基于COMSOL软件的深埋地下工程围护结构热湿耦合传递模拟

围护结构内的热湿耦合传递是影响地下工程热湿负荷的重要因素,为了研究深埋地下工程中围护结构的热湿行为,通过建立热湿耦合传递模型,以两种衬砌结构为研究对象。在进行热湿传递模拟时,为体现含湿量对材料导热性能和传湿性能的影响,模型中将建筑材料的各项参数均表示为含湿量的函数。利用COMSOL Multiphysics的偏微分方程接口,模拟围护结构的热湿吸放过程,并比较两种衬砌结构的热湿传递规律。模拟结果表明:围护结构的热湿负荷变化略滞后于工程内部空气的温湿度的变化过程;离壁式衬砌结构的热负荷远小于贴壁式衬砌结构;离壁式衬砌中的空气夹层能有效增加围护结构的热阻,但是会降低围护结构的传湿阻力;离壁式衬砌结构和室内空气的传湿量略小于贴壁式衬砌结构,两者相差大约30%;离壁式衬砌更能够减小深埋地下工程的热湿负荷,降低工程能耗水平。

Coupled Heat and Moisture Transfer Simulation of Deep Underground Envelopes Based on COMSOL

Coupled heat and moisture transfer in envelopes significantly affects the heat and moisture loads of the underground buildings. In order to study the hygrothermal performance of two kinds of deep underground lining structures, a heat and moisture coupling transfer model was developed. The influence of the moisture content on the thermal conductivity, moisture transport character of the envelope structure is usually neglected unreasonably, resulting in calculation errors. The material properties was expressed as a function of moisture content to reflect the influence of moisture content on the heat and moisture transfer in the model. A partial differential equation interface in COMSOL Multiphysics was used to implement the simulation with a transient boundary conditions and the temperature field ,moisture field of the structures was abtained. The simulation results show that the thermal load of the off-wall lining structure is much smaller than that of the adherent lining structure; moisture flux between the off-wall lining structure and indoor air is slightly smaller than that between adherent lining structure and indoor air, which is about 30%; So off-wall lining structure performs better in reducing energy consumption of deep underground buildings.