In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to...In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to reduce heat loss in buildings.Vacuum insulation panels(VIPs),a type of high-performance insulation material,have been increasingly utilised in the construction industry and have played an increa-singly important role as their performance and manufacturing processes continue to improve.This paper provides a review of the factors affecting the thermal conductivity of VIPs and presents a detailed overview of the research progress on core materials,barrier films,and getters.The current research status of VIPs is summarised,including their thermal conductivity,service life,and thermal bridging effects,as well as their applications in the field of architecture.This review aims to provide a comprehensive understanding for relevant practitioners on the factors influencing the thermal conductivity of VIPs,and based on which,measures can be taken to produce VIPs with lower thermal conductivity and longer service life.展开更多
A new insulation system with inorganic A-B-A insulators was proposed to improve the surface flashover performance in vacuum. Inorganic A-B-A insulator samples of Mo/Al2O3 cermet-Al2O3 ceramic-Mo/Al2O3 cermet were prep...A new insulation system with inorganic A-B-A insulators was proposed to improve the surface flashover performance in vacuum. Inorganic A-B-A insulator samples of Mo/Al2O3 cermet-Al2O3 ceramic-Mo/Al2O3 cermet were prepared, in which the conductivity and permittivity of the Mo/Al2O3 cermets were controlled through different amount of metallic molybdenum powder added. The effects of both conductivity and permittivity of Mo/Al2O3 cermets on the DC and impulse surface flashover voltage in vacuum were experimentally investigated. The result showed that the DC and impulse surface flashover voltage were improved by 52% and 95%, respectively. For the distribution of electric field, two triple junctions, i.e., vacuum-layer A-cathode （TJ1） and vacuum-layer A-layer B （TJ2） were prepared with the introduction of layer A into the A-B-A insulation system. Based on the electric field distribution obtained via electrostatic field simulation and Maxwell-Wagner three-layer model, the electric field of T J1 decreases while that of T J2 increases with the increase in conductivity and permittivity of layer A under applied DC and impulse voltage, respectively. Therefore, the improvement of surface flashover performance of A-B-A insulators has been reasonably explained.展开更多
In order to achieve the objective of controlling IR radiation characteristics of space target,we design multilayer insulation film structure to cover the target.In space environment the structure comes to cryogenic va...In order to achieve the objective of controlling IR radiation characteristics of space target,we design multilayer insulation film structure to cover the target.In space environment the structure comes to cryogenic vacuum multilayer insulation film structure.It can quickly lower the surface temperature of space target,approaching to the ultra-low temperature of the space environment.A vacuum simulation verification test was designed and performed.Through the analysis of test results,we can see that the surface temperature of space target covered by the structure changes with the ambient temperature,having no direct relationship with internal temperature of the target.Therefore,the designed cryogenic vacuum multilayer insulation film structure has excellent IR radiation control performance.It can reduce the target’s IR radiation intensity so as to reduce the probability of detection by IR detectors.展开更多
Vacuum insulation panels provide unprecedented possibilities for renovating the existing building stock in a manner that reduces the thermal losses through the building envelope. This study is focused on the implement...Vacuum insulation panels provide unprecedented possibilities for renovating the existing building stock in a manner that reduces the thermal losses through the building envelope. This study is focused on the implementation of VIPs （vacuum insulation panels） in energy retrofit projects with rendered outer walls. Particular emphasis is put on reducing the thermal bridges due to mechanical fasteners and at the joints of the panels. These are evaluated through a parametric study of the impact of the thermal conductivity of the joints of the panels and the adjacent insulation layer as well as the material of the fasteners. The study is carried out with 3D FEM （finite element method） simulations software. Furthermore, the moisture conditions in the construction are studied. The dynamic moisture behavior of a wall construction is modeled with a two dimensional FEM model. The long term effects of vapor diffusion are investigated in terms of accumulated moisture and the risk of condensation. The results illustrate that vacuum insulation on the outside of the wall construction does not pose a moisture problem to the construction. The simulations are based on a draft of a new technical solution for the refurbishment of a building that is typical for the great Swedish building program of the 1970s.展开更多
