Pressure drop analysis for organic Rankine cycle power generation system using low-grade heat sources

Abstract

Pressure drops are unavoidable when testing or applying power generation systems. Similar to any other system, the organic Rankine cycle (ORC) power generation system also experiences pressure drops. This study focused on analyzing the pressure drop in the plate heat exchanger of the evaporator, the condenser, and the piping to minimize the occurrence of a decrease in the system performance. Three scenarios, organic fluids R141b (scenario 1), R245fa (scenario 2), and R227ea (scenario 3), are used to determine the working fluid with the lowest pressure drop at a heat source with a temperature of 95 °C. The analysis was performed with data from an ORC system that had been installed in a laboratory. Pressure drop calculation was divided into cold and hot sides because of the presence of two fluid flows in the evaporator and condenser. Each side was divided into two zones because of a phase change in the evaporator and the condenser. The pressure drops from the plate and through the port were calculated in the evaporator and the condenser, and the pressure drop in the piping system completed the analysis. The analysis results showed that the total pressure drop in the evaporator and condenser for scenarios 1, 2, and 3 are 0.268 bar, 0.173 bar, and 0.134 bar, respectively. In addition, the total pressure drop in the piping system is 0.069 bar, 0.075 bar, and 0.081 bar for scenarios 1, 2, and 3. Therefore, scenario 3 had the lowest total pressure drop than other scenarios.