Study On The Air-conditioning Environmental Characteristics Of Apple Air-conditioning Box During Cold Chain Transportation

Cold chain logistics,as an important part of the chain to ensure product quality and safety,has become an important indicator of the level of a country’s economic development.The development of cold chain logistics is of great significance to promote the development of related industries,enhance industrial competitiveness.Air conditioning technology as a new type of apple storage can be used throughout the apple process from picking,storage and retail,which is low cost,easy to manage and flexible to operate.In this thesis,a non-steady-state numerical computational model of gas flow and mass transfer was established to study the changes in environmental parameters during gas conditioning transport.The main research work is as follows.An Apple Breathing Intensity UDF program was written to simulate the change in apple respiration rate with the difference of O₂ and CO₂.The change rule of O₂ and CO₂component concentration was simulated by UDF program and calculation model.The changes in the concentration of CO2 components were in good agreement with the calculation results of related empirical formulas.The relationship between O2 and CO2 concentrations and time was derived,by analyzing the changes in O2 and CO2 concentrations and distribution patterns during the refrigerated transport phase of the air-conditioned box.The concentrations of O₂ and CO2 were all within the range of suitable apple modified atmosphere transportation,which means there will be no anaerobic breathing during the refrigerated transportation of the the air-conditioned box.At the same time,the concentration distribution of O2and CO2 in different stages of modified atmosphere transportation was analyzed,the unevenness was evaluated as well.The effect of conditioned air refrigerated transport on apple respiration rate was studied by comparing the changes in the respiration rate of conditioned air refrigerated transport apples and ordinary refrigerated transport apples.Refrigerated transport of the air-conditioned box can reduce the aerobic respiration rate by about 73.5%.In order to implement the concept of the entire fresh-keeping chain,to ensure that the air-conditioned box can be quickly entered into the cold storage after the modified atmosphere transportation,the air exchange speed and the duration of the air-conditioning box during the pre-cooling process were determined by changing the air supply parameters.The best air velocity was selected from 0.8m/s,1.2m/s and1.5m/s by comparing the CO2 change law at the exit.The optimal ventilation duration was determined by studying the CO2 emission efficiency at different times during the ventilation process.In this thesis,a three-dimensional mathematical solution model of the refrigerated transportation and ventilation process of the air-conditioned box was established,and the O₂ and CO₂ concentration changes during the refrigerated transportation of the apple modified atmosphere box were obtained.The results of this calculation have important reference value for the improvement of environmental control and management level during the transportation of apple modified atmosphere boxes.