Research On Special Heat Pump Membrane Distillation Device For Heat Sensitive Liquid Treatment

Membrane distillation is a technology that can concentrate or separate liquid at low temperature and atmospheric pressure and also has good applicability to the liquid which is difficult to be treated by conventional methods such as high concentration,high viscosity,easy gas foam and so on.Membrane distillation can be applied to the concentration separation of various heat sensitive liquids in food,medicine and chemical industries.Heat pump is a highly efficient device that consumes a small amount of electrical energy to produce multiple heat energy.The integration of the heat pump with the membrane distillation would significantly reduce the energy consumption of the membrane distillation process.The paper aimed at making up the special heat pump membrane distillation device which can realize the treatment of the heat sensitive liquid at atmospheric pressure,low temperature and low energy consumption.Theoretical and experimental research on this device was carried out systematically in this paper.Aiming at the development of special membrane distillation module for heat sensitive liquid treatment with high thermal efficiency,the hollow fiber cluster-sleeve tube type air gap membrane distillation module was constructed and its mathematical model based on its characteristic equations was established.Its performance simulation software was compiled and used to analyze the influence of the change of key parameters on the performance of this membrane distillation module.As a guide,the hollow fiber cluster-sleeve tube type air gap membrane distillation module was developed and its performance was tested.The permeate flux could reach 2.60kg/(m2·h)and the thermal efficiency could reach 56.3%.Based on the treatment of a certain heat sensitive liquid,the special heat pump membrane distillation device for heat sensitive liquid treatment was constructed and its mathematical model based on its characteristic equations was established.The performance simulation software for the device was compiled and the influence of key parameters on the device performance was calculated and analyzed.A heat pump membrane distillation experimental device for heat sensitive liquid was developed and apple juice was used as feed liquid.For the two experimental schemes based on different processes,the reliability of liquid concentration at atmospheric pressure and low temperature,the change rules of device operating parameters with time,the performance indicators of the device under typical stable operating conditions,the adaptability and separation effect of apple juice treated with polypropylene membrane distillation module and so on were researched systematically.The results showed that the device was stable in operation.The separation of apple juice could be carried out efficiently under the different working conditions where the temperature of feed liquid into the membrane distillation module was 27.3℃ and 42.7℃,the rejection rate could reach above 97.0%.