仓储粮堆通风干燥湿热传递模型的研究进展

Research Progress on Moisture and Heat Transfer Model for Ventilation Drying of Grain under Bulk Storage

摘要:

从古到今，治国理政的首要之务是粮食安全。粮食仓储安全尤为重要，关系到一个国家的国家安全。由于粮食干燥储存方法原始、干燥技术落后等原因，我国每年收获后会损失大量粮食。粮食中湿热分布不均不仅会降低粮食的品质，而且会因霉变、虫害等问题严重影响食品安全。因此，如何快速、均匀而又低能耗地降低粮堆含水率或者温度，保证粮食品质，同时节约能源，是粮食干燥储藏研究的一个重要方向，具有重要的理论及现实意义。通风干燥是保证储粮中湿热均匀分布的重要措施，建立干燥模型预测粮堆的湿热分布是研究粮堆干燥过程中湿热传递的重要手段。该研究综述了粮堆湿热传递的经验模型、连续模型和离散模型，其中经验模型容易获得，但是应用较少；连续模型应用较多，但不能反映粮堆的孔隙结构；离散模型可以很好的反应粮堆的孔隙结构，但其计算量大，并且难以理解和构建。最后该研究指出可以根据不同的湿热传递过程，结合先进的计算方法和处理技术，建立相应的模型，以满足不同的模拟要求，并对粮堆通风干燥湿热传递模型未来的研究方向进行了展望。

Abstract:

Food security has been at the forefront of state governance throughout history. The safety of grain storage is particularly important, which is related to the national security of a country. A large amount of grain is lost after harvest every year owing to reasons such as the primitive grain drying and storage methods and the backward drying technology. The uneven distribution of moisture and heat in stored grain will not only lower the quality of grain, but also seriously affect the food safety of grain caused by mildew, insect pests and other problems. Therefore, how to reduce quickly and uniformly the moisture content or temperature of bulk grain piles with low energy consumption to ensure grain quality while saving energy is an important direction for grain drying and storage research, which has profound theoretical and practical significance. Ventilation drying is an important measure to ensure the uniform distribution of moisture and heat in stored grain, and constructing a drying model to predict the moisture and heat distribution of grain pile is an important means to study the moisture and heat transfer during the drying process of grain piles. This paper reviewed three models of moisture and heat transfer in bulk grain piles, the empirical model, continuum model and discrete model. The empirical model is easy to obtain but rarely used. The continuum model is widely used, but it cannot reflect the pore characteristics of grain piles. The discrete model reflects well the pore structure of grain piles, though it relies on large amounts of calculations and is difficult to understand and construct. Finally, it is pointed out in this paper that corresponding models can be established in combination with advanced calculation methods and processing techniques according to different moisture and heat transfer processes to meet different simulation requirements. In addition, the future research direction of moisture and heat transfer models for ventilation drying of grain pile under storage is also prospected in this paper.