Research On Humidity-controlling Wall Materials And Its Moisture Absorption And Desorption Capability

The development and application of eco-architecture and eco-building materials has been highly concerned at present due to the demand of high living standard and better comfort as well as health arising out of the rapid growth of our economy. Biomass is a renewable resource with some kinds of special properties which could be suitable for making wall material of special functions following within eco-building materials, and also quite abimdant in China. Therefore, using biomass to make such wall material is quite interesting in our country. It is expected such wall material could be helpful in achieving more comfortable human settlement, and excellent IEQ.The work of this paper is carried out under the contract, between Tianjin University and European Commission. The goal of the project is to develop a new bio-based building material, named HCWM here, which can adjust indoor relative humidity by its moisture absorption and desoiption capability. The final objective of the project is to achieve energy savings in buildings through the reduction of energy consumped by the conventional air conditioning device and meanwhile to improve IEQ. In addition, the work could be contributing to outdoor environmental quality by re-using biomass wastes thereby reducing the pollutions associated with biomass open-field burning.The thesis firstly presents the state-of-the-art progress on R&D of eco-building materials and humidity-controlling materials, on building energy savings, on the renovation of wall materials and on biomass utilization. The information provides a strong base for R&D of HCWMs in our Lab. Then theoretic analysis related to the moisture migration process inside building envelopes is made and the mathematical modeling on heat and moisture migration process is established Besides, the mechanism of humidity-controlling materials is clarified. Later, in the laboratory, HCWMs were produced in batch by using agriculture residues and additive as partial raw materials under different, ratio in the lab-made experimental platform. Finally, a device for testing humidity- controlling performance of HCWMs made is designed and developed. Furthermore, the other performances, for example thermal performance, are also been tested.After many times of testing lab-made HCWMs, EMC-φ, EMC-t, and φ-t curves are obtained and further analysed. As a result, if the ratio of biomass toadditive is 21-IK the peifonnance of HCWMs appears sat.isfact.oiy. When the ambient relative humidity is at the range of 40°/b-'70°/ik the moisture migration capability of HCWM is obviously foreseen. In addition, the coefficient of thermal conductivity of HCWM is about 0.09--0.15W/niK . Based on the data obtained, it is concluded that the HCWM made in our lab could achieve the goal of the project.