被动式热激活复合墙体热特性实验研究

Experimental Study of the Thermal Characteristics of a Passive Thermo-Activated Composite Wall

内嵌管建筑围护结构具备良好的节能潜力和设计隐蔽性,可利用低品位可再生能源隔绝室外气候对室内环境的影响,受到建筑师和工程师的共同关注.针对主动式热激活建筑系统存在的驱动耗能高、运行维护困难等问题,采用两相热虹吸回路替代传统显热热交换系统,提出被动式热激活建筑系统概念.设计并搭建了被动式热激活复合墙体模块检测平台,研究了冬季模式下热源温度和充液率对建筑集成用回路热管运行特性以及复合墙体热特性影响.蒸发器出口与冷凝器进口及出口的高差分别为2.1 m及1.5 m条件下的实验结果表明:不同热源温度条件下建筑集成用回路热管均可成功启动和运行,即使在25℃低热源温度条件下回路热管的启动速度值也可达0.06℃/s(此时充液率为60%),验证了被动式热激活建筑系统的技术可行性;不同热源温度下,最佳充液率并非固定值,约为116%,保温隔热情景或中性情景下可适当降低充液率以获得更快的系统启动速度,而在辅助供能以及直接供能情景下则需适当提高充液率以获得较低的注热热阻;冷凝段是制约被动式热激活复合墙体热传输效率的主要瓶颈,总热阻中冷凝器热阻占比最大,约为58.4%~94.4%;注入热量可以明显提升围护结构温度,并在承重层与保温层之间建立温度分界面,达到保温隔热和辅助供能等设计目的.

Pipe-embedded building envelopes can be used to protect the indoor thermal environment from the impact of the outdoor climate,which is of particular interest to architects and engineers,because of their excellent performance and invisibility.To address the problems of high driving energy consumption and difficult operation maintenance of active thermo-activated building system,the concept of a passive thermo-activated building system,in which the traditional sensible heat exchange system is replaced with the two-phase thermosyphon loop(TPTL),is proposed.A module test platform is designed and built to analyze the influence of key factors,such as heat source temperatures and filling ratios,on the operation characteristics of the TPTL and the thermal characteristics of the composite wall in winter mode.The height difference value between the evaporator outlet and the condenser inlet/outlet of the experimental prototype is 2.1 m/1.5 m.Results show that the TPTL for building integration can be started and operated successfully at different heat source temperatures,which verify the feasibility of the proposed concept of a passive thermo-activated building system.Even under the condition of low heat source temperature,eg,25℃,the startup speed of the TPTL can reach 0.06℃/s(liquid filling ratio is 60%).Moreover,the optimum filling ratio of the investigated TPTL(approximately 116%)varies at different heat source temperatures.In detail,the filling ratio can be decreased appropriately to obtain a faster startup speed when the thermal insulation or neutral scenario is active,whereas the filling ratio can be increased appropriately to obtain a low heat injection resistance when the auxiliary and direct energy supply scenarios are active.Moreover,the condensation thermal resistance accounts for the largest proportion of the total thermal resistance of the system(approximately 58.4%to 94.4%),indicating that the condensation section is the main bottleneck restricting the heat transfer efficiency of the passive thermo-activated building system.In addition,the injected heat can obviously increase the temperature of the enclosure structure and establish a distinct temperature interface between load-bearing and thermal insulation layers to achieve the design purpose of thermal insulation and auxiliary energy supply.