Design of plate heat exchangers for use in medium temperature organic Rankine cycles

Abstract

An organic Rankine cycle (ORC) is used to efficiently recover the exhaust gas waste heat discharged from a ship. One of the crucial factors that determines the efficiency of an ORC system is the heat exchanger used in it. In this study, a plate heat exchanger is used as the heat exchanger for the evaporator and condenser in an ORC system. This is because a plate heat exchanger can achieve smaller size and higher heat transfer coefficient in contrast to the shell-and-tube heat exchanger by reducing the heat transfer area. In order to determine the heat transfer area of the evaporator and the condenser, an appropriate heat transfer correlation should be selected according to the flow path and fluid condition. Therefore, the heat transfer area of the evaporator in an ORC system is obtained by using the evaporation heat transfer correlation of Kim et al. In addition, the heat transfer area of the condenser in an ORC system is calculated using the condensation heat transfer correlation of Yan et al. From the results obtained by this simulation, the existing evaporation and condensation heat transfer coefficients in the literature are compared and analyzed.