辐射供冷空调系统防结露最佳安全温差预测模型研究

发布时间：2018-04-24 06:14

本文选题：辐射供冷 + 防结露　；参考：《天津商业大学》2017年硕士论文

【摘要】：辐射空调系统起源于欧洲,辐射供冷空调系统是在房间地板、吊顶等围护结构内嵌入冷水管网形成冷辐射面,通过冷辐射面与室内其他环境形成以辐射换热为主并伴随对流换热的空调系统。辐射供冷空调系统以其良好的节能性和舒适性而被认为是目前最具应用潜力的空调形式之一。但辐射供冷空调系统由于冷辐射面温度较低,当空气湿度较大时,易在冷辐射面上形成结露现象,不仅影响系统正常运行,而且影响房间卫生。因此结露现象的发生成为限制辐射供冷空调系统广泛推广应用的主要问题。结露是由于辐射供冷空调系统冷辐射面表面温度低于周围空气露点温度而引起的水蒸气凝结现象。因此,要研究辐射供冷空调系统的防结露问题,掌握辐射供冷空调系统辐射板表面温度的动态变化和辐射板周围空气的露点温度动态变化至关重要。本课题是在课题组已经完成辐射供冷空调系统辐射板表面温度动态变化规律的基础上,对辐射供冷空调系统辐射板贴附层空气露点温度与各影响因子的关系、以及在室内人员发生变化时贴附层空气露点温度动态变化的研究,在辐射板表面温度与贴附层空气动态变化规律结果基础上,研究一种防结露最佳安全温差预测模型。首先通过实验研究了室内热源变化时对贴附层空气干球温度的变化,进而分析了室内热源对贴附层空气露点温度的影响。接着对室内人员增加时,贴附层空气露点温度的动态变化进行了分析研究。在实验研究的基础上,对实验房间建立物理模型,运用FLUENT软件对模型进行模拟研究,作为实验研究的补充和扩展,得出辐射供冷空调系统贴附层空气露点温度与各影响因子的关系,并通过线性回归分析得出适用于多种工况的贴附层空气露点温度与各影响因子通用关系式。最后联立板温与露点温度关系式,通过求解获得一种辐射供冷空调系统防结露控制的最佳安全温差预测模型。本课题的研究主要有以下结论:(1)与温度相关的影响因子对辐射供冷空调系统贴附层空气露点温度的影响较小,可以忽略不计,如板表面温度、内围护结构表面温度、室内热源等。而与室内空气含湿量分布相关的影响因子对贴附层空气露点温度影响较大,包括湿源强度、湿源距贴附层的距离等;(2)室内人员增加时,贴附层空气露点温度先以负指数形式增大,随后趋于稳定。室内人员增加不同、湿源距贴附层距离不同,贴附层空气露点温度增大的速率和最后稳定时达到的温度值不同。湿源强度越大、湿源距贴附层越近时,贴附层空气露点温度增加越快且最终稳定时达到温度值越高。(3)尽管人员增加时室内贴附层空气露点温度增大,但与提高供水温度后辐射板表面温度升高速率相比仍增加缓慢,只有当室内人员增加较多,即湿源强度足够大时,板温增加速率与露点温度增加速率才接近,研究得出了此种情况下的防结露最佳安全温差预测模型。(4)对室内人员增加后贴附层空气露点温度变化和提高供水温度、降低供水流量后板表面温度变化曲线联立分析可以看出,对不同室内湿源增加工况和不同防结露调节工况,研究最佳安全温差的关键是要分析辐射板表面温度变化斜率和贴附层空气露点温度变化斜率。另外,降低供水流量对辐射供冷空调系统防结露的效果较小,提高供水温度和关闭供水可以有效防止辐射供冷空调系统结露的发生,并且通过二者曲线变化可以寻找某工况下防结露的最佳调节时间和最佳安全温差。本研究将辐射供冷空调系统辐射板表面温度动态变化和贴附层空气露点温度动态变化联立分析,得出了不同工况下不同调节方式下的最佳调节时刻和最佳安全温差。本课题结果对辐射供冷空调系统的推广应用提供理论支持,研究方法也为辐射供冷空调系统防结露提供参考。
[Abstract]:The radiation air conditioning system originated in Europe. The radiation cooling air conditioning system is embedded in the room floor, the ceiling and other enclosure structures to form cold radiation surface, and form the air conditioning system with radiation heat transfer and convection heat transfer through the cold radiant surface and other indoor environment. The radiation cooling air conditioning system has good energy saving and comfort. It is considered to be one of the most potential air conditioning forms at present. But the radiation cooling air conditioning system, because of the low temperature of the cold radiant surface, is easy to form condensation on the cold radiation surface when the air humidity is large, which not only affects the normal operation of the system, but also affects the health of the room. This condensation phenomenon becomes the limitation of the radiation cooling air. The condensation is due to the condensation phenomenon caused by the surface temperature of the cold radiation surface of the radiation cooling air conditioning system which is lower than the ambient air dew point temperature. Therefore, it is necessary to study the anti condensation problem of the radiation cooling air conditioning system and master the dynamic change of the surface temperature of the radiation plate on the radiation cooling air conditioning system. The dynamic change of the dew point temperature of the air around the radiant plate is very important. On the basis of the dynamic change of the surface temperature of the radiant plate on the radiation cooling air conditioning system, this topic is on the relationship between the air dew point temperature of the radiation plate attached layer and the influence of the influence factors on the radiation plate and the changes in the indoor personnel. The dynamic change of air dew point temperature in the attached layer is studied. On the basis of the results of the surface temperature of the radiant plate and the dynamic change rule of the attached layer air, a prediction model for the optimum safety temperature difference is studied. First, the change of the air dry ball temperature in the attached layer is studied by the experiment, and the indoor heat source is analyzed. The