Design And Operation Performance Study Of Supercritical CO₂ Brayton Cycle Solar Power And Seawater Desalition System

In the 21st century,although many countries advocate the use of clean energy,they still rely on traditional fossil energy to maintain certain development,which has also led to a series of environmental problems.The development of new energy has always been in the stage of supplement and constantly improving.Solar energy,as a renewable new energy,has the advantages of clean,environmental protection,sustainable and long-term,and has become one of the important choices to deal with energy shortage and environmental pollution.Solar power generation and desalination systems using the Supercritical carbon dioxide(S-CO₂)Brayton cycle can be considered as one of the most promising developments in energy in the future.This study proposes the design a new tower concentrated solar power and desalination(CSPD)system using S-CO₂ Brayton cycle and multistage flash(MSF)desalination technology and evaluates the performances of the CSPD system.The main study contents and conclusions are:Firstly,the working principle and flow of the CSPD system are given.The CSPD system mainly includes the solar block,S-CO₂ Brayton cycle power block and seawater desalination block.The solar tower thermal system and heat storage system are used in the solar block.The desalination block employs the MSF desalination system.The power and desalination blocks are both driven by the solar energy directly.The the CSPD system is modeled by using the Ebsilon code.Secondly,the operating behavior and exergy analyses of the CSPD system are launched.The results show that the S-CO₂ Brayton cycle efficiency is 36.6%.The output power of the CSPD system is 50.1 MW,and the daily fresh water output is 4050.8 t.The CSPD system can be used for solar power generation and desalination simultaneously according to a preset operating strategy.Exergic analysis results show that the solar energy tower receiver and heat exchanger of seawater desalination system have two maximum exergy losses and two lowest exergic efficiency,which has great potential for improvement in the future.Finally,the economic and environmental protection analyses of CSPD system are conducted.The analysis results show that the CSPD system has the equivalent levelized electricity cost of 0.059$·k Wh^-1 and levelized water cost of 1.15$·t^-1,indicating that the system is economically feasible.Compared with coal-fired power plants,the annual emission reductions of soot,sulfur dioxide,carbon dioxide and nitrogen oxide of the power block of the CSPD system are 582.9 t,1001.8 t,40681.1 t and 947.2 t,and those of the seawater desalination block are 76.9 t,132.2 t,5369.2 t and 125.0 t,respectively.That shows good environmental protection benefits of the CSPD system.