| In recent years,with the development of science and technology,China’s frozen food industry to carry out rapid development,the number and type of frozen food has been increasing.The traditional food freezing process is to facilitate food delivery and long-term storage.Because of the continuous improvement of living standards,nowadays people demand for frozen food not only for storage,but also focus on the pursuit of food taste and price.For industrial production,not only should we focus on production speed,but also on product quality.Firstly,this paper builds on the review of a large amount of information and the analysis and summary of the working principle and working condition of the existing impregnating freezing device,and puts forward the improvement plan and technical requirements according to the existing conditions,based on SolidWorks 3D modeling software for the new impregnating freezing device to carry out 3D modeling design,and proposes the working principle diagram of the new impregnating freezing device and the working flow diagram of the device.The key components are selected according to the theoretical analysis.The control system of the device and the human-machine interface are designed using PLC.Next,the simulation model was created according to the computational fluid theory and heat transfer theory,and the discretization of the simulation model was completed by the preprocessing software.Two variables,refrigerant flow rate and basket speed,were set by fluent software to consider the effects of these two variables on pork freezing speed and freezing quality unilaterally and orthogonally at-20℃.To explore the general pattern,multiple control experiments were designed for each variable.Through the analysis of the above two result data,it can be known that the two variables can improve the freezing speed as well as the freezing quality when orthogonal,therefore,in order to improve the freezing quality of pork,it is necessary to increase the refrigerant flow rate and the speed of the carrier basket at the same time,and the simulation data show that the freezing time shortening efficiency depends on the speed of the carrier basket and the speed of the carrier basket.The simulation data show that the freezing time reduction efficiency decreases with the increase of the rotational speed of the carrier basket and the flow rate of the refrigerant,and it can be determined that the freezing time reduction efficiency is zero when the flow rate of the refrigerant reaches 5 m/s and the rotational speed of the carrier basket is 5 rad/s.Finally,this paper provides a theoretical analysis of this situation by heat transfer theory.Finally,based on the device design in Chapter 2 and the simulation results in Chapter 3,the experimental device was set up and debugged,and the final selection of the refrigerant flow rate v=1,2,3 m/s and the carrier basket speed r=1,2,3 rad/s was made based on the actual situation,taking into account the safety and economy of the device.Under the above experimental variables,the freezing of pork samples was completed,the temperature of the center of pork was detected by temperature sensors and the pork samples were sliced and processed,and the cells of the frozen and thawed pork samples were observed using an electron optical microscope,and by recording the freezing time and calculating the cell breakage rate,it can be concluded that at v=3 m/s and r=3 rad/s,the pork cells The cell breakage rate after thawing at the fastest freezing speed was as low as 13%,which was the best level for all the observed samples,and the growth rate of freezing time was the same as the decreasing trend of the simulated data.Finally,this paper analyzes the errors between the simulated and experimental data,and shows the reasons for the formation of errors.This article conducted improved design and experimental research on immersion refrigeration equipment,enriching the theoretical system of immersion refrigeration and providing new ideas for the future development of immersion refrigeration. |
PDF Full Text Request