Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid...Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.展开更多
In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using ...In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge. Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O2 concentration of 0.1%. The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream. It seems that SO2 could not be removed unless there is Ar in the dry gas stream. The mechanism of removal of NO and SO2 in the dry gas stream was discussed.展开更多
The thermal stability, particle size and morphology and oil absorption of aluminum hydroxide(ATH) treated by drymodification with three different modifiers were investigated. The experimental results show that the the...The thermal stability, particle size and morphology and oil absorption of aluminum hydroxide(ATH) treated by drymodification with three different modifiers were investigated. The experimental results show that the thermal stability of ATHpowder is markedly improved by dry modification technology with the following modifiers such as phosphoric acid, polyacrylic acidand the mixture of phosphoric acid and polyacrylic acid. The best effect comes from pure phosphoric acid, and the initial temperaturefor the loss of crystal water of ATH powder modified with pure polyacrylic acid can reach about 202 ℃ that is approximately 10 ℃higher than that of ATH powder before modification. The phenomena of agglomeration and macro-aggregate badly exist in ATHpowder modified with the modifiers containing phosphoric acid. The growth of particles and agglomerations of powders are notevident in ATH powder modified with pure polyacrylic acid. The oil absorption of ATH powder modified with the modifierscontaining phosphoric acid is apparently larger than that of original ATH powder and ATH powder modified with pure polyacrylicacid. The oil absorption of the ATH powder modified with pure polyacrylic acid is slightly smaller than that of original ATH powder.展开更多
Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid a...Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.展开更多
Drying shrinkage of thermal insulation mortar with glazed hollow beads was measured by a vertical length comparator, and the influences of fly ash with different contents（0, 18%, 36%, and 54% were used） on the long-...Drying shrinkage of thermal insulation mortar with glazed hollow beads was measured by a vertical length comparator, and the influences of fly ash with different contents（0, 18%, 36%, and 54% were used） on the long-term drying shrinkage were discussed. The mass loss was measured by the weighting method and the pore structure was characterized using three different methods, including the light microscopy, the mercury intrusion porosimetry（MIP）, and the nitrogen adsorption/desorption（NAD） experiments, and the correlations among them were researched. The results show that drying shrinkage process of thermal insulation mortar includes three steps with increasing curing time： the acceleration period（before 7 d）, the deceleration period（7-365 d）, and the metastable period（after 365 d）. Drying shrinkage in the first stage（7 d before） increases quickly owing to the fast water loss, and its development in the last two stages is attributed to the increment of the pore volume of mortar with the radius below 50 nm, especially the increment of the pore volume fraction of the pore radius within the size range between 7.3 nm and 12.3 nm. There is no change in the drying shrinkage development trend of mortar with fly ash addition, and three steps in the service life, but fly ash addition in the mortar restrains its value. There is a linear relationship between the drying shrinkage and fly ash content, which means that drying shrinkage reduces with fly ash addition.展开更多
文摘Compressed earth blocks (CEB) are an alternative to cement blocks in the construction of wall masonry. However, the optimal architectural construction methods for adequate thermal comfort for occupants in hot and arid environments are not mastered. This article evaluates the influence of architectural and constructive modes of buildings made of CEB walls and concrete block walls, to optimize and compare their thermal comfort in the hot and dry tropical climate of Ouagadougou, Burkina Faso. Two identical pilot buildings whose envelopes are made of CEB and concrete blocks were monitored for this study. The thermal models of the pilot buildings were implemented in the SketchUp software using an extension of EnergyPlus. The models were empirically validated after calibration against measured thermal data from the buildings. The models were used to do a parametric analysis for optimization of the thermal performances by simulating plaster coatings on the exterior of walls, airtight openings and natural ventilation depending on external weather conditions. The results show that the CEB building displays 7016 hours of discomfort, equivalent to 80.1% of the time, and the concrete building displays 6948 hours of discomfort, equivalent to 79.3% of the time. The optimization by modifications reduced the discomfort to 2918 and 3125 hours respectively;i.e. equivalent to only 33.3% for the CEB building and 35.7% for the concrete building. More study should evaluate thermal optimizations in buildings in real time of usage such as residential buildings commonly used by the local middle class. The use of CEB as a construction material and passive means of improving thermal comfort is a suitable ecological and economical option to replace cementitious material.
基金Project supported by the National Natural Sciences Foundation of China(No.50576037)Natural Science Foundation of Jiangsu Province(No.BK2006198)
文摘In order to investigate the feasibility of sequential removal NO and SO2 using non-thermal plasma and adsorbent simultaneously, the removal of NO and SO2 from dry gas stream （NO/SO2/N2/O2） with very little O2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge. Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O2 concentration of 0.1%. The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream. It seems that SO2 could not be removed unless there is Ar in the dry gas stream. The mechanism of removal of NO and SO2 in the dry gas stream was discussed.
基金Project(06SK2011) supported by the Science and Technology Program of Hunan Province, China
文摘The thermal stability, particle size and morphology and oil absorption of aluminum hydroxide(ATH) treated by drymodification with three different modifiers were investigated. The experimental results show that the thermal stability of ATHpowder is markedly improved by dry modification technology with the following modifiers such as phosphoric acid, polyacrylic acidand the mixture of phosphoric acid and polyacrylic acid. The best effect comes from pure phosphoric acid, and the initial temperaturefor the loss of crystal water of ATH powder modified with pure polyacrylic acid can reach about 202 ℃ that is approximately 10 ℃higher than that of ATH powder before modification. The phenomena of agglomeration and macro-aggregate badly exist in ATHpowder modified with the modifiers containing phosphoric acid. The growth of particles and agglomerations of powders are notevident in ATH powder modified with pure polyacrylic acid. The oil absorption of ATH powder modified with the modifierscontaining phosphoric acid is apparently larger than that of original ATH powder and ATH powder modified with pure polyacrylicacid. The oil absorption of the ATH powder modified with pure polyacrylic acid is slightly smaller than that of original ATH powder.
文摘Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.
基金Funded by the National Key Technology R&D Program of China during the 12th Five-year Plan(No.2012BAJ20B02)
文摘Drying shrinkage of thermal insulation mortar with glazed hollow beads was measured by a vertical length comparator, and the influences of fly ash with different contents（0, 18%, 36%, and 54% were used） on the long-term drying shrinkage were discussed. The mass loss was measured by the weighting method and the pore structure was characterized using three different methods, including the light microscopy, the mercury intrusion porosimetry（MIP）, and the nitrogen adsorption/desorption（NAD） experiments, and the correlations among them were researched. The results show that drying shrinkage process of thermal insulation mortar includes three steps with increasing curing time： the acceleration period（before 7 d）, the deceleration period（7-365 d）, and the metastable period（after 365 d）. Drying shrinkage in the first stage（7 d before） increases quickly owing to the fast water loss, and its development in the last two stages is attributed to the increment of the pore volume of mortar with the radius below 50 nm, especially the increment of the pore volume fraction of the pore radius within the size range between 7.3 nm and 12.3 nm. There is no change in the drying shrinkage development trend of mortar with fly ash addition, and three steps in the service life, but fly ash addition in the mortar restrains its value. There is a linear relationship between the drying shrinkage and fly ash content, which means that drying shrinkage reduces with fly ash addition.