By analyzing the insulation effect of argon-filled tubing and vacuum-insulated tubing before and after hydrogen permeation respectively,a conclusion can be drawn that the insulated tubing filled with high pressure arg...By analyzing the insulation effect of argon-filled tubing and vacuum-insulated tubing before and after hydrogen permeation respectively,a conclusion can be drawn that the insulated tubing filled with high pressure argon is better than the vacuum insulated tubing considering the lifetime and heat insulation effect.展开更多
The field electron emission plays a vital role in the process of vacuum discharge breakdown. The electric field strength at the cathode tip is significant to the generation char- acteristics of vacuum arc metal plasma...The field electron emission plays a vital role in the process of vacuum discharge breakdown. The electric field strength at the cathode tip is significant to the generation char- acteristics of vacuum arc metal plasmas. To increase the field strength at the cathode tip, a coaxial electrode plasma source was employed with an insulator settled between the electrodes. The math expression of the field strength is derived based on the Gauss theory. The impact of the insulator on the electric field and parameters of plasmas were investigated by MAXWELL 3D simulation software and the Langmuir probe. In addition, a composite insulator was adopted to further strengthen the field strength. A series of experiments were performed to focus on the role of the composite insulator in detail. The experimental and simulation results indicate that, a reasonable layout of the insulator, especially the composite insulator, can effectively increase the field strength at the cathode tip and the plasma density.展开更多
To expand the application of multi-layer graphene in water-based systems, modified multi-layer graphene was prepared by vacuum impregnation with silica sol and carbon-embedded heat treatment at 300, 500 or 700 ℃ for ...To expand the application of multi-layer graphene in water-based systems, modified multi-layer graphene was prepared by vacuum impregnation with silica sol and carbon-embedded heat treatment at 300, 500 or 700 ℃ for 3 h. The phase composition, microstructure and wettability of the modified multi-layer graphene heat treated at different temperatures were studied. The results show that the water wettability of the modified multi-layer graphene is improved after vacuum impregnation with silica sol and carbon-embedded heat treatment;the optimum heat treatment temperature is 300 ℃, and the modified multi-layer graphene has the water wetting angle of 64.7°.展开更多
To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation character...To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation characteristics of plasma of the electrode are investigated, effects of diameter of insulating sleeve, variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed. Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions. Moreover, the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve. The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.展开更多
In order to solve the water issues when 13X zeolite was applied to capture CO 2 from wet flue gas by vacuum swing adsorption process, multi-layered adsorption system was considered regarding activated alumina F200 and...In order to solve the water issues when 13X zeolite was applied to capture CO 2 from wet flue gas by vacuum swing adsorption process, multi-layered adsorption system was considered regarding activated alumina F200 and silica gel based Sorbead WS as pre-layer materials. LBET (extended Largmuir-BET) model and extended CMMS (cooperative multimolecular sorption) equation were simulated respectively to describe water loading on F200 and Sorbead WS. The two equations can be well added into our in-house simulator to simulate double-layered CO 2 -VSA (vacuum swing adsorption) process. Results indicated that water can be successfully stopped in pre-layers with a good CO 2 capture performance.展开更多
文摘In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to reduce heat loss in buildings.Vacuum insulation panels(VIPs),a type of high-performance insulation material,have been increasingly utilised in the construction industry and have played an increa-singly important role as their performance and manufacturing processes continue to improve.This paper provides a review of the factors affecting the thermal conductivity of VIPs and presents a detailed overview of the research progress on core materials,barrier films,and getters.The current research status of VIPs is summarised,including their thermal conductivity,service life,and thermal bridging effects,as well as their applications in the field of architecture.This review aims to provide a comprehensive understanding for relevant practitioners on the factors influencing the thermal conductivity of VIPs,and based on which,measures can be taken to produce VIPs with lower thermal conductivity and longer service life.
