| In recent years,China's quick-frozen food industry has developed rapidly,and the types and quantity of quick-frozen food are also increasing.In the process of producing quick-frozen food,especially in the tunnel freezer,the appropriate wind speed is very important for the effect of quick-frozen food.The traditional tunnel freezer mainly uses air cooling for cooling.The equipment needs precooling before operation.The long precooling time leads to high energy consumption and reduced production efficiency;When the production of quick freezing is increased,the temperature in the tunnel will rise with the increase of production,and the maximum cooling degree of the cooling fan is-40?.At this time,a lot of energy needs to be consumed to cool down.To solve the problems of high energy consumption and low production efficiency,a double refrigeration tunnel type quick freezer is designed,which mainly adopts aircooled quick freezing and liquid CO2 freezing device to assist in cooling.During precooling,two quick freezing methods precooling the tunnel at the same time.When the set temperature is reached,close the liquid CO2 freezing device to shorten the precooling time;When the workload is increased,the auxiliary air-cooled quick freezing is used for cooling,and the temperature of the sprayed dry ice can reach-78.5?,so as to reduce the temperature in the tunnel in a short time,so as to save energy consumption and improve the economic benefits of the enterprise.According to the use requirements of quick freezing equipment and the main characteristics of double refrigeration quick freezing mode,the working principle and structure of double refrigeration tunnel quick freezing machine are designed as a whole.The main mechanical structure of this design includes four parts:tunnel overall structure,transmission device,refrigeration unit and liquid CO2 freezing device.The specific structure and transmission system of each device are designed according to the design criteria,and the overall mechanical structure is reasonably arranged.SolidWorks software is used for modeling and fluent software is used for numerical simulation of the temperature field and velocity field in the quick freezing tunnel of the double refrigeration tunnel quick freezing machine.Through multiple numerical simulation analysis,four air supply speeds of 6m/s,7m/s,8m/s and 9m/s are selected to analyze the change law in the quick freezing tunnel.The optimal air supply speed is determined by comparing the speed and temperature cloud diagram changes of X-Y,X-Z and Y-Z sections.On the basis of selecting the best air supply speed,a liquid CO2 freezing device is added,the changes before and after adding the device are compared,and the numerical simulation analysis is carried out from two aspects of steady-state and transient.The research results show that on the basis of considering the principle of energy conservation and environmental protection and refrigeration effect,the simulation analysis of the distribution of three sections of velocity field and temperature field can be concluded that the air supply speed of cooling fan is more reasonable when it is 8m/s.On this basis,after adding liquid CO2 freezing device,the overall cooling effect is good,which can improve the quick freezing effect,shorten the tunnel precooling time,improve production efficiency,save costs and increase the economic benefits of enterprises,which is of great significance. |
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