Abstract: Studies on life cycle assessment of three typical building thermal insulation materials including polystyrene board, rock wool board, and rigid foam polyurethane board related to building energy-saving were carried out. Based on the method of life cycle assessment, "1 kg of thermal insulation material" is first selected as one of the functional units in this study based on the production field data statistics and general market transaction rules of the thermal insulation materials, and life cycle resource consumption, energy consumption and exhaust emission of the three products in China are deeply surveyed and analyzed. The abiotic depletion potential (ADP), primary energy demand (PED), and global warming potential (GWP) for production of 1 kg of the three thermal insulation materials are calculated and analyzed. Furthermore, the functional unit is extended to be "1 m2 of thermal insulation material meeting the same energy-saving requirements" so as to compare the difference of environmental friendliness among the three building thermal insulation materials, and the corresponding life cycle environmental impact is also calculated and analyzed. As shown by the results, where calculated in unit mass, the order of production life cycle environmental impact significances of the thermal insulation materials is as follows: rock wool board < polyurethane board < polystyrene board. However, where calculated in unit area (m2) meeting the 65% energy-saving requirements, the production life cycle environmental impact significances of the three kinds of insulation materials are sorted as polystyrene board < polyurethane board < rock wool board, whatever the region is, which is opposite with that of the results for the insulation materials in unit mass (kg). The reason for such difference is that they have different volume weights and heat conductivity coefficients. The polystyrene board has a smaller volume weight and the smallest heat conductivity coefficient, whereas the rock wool board has the highest volume weight and heat conductivity coefficient.
Source of the project fund. Subject "the Research and Application of Life Cycle Assessment Technology to the Building Materials for Building Engineering in Typical Regions" of the National Science & Technology Pillar Program during the Twelfth Five-year Plan Period (No.: 2011BAJ04B06)
Abstract: The area of building external windows is about 30% of the total area in building envelope, but the energy loss of the external windows accounts for over 50% of the building energy. Building external windows is the weakest parts of insulation performance in building envelope. Based on the method of life cycle assessment (LCA), this article deeply surveys and analyzes the resource consumption, energy consumption and pollutant emissions of bridge-cut-off aluminum alloy windows, unplasticized polyvinyl chloride (PVC-U) windows and aluminum-wood composite windows. This article calculates five main environmental impacts of functional unit (per m2) for the three products including the non-renewable resource consumption, energy consumption, greenhouse effect, acidification and eutrophication. The results show that to meet local design standard for energy efficiency and to achieve the same energy-saving effect, the environmental impacts of different climate zones in external windows from low to high are in the following order: unplasticized polyvinyl chloride (PVC-U) windows with 70 series (4 or 5 cavity), aluminum-wood composite windows with 68 series, un-plasticized polyvinyl chloride (PVC-U) windows with 60 series (3 cavity), bridge-cut-off aluminum alloy windows (55-58 series, the height of PA66 from 14.8mm to16.8mm), and bridge-cut-off aluminum alloy windows (65-70 series, the height of PA66 from 22mm to 35mm). This research provides domestic basic data for building external windows and green building.
Abstract: Thermoelectric efficiency power generation represented based on the transportation equations obtained under different physical boundary conditions in the present investigation. The figure-of-merit and power factor derived from optimizing thermoelectric efficiency and maximizing power output. It is interesting to note that the maximum output power reached when the load resistance was the thermoelectric adiabatic resistance, while the optimized thermoelectric efficiency responded the isothermal resistance. The possible approach to characterizing these thermoelectric parameters proposed in the present investigation.
Abstract: The shear property of the thermoelectric material Bi2Te3 is inextricably linked with its layer structure. By the molecular dynamics method, the mechanism of shearing deformation was studied in this paper. In the simulation, cubic single-crystal simulation cells with different layer directions inside were adopted, ensuring that the c axis of crystal lattice can be along, across and 45o deviated from the shear stress. Compared with all the calculation models, the results show that when the shear stress increases, slip occurs along the Te1-Te1 adjacent layers which are connected by the weak van der Waals bonding, and ultimately leads to structural fracture. Furthermore, size effect and loading modes can also impact the behavior of shearing deformation, however, in very different ways. Future efforts should be focused on the influence of the creation and motion of defects during the deformation as well as temperature effect and strain rate effect.
Abstract: CuxBi2Te3 films were prepared by chronopotentiometry electro-deposition on indium tin oxide (ITO)-coated glass substrates from an aqueous acidic electrolyte at room temperature. The films were deposited at the same current density but in electrolyte with different Cu2+ concentrations: 0.1, 0.25, 0.5, 0.75 or 1mM. The phase composition and morphology of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscope, respectively. The electrical conductivity and Seebeck coefficient of the CuxBi2Te3 films were measured after being transferred onto a non-conductive rubberized fabric support. All the films showed n-type conduction with Seebeck coefficient in the range of-63 to-84μV/K, and the electrical conductivity in the range of 90 to 185S/cm. The film deposited from an electrolyte with 0.5mM Cu2+ showed higher power factor ~130 μW/K-2m-1.
Abstract: The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in various conditions, were investigated in the temperature range from 323K to 1073K. Both the electrical resistivity and the absolute Seebeck coefficient decreased with the deepening degree of oxygen-reduction. However, the decrease of the electrical resistivity had a major influence on the thermoelectric power factor. Therefore, the more heavily reduced sample can gain the higher value of thermoelectric power factor. It has been observed that the thermal conductivity increased with the deepening degree of oxygen-reduction, which indicates that the scattering of the oxygen vacancies produced by reduction does not play a dominant role in the thermal conduction. In spite of the increase of the thermal conductivity, the oxygen-reduction still promoted the thermoelectric figure of merit via the increase of the thermoelectric power factor. And the most heavily reduced Sr0.61Ba0.39Nb2O6 ceramic has the highest thermoelectric figure of merit (~0.18 at 1073 K) among all the samples.
Abstract: In order to prevent the sublimation of Sb, protective Mo coatings were deposited on the CoSb3 substrate by DC magnetron sputtering. Thermal aging behavior of CoSb3 with Mo coating was investigated by accelerated experiment at 650oC for 24h. The results indicated that Mo coatings exhibit columnar crystal and body-centered cubic structure. It was found that the weight loss decreases with the increasing thickness of Mo coating. In comparison with naked CoSb3 material, the degradation of thermoelectric properties of CoSb3 with Mo coatings decreases under accelerated thermal aging test.
Abstract: Ba0.2Sr0.8Co0.9Nb0.1O3-δ (BSCN0.2)-xGd0.1Ce0.9O1.95 (GDC) (x = 10, 20, 30 and 40 wt.%) composite cathodes were investigated for the potential application in the IT-SOFCs. The results of chemical compatibility measurement show that a small number of Gd and/or Ce ions may melt into the lattice of BSCN0.2 to form BSCN0.2-GDC solid solution. Thermal expansion coefficients effectively reduced by the incorporation of GDC. The electrochemical performance of BSCN0.2-xGDC composite cathodes increased with increasing x from 10 to 30 wt.%. When x = 30 wt.%, the area specific resistances were only 0.040 and 0.017 Ω cm2 at 750 and 800oC, respectively. This improved electrochemical performance is attributed to the good thermal expansion match between BSCN0.2-xGDC composite cathode and GDC electrolyte, and the increased oxygen vacancy concentration. With further increasing x, the electrochemical performance of the composite cathode decreased. This result may be due to the ambipolar resistance model of porous composite cathode and the poor electrical conductivity of BSCN-40GDC. The maximum power densities of a BSCN0.2-30GDC/La0.9Sr0.1Ga0.8Mg0.2O3-δ/NiO-Sm0.2Ce0.8O1.9 single-cell achieve 537 and 722 mW cm-2 at 750 oC and 800oC, respectively. These results indicate that the BSCN0.2-30GDC composite cathode is a promising candidate for IT-SOFC.
Abstract: A study of depositing high quality c-axis oriented polycrystalline aluminum nitride thin film at room temperature was presented. Aluminum nitride films were grown by mid-frequency (MF) reactive sputtering. Metallic aluminum target was used to deposit AlN films in Ar/N2 gas mixture. A 50nm thick of N-rich AlN buffer layer was deposited at the initial stage of sputtering process to improve the film quality. The composition, preferred orientation and residual stress of the films were analyzed by EDS, XRD and Raman microscope, respectively. The results showed that the N-rich AlN buffer layer improved the textured degree and reduced the residual stress significantly of the AlN thin films. The near stoichiometric AlN thin film with highly textured degree was obtained. The FWHM value of the rocking curve for (0002) diffraction peak was about 1.6°, and the residual tensile stress was about 500MPa. The piezoelectric d33 coefficient increased with the decreasing of FWHM value, and the highest d33 coefficient of 3.6 pF/C was obtained.
Abstract: The electrical and physical properties of ZnO-CeO2 thin films on n-type Si (100) substrates have been examined by sol-gel method. In addition, the structures were heat treated at different temperatures from 600 to 700oC using the RTA (Rapid Thermal Annealing) process and investigated the influence of RTA effect on their properties. The diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. All films exhibited ZnO-CeO2 peaks orientation perpendicular to the substrate surface and the grain size with the dependent on annealing temperature. The dependence of the physical and electrical characteristics on various annealing temperatures was investigated.