| With the improvement of the society, the role of energy has become increasingly important for economic development. The ratio of building energy consumption in the field of energy consumptions becomes larger and larger. In order to reduce building energy consumption and improve the efficiency of building energy conservation, insulation materials with high performance should be used in constructions. Therefore, vacuum insulation panels (VIPs) have gradually got seriously attention. Recently, VIPs have widely applied in building envelopes, such as flat roof terraces and wall insulation material. And some problems also occur during its application. However, little comprehensive study presents detailed description of VIP preparation, degradation of different kinds of VIP barrier envelopes exposed to extreme environment and the thermal behavior of VIP-PCM combinded panels. Thus, this thesis comprehensively investigated the performamce VIPs and provided a technical guidance and experimental basis for the application of VIPs.During the preparation of VIPs, different nano-size raw materials, such as fumed silica (fs), precipitated silica (ps), silica fume (sf) were selected as the potential candidates for VIPs’ core materials. And this paper aimed to find the optimal molding pressure, drying time and packing time of VIPs with diffent core materials. The results showed that VIPs with core materials fumed silcia had the lowest thermal conductivity (λ=3.741mW/m·K). The thermal conductivity of VIPs decreased with the increasing mass fraction of silica fume. VIPs with precipitated silica as core materials had the lowest cost, and its performance (X=4.856mW/m-K) could still meet the requirements of VIPs application.And the paper investigated the time-dependent degradations of three types of commonly used envelopes (aluminum film, metallized film and metallized film coated with alkali-resistant (AR) fiberglass mesh) and VIPs covered by these three envelopes by simulating environmental conditions with four types of alkaline solutions (NaOH solution with pH=7,11,13 and saturated Ca(OH)2), two different temperatures (20℃ and 60℃), and local stress concentration. The results demonstrated that stress and high temperature accelerated the degradation of envelopes and such degradation became more serious with increased pH value and temperature. In addtion, it was also observed that the thermal conductivity of VIPs increased quickly when they were exposed to both higher alkalinity and high temperatures. MF and GF owned better resistance to high-temperature and alkaline solution than AF.The form-stable phase change materials (PCMs) were prepared by absorbing paraffin into three different hydrophilic and hydrophobic fumed silica, precipitated silica, silica aerogel and hydrophilica expanded perlite. The results indicated that the paraffin content (mass of paraffin/mass of paraffin and powders) of form-stable PCMs prepared by hydrophilic materials is higher than that prepared by hydrophobic materials. The appropriate mass fractions of paraffin mixture in the composite were 65%,70-73% and 78% for hydrophilic ps, fs and aerogel. However, there were 58%,65% and 71% for hydrophobic ps, fs and aerogel. Form-stable PCMs prepared by hydrophilic precipitated silica were used to prepare vacuum insulation panel (VIP) and PCM combined panels. And the thermal behavior of the combined panel was also tested.The results revealed that the addition of form-stable PCMs had effectively reduced the inner temperature variations.In order to obtain the impact of PCM on energy saving when VIP-PCM combined panels were installed in constructions, EnergyPlus energy simulation was carried out on two differnet types of buildingds with five different weather data in China. The results showed that VIPs and VIP-PCM combined panels prepared in this paper did well in energy saving especially for cold regions. However, panels were not suitable for hot regions. Heat hardly transfers to the outside from inner space of the buildings due to its high performance in insulation, thereby increases building energy consumption. In summary, appropriate application of VIPs and VIP-PCM combined panels could reduce the total building energy consumptions compared with common used insulation materials, such as PU. |
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