition, the parameters of pressure and the inlet temperature of the turbine and the superheat temperature value of the inlet flow to the turbine were optimized by the multi-objective optimization. The optimization results showed that the parameter influencing the thermodynamic and economic indicators most is the ORC pressure ratio. The optimized results of the two scenarios were compared according to thermodynamic and economic analysis and the best results were obtained for scenario 2 and fluid R123. For this case, the levelized cost of electricity (LCOE), Total Investment Cost (TIC) and electricity generation are 0.05776 $/kWh, 317,528 $ and 202.5 kW, respectively. Moreover, studying 20 countries in all the five continents, showed that developed countries were the ones with the minimum and maximum payback periods.