Working Fluid Distribution of a 315 kW Organic Rankine Cycle System in the off-design Conditions

orc2019 Tracking Number 63

The research in this paper is based on a 315kW organic Rankine cycle (ORC) system using brazed plate heat exchangers and a radial turbine. In order to study the law of distribution and change of the working fluid in the off-design conditions, this paper takes the working fluid distribution as the research target and uses the moving boundary method to establish the heat exchanger simulation model. 315kW ORC power generation tests working with R134a were performed, and the test data is used for calculating the level of the brazed plate heat exchangers which is difficult to measure directly, and the error is within ± 5%. The working fluid distribution were obtained under different conditions of evaporator outlet superheat degree (13~21.5°C), condenser outlet supercooling degree (4~11.5°C) and working fluid pump flow (2~20kg/s). Combined with the temperature distribution of the heat exchanger and the power generation of the system, the performance characteristics of the system under off-design conditions are analysed. The research results show that the change of working fluid flow rate, superheat degree and supercooling degree are all have effects on the distribution of working fluid in the system. And the influence of working fluid flow rate is the most significant. The working fluid distribution can directly reflect the working state of the heat exchanger, and the stability of the system operation. The research results provide reference for the heat exchanger design margin of the ORC power generation system, and provide guidance for the stable and safe operation of the control system.