基金supported by National Science Fund for Outstanding Young Scholars of China (No. 50625721)
文摘A new insulation system with inorganic A-B-A insulators was proposed to improve the surface flashover performance in vacuum. Inorganic A-B-A insulator samples of Mo/Al2O3 cermet-Al2O3 ceramic-Mo/Al2O3 cermet were prepared, in which the conductivity and permittivity of the Mo/Al2O3 cermets were controlled through different amount of metallic molybdenum powder added. The effects of both conductivity and permittivity of Mo/Al2O3 cermets on the DC and impulse surface flashover voltage in vacuum were experimentally investigated. The result showed that the DC and impulse surface flashover voltage were improved by 52% and 95%, respectively. For the distribution of electric field, two triple junctions, i.e., vacuum-layer A-cathode （TJ1） and vacuum-layer A-layer B （TJ2） were prepared with the introduction of layer A into the A-B-A insulation system. Based on the electric field distribution obtained via electrostatic field simulation and Maxwell-Wagner three-layer model, the electric field of T J1 decreases while that of T J2 increases with the increase in conductivity and permittivity of layer A under applied DC and impulse voltage, respectively. Therefore, the improvement of surface flashover performance of A-B-A insulators has been reasonably explained.
基金Sponsored by the High-tech Research and Development Program of China (Grant No. 2007AA701101B)
文摘In order to achieve the objective of controlling IR radiation characteristics of space target,we design multilayer insulation film structure to cover the target.In space environment the structure comes to cryogenic vacuum multilayer insulation film structure.It can quickly lower the surface temperature of space target,approaching to the ultra-low temperature of the space environment.A vacuum simulation verification test was designed and performed.Through the analysis of test results,we can see that the surface temperature of space target covered by the structure changes with the ambient temperature,having no direct relationship with internal temperature of the target.Therefore,the designed cryogenic vacuum multilayer insulation film structure has excellent IR radiation control performance.It can reduce the target’s IR radiation intensity so as to reduce the probability of detection by IR detectors.
文摘Vacuum insulation panels provide unprecedented possibilities for renovating the existing building stock in a manner that reduces the thermal losses through the building envelope. This study is focused on the implementation of VIPs （vacuum insulation panels） in energy retrofit projects with rendered outer walls. Particular emphasis is put on reducing the thermal bridges due to mechanical fasteners and at the joints of the panels. These are evaluated through a parametric study of the impact of the thermal conductivity of the joints of the panels and the adjacent insulation layer as well as the material of the fasteners. The study is carried out with 3D FEM （finite element method） simulations software. Furthermore, the moisture conditions in the construction are studied. The dynamic moisture behavior of a wall construction is modeled with a two dimensional FEM model. The long term effects of vapor diffusion are investigated in terms of accumulated moisture and the risk of condensation. The results illustrate that vacuum insulation on the outside of the wall construction does not pose a moisture problem to the construction. The simulations are based on a draft of a new technical solution for the refurbishment of a building that is typical for the great Swedish building program of the 1970s.
文摘By analyzing the insulation effect of argon-filled tubing and vacuum-insulated tubing before and after hydrogen permeation respectively,a conclusion can be drawn that the insulated tubing filled with high pressure argon is better than the vacuum insulated tubing considering the lifetime and heat insulation effect.
基金supported by the Scientific Research Starting Foundation for Returned Overseas Chinese Scholars,Ministry of Education,China(Nos.E07C30010 and EJ06014)
文摘The field electron emission plays a vital role in the process of vacuum discharge breakdown. The electric field strength at the cathode tip is significant to the generation char- acteristics of vacuum arc metal plasmas. To increase the field strength at the cathode tip, a coaxial electrode plasma source was employed with an insulator settled between the electrodes. The math expression of the field strength is derived based on the Gauss theory. The impact of the insulator on the electric field and parameters of plasmas were investigated by MAXWELL 3D simulation software and the Langmuir probe. In addition, a composite insulator was adopted to further strengthen the field strength. A series of experiments were performed to focus on the role of the composite insulator in detail. The experimental and simulation results indicate that, a reