Desalination System Based On Medium Temperature Thermal Oil Collector Coupled With New Phase Change Thermal Storage Material

In the case of increasing scarcity of water resources in China,the application of solar multi-effect desalination technology in coastal island areas can effectively solve the problem of energy sources required for desalination,and can obtain fresh water several times the amount of steam through the reuse of secondary steam;However,due to the intermittent and unstable nature of solar energy,there is a time mismatch between heat collection and heat use,the use of phase change materials to improve thermal storage efficiency is an important way to solve the energy mismatch problem.Therefore,this paper focuses on solar energy with phase change thermal storage to provide heat for desalination system and produce fresh water for daily use of island residents and to meet the demand of tourists as follows:(1)In order to meet the heat demand of desalination system,a new U-shaped structure design of medium-temperature heat-conducting oil collector is selected,the structure of this new medium-temperature heat-conducting oil collector is introduced,its heat-collecting performance and thermal efficiency are analyzed by building the experimental bench of tandem collector,the corresponding mathematical model is built,and the corresponding conclusions are obtained to lay the foundation for matching with desalination system.(2)A composite inorganic salt phase change thermal storage material was selected to match the collector optimally,an experimental system and mathematically modeled of phase change thermal storage tank was built.Using electric heating rods instead of solar energy to investigate the thermal storage and discharge characteristics of the phase change material and its effect in combination with medium temperature thermal oil collector.(3)Update the design of the desalination system model,so that seawater evaporates instantly under atmospheric pressure in the flash chamber of the new structure design,and the primary steam generated enters the multi-effect condensing tank of different structures for condensation and heat exchange,and heat-conducting oil is directly passed into the flash chamber to provide heat,and the whole process is carried out under atmospheric pressure,which reduces the trouble of vacuum extraction,and the water production ratio can be close to 2.The mathematical model of the desalination system is established,which lays the foundation for matching different systems and realizes a simple and efficient water production system.(4)A small island area in Hainan was selected as the water supply object,and the new thermal oil solar energy with phase change thermal storage was used to provide energy to the desalination system.By calculating the physical model and mathematical model of the solar desalination system,a desalination system with a design scale of 15m~3/d,14h/d uninterrupted operation was established.At the same time,we obtained the solar collector system matching the new desalination system,the phase change heat storage system and the wind power system for economic analysis,and simulated the system process with Aspen Plus software to obtain the simulation results,and compared them with the calculation results to verify the accuracy of the calculation results.