| With the strengthening of China’s comprehensive strength,exploration in aerospace,aviation,deep sea,water conservancy,hydropower,nuclear power and other fields has advanced by leaps and bounds.Core is an important kind of physical geological data,so it is very important to properly preserve the mined core.The environmental parameters such as temperature and humidity stored directly affect the quality of core,and also affect the results of subsequent analysis of core components.Adopting a reasonable storage mode can effectively improve the air flow in the cabinet,improve the uniformity of air temperature and velocity distribution,reduce the energy consumption of the refrigerator and ensure the storage quality of the core,so that the analysis results of the core are more authentic and reliable.In this paper,the core freezer in a geological research institute in Qingdao is taken as the research object,and the influence of air supply parameters and cargo stacking mode on the temperature field and velocity field inside the freezer is mainly studied by combining numerical simulation and experiment.The main research work of this paper is as follows:Based on the actual structure of the refrigerator,the similarity principle is used to calculate and build the refrigerator model test platform.The two-way fluid-structure coupling model between the air and the core in the freezer was established,and the grid independence of the model was verified.The distribution law of the flow field and temperature field in the freezer under under various working conditions was studied,which provided a reference for the location of the core storage.The three-dimensional RNG k-ε turbulence model was established.Considering the influence of external environment and core on the internal environment of the refrigerator,the influence of air supply speed,air supply temperature and core stacking mode on the internal air temperature and velocity field of the refrigerator was studied,and the uniformity of temperature and velocity field in the refrigerator under different working conditions was evaluated and optimized.The results show that:(1)When the refrigerator is empty,the air distribution in the cabinet is more uniform.There is a large vortex at the lower to the right.The flow velocity in the center of the vortex area is slow and the temperature is high.Therefore,the temperature on the monitoring line L0-L6 shows a trend of first decreasing,then increasing and then obviously decreasing.(2)In the condition of heat dissipation of six-layer core with full cabinet,with the increase of cooling time,the bottom of freezer cools down first,and then the cooling area gradually expands upward.When the air supply speed is 4.7m/s and the air supply temperature is-3℃,and when t=360min,most of the air temperature in the refrigerator is at the optimal storage temperature of the core.The highest temperature near the core is 3.9℃,and the lowest temperature is-0.3℃(only the first layer left row core).After the airflow enters the refrigerator,due to the constraints of the wall and core wall,an intermittent pipeline is formed,the diffusion effect of the airflow is weakened,and the attached flow distance is increased.Compared with empty storehouse,stacking goods on one side of the air supply outlet will make the airflow reach the bottom of the refrigerator faster and faster,which can promote the flow of air into the bottom of the refrigerator and promote the heat exchange in the refrigerator.(3)Only half a tank goods,different goods stacking method,temperature field and velocity field inside ark present a different distribution,when the fourth,five,six layer stacking is used,the average flow velocity in the freezer,the biggest turbulence inside ark is larger,combined with core near the inlet,air contained in the heat transfer effect is better,the uniform temperature distribution,the lowest temperature.Compared with the three stacking methods,when the air supply temperature was-3℃ and the air supply speed was 4.2m/s,the temperature distribution in the cabinet all met the core storage requirements after 120 min,but the temperature in the warehouse dropped fastest when the fourth,fifth and sixth layers were stacking.(4)Increasing the wind speed has little effect on the air speed in the refrigerator,but it has a better promoting effect on the uniformity of air distribution.The air supply speed increases from 3.5m/s to 4.7m/s,but the speed field in the cabinet does not change significantly,while the temperature can be well improved.Therefore,in the design of the air supply system of the freezer in the core warehouse,the temperature uniformity inside the freezer can be improved by increasing the wind speed.(5)By comparing the temperature distribution of each horizontal monitoring line at different supply temperatures,each horizontal monitoring line presents the same temperature distribution law at different supply air speeds.The higher the supply air temperature is,the less the interference from the external environment is,the more uniform the temperature field in the refrigerator is,and the smaller the non-uniformity coefficient is.(6)Under the condition of full tank without heat source,after the air is sent out from the air supply outlet,part of the air impacts on the upper surface of the core and then moves to the left,and the air is gradually heated up;Below the return air outlet,under the action of thermal buoyancy and return air outlet,the air flow resistance is small,the heat transfer is fast,and the temperature is low.The temperature of the horizontal test line increases first and then decreases along the positive direction of the X-axis as a whole.(7)The velocity distribution of the jet attached to the simulation results was compared with the empirical formula,which showed a high degree of agreement.The comparison between the numerical simulation results of empty storage and the experimental results shows that the two have a high degree of agreement,indicating that the numerical simulation results have high reliability. |
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