The Evaluation On Moisture Buffering Capacity Of Hygroscopic Materials And Its Application In Rooms With Radiant Cooling System

Indoor humidity affects every aspect of daily life,such as museums,galleries and other places as well as textile and other production processes which have high requirements on humidity.The application of hygroscopic material on the interior surface of building envelope is a passive means to control indoor humidity and avoid condensation on the wall surface.Hygroscopic materials have porous properties and can adsorb or desorption water molecules.Due to its ability to absorb and release moisture,the hygroscopic material can maintain the indoor humidity level within a certain range.In this paper,the mathematical model of MBV is summarized and modified.According to the research results of some researchers,the existing model is not accurate,so in recent years,many researchers have modified the model,but most of the modifications are based on the assumptions of the model,and the modification methods are also limited.MBV model is extrapolated from the theory of heat transfer,but the process of heat transfer and moisture transfer have many difference,so we concentrate on material internal pore structure for the correction,the results show that for all materials the relative error of MBV decreases.But it did not show any regularity,so the next step research should start from the internal pore structure types,as well as the integration of various correction methods,in order to obtain more accurate mathematical model.In this paper,the heat and humidity transfer model is summarized and analyzed,and based on the experiments of Lawrence laboratory in the United States,the appropriate mathematical model is selected for modeling,and the experimental data are used for modification.Furthermore,the hygroscopic properties of hygroscopic materials under the effect of radiation heat transfer are investigated.Some hygroscopic materials are divided into three categories according to their different properties.The simulation results show that radiant heat transfer has little effect on the overall performance of hygroscopic materials.This paper also gives some suggestions for materials selection.In practical applications,if we don't need to consider economic factors,strength requirements,insulation performance,etc.,the material with large moisture capacity and large water vapor permeability is the best choice.In other conditions,materials with high water vapor permeability are preferred for buildings with short-term moisture load,and materials with large moisture capacity are preferred for buildings with long-term moisture load.