DETERMINATION OF OPTIMUM FLUID FOR DIFFERENT HEAT SOURCE TEMPERATURES BASED ON MULTI-OBJECTIVE FUNCTIONS IN THE ORGANIC RANKİNE CYCLE

Abstract

In this study, the optimum fluid was determined by using Non-dominated Sorting Genetic Algorithm-II (NSGA-II) within the scope of Organic Rankine Cycles (ORC) low temperature applications. Heat source temperatures are taken as 90, 100 and 110 °C. Fluid optimization was performed by comparing the performance of 8 fluids from 4 different categories under different criteria (dry-R601 and R601a, isentropic-R141b and R123, wet-R152a and R134a, new generations-R1234yf and R1234ze). Objective functions have been established under the parameters of Energy, Exergy, Economy and Environment (4E). In ORC systems, every organic fluid has certain advantages and disadvantages. It is seen that the studies on organic fluid selection meet a single goal from the system performance parameters. However, it has been observed that the turbine power performance is not at the desired level due to the required evaporator capacity of the fluid, which performs well in terms of thermal efficiency in ORC systems. Therefore, it is necessary to determine the percentage of organic fluid that can be used by optimizing it under different objective functions. In this study, the optimum fluid was determined for ORCs operating under 90, 100 and 110 °C heat source temperatures by evaluating different objective functions together.