Study On Preparation Of Refrigerator Cooling Phase Change Material And Improvement Of Refrigerator Performance

In recent years,with the improvement of industrialization and living standard,the electricity consumption is increasing day by day.Household appliances account for a large part of the electricity consumption.Among them,the household refrigerator has become the household appliances with the highest energy consumption due to its continuous operation.China is a big producer and consumer of refrigerators.The research on energy-saving technology of refrigerators plays an important role in reducing energy consumption.At present,the main methods to reduce the energy consumption of refrigerator are to improve the efficiency of compressor,the heat insulation performance of heat preservation materials and the heat transfer performance of heat exchanger.However,it is expensive to improve the compressor and insulation materials,and the evaporator is the main source of the cooling capacity in the refrigerator,so it is a good solution to enhance the heat transfer effect of the evaporator.Therefore,this paper proposes to integrate phase change materials into the evaporator,so that the phase change materials can accumulate cold amount during the operation of the refrigerator,and release the charging capacity after the refrigerator compressor stops,so as to extend the compressor's downtime,,delay the temperature fluctuation in the refrigerator,improve the performance of the refrigerator heat exchanger,and provide a basis for the research of energy-saving refrigerator.The main work and research results of this paper are as follows:(1)Screening through a large number of experiments,the phase change material ZW-3,which is suitable for refrigerator freezer,was preliminarily configured by step cooling curve method and differential scanning calorimetry.In view of its large supercooling degree and easy leakage and phase separation in use,adding nucleating agent is put forward to reduce the degree of supercooling,using carboxymethyl cellulose and super absorbent polymer to improve the easy leakage and storage capacity of PCM.Eventually,ZW-7 was prepared,and the thermal physical property was tested.(2)The phase change cold storage material ZW-7 was applied to the evaporator of refrigerator freezer,the physical and mathematical model of cold storage refrigerator were established,the temperature field of cold storage refrigerator were studied by ANSYS-FLUENT,the charging and discharging process of phase change materials were analyzed,researching its effect on the performance of the refrigerator,and to establish a experimental platform for experimental verification,verify the effectiveness of the model.(3)The effects of different thickness and different placement of the cold storage plate on refrigerator compressor on-off time and the temperature distribution in the refrigerator were simulated,so that the phase change material can be used more efficiently.It is found that adding cold storage plate can prolong the compressor's downtime,slow down the temperature rise in the refrigerator,and reduce the running time ratio of refrigerator compressor from 30.1% to 26.8%.However,the thickness of the cold storage plate should not be too thick,which will increase the production cost,and the cold storage material will be partially solidified or partially melted,which will reduce the effectiveness of the phase change material.Reasonable placement of the cold storage plate can make the temperature distribution in the refrigerator more even,providing a better temperature environment for food storage.(4)The application of phase change materials in refrigerator was verified by the experimental platform of cold storage refrigerator,and the validity of the model was verified.Besides,the effect of PCM addition on temperature fluctuation in refrigerator under different operation mode was studied experimentally.As a result,the temperature fluctuation in the refrigerator can be reduced by the addition of PCM,and the holding time after power off can be prolonged.Under the situation of on-load and no-load,the compressor operation rate is reduced by 7.2% and 8.11%,respectively.The above research results provide theoretical and reference basis for the design of cold storage refrigerator.