Reverse osmosis desalination driven by low temperature supercritical organic rankine cycle

A supercritical organic rankine cycle (SORC) driven seawater reverse osmosis (RO) system (SORC-RO) is proposed. The proposed system is suitable for using both recirculating heat sources such as, solar thermal, and once-through thermal energy resources, such as, waste heat or geothermal. The SORC-RO system is analyzed using two types of low-grade heat sources with a maximum temperature of 150 °C and compared with the conventional organic rankine cycle driven seawater reverse osmosis system (ORC-RO). The results show that the SORC-RO system is able to make use of different heat sources and provide relative stable performance. If the source is waste heat, the SORC-RO system could make full use of the heat source and reduce thermal pollution to the environment. A comprehensive list of working fluids candidates for the SORC-RO system using low-grade heat sources less than 150 °C is proposed based on the critical pressure and temperature of the fluids.