Operating Characteristics of Working Fluid Pump in a 315 kW Organic Rankine Cycle System

orc2019 Tracking Number 152

In the organic Rankine cycle (ORC) power generation system, the working fluid pump, as a boosting component, determines the stability, efficiency and safety of the system. This paper is based on ORC power generation test of 315kW, which uses R134a as the working fluid and variable frequency multistage centrifugal pump as the working fluid pump. In order to explore the effect of the cold source on the operating characteristics of the working fluid pump, the system load and the pump speed (960~2960rpm) are all increased at different cooling water temperatures (279K、283K、287K、291K) while maintaining the evaporator outlet superheat degree at 20±1K. The parameters such as the temperature, pressure and flow rate were measured, and the performance curve, output power , the Net Positive Suction Head available (NPSHa) and efficiency of the pump under off-design conditions were studied. The experimental results show that the rotational speed of the working fluid pump has a significant effect on the NPSHa. As the pump speed increasing, the temperature and pressure of the working fluid at the pump inlet are affected, leading to NPSH rising first and then decreasing.. When the cooling water temperature is 291K and the pump speed is 2250 rpm the NPSHa reaches the maximum value of 10.8m water head. In addition, at the same speed, the increase of the temperature of the cooling water increases the flow rate and the pump outlet pressure, at the same time, the NPSHa of the pump increasing. The research results could provide guidance and reference for the efficient operation and cavitation protection of the working fluid pump in the ORC system.