Performance analysis of an Organic Rankine Cycle depending on heat exchanger components optimization

This study focuses on optimizing and analyzing the performance of an Organic Rankine Cycle (ORC) which includes four heat exchanger units: a preheater, evaporator, superheater, and condenser. The preheater, evaporator, and superheater are finned tube heat exchanger types, selected for their superior performance in light of the low heat transfer coefficient of air. On the other hand, the condenser is a horizontal shell and tube type, chosen for its simple structure and high efficiency. The study aims to develop a comprehensive design and optimization methodology for each heat transfer component to achieve the perfect design with the minimum surface area while keeping the pressure drop below 0.2 bar, as there is a trade-off between these parameters. Firstly, thermodynamic calculations based on ideal cases (neglecting pressure drop across the heat exchangers) were carried out for six different fluids: R245fa, R123, R600, R236fa, R142b, and R600a. These fluids were selected for their preferable properties and all calculations were performed under the same working conditions for all selected refrigerants. Based on the information collected from these calculations, 1244 distinct designs for all heating units were reached. An optimum design was selected for each heat exchanger component by applying step-by-step design and optimization methods, balancing between minimal surface area and low pressure drop. Finally, performance analysis of the ORC based on these designs was performed to test how these designs affect the overall performance of the ORC. The study aimed to conform with the expected results of low equipment cost and high ORC performance compared to the ideal case, which was found to be more than 98% for all selected fluids.