混凝土辐射末端传热特性模拟及应用研究

发布时间：2018-07-01 15:14

  本文选题：混凝土辐射供暖系统 + 蓄放热特性　； 参考：《清华大学》2015年硕士论文

【摘要】：混凝土辐射空调系统作为一种区别于传统对流空调系统的空调方式,在住宅供暖、大空间供冷供暖等领域得到广泛应用。混凝土辐射空调系统的末端是具有较大热惯性的混凝土,且具有较大的铺设面积。稳态情况下,混凝土辐射末端主要以长波辐射换热形式与室内换热,且对人体具有较大的角系数;在室内外条件发生较大变化或者间歇供热等情况下,混凝土辐射末端良好的蓄放热特性会平抑室内热环境的波动,维持室内热环境的恒定。目前,辐射末端与对流末端的比较多以模拟计算为主,同时混凝土建筑蓄热的研究较多忽略了蓄放热特性对室内热环境的影响,混凝土热惯性和相应热源结合的应用案例和计算较少。本论文主要针对上述问题展开研究,对混凝土辐射供暖房间和传统对流末端供热房间的热舒适性和负荷进行了对比,对混凝土末端的惯性利用及相应热源匹配展开相关研究。通过分块离散混凝土辐射末端的方式,考虑混凝土埋管内流动热媒的温度变化,建立起混凝土末端的准二维传热模型;通过状态空间法对围护结构进行离散划分,建立起整个围护结构的矩阵传热方程。将混凝土末端传热模型和围护结构传热模型联立,可以对混凝土辐射末端供暖房间进行稳态计算和非稳态计算。提出了围护结构等效热损失温度的概念,在等效热损失温度和人体操作温度的基础上利用相对变化系数△t_(loss)/△t_(op)比较末端稳态传热性能,末端较小的相对变化系数△t_(loss)/△t_(op)对应末端在相同的操作温度情况下房间负荷较低。针对混凝土辐射末端的惯性利用和热源匹配形式,选取了两个应用案例进行研究。将混凝土辐射末端与城市集中热网结合,并采用合适的通断控制策略,可以最大限度降低供热系统回水温度,提高系统能源利用效率。将混凝土辐射末端与太阳能热源结合组成分散式太阳能供暖系统,应用在太阳能资源丰富的青藏高原地区,房间温度可以在全天保持在17℃以上,且室内温度波动较少,供暖效果良好;利用动态热阻对分散式供暖系统的传热过程进行了研究,提出了运行改进的相关优化策略。
[Abstract]:As a kind of air conditioning system different from the traditional convection air conditioning system, the concrete radiation air conditioning system has been widely used in residential heating, large space cooling heating and other fields. The end of the concrete radiative air conditioning system is the concrete with large thermal inertia, and has a large laying area. Under steady state, the radiation end of concrete is mainly in the form of long wave radiation heat transfer and indoor heat transfer, and has a large angle coefficient to the human body, in the case of large change of indoor and outdoor conditions or intermittent heating, etc. The good heat storage and exothermic property of the radiation end of concrete will restrain the fluctuation of indoor thermal environment and maintain the stability of indoor thermal environment. At present, the comparison between the radiation end and the convection end is mainly based on the simulation calculation, and the research on the heat storage of concrete buildings neglects the influence of the heat storage and exothermic characteristics on the indoor thermal environment. The application and calculation of concrete thermal inertia and corresponding heat source are few. In this paper, the thermal comfort and load of the concrete radiant heating room and the traditional convection end heating room are compared, and the inertia utilization of concrete end and the corresponding heat source matching are studied. The quasi-two-dimensional heat transfer model of concrete end is established by taking into account the temperature change of flowing heat medium in concrete pipe, the state space method is used to divide the enclosure structure, and the heat transfer model of concrete end is established by dividing the radiating end of concrete into blocks and considering the temperature change of flowing heat medium in concrete pipe. The matrix heat transfer equation of the whole envelope structure is established. The heat transfer model of concrete end and the heat transfer model of enclosure structure can be used to calculate the steady and unsteady state of concrete radiating end heating room. In this paper, the concept of equivalent heat loss temperature of enclosure structure is proposed. Based on the equivalent heat loss temperature and the operating temperature of human body, the steady-state heat transfer performance of the end is compared by using the relative coefficient of variation t _ (loss) / t _ (op). The relative coefficient of variation (t _ (loss) / t _ (op) corresponding to the lower end is lower room load at the same operating temperature. Aiming at the inertial utilization and heat source matching of the radiation end of concrete, two application cases are selected to study. Combining the radiation end of the concrete with the urban centralized heat network and adopting the appropriate on-off control strategy, the backwater temperature of the heating system can be minimized and the energy utilization efficiency of the system can be improved. A distributed solar heating system is formed by combining the radiation ends of concrete with solar heat sources. The system is applied to the Qinghai-Tibet Plateau, where solar energy resources are abundant. The room temperature can be kept above 17 鈩，

本文编号：2088191