Atmospheric exposure tests including two experimental stages of high temperature-spraying water cycle and heating-refrigeration cycle were carried out on three currently used ETIS of expanded polystyrene（EPS） board,...Atmospheric exposure tests including two experimental stages of high temperature-spraying water cycle and heating-refrigeration cycle were carried out on three currently used ETIS of expanded polystyrene（EPS） board,polystyrene granule mortar and polyurethane foam in order to study the weatherablility of external thermal insulation system（ETIS）.The change rules of adhesive strength were hereby studied at different time period of atmospheric exposure tests.The experimental results show that the adhesive strength of three kinds of ETIS changes a little during high temperature-spraying water cycle,but the adhesive strength of ETIS with EPS board decreases significantly after heating-refrigeration cycle.The lowering rate of adhesive strength with painting finishes is obviously faster than that of tile finishes for ETIS of EPS board during heating-refrigeration cycle.The weatherability of ETIS with EPS board is worse than the other two,and ETIS of polystyrene granule mortar and polyurethane foam are more suitable than ETIS of EPS board in cold area.展开更多
The finite element model of an external thermal composite insuiation system, thin rendered expanded polystyrene （ EPS ） board, was built with ANSYS 1.0, which had two forms： one with window and one without window. ...The finite element model of an external thermal composite insuiation system, thin rendered expanded polystyrene （ EPS ） board, was built with ANSYS 1.0, which had two forms： one with window and one without window. The finite element analysis results show that the EPS board had very good insulation capacity at both high or low temperature, stress concentration was produced in the center of wall and around window, and the maximum deformation was observed at the edge of board and the minimum deformation was in the center.展开更多
With the rapid development of the construction industry today, external wall insulation technology has become an important part of the construction industry. Aiming at the influence of many factors such as material se...With the rapid development of the construction industry today, external wall insulation technology has become an important part of the construction industry. Aiming at the influence of many factors such as material selection, construction technology and structural design of external wall insulation technology, this paper analyzes the causes and hazards of cracks in the external wall insulation system of buildings, and sums up the parts in the structure that are prone to cracks. Through the above analysis, the corresponding crack prevention research is carried out, and measures are proposed in the aspects of construction and material selection to reduce the cracking of the external thermal insulation layer of the external wall and prolong the service life of the external thermal insulation system of the external wall, which provides a theoretical basis for the crack prevention measures in actual projects.展开更多
The method for calculating wall surface heat storage coefficient was introduced,and the coefficients of several common walls with light-weight external thermal insulation materials and the traditional solid clay brick...The method for calculating wall surface heat storage coefficient was introduced,and the coefficients of several common walls with light-weight external thermal insulation materials and the traditional solid clay brick wall were calculated.In order to study the impact of light-weight external thermal insulation materials,a contrasting experiment was carried out between an external insulated room and an uninsulated room in August,2010,in Chongqing,China.The result shows that outside surface heat storage coefficient of the insulated wall is much less than that of the traditional wall.However,during sunny time,the surface temperature of external walls of the insulated room is obviously higher than that of the uninsulated room.In different orientations,due to different amounts of solar radiation and being irradiated in different time,the contrasting temperature difference(CTD) appears different regularity.In a word,using light-weight external thermal insulation materials has a negative impact on building surrounding thermal environment and people's health.Finally,some suggestions on how to eliminate the impact,such as improving the surface condition of the building envelop,and plating vertical greening,are put forward.展开更多
This study investigates the potential for enhancing the thermal performance of external walls insulation in warmer climates through the combination of phase change materials(PCMs)and bio-based materials,specifically h...This study investigates the potential for enhancing the thermal performance of external walls insulation in warmer climates through the combination of phase change materials(PCMs)and bio-based materials,specifically hemp wool and wood wool.Experimental tests using the heat flow method(HFM),and numerical simulations with ANSYS Fluent software were conducted to assess the dynamic thermal distribution and fluid-mechanical aspects of phase change materials(PCMs)within composite walls.The results demonstrate a notable reduction in peak indoor temperatures,achieving a 58%reduction with hemp wool with a close 40%reduction with wood wool when combined with PCMs.Fluid-mechanical analysis indicates that PCMs act as efficient indoor temperature regulators by storing excess heat during hot periods and releasing it later during phase transitions.Furthermore,the homogeneous distribution of the liquid fraction and natural convection during phase change contribute significantly to the improvement in heat transfer rates,resulting in a 96%reduction compared to hemp wool and wood wool without PCMs.展开更多
