High Efficiency Solar Desalination Control System

Freshwater is necessary for human survival. With the development of globaleconomy and the increase of population, water crisis is more and more serious. Inorder to solve the problem of shortage of freshwater, human beings take method of"broaden source of income and reduce expenditure ". On the one hand, human beingshave to save water. On the other hand, we need to promote desalination of seawaterseriously. At the same time, the human society is facing a serious threat of energyshortage and environmental deterioration. So it’s significant for sustainabledevelopment of our society if the shortage of water can be solved with new energysuch as solar energy. As all we know the solar desalination is imminent.Zhejiang province propose to develop the Marine economy, solar desalination isthe most important parts. In order to solve the water scarcity problem of Zhoushan’sislands, we designed a high efficiency solar desalination device, it includingconcentrated solar thermal, plate type heat exchanger, low temperature multiple effectdistillation. We also configured a control system for this device to achieve the goal ofcontrolling energy during solar desalination by controlling the working mediumflow, improve the rate of heat utilization to make seawater desalination efficient.Firstly, we designed a high efficiency solar desalination device, with solarthermal groove set, two grades plate heat exchanger, low temperature multi-effectwater distiller, attach the heat oil tank and water tank as energy storage device. Thismethod achieves energy collection and storage. We designed and customized a smalllow-temperature multi-effect distillation device for seawater desalination.Secondly, for the solar desalination device, we configured a whole controlsystem to control the flow of working medium when the device is working. On thedevice, we layout many temperature sensor, flow sensor and so on, detecting the stateof working medium and input those signals into controllers, then the controllersprocess those signals, and output an instruction to change the flow rate of workmedium, control the procession of heat energy cycle. Here we take the hierarchicalcontrol strategy, the underlying systems like solar collection, heat transfer, seawaterdesalination are controlled by themselves underlying controllers independent, theupper controller achieves the three underlying controllers optimization scheduling.Finally, for the three underlying control systems, according to the three underlying systems’ requirements to complete design of the underlying controller, andanalyzes the control effect by using the PID control and model predictive control, andthe simulation results are given. For the upper controller, analysis of highefficiency solar seawater desalination device working status, and gives the controlstrategy.We analyze the solar desalination from angle of control, make the system runsautomaticly and improve its heat utilization rate and desalination efficiency, changethe stereotyped horizon of researching desalination just consider the thermal, providea new insight for the future development of solar desalination technology.