Molecular Dynamics Simulation And Experimental Study Of Non-azeotropic Mixtures

For automatic cascade refrigeration system,the most important is the selection of azeotropic mixture refrigerants and matching,combining the requirements of environmental protection,selection of environmental protection and can achieve the same cooling effect of refrigerant refrigeration industry research hot topic,because the working mechanisms of mixed working medium is relatively pure working medium is more complex,increasing the difficulty of experiments to explore,so in this paper,combined with molecular dynamics simulation method from the Angle of the micro pure medium,binary and ternary mixed working medium mixed working medium is simulated,to explore the optimal formula of the mixed working medium and experimental exploration results were analyzed.(1)According to the comprehensive selection of non-azeotropic mixing medium,the two groups of working quality pairs,R22/R23/R14 and R134a/R23/R14,which are suitable for the experimental conditions,were selected.(2)Combined with molecular dynamics simulation method for pure working medium density with temperature,pressure and the relationship between vapor and liquid phase equilibrium properties of working medium,and explore different mass ratio of binary mixed working medium(R22/R23,R134a/R23,R23/R14)the content of the material for the binary system balance ability and the influence of diffusion capacity,provide a reference for subsequent ternary hybrid basis.Based on the simulation results of binary mixing medium,the optimal ratio of ternary mixing medium was obtained by means of the gradual simulation and analysis of the separation rate of each working medium.(3)Based on the self-overlapping refrigeration system,two pairs of ternary non-azeotropic mixing medium were experimentally studied to explore the optimal ratio of the two groups of mixing medium when the final evaporation temperature reached about-100?,and the results were compared with the simulation results.(4)According to the entropy generation formula of each process of the two groups of quality pairs in the experimental equipment,the reasons for the entropy generation loss of each process are analyzed by combining with the calculation results,and finally the overall method is proposed to improve the COP of the system.In using molecular dynamics simulation method and the experiment to explore the optimal proportion of mixed working medium,experiments of R22/R23/R14 and R134a/R23/R14 optimal proportion comparing with the results simulated values,environmental protection refrigerants everything as high boiling refrigerant in the mixed working medium can not only improve the efficiency of the medium temperature refrigerants condensation,also can improvethe flow of medium temperature refrigerants,and guarantee the purity of it,obviously with the increase of the refrigerating capacity of the system,thus the COP value of the since the cascade system,from the environmental protection and improve the COP of the system into consideration,As long as a reasonable ratio is found,R134 a can replace R22 and be used in the self-cascade refrigeration system.For molecular dynamics simulation,it is feasible to explore and predict known or unknown thermodynamic properties of pure working media and mixed working media by using reasonable force field and potential energy model and parameters.