Material Compatibility of Hexamethyldisiloxane as Organic Rankine Cycle Working Fluids at High Temperatures

The organic Rankine cycle (ORC) is a promising technology for industrial waste heat recovery and renewable energy utilization. High temperature ORCs have attracted particular interest because of their high thermal efficiencies and outputs. The material compatibility of working fluid is a significant limitation for the working fluid selection and system design for high temperature ORCs. This work presents a method for studying the material compatibility of ORC working fluids based on the calculated conditions of the ORCs and matching of components, temperatures, and materials. Hexamethyldisiloxane (MM) was chosen as the test fluid. The experimental results show that 304 stainless steel has better compatibility with MM than copper as the material of evaporators. Fluoric rubber is not a suitable sealing material for high temperature ORCs with MM as the working fluids because of the bad compatibility. Mineral oil has better compatibility with MM than polyol ester (POE) lubricant as the lubricant for the fluid pump.