Study On The Cold Storage Potential And The Application Zoning Of Winter Ventilation For Granaries

National grain reserve is an important material basis to ensure social stability and economic development.At present,China has established a national grain reserve system,but in the process of grain storage,it still faces the problem of grain aging and deterioration caused by high grain temperature.Low-temperature grain storage can reduce grain losses while ensuring the quality of stored grain,helping to solve the current problem of grain storage deterioration.Winter ventilation and storage is one of the methods to achieve low-temperature grain storage,with low energy consumption and low cost compared to mechanical refrigeration,but its effectiveness depends on the geographical characteristics and climatic conditions of each region.There is a lack of research on the application effect of this method in different regions of grain silos in China,which limits the promotion and application of this method.Based on this,this paper takes the most typical cottage silo in China as the representative silo,selects cities in different regions of China,uses numerical simulation methods to quantify and analyze the effect of using the winter ventilation and cold storage method in each region,and establishes a database of the winter ventilation and cold storage potential of Chinese silos.Finally,according to the difference of potential values of each representative city,the application potential of winter ventilation and cold storage method of grain silos is zoned,and the application potential zoning map is given.Based on the research objectives of this paper,this study is divided into the following steps: In the first step,based on the geographical environment and the current development status of grain silo buildings in China,cottage silos were selected as representative grain silos and 62 representative cities through literature review,questionnaire survey and field research,and the characteristics of typical cottage silo buildings were obtained.In the second step,a numerical model of grain silos is established based on the architectural characteristics of representative grain silos,and the validity of the modeling method is verified by using the measured data as the benchmark.After that,taking Zhengzhou city as an example,the effect of applying the winter ventilation and cold storage method to grain silos in Zhengzhou city was studied by simulating the climatic conditions in Zhengzhou city,and evaluated by two criteria,(1)the duration of maintaining a cold environment and(2)the number of cooling degree days required for the grain silos to maintain a cold environment throughout the year,respectively,according to the low-temperature storage standard.The results showed that after applying the method,the grain pile in the grain silo in Zhengzhou city could maintain low temperature storage for 126 days,and the number of refrigeration degree days required for the silo during the period beyond the low temperature storage range was 928.1°C-d.The two values were taken as the values of the winter ventilation and storage potential of the grain silo in Zhengzhou city.In the third step,the simulation process of Zhengzhou City was applied to the remaining 61 representative cities,and the typical meteorological year data of each city was used as the climatic conditions to simulate and study the winter ventilation and cold storage potential values of grain silos in all representative cities,to establish a database of winter ventilation and cold storage potential of grain silos in China,and to adopt the cluster analysis method to carry out the zoning of winter ventilation and cold storage potential of grain silos in China,and according to the two potential evaluation criteria,two kinds of potential were thus drawn potential zoning maps.In the fourth step,for the zoning,the characteristics of each potential zoning were analyzed,and the two zoning were compared to analyze the reasons for the differences.In this study,a database of winter ventilation and cooling storage potential of grain silos in China was established,and a study on the distribution of winter ventilation and cooling storage potential zones in China was completed.According to the two criteria of the length of time to maintain the low-temperature environment in grain piles and the number of cooling degree days required to maintain the low-temperature environment in grain silos throughout the year,China was divided into five potential ranking zones and six potential ranking zones,respectively,with obvious differences between each ranking zone.Based on the results of this zoning,it is possible to clearly and directly understand whether and to what extent winter ventilation and cooling storage methods can be used in grain silos in different regions,providing a reference for relevant specifications and a basis for grain silo management practices.