The Design And Experimental Study Of Special Membrane Distillation Configurations

This paper analyzes the configurations design from the aspects of improving the cold side energy drive and hot side energy drive configuration of membrane distillation.In the experiment,the cold source in the natural is used as the driving force for the energy on the cold side of membrane distillation,and renewable energy is used as the driving force for the energy on the hot side.First,an improved air-cooled membrane distillation configuration on the cold side was designed and built,which uses air instead of cooled-water for cooling.Secondly,a floating solar-driven membrane distillation configuration with improved cold side and hot side was implemented,which used solar energy,wave energy,sea water to operate.In this paper,the operation performance of the device under different operating parameters is studied from the aspects of experiment and simulation,and the feasibility of the device is explored.In the improved configurations of the cold side energy driving force,the influence of configuration parameters such as the thermal conductivity of the condensing plate,the type of fins,and the wind speed on the performance of the air-cooled membrane distillation configuration is explored.Through experiments and theoretical analysis,it is concluded that the performance of air-cooled membrane distillation is poor under natural convection conditions.Increased wind speed in forced convection can improve the heat transfer capacity of air-cooled,and the thermal conductivity of the condensing plate is also positively correlated with the heat transfer capacity of the condensing side.The fins can increase the heat dissipation area.The larger the surface area ratio of the fins,the stronger the heat transfer capacity of membrane distillation.As the wind speed increases,the air-cooled membrane distillation is limited by the heat transfer on the condensing side or the air gap,the increasing trend of the permeation flux of membrane distillation slows down,and the heat transfer limit occurs.At a certain wind speed and cooled-water flow rate,air cooling can be similar to cooled-water cooling permeation flux,which confirms the effectiveness of air-cooled membrane distillation.In the improved configurations of the cold-side driving force and the hot-side driving force,the operation performance of different configurations under conditions such as the temperature and the flow rate of the feed are analyzed,and the membrane distillation configurations is continuously improved.Experiments and flow simulations are used to explore the influence of solar energy,wave energy of the device.Through the experiment,it is concluded that the flow rate of the feed has little effect on the experiment,and the change of the temperature of the feed will affect the driving force of the membrane distillation mass transfer,the thickness of the air gap increases,and the driving force of mass transfer decreases.The upward evaporating configuration is more conducive to the condensation of water vapor,and its permeation flux is higher than the downward evaporating configuration.When the wave uses as a driving force,it can promote the circulation of the feed in the heating side and membrane distillation module,increase the temperature of the feed in the membrane distillation module,and destroy the temperature polarization of the feed near the membrane.As the concentration of the feed increases,the driving force for mass transfer decreases.This paper has verified the effectiveness of the improved configurations of membrane distillation energy through experiments and simulation analysis.It verified the feasibility of natural cold sources such as air and sea water as the driving force for the cold side of membrane distillation.Also verified the feasibility of the renewable energy solar energy is used as the heat driving force,wave energy can be used as the cyclic driving force.In the improvement of the driving force of the improved membrane distillation energy,the temperature of the feed does not need to be too high,and the temperature of the cold source can be similar to the surrounding temperature.Therefore,renewable energy can be used to heat the feed,and the natural cold source cooling device can be selected to utilize,driving force such as waves can be used to circulate.The improvement of membrane distillation energy driving force configurations can reduce the primary energy consumption of membrane distillation and streamline membrane distillation equipment.