Application Research Of Thermoelectric Refrigeration In Air Gap Membrane Distillation System

In the solar energy air gap membrane distillation system, cooling capacity required by membrane distillation process is generally provided by the mechanical refrigeration system. Due to the complex structure and large power consumption of mechanical refrigeration systems, it is needed to seek new refrigeration form in order to simplify the system structure and improve energy utilization. In this paper, thermoelectric refrigeration technology is introduced into the solar energy air gap membrane distillation system, and it is from two aspects of theory and experiment to study the coupling between thermoelectric refrigeration and membrane distillation process.Through the analysis of heat transfer in membrane distillation process, the expression of the cooling load in membrane distillation process is build. the cooling load calculation of the original membrane component show that the major part of the cooling load in membrane distillation process is latent heat release, and that the proportion of latent heat release and sensible heat release increase gradually with the increase of difference between cold and hot side of membrane temperature. According to the analysis of the maximum refrigerating capacity working condition and the maximum temperature difference working conditions of thermoelectric refrigeration, the expression of thermoelectric refrigerator intrinsic parameters is derived. furthermore, MATLAB software is used to calculate the performance of thermoelectric refrigeration and output related performance curve.Through the analysis of membrane distillation process and thermoelectric refrigeration, get sufficient and necessary conditions for the coupling between thermoelectric refrigeration and membrane distillation process are sufficient refrigerating capacity provided by thermoelectric refrigerator and high temperature difference bwtween the warm side and cold side of membrane. Uscing the previous experiment data of air gap membrane distillation system as foundation data to do the coupling calculation, the coupling characteristic parameters, coupling condition and the optimal coupling conditions are defined, and the general form of coupling characteristic parameters equation is established. Combining with engineering practice, the coupling characteristic parameters equation is solved. The solution does not show that the lower the cooling temperature is, The greater the membrane distillation flux will be. To select the optimal coupling condition, two kinds of judgment standard named the biggest flux standard and the optimal economy are proposed. Through the contrast analysis of two kinds of judgment standard, it is found that only a handful of coupling conditions can meet the two kinds ofjudgment standard simultaneously, and with the increase of feed temperature, the difference of membrane distillation flux depending on two kinds of judgment standard increases gradually in waves.A thermoelectric refrigeration membrane distillation cold chamber with water cooled heat dissipation components was built, and experimental research on component performance is done. Results show that the thermoelectric refrigeration membrane distillation cold chamber refrigerates rapidly, it can attain to stable operation in five minutes. When the input current of thermoelectric refrigerator is steady, refrigeration temperature gradually decreases with the increase of heat dissipation intensity, until the heat dissipation intensity reaches a critical value. When the heat dissipation intensity of the component meet the requirement, the cold dissipation intensity will affect the refrigeration temperature, the larger the cold dissipation intensity is, the higher the refrigeration temperature will be. When the cold dissipation intensity of the component is steady, if value of the heat dissipation intensity is smaller than the critical value, the input power decreases with the increase of the heat dissipation intensity, until to the critical input power. The analysis about the thermoelectric refrigeration performance of the component shows that the thermoelectric refrigeration components can provide large refrigeration power and cooling efficiency under the small input current condition.Compared with the original air gap membrane distillation system, the new thermoelectric refrigeration air gap membrane distillation system doesn’t have complicated mechanical equipment and piping system, so it is miniature. It does’t use refrigerant, so there is no environmental impact. It refrigerates rapidly, and its adjustment is simple, its operating conditions can be adjusted according to the change of solar radiation in any time. The investigation of the paper establishes the foundation for theoretical research and practical application of solar air gap membrane distillation system with thermoelectric refrigeration.