Moyou Andre Yves, Njifenjou Abdou, Tiam Kapen Pascalin, Fokwa Didier
Laboratory of Mechanics, University of Douala, Douala, Cameroon.
Laboratory of Energy Material Modeling and Method, National Higher Polytechnic School of Douala, University of Douala, P.O.BOX 2701, Douala, Cameroon.
Heliyon. 2024 Jul 3;10(13):e34058. doi: 10.1016/j.heliyon.2024.e34058. eCollection 2024 Jul 15.
The buildings of the city of Douala in Cameroon have been experiencing degradation for several decades due to the climate characterized by high humidity and oppressive heat. As a result, large grayish or black stains can be observed on these buildings. We sometimes witness the subsidence of the slab of the balconies, the cracking of the walls and the collapse of the buildings worn by the humidity. These damages are generally caused by infiltration and capillary rise. In addition, it has been demonstrated that people living in damp buildings are at risk of illnesses such as asthma and lung infections. Therefore, the novelty of this work is threefold: (i) it proposes for the very first time a numerical study of the transport of humidity and heat through the porous walls of buildings constructed with concrete material, the main construction material in the city of Douala; (ii) It was determined what level of indoor thermal comfort was appropriate for sleeping inside a real three-dimensional G+1 complex residential building constructed with concrete blocks; and (iii) Using the geographical coordinates, and time data, the sun radiation's direction of incidence was assessed throughout the simulation. The computation was performed using Comsol Multiphysics 6.0 software. The distributions of temperature, relative humidity as well as moisture level were presented at various periods. It appears from the results that face to this high humidity, the concrete material retains a large quantity of water for a considerable periods of time, which weakens the steel reinforcement of concrete which is corroded by rust. The computation of thermal comfort in the 3D building showed that the various rooms of the building were not comfortable during the night since temperature inside the building increased progressively due to diffusion of heat. In addition, the numerical solutions indicated that the energy stored within the walls diffused from the external walls to the internal walls during the night. It was also demonstrated that the walls of the building were warmer than the windows, doors and the roof at the computational times, which simply revealed a greater storage capacity of heat in the concrete blocks material. The findings highlighted that the temperature decreased rapidly in a thickness of 0.06 m of the concrete block during the nine days and this decrease was attenuated in the second part of the thickness of the concrete block (0.14 m).
由于喀麦隆杜阿拉市气候潮湿闷热，几十年来该市的建筑物一直在不断退化。因此，可以看到这些建筑物上有大片灰色或黑色污渍。我们有时会目睹阳台楼板下沉、墙壁开裂以及因潮湿而受损的建筑物倒塌。这些损坏通常是由渗透和毛细上升引起的。此外，研究表明，居住在潮湿建筑物中的人有患哮喘和肺部感染等疾病的风险。因此，这项工作的新颖之处有三点：（i）首次对湿度和热量通过用混凝土材料建造的建筑物多孔墙壁的传输进行了数值研究，混凝土是杜阿拉市的主要建筑材料；（ii）确定了在一座用混凝土砌块建造的真实三维G + 1复合住宅楼内睡觉适宜的室内热舒适度水平；（iii）利用地理坐标和时间数据，在整个模拟过程中评估了太阳辐射的入射方向。计算使用Comsol Multiphysics 6.0软件进行。给出了不同时间段的温度、相对湿度以及湿度水平分布。结果表明，面对如此高的湿度，混凝土材料在相当长的一段时间内会保留大量水分，这会削弱混凝土中的钢筋，使其生锈腐蚀。三维建筑内热舒适度的计算表明，由于热量扩散，建筑物内的温度在夜间逐渐升高，因此建筑物的各个房间在夜间都不舒服。此外，数值解表明，夜间墙壁内储存的能量从外墙扩散到内墙。计算还表明，在计算时刻，建筑物的墙壁比窗户、门和屋顶更暖和，这仅仅表明混凝土砌块材料的蓄热能力更强。研究结果突出表明，在九天时间里，混凝土砌块厚度0.06米处的温度迅速下降，而在混凝土砌块厚度的第二部分（0.14米），这种下降有所减弱。
