| A new model of jet-refrigeration cycle with the binary mixture refrigerant is presented in the thesis, in which the disadvantage of traditional jet-refrigeration system using pure refrigerant, i.e. refrigerant evaporating at relatively high temperature due to low pressure ratioβ, has been removed. Owing to the characteristics of binary mixture refrigerant evaporating at low temperature and of wet compression of ejector, it makes possible to lower the evaporating temperature under the same pressure ratio and furthermore to extend the application of jet- refrigeration.In present thesis, the feasibility study on the jet-refrigeration cycle with the binary non-azeotropic refrigerant is carried out and afterwards the thermodynamics cycle is preformed using a self-made mathematical model. Theoretical analysis and numerical calculation indicate that the low-temperature evaporation of binary mixture in an ejector-cooling system is possible thereby improving its refrigerating quality. The ejector, in itself, is applicable for the compression of binary mixture and therefore guarantee the above-mentioned special cycle at technical aspect. As the most important component, the design of ejector is crucial to influence the performance of the whole system. In my thesis, a new numerical method of modeling ejector is presented, which is based on the properties of the working fluid,fundamental thermodynamics, vapor-liquid equilibrium and fluid mechanics taking into account the disadvantages of classical methods --thermodynamics or gas aerodynamics. According to this model, the numerical calculation of an ejector with two-phase high speed flow is performed and the design is subsequently made. Using three numerical methods mentioned above, the comparison of the results coming from theoretical calculation is made, and afterwards experimental comparison of results is done. The results strongly support the numerical method developed here. In detail, the presented numerical method has several advantages over already known two methods. This method can be used to obtain all key data related to the geometrical sizes of the ejector, and to determine the marginal limitations of the pressure ratio and of jet coefficient. Following the above-mentioned work, the paper presents the theoretically computed results, using HFC refrigerants (R123 and R141b) instead of R11 because of R11 having higher ozone depletion potential but HFC refrigerants having lower ozone depletion potential. The results indicated that R141b can even result in higher COP value of circulating operation, compared with R11 . Despite all the above efforts, it is still difficult to solve the evaporating temperature T0 depending on the pressure ratio β. Therefore, the replacement of pure operating working fluid by binary mixture has to be considered in order to expect low evaporating temperature without varying the pressure ratio. This paper hereby analyzes the possibility of using binary non-azeotropic refrigerant in jet refrigeration cycle. The tried working pairs are R123/R142b,R123/R318,R141b/R142b and R318/R141b, formulated by the same theory as used for pure refrigerant and by the PR equation of state and its mixing rules. The theoretical calculations indicate that refrigerating quality could be improved if the binary mixtures evaporate just in low-temperature region. The results obtained from experiments with four working pairs confirm the ideal represented early, i.e. lower evaporating temperature (6℃ less) under approximate pressure ratio and larger value of COP up to 10% more.
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