influence of the air dew point temperature on the attached layer. Then the dynamic changes of the air dew point temperature of the attached layer are analyzed and studied. On the basis of the experimental study, the physical model of the experimental room is established and the model is simulated by FLUENT software. As a supplement and expansion of the experimental research, the radiation cooling air space is obtained. The relationship between the air dew point temperature of the attached layer and the influence factors, and through the linear regression analysis, the general relation between the air dew point temperature of the attached layer and the influence factors is obtained. Finally, the formula of the relationship between the temperature and the dew point temperature of the joint plate is obtained, and the best way to prevent the condensation control of the radiation cooling air conditioning system is obtained by solving the formula. The main conclusions of this study are as follows: (1) the effect of temperature related factors on the air dew point temperature of the attached layer of the radiation cooling air conditioning system is small, which can be ignored, such as the surface temperature of the plate, the surface temperature of the inner enclosure structure, the indoor heat source and so on, and the influence on the indoor air moisture content distribution. Factors have great influence on the air dew point temperature of the attached layer, including the strength of the wet source and the distance from the attachment layer of the wet source. (2) when the indoor personnel increase, the air dew point temperature of the attached layer increases first in the negative index form, and then tends to be stable. At the end of the stability, the temperature values are different. The greater the strength of the wet source, the closer the wet source spacing is, the faster the air dew point temperature in the attached layer increases and the final stability reaches the higher temperature. (3) although the air dew point temperature of the indoor attached layer increases while the personnel increase, it is still compared with the increase of the surface temperature of the radiant plate after the increase of the water supply temperature. Increase slowly, only when the indoor personnel increase more, that is, when the strength of the wet source is large enough, the increase rate of the plate temperature and the rate of dew point temperature increase is close. (4) the temperature variation of the air dew point in the attached layer and the water supply temperature are increased and the water supply is reduced. The joint analysis of the surface temperature variation curve of the flow back plate shows that the key to the study of the optimum safety temperature difference is to analyze the slope of the surface temperature change and the air dew point temperature change slope of the attached layer. The effect of anti condensation is small. Improving the water supply temperature and closing the water supply can effectively prevent the condensation of the radiation cooling air conditioning system, and the optimum adjustment time and the best safety temperature difference can be found through the change of the two curve. The dynamic change of the air dew point temperature of the attached layer is analyzed, and the optimum adjustment time and the best safety temperature difference are obtained under different operating conditions. The results of this paper provide theoretical support for the popularization and application of the radiation cooling air conditioning system, and the research method also provides reference for the anti condensation of the radiation cooling air conditioning system.

【学位授予单位】：天津商业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU831.3

【参考文献】