Applied Research Of Homemade Phase Change Material Emulsion In Liquid Cooling Garments

Due to the impact of climate warming,the frequency of heat waves around the world has increased year by year.As of 2017,about 30% of the world's population is exposed to lethal high temperatures for at least 20 days a year,and the proportion is increasing.The heat stress caused by scorching weather will reduce the productivity of workers and threaten their health.Heat stress has become a social problem that can not be ignored.The individual cooling suits can effectively solve the problem of occupational heat stress.Compared with the traditional air conditioning system,it has a low economic cost,high flexibility and can be used in many occasions.Therefore,the liquid cooling garments were selected and optimized.Firstly,a cold storage liquid cooling suit was designed,and its performance under different working conditions was obtained through CFD simulation.Secondly,paraffin wax was used as the dispersed phase and water as the continuous phase to prepare the phase change material emulsion,and its properties were tested.Then,based on the prepared emulsion,a new set of hybrid cooling suit is proposed,and the heat transfer performance and the wearing comfort of the hybrid cooling garment were obtained through CFD simulation.Finally,two sets of cooling suit samples were made,and subjective feeling experiments were carried out to verify the accuracy of the simulation.The research shows that the mass flow of liquid cooling clothing is suitable to control between 80-120kg/h.The inlet temperature has a linear relationship with the cooling capacity.The inlet temperature can be adjusted according to different working conditions.The total cooling capacity of the liquid cooling garment sample prepared is 115.17 W,and it can be effectively maintained for 2 hours in the sitting position.However,it is found that the wearing comfort and reliability of liquid cooling garments need to be improved.Secondly,50wt%paraffin emulsion was successfully prepared by paraffin wax with melting points of 18,20,and 24?.The maximum latent heat is 103.58J/g.Then,the comfort and reliability of the hybrid cooling suit are greatly improved.The simulation results show that the cooling power of the mixed cooling suit tends to be stable when the paraffin emulsion is in the phase change temperature region.The human body feels most comfortable at this time.The melting point of paraffin in the emulsion significantly affects the cooling power of the hybrid cooling garment.According to the characteristic,the cooling capacity of the hybrid cooling garment can be adjusted to improve wearing comfort.The hybrid cooling garment with 18? paraffin emulsion as the medium can meet the heat dissipation requirements of moderate and below labor intensity,especially suitable for light labor.The Hybrid cooling sample garment carries2.5kg of 18? paraffin emulsion,which can be effectively maintained for 60 minutes under light labor condition.The simulation results show that the average effective cooling power is79.88 W.Finally,the advantages and disadvantages of liquid cooling garment and hybrid cooling suit are compared.and the design criteria of them are summarized,which provides a new idea for the design and application of individual cooling suit,and has a certain reference value and guiding significance for promoting the application of individual cooling suit.