A coupled finite element model has been developed to simulate heat and water transfer across earth walls, considering pore water phase changes and the associated latent heat fluxes. The adopted approach simplifies parametric analyses by expressing all material hygrothermal properties as functions of porosity and water retention characteristics. The model is used to assess the influence of pore water latent heat on the passive hygrothermal regulation provided by two infinite earth walls that enclose an idealised room exposed to an external cold, humid climate. The findings indicate that latent heat buffering by pore water in earth walls increases with greater relative humidity gradients between the outdoor and indoor environments. The low vapour diffusivity confines latent heat production to the outer cold wall region where pore vapour condenses. The condensed moisture then flows inward and re-evaporates in the inner region of the wall. Additionally, the phase changes of water crossing the wall interfaces contribute to latent heat buffering, thereby enhancing hygrothermal efficiency. The process of pore vapour condensation and liquid transport intensifies with higher volumetric capacity and diffusivity of liquid water, which in turn increase with greater porosity, steeper retention curves, and larger saturation levels. Hydraulic effusivity is defined as a function of the volumetric capacity and diffusivity of liquid water to measure latent heat exchanges. Large hydraulic effusivity values indicate a greater potential for latent heat buffering. Finally, when compared to conventional concrete walls, earth walls demonstrate considerably better hygrothermal performance, which is mostly attributed to greater latent heat exchanges.

中文翻译：

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潜热对土方建筑材料湿热性能影响的研究


考虑了孔隙水相变和相关的潜热通量，开发了一个耦合的有限元模型来模拟跨土墙的热和水传递。所采用的方法将所有材料湿热特性表示为孔隙率和保水特性的函数，从而简化了参数分析。该模型用于评估孔隙水潜热对两个无限土墙提供的被动湿热调节的影响，这些土墙将一个暴露在外部寒冷潮湿气候中的理想房间包围起来。研究结果表明，随着室外和室内环境之间相对湿度梯度的增大，土墙中孔隙水的潜热缓冲增加。低蒸汽扩散率将潜热产生限制在孔隙蒸汽冷凝的外冷壁区域。然后，冷凝的水分向内流动，并在墙壁的内部区域重新蒸发。此外，水穿过壁界面的相变有助于潜热缓冲，从而提高湿热效率。孔隙蒸汽冷凝和液体传输过程随着液态水体积容量和扩散率的增加而加剧，而液态水的体积容量和扩散率又随着孔隙率的增加、保留曲线的陡峭和饱和度的增加而增加。水力喷发率定义为液态水的体积容量和扩散率的函数，用于测量潜热交换。较大的水力喷发率值表明潜热缓冲的可能性更大。最后，与传统的混凝土墙相比，土墙表现出更好的湿热性能，这主要归因于更大的潜热交换。