Sub-atmospheric Pressure Desalination System Powered By Solar Compound Parabolic Concentration

Fresh water is the source of human life.Solar desalination is an effective way of both environmental protection and energy saving.The common collectors for solar desalination are vacuum tube collectors and flat plate collectors.This kind of collector has low heat collection efficiency and can only be heated and evaporated.In addition,solar seawater desalination is commonly performed under atmospheric pressure,and the system has low performance coefficient and efficiency.This paper studies a sub-atmospheric pressure seawater desalination powered by compound parabolic concentrator(CPC).The heating rate increases so that the water reaches the boiling point faster.On the other hand,a sub-atmospheric pressure is provided to improve the system efficiency the freshwater output.The freshwater production and the performance coefficient of the system have been calculated.The experimental research has been carried out.The main research work and conclusions are as follows:1.The theoretical model of vacuum tube collector and CPC is established,and the performance of CPC and vacuum tube collector are explored.The results show that: The vacuum tube collector heated continuously,and the highest temperature can reach about 65?.The highest heating temperature of 16 tubes is similar to that of 20 and 25 tubes.The highest temperature for heating one CPC is about 90?,the highest temperature for heating two CPCs in series is about 96.8?,the highest temperature for heating three CPCs in series is about 97?,and the heating rate of two CPCs is similar to that of three CPCs.2.A theoretical model of CPC sub-atmospheric pressure seawater desalination was established.The effects of the CPC groups,CPC inclination angle,system pressure and water flow rate on freshwater production rate and system performance coefficient were studied.The results show that: The freshwater production rate of two CPCs and three CPCs are similar.Three CPCs consume more energy,so the device performance coefficient is lower than two CPCs.When the CPC inclination angle is 15°,the freshwater production rate and the system performance coefficient are the highest;The faster water flow rate,the more fresh water is produced,but the130 kg/h water flow rate is higher in the electricity consumption,so system performance coefficient is relatively low;The freshwater production rate and the system performance coefficient increase when the pressure decreases.The freshwater production rate can reach 2.19 kg/h,and system performance coefficient can reach 1.73 when the pressure is 70 k Pa,3.For different pressures and different groups of CPC,the freshwater production and the performance coefficient of the system were experimentally studied.The results show that: When the pressure is 70 k Pa,the maximum freshwater production rate is 1.68 kg/h and the system performance coefficient can be up to 1.43 when a CPC is used;The maximum freshwater production rate is 1.86kg/h and the system performance coefficient can be up to 1.56 when two CPCs are used;The maximum freshwater production rate is 1.93 kg/h and the system performance coefficient can be up to 1.62 when three CPCs are used;...