Performance Study Of Spray Flash Desalination System Coupled With Solar Collector

Water is of great importance to human survival and development.At present,the shortage of fresh water resources has become a global environmental problem,and desalination technology is undoubtedly one of the most promising solutions.In order to overcome and improve the shortcomings and deficiencies of traditional desalination technology and further reduce the energy consumption and cost of desalination,the research of new desalination technology has become an important issue in today’s time.Spray flash technology has become an effective solution to solve the traditional thermal desalination technology as well as the shortage of fresh water resources due to its advantages of low energy consumption,good separation effect and high cooling capacity.The analytical study of the thermodynamic properties of flash sprays is essential to improve the efficiency of desalination systems.First,based on the analysis of evaporation and condensation processes in each stage,and the calculation of heat balance,mass balance and salt balance equations in each stage,the model of spray flash desalination system coupled with solar thermal collector is calculated and model validation is carried out in this paper.At the same time,a mathematical model of the change of the corridor value is established based on the second law of thermodynamics to analyze the influence law of different input parameters on the system efficiency and thermodynamic performance,so as to further obtain the operating parameters for cost reduction and efficiency improvement.The results show that the cooling water inlet flow rate close to the feed water flow rate is the best,and the system operation efficiency reaches the highest under this condition;under the same condition,the small droplet size and large seawater flow rate will improve the evaporation efficiency and the evaporation volume of seawater;the higher TBT increases the productivity and thus improves the heat recovery efficiency,provides more heat for the heat recovery process,and reduces the required specific heat exchange area;when the cooling water inlet flow rate increases,the efficiency of the chamber gradually increases,however,at a higher cooling water flow rate,the rising trend reverses and begins to gradually decline.Secondly,based on the results of exergy analysis and thermoeconomic theory,a thermoeconomic model of multi-stage jet flash system coupled with solar collector is established,including exergy cost model and thermoeconomic cost model.By calculating the cost of all exergy loss flows,the cost formation process and cost flow in the system are understood.By analyzing the influence of different parameters on the unit exergy cost value,the input parameter ratio during the operation of the system can be better regulated,and the operating cost can be reduced under the premise of ensuring high efficiency and energy saving.The results show that when the exergy economic coefficient is high,the system cost can be reduced by reducing the seawater flow rate or reducing the seawater top temperature;the increase of seawater flow will not change the initial investment cost of the system.As the exergy cost increases,the exergy economic coefficient gradually decreases.Finally,in order to improve the performance of the system,the spray flash desalination system was optimized by response surface method.The central composite design method of response surface design was used to select the appropriate input factors and response results.The regression analysis of the calculated data was carried out.The statistical parameters were estimated by variance analysis.The relevant regression equation was established by the calculation results.The proportion of the influence of each input parameter on the system performance was studied and analyzed,and the significance order and interaction relationship were determined.The optimal system operating parameters are obtained as follows : the top brine temperature is 344 K,the operation stage is 11,the seawater inlet flow rate is 11 kg / s,the cooling water inlet temperature is 301 K,the height of the flash chamber is 1 m,and the droplet diameter is 100 μm.