冷库预冷流动传热物理场分布研究

Study on Distribution of Physical Fields Regarding to Airflow and Heat Transfer of Room Cooling

冷库预冷是传统的果蔬采后预冷方法,前人研究通过数值模拟使冷库预冷过程的流场和温度场可视化,本文进一步分析空气流速、局部平均空气龄、温度、熵产、(火用)损和(火积)耗散等物理场的分布特性,指出其间存在密切联系。塑料筐周围的空气流速和流向与内部的局部平均空气龄有关,并影响内部的传热速率。传热熵产率、传热(火用)损率和(火积)耗散率的分布特性及其变化趋势相似,局部高值与局部平均空气龄较低的区域均出现在塑料筐的表面。

Room cooling is a traditional precooling method for postharvest fruits and vegetables.Visualization of the flow field and temperature field during room cooling by numerical simulation has been achieved in previous studies.In this work,the distribution characteristics of physical fields such as air velocity,local mean air age,temperature,entropy production,exergy destruction and entransy dissipation are comprehensively analyzed,and the close relationships among these physical fields are pointed out.The air velocity and flow direction around the bins are related to the inside local mean air age,and further affect the heat transfer rate herein.Similar distribution characteristics and variations are found for the rates of entropy generation,exergy destruction and entransy dissipation regarding to heat transfer,whose locally high values as well as low local mean air age tend to be on the surfaces of bins.