Study On The Small-Sized Seawater/Brackish Water Desalination Plant Using Solar Energy

With the rapid development of modern industry and the surge in world population, On the one hand, the demand for fresh water increases rapidly, on the other hand, a large number of industrial waste discharge, making a large number of rivers and lakes had been seriously polluted, causing the few and far between fresh water resources had been destroyed, thus further exacerbate the contradictions of human water supply and demand, so many countries and regions facing water crisis, how to solve the shortage of fresh water is a world problem and urgently needed to solve. In the recent years, using of pollution-free solar energy for desalination of seawater, take the road of sustainable development have become the focus to the countries of the world.Based on systematic understanding the situation of desalination technology in domestic and foreign, mastering the Properties of main medium in seawater desalination, and the basic heat and mass transfer theory ,this paper proposed a method of seawater or brackish water desalination. It combined flat air collector and vacuum collector tubes with heat pipes, using the principle of air humidification and dehumidification. Vacuum collector tubes with heat pipes heating salt water in distiller, using micro-suction method introduced hot air from flat air collector into sea water inside the distiller, interchanger the heat with salt water through the micro-holes on a aeration device to achieve the air humidity. Then obtain fresh water outside horizontal tubes after dehumidification and condensation of the humid air.Fabricated the prototype of small seawater or brackish water desalination device using solar energy, including distiller and the nog, flat solar air collector and the kickstand, vacuum collector tubes set with heat pipes, condenser, fan and connecting pipes. This device takes advantage of the evaporation in vacuum and the condensations in pressure, artificial disturbance source, destroy the boundary layer, reducing the boundary layer thickness and so on, to strengthen heat transfer in the system. And used hair dryer to simulate experiments, and found the main factors that impact the system evaporation: hot air temperature, air flow, temperature and initial amount of water.Running operation test have been done about the experimental prototype, actual exhaust thermal efficiency of flat air collector is 66%, thermal efficiency of the opening distiller in stagnation to sun is 27.4%, thermal efficiency of closed to run is 65%, evaporation condensation ratio of the device is 50%. Experiments show that: vacuum collector tubes set with heat pipes has a good heating performance on the water in distiller and the temperature run faster , each parameter was on a very good following performance to the total solar radiation intensity during the test, continuous inner heat supply in distiller had a significant influence on the evaporation of the system.