【作者】 张恺；

【导师】 张小松；

【作者基本信息】 东南大学 ， 供热、供燃气、通风及空调工程， 2015， 博士

【摘要】 目前,空气调节技术已被广泛的应用到世界各地的各个领域中,并且随着人们生活水平的不断提高,空调系统的功能已经由仅仅需要满足房间内部基本的温湿度要求,逐渐变为如何提高室内的空气品质及改善人员的热舒适性。然而,提高室内的空气品质及改善人员的热舒适性往往意味着需要付出更高的能耗。对此,地板送风空调系统以其较好的室内空气品质和热舒适性,以及潜在的节能优势,使得这种空调方式具有很好的应用前景。但是良好的气流组织及温度分布却是充分发挥地板送风空调系统诸多优势的关键所在。因此,本文通过数值模拟与实验研究相结合的方式对基于多孔板／格栅板的地板送风空调系统的气流组织与温度分布特性进行了系统的研究,具体研究内容及主要结论如下：针对送风末端为多孔板的地板送风空调系统中地板静压箱的送风特性,提出空气渗漏损失系数模型及静压箱的出口与进口速度比率系数模型,进而对静压箱内压力与速度分布的理想模型进行优化。然后通过实验对空气渗漏损失系数模型及静压箱的出口与进口速度比率系数模型进行分析及验证。该优化模型可将系统漏风对静压箱内压力与速度分布的影响引入到理想模型中,并简化边界条件的求解及测量工作。对采用不同送风末端的地板静压箱的热衰减特性进行了研究,通过静压箱的热衰减比率系数深入分析了系统的送风温度,送风量,和送风末端的型式等因素对静压箱的热衰减的影响。通过实验得出静压箱的热衰减比率系数的变化规律,形成对地板静压箱的热衰减特性的规律性认识,为地板送风空调系统送风参数的选择及静压箱的配置提供依据。对影响地板送风空调系统热力分层的特性参数进行研究,提出热力分层特性点及温差比率的概念,并对其进行回归分析及数学建模。同时,根据回归分析的结果推导出适用于不同送风末端地板送风空调系统的送风量求解模型及限定条件。该送风量求解模型可以简化地板送风空调系统送风量的求解过程,并为系统温度分层的控制及冷负荷的求解提供理论基础。提出以大尺寸的多孔板和格栅板作为办公建筑中地板送风空调系统内区送风末端的配置方式,并通过实验对比了分别采用旋流散流器,多孔板,以及格栅板三种不同型式送风末端时房间的温度分布情况。进而对采用多孔板／格栅板的地板送风空调系统进行了深入的研究,得出送风温度和送风量对系统气流组织与温度分布的影响规律,为多孔板和格栅板在地板送风空调系统中的应用提供指导。为缓解数据机房内温度分布不均,以及能耗较大等问题,提出一种改善机房及机柜气流组织的方法,并对以格栅板作为送风末端的地板送风机房空调系统的温度分布进行优化。该优化方法可以在不增加系统能耗的情况下,有效改善机房及机柜的温度分布情况。同时,通过实验对优化系统进行了验证,并将封闭冷通道的方法进一步应用到该优化后的系统中,探讨封闭冷通道的方法对优化系统的适用性,为该优化方法的应用提供指导。更多还原

【Abstract】 Heating, ventilation and air conditioning (HVAC) systems have been widely used in many parts of the world. Nowadays, the purposes of HVAC system are mainly focused on the improvement of indoor thermal comfort (ITC) and indoor air quality (IAQ). Nevertheless, the better ITC and IAQ usually mean more energy consumption. As one of the forced air ventilation methods, the underfloor air distribution (UFAD) system has been a subject of active research for its potential advantages of better ITC, IAQ, and energy saving. However, a better distribution of airflow and temperature is critical to achieve the advantages of UFAD system. Therefore, the airflow and temperature distribution in the perforated tiles/grille diffusers UFAD system is researched with simulations and experiments in this study. The details and the main conclusions are as follows:The coefficients of the air leakage and the velocity ratio are proposed account for the characteristics of the UFAD system with perforated tiles, and thus the ideal model for the velocity and pressure in the underfloor supply air plenum (USAP) is optimized. The effect of air leakage on the distribution of velocity and pressure in the USAP is considered in the optimized model, and the measurement of the boundary conditions is also simplified with this model. Furthermore, the coefficients of the air leakage and the velocity ratio are verified with the experiments.The characteristics of thermal decay in the USAP are analyzed for the different terminal device systems. The effects of SAT, airflows, and type of the terminal device on the thermal decay in the USAP are discussed in details with the coefficient of thermal decay, and thus the rules for the variation of the coefficient of thermal decay are derived from the experiments. Furthermore, the fundamental understanding of thermal decay in the USAP for different terminal device is concluded, which is also a guiding significance of configuring the USAP.The key parameters for the thermal stratification as well as the coefficient of temperature gradient are proposed base on different terminal device in the UFAD system, and thus the regression models for the key parameters and the coefficient are derived from the experiments. Furthermore, the model for calculating the airflows is deduced according to the regression models, which simplify the calculation of airflow for the UFAD system. In addition, the control of the thermal stratification and the cooling load calculation also can be achieved on the basis of these models.The new and unconventional way of conditioning the interior zones in UFAD buildings by employing large-area perforated tiles/grille diffusers is proposed, and thus the temperature distributions for the UFAD system with swirl diffusers, perforated tiles, and grille diffusers are compared. The effects of SAT and airflows on the temperature distribution for the UFAD system with perforated tiles/grille diffusers are discussed in depth, which will help to understand the characteristics of the airflow and temperature distribution for the UFAD system with perforated tiles/grille diffusers.To improve the temperature distribution and energy consumption in the UFAD data center, a method on the basis of optimizing the airflow distribution is proposed. The optimized model is validated in the grille diffusers UFAD data center, and then the cold aisle in this data center is closed for the purpose of further optimization. With the optimized model, the temperature distribution in the UFAD data center with grille diffusers is improved effectively without any additional energy consumption. Furthermore, the results also provide guidelines for the application of this method.更多还原