In heavy metal industrial areas,the issue of insulation flashover caused by metal contamination on the external insulation of transmission lines has become increasingly prominent.This paper investigates the U160B/155 ...In heavy metal industrial areas,the issue of insulation flashover caused by metal contamination on the external insulation of transmission lines has become increasingly prominent.This paper investigates the U160B/155 porcelain insulator,examining how iron,copper and zinc metal contaminations affect its AC flashover characteristics.Furthermore,combining with leakage current,the flashover mechanism of the insulators under the influence of metal particles is analysed.The research results indicate that as the metal content increases,the insulator's flashover gradient(E_(L))decreases by up to 2.3%-17.2%.Different metal compositions exhibit consistent mechanisms,similarly impacting insulator's dielectric strength with copper showing slightly weaker effect.And then,based on the mechanism of metal particles'influence on the insulator's AC flashover,a formula for calculating E_(L) is proposed and the calculated results are basically consistent with the experimental conditions.Finally,different metal compositions have similar effects on the leakage current,with an increase in metal content leading to an increase in the critical leakage current,which gradually tends to saturation.The research findings of this paper can provide references for AC flashover prediction,assessment and prevention of external insulation in areas with metal contaminants in pollution sources.展开更多
The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm.By comparing and analyzing the differences in gap breakdown voltage between the sand&dust environment and clea...The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm.By comparing and analyzing the differences in gap breakdown voltage between the sand&dust environment and clean air,some problems were investigated,such as effects of wind speed and particle concentration on the breakdown voltage,differences of gap discharge characteristics between the dust&sand medium and the clean air medium.The results showed that compared with the clean air environment,the dust&sand environment had a decreased gap breakdown voltage.The longer the gap distance,the greater the voltage drop;the breakdown voltage decreased with the increase of particle concentration in flow.With the increase of wind speed,the breakdown voltage decreased at the beginning and rose afterwards.The results of the paper may helpful for further research regarding the unidentified flashover and external insulation characteristics of the HV power grid in the dust&sand environment.展开更多
基金Funded by the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20050487017)
文摘Atmospheric exposure tests including two experimental stages of high temperature-spraying water cycle and heating-refrigeration cycle were carried out on three currently used ETIS of expanded polystyrene（EPS） board,polystyrene granule mortar and polyurethane foam in order to study the weatherablility of external thermal insulation system（ETIS）.The change rules of adhesive strength were hereby studied at different time period of atmospheric exposure tests.The experimental results show that the adhesive strength of three kinds of ETIS changes a little during high temperature-spraying water cycle,but the adhesive strength of ETIS with EPS board decreases significantly after heating-refrigeration cycle.The lowering rate of adhesive strength with painting finishes is obviously faster than that of tile finishes for ETIS of EPS board during heating-refrigeration cycle.The weatherability of ETIS with EPS board is worse than the other two,and ETIS of polystyrene granule mortar and polyurethane foam are more suitable than ETIS of EPS board in cold area.
基金The Research Fund for the Doctoral Pro-gram of Higher Education of China(No.20050487017)
文摘The finite element model of an external thermal composite insuiation system, thin rendered expanded polystyrene （ EPS ） board, was built with ANSYS 1.0, which had two forms： one with window and one without window. The finite element analysis results show that the EPS board had very good insulation capacity at both high or low temperature, stress concentration was produced in the center of wall and around window, and the maximum deformation was observed at the edge of board and the minimum deformation was in the center.
文摘With the rapid development of the construction industry today, external wall insulation technology has become an important part of the construction industry. Aiming at the influence of many factors such as material selection, construction technology and structural design of external wall insulation technology, this paper analyzes the causes and hazards of cracks in the external wall insulation system of buildings, and sums up the parts in the structure that are prone to cracks. Through the above analysis, the corresponding crack prevention research is carried out, and measures are proposed in the aspects of construction and material selection to reduce the cracking of the external thermal insulation layer of the external wall and prolong the service life of the external thermal insulation system of the external wall, which provides a theoretical basis for the crack prevention measures in actual projects.
基金Project(2011BAJ03B13) supported by the National Key Technologies R&D Program of China
文摘The method for calculating wall surface heat storage coefficient was introduced,and the coefficients of several common walls with light-weight external thermal insulation materials and the traditional solid clay brick wall were calculated.In order to study the impact of light-weight external thermal insulation materials,a contrasting experiment was carried out between an external insulated room and an uninsulated room in August,2010,in Chongqing,China.The result shows that outside surface heat storage coefficient of the insulated wall is much less than that of the traditional wall.However,during sunny time,the surface temperature of external walls of the insulated room is obviously higher than that of the uninsulated room.In different orientations,due to different amounts of solar radiation and being irradiated in different time,the contrasting temperature difference(CTD) appears different regularity.In a word,using light-weight external thermal insulation materials has a negative impact on building surrounding thermal environment and people's health.Finally,some suggestions on how to eliminate the impact,such as improving the surface condition of the building envelop,and plating vertical greening,are put forward.
文摘This study investigates the potential for enhancing the thermal performance of external walls insulation in warmer climates through the combination of phase change materials(PCMs)and bio-based materials,specifically hemp wool and wood wool.Experimental tests using the heat flow method(HFM),and numerical simulations with ANSYS Fluent software were conducted to assess the dynamic thermal distribution and fluid-mechanical aspects of phase change materials(PCMs)within composite walls.The results demonstrate a notable reduction in peak indoor temperatures,achieving a 58%reduction with hemp wool with a close 40%reduction with wood wool when combined with PCMs.Fluid-mechanical analysis indicates that PCMs act as efficient indoor temperature regulators by storing excess heat during hot periods and releasing it later during phase transitions.Furthermore,the homogeneous distribution of the liquid fraction and natural convection during phase change contribute significantly to the improvement in heat transfer rates,resulting in a 96%reduction compared to hemp wool and wood wool without PCMs.
基金supported by the Natural Science Foundation of Chongqing,China(Grants CSTC2024YCJH-BGZXM0060,CSTB2023NSCQLZX0021)Central University Basic Research Funds Project(Grant 2023CDJYXTD-005).
文摘In heavy metal industrial areas,the issue of insulation flashover caused by metal contamination on the external insulation of transmission lines has become increasingly prominent.This paper investigates the U160B/155 porcelain insulator,examining how iron,copper and zinc metal contaminations affect its AC flashover characteristics.Furthermore,combining with leakage current,the flashover mechanism of the insulators under the influence of metal particles is analysed.The research results indicate that as the metal content increases,the insulator's flashover gradient(E_(L))decreases by up to 2.3%-17.2%.Different metal compositions exhibit consistent mechanisms,similarly impacting insulator's dielectric strength with copper showing slightly weaker effect.And then,based on the mechanism of metal particles'influence on the insulator's AC flashover,a formula for calculating E_(L) is proposed and the calculated results are basically consistent with the experimental conditions.Finally,different metal compositions have similar effects on the leakage current,with an increase in metal content leading to an increase in the critical leakage current,which gradually tends to saturation.The research findings of this paper can provide references for AC flashover prediction,assessment and prevention of external insulation in areas with metal contaminants in pollution sources.
基金supported by the Major Research Plan of National Natural Science Foundation of China"Influence of Sanddust Environment on External Insulation Characteristics for High-voltage Insulator"(Grant No.90210006)China Postdoctoral Science Foundation Project"Study on External Insulation Characteristics and Discharge Law of High-voltage Insulator in Sand-dust Environment"(Grant No.20070411125)
文摘The experiments of plane-plane gap discharge was carried out in an environment of artificial sandstorm.By comparing and analyzing the differences in gap breakdown voltage between the sand&dust environment and clean air,some problems were investigated,such as effects of wind speed and particle concentration on the breakdown voltage,differences of gap discharge characteristics between the dust&sand medium and the clean air medium.The results showed that compared with the clean air environment,the dust&sand environment had a decreased gap breakdown voltage.The longer the gap distance,the greater the voltage drop;the breakdown voltage decreased with the increase of particle concentration in flow.With the increase of wind speed,the breakdown voltage decreased at the beginning and rose afterwards.The results of the paper may helpful for further research regarding the unidentified flashover and external insulation characteristics of the HV power grid in the dust&sand environment.
