Ecological optimization for a combined diesel-organic Rankine cycle

A mathematical model of a steady combined diesel-organic Rankine cycle with finite heat resistance and heat leakage is proposed. Performance of the studied combined cycle has been numerically analyzed based on the ecological criterion and endothermic rate optimization method. The variations of optimal power, optimal efficiency and optimal ecological criterion with the endothermic rate, and the relations between optimal ecological criterion, optimal efficiency and optimal power are studied by numerical calculation. Results show that the optimal power does not vary with the endothermic rate; optimal ecological criterion and optimal efficiency decrease with the increase of heat leakage. The efficiency under the optimal ecological criterion is larger than that under the optimal power while both of them are less than the optimal efficiency. The heat leakage brings the quantitative and qualitative impact on the power output and efficiency of the combined cycle. The power output, ecological criterion and efficiency of ORC increase with the increasing evaporation temperature and superheated temperature.