| Thermosensitive material liquid,such as fruit,vegetable juice,milk,liquid medicine,and beer need to be cooled,to prevent microbes breeding and browning ensuring the quality of material liquid.Take milk cooling storage installation mainly used in small-medium pasturelands as an instance,the paper systematically researched heat-transfer process between liquid and refrigeration medium,matching of refrigeration unit and liquid storage installation.Firstly,by analyzing the cooling process of milk cooling storage installation,defined the heat-transfer basic links,and influence factors,summarize that main restrictions of cooling process are milk ice point,stirring speed,heat-transfer surface,flowage of refrigerant and temperature.Synthesized heat transfer of both sides,calculated the total heat-transfer coefficient.By analyzing the change of heat-transfer rate and refrigerant and milk cooling speed with the change of all the factors.The main strengthening measures of milk cooling and the optimum range of operation process are given.Secondly,the matching of refrigeration unit storage unite have an important impact on performance.Calculated milk cooling load,then analyzed capillary refrigeration unit,thermal expansion valve refrigeration unit and electronic expansion valve refrigeration unit.Contrasted the refrigerating capacity in different seasons and the matching with milk cooling load.Results showed that the capillary refrigerant unit had large deviation,thermal expansion valve unit is medium,electronic expansion valve could be better matched.Finally,by the analysis above,set up capillary refrigeration unit bench and electronic expansion valve refrigeration bench.By conducting the experiment under different operating conditions,analyze the change of refrigerating capacity,electric current pressure.The final analysis conclusion is that electronic expansion valve refrigeration unit fit best,and capillary refrigeration unit fluctuates a lot. |
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