Stirling engine powered reverse osmosis for brackish water desalination to utilize moderate temperature heat.

Abstract A hybrid system consisting of RO (reverse osmosis) and SE (Stirling engine) was proposed to utilize the moderate temperature heat for the brackish water desalination. The performance of two configurations was systematically investigated. Config. II employs ERD (energy recovery device) to harvest the residual pressure energy in outlet feed solution for the pre-pressurization of inlet feed solution while Config. I does not. Impacts of substance temperature in the SE heater and RO hydraulic pressure difference on the fresh water recovery ability and energy consumption were investigated. Results indicated that Config. I presents the highest recovery rate of 17.3% while Config. II gets the largest fresh water production of 34.2 L/h. As to the energy consumption, a lowest specific energy consumption of 2.5 kW · h / m 3 and specific thermal energy consumption of 35.9 MJ/m 3 were achieved in Config. II, which exhibits much more effectively compared to those obtained in Config. I. Furthermore, the performance comparison under the ideal and non-ideal SE models was also conducted. Highlights • High flow rate can reduce the osmotic pressure difference aside membrane. • High hydraulic pressure difference is beneficial for system performance. • Energy recovery device reduces the specific thermal energy consumption by 52%. • Energy consumption can be reduced up to 35% with a more efficient Stirling engine. [ABSTRACT FROM AUTHOR]