【作者】 何媛；

【导师】 南晓红；

【作者基本信息】 西安建筑科技大学 ， 供热、供燃气、通风与空调工程， 2008， 硕士

【摘要】 在国家节能减排政策的背景下,冷库的节能问题备受关注。冷库建筑具有内冷外热的特点,因此当开关冷库大门时,由于室内外风压和热压的作用,在冷库大门处将产生强烈的热湿交换,导致冷负荷增加,安装大门空气幕是冷库节能的重要措施。本文以一个实际冷库为研究对象,全面建立了关于冷库冷藏间、空气幕及室外环境的CFD稳态模型,通过现场测试冷库空气幕的有关参数,并与CFD预测结果进行比较,以此对CFD模型作了进一步验证和修改。模拟结果和测试结果显示本文所建立的CFD模型可以用来预测冷库空气幕的部分性能。本文采用CFD的方法主要从以下方面进行了研究:(1)模拟了冷藏间内冷风机不同吹风速度下的气流流场,为采用以冷风机为制冷设备的冷库设计提供了理论指导。(2)在冷库大门开启而空气幕不开启的情况下,成功地预测了穿过冷库大门的冷风渗透率,通过比较经验公式、理论分析和CFD预测的结果,得出Gosney、Fritzsche和Tamm修正公式可以用来计算穿过冷库大门的冷风渗透率,其中Gosney公式计算结果和CFD预测结果最接近。(3)在冷库大门和空气幕同时开启的情况下,全面模拟了空气幕不同结构参数对其性能的影响。分析了喷口宽度分别为0.03m、0.05m和0.1m时空气幕效率的变化,指出薄的喷口宽度有利于空气幕的设计和现场安装;当改变影响空气幕性能的出口射流速度时,通过比较分析空气幕效率的变化,得出总存在一个使得空气幕效率最大的射流速度;还模拟了不同喷射角度下的空气幕效率,指出相对于0°和30°来说,15°的安装角可以改善空气幕的效率。更多还原

【Abstract】 With the requirement of energy-saving and ejection-decreasing, more and more attention is taken to the issue of energy saving of cold stores. The cold store building is featured with cold inside environment and warm outside environment. When the cold store is open, the strong exchange of heat and mass takes place owing to the wind pressure and thermal pressure between the inside and outside of a cold store, leading to the increase in cold load. So air curtain is usually installed at the entrance in order to save energy.A steady model was proposed for the springhouse, the air curtain and the outside environment of a cold store based on CFD. The performances of air curtain of a cold store were tested on site. The CFD model was validated and inproved by comparing the CFD predictions and the test results. The simulation results show that the mumerical model can be applied to predict the performance of air curtain.The following researchs were carried out with the CFD technique. (1) The air flow field in springhouse was numerically studied. The research results can be helped to the design of cold a store. (2) The air infiltration is successfully predicted for the case when the cold store entrance is open but the air curtain dose not work. The analytical models of Gosney, Fritzsch and Tamm modified were comparied and the results of Goseny model provided closest comparison with the CFD predictions. It’s showed that the three analytical models can be used to predict the infiltration through the cold store entrance. (3) As the cold storage entrance is open and the air curtain works at the same time, the air curtain performances, with different structure parameters, were simulated and predicted comprehensively. The changes of air curtain effectiveness were analyzed when the outlet is 0.03m, 0.05m and 0.1m, respectively. A narrow outlet is proved to be favorable to the design and installation. Furthermore, the effectiveness changes with different jet velocities were analyzed. It is found that the effectiveness of the air curtain is dependant on the jet velocity and an optimal value of the jet velocity exists. Furthermore, the effect of jet angle on the effectiveness of the air curtain was also numerically predicted. The effectiveness is better at the jet of 15°than at jet angle of 0°and 30°.更多还原