| Adopting parallel dual evaporators in the refrigerator of Multitemperature zone can improve the temperature control accuracy of the cabinet air and the refrigerator system energy efficiency effectively,so the refrigerator with parallel dual evaporators has received more and more refrigerators enterprises attention.In the new proposed national refrigerator standard,the refrigerator energy efficiency indicators are improved,so the refrigerators enterprises need to develop better refrigerators product using energy-saving design which can meet higher energy efficiency standards.In order to meet the urgent demand for the design of the refrigerator system with parallel dual evaporators,in this paper,the transient performance calculation method of the parallel evaporator is established,and the control strategy based on temperature priority level is put forward by optimizing the existing system control strategy.Based on the above research,the system and component performance simulation software of the refrigerator with parallel dual evaporators is developed.The research achievements are described as follows:(1)The transient performance calculation method of parallel dual evaporator is developed.In the present study,all the operating modes and the forms of changing modes of the parallel evaporator is summarized,and the distribution of the refrigerants in different operating modes before and after transformation is analyzed,then the formulas for the mass,energy and other parameters of the refrigerant in different distribution states is established,and the smooth transition rules of each mode which based on the assumption of linear distribution of enthalpy are established.Based on the above analysis,the calculation method of transient performance for parallel dual evaporators is developed.The proposed algorithm is embedded to mature simulation software,and the results show that simulation results are in good agreement with the experimental data,and the relative deviation between the simulation results and the experimental data is less than 10%,which can be used in the dynamic simulation of the parallel double evaporator.(2)The control strategy of parallel double evaporator refrigerator based on temperature priority is developed.In this paper,the problems and causes of the existing sequential control strategies in the common dynamic conditions of the refrigerator system is analyzed.Based on those analyses,a new control strategy which switch the refrigeration cycle according to the urgency level of the two cabinet is put forward,that is control strategy based on the temperature priority.Then the new control strategy how to solve the problems of the existing sequential control strategy is analyzed.Three exiting sequential control strategies and one new control strategy are embedded in the simulation program,the results show that under the new control strategy,there is no problem of exceeding the upper cabinet air temperature limit,and the deviation of the average temperature is within 0.6K,and the maximum energy saving rate is more than 8.5%.(3)The system and component performance simulation software of the refrigerator with parallel dual evaporators is developed.Based on the analysis of the function of the simulation software,the whole framework of the software is established.Then,the appropriate calculation model is selected according to the demand of the software.At last,the MFC simulation software is developed based on the MFC dialog box.The simulation results show that the simulation software developed in this paper can predict the performance trend of the system correctly and has good simulation precision.The deviation of system energy consumption simulation results and experimental data is within 5%,and the calculation time is less than 200 seconds;the average deviation of calculation results and experimental data for components and energy efficiency is less than 7%,each calculation of the average speed is less than 20 seconds,can improve the efficiency of refrigerator designers significantly. |
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