Performance evaluation of a co-production system of solar thermal power generation and seawater desalination

Abstract

Increasing power cycle efficiency is an important way to reduce the cost of the solar thermal power generation. The power generation system using a supercritical carbon dioxide (s-CO2) Brayton cycle has the advantages of high cycle efficiency, small equipment size and low corrosion. Then, low temperature waste heat generated by the s-CO2 Brayton cycle can be used as the low temperature heat source for multi-effect desalination. This paper discusses a s-CO2 Brayton cycle integrated with a multi-effect seawater desalination system. The heat input of the s-CO2 Brayton cycle is from a central-tower solar receiver. The residual heat of the s-CO2 Brayton cycle is the heat input of the multi-effect distillation system. The results show that the integration of multi-effect desalination system does not affect the s-CO2 Brayton cycle efficiency. With the increase of split ratio of the compressor, Brayton cycle efficiency increases and then decreases, and the water production decreases and then increases. With the increase of turbine inlet temperature, Brayton cycle efficiency increases while freshwater production varies insignificantly. After optimizing the design of the cogeneration system, solar thermal power efficiency is 24.04%, the cost of electricity generation can be reduced, the LCOE is 0.081$/kWh. by using the waste heat generated from the power cycle. realized electricity-water cogeneration, the fresh water production from 5-effect MED is 459m3/day, and the unit cost of freshwater UPC of 0.81$/m3.