摘要
为了研究高温季节粮食平房仓屋面架空层隔热性能的主要影响因素,采用计算流体力学对具有架空层通风结构的粮食平方仓进行数值模拟,并采取实验仓实验对模型进行了验证。实验结果表明,模拟结果与实验数据有较好的一致性,模型较为合理。在粮堆初始温度和储藏时间相同的条件下,基于所建立的数学模型,对具有不同空气层厚度、不同架空层通风气流速度的粮食平房仓进行了模拟,并研究了架空板表面高反射涂层的影响。结果表明,在主导风向上利用湍流换热入口段效应,可以提高架空层散热速率,减少仓内热量积聚,使上层粮温与"闷顶"式架空层相比降低了2. 1℃,扩大了粮堆内部"冷心"区域;在0. 2 m空气层厚度下,外界风速约为5 m/s时,架空层内形成的流动即可有效带走由架空板传入的积热,有效阻隔屋面向仓内的传热;而当架空层气流速度为2 m/s时,架空层的最佳厚度为δ=0. 3 m。在高温季节自然对流风速范围内(1～5 m/s),根据湍流入口段长径比来设置架空层空气厚度较提高气流速度或单一采用高反射涂层更有利于改善架空层隔热效果。
A simulation was performed in order to study the thermal insulation performance of a grain storehouse, with the ventilation structure of the high - temperature season was carried out by CFD, and the experiment cabin experiment was adopted to verify the model. A comparison was made between the simulation results and the test data from an experiment storehouse in Zhengzhou, which gave a satisfying coherence. Under the same conditions of the initial temperature and storage time of the grain pile, the grain bungalow bin with different air layer thickness and different air flow velocity was simulated on the basis of the established mathematical model, and the effect of the high reflection coating on the surface of the overhead plate was studied. The results indicated that the most influential factor for thermal performance was the turbulent heat exchange occurred in the overhead roof. An overhead roof along the most frequent wind direction is more capable to generate this turbulence than a full - open roof does. Entrance effects of a turbulent developing flow should be used for a feasible match between the geometric parameters and the flow velocity, which results in a more efficient thermal insulating and thus a temperature drop of about 2.1℃ in the upper grain bulk. That is, a larger low -temperature region in the grain bulk can be expected. With ventilated overhead roof, an enhancement in thermal insulating cannot be obtained by only a reflective coating or increased velocity of air flow. Furthermore, the optimized 8 was 0. 3 m at a 0.2 m/s of air velocity, and a 5 m/s velocity was demanded for the condition of 8 = 0.2 m. The thickness of the air in the overhead roof should be designed according to the length - diameter ratio of turbulent developing flow along the most frequent wind direction when a natural convection is taken into consideration （1 -5 m/s velocity of air flow）.
作者
陈雁
王子嘉
雷轩邈
Chen Yan;Wang Zijia;Lei Xuanmiao(College of Civil Engineering and Architecture,Henan University of Technology,Zhengzhou 450001)
出处
《中国粮油学报》
EI
CAS
CSCD
北大核心
2018年第9期93-99,共7页
Journal of the Chinese Cereals and Oils Association
基金
国家重点研发计划(2016YFD0401601)
关键词
粮食平房仓
架空层
通风
粮堆
温度场
grain storehouse
overhead roof
ventilation
grain bulk
temperature field
