Simulation Modeling and Working Fluid Usage Reduction for Small-Scale Low-Temperature Organic Rankine Cycle (ORC) Plate Heat Exchangers

In response to the increasingly severe energy crisis and global warming, ORC systems have attracted considerable attention owing to their ability to harness waste heat for power generation. Reducing the amount of organic working fluid in the heat exchanger can improve the economic performance of the ORC system. To achieve this aim, a new simulation model for plate evaporators and condensers of small/micro-scale ORC systems was developed, which can estimate the amount of organic working fluid and the outlet parameters. An ORC test rig was constructed to validate the model. Several experiments cases with different inlet temperatures were conducted. After validation, the impact of adjusting the operational and geometry parameters of the heat exchangers on the amount of organic working fluid was investigated. The results showed that appropriately increasing the temperature of the heat sources and cold sources or narrowing the heat exchanger width reduced the amount of working fluid in both the condenser and evaporator by over 30%. When adjusting the operational flow rate, the comprehensive impact on both the evaporator and condenser must be considered. The maximum mass was reduced by approximately 15.4%. The study results offer insights into designing plate evaporators and condensers for small/micro-scale ORC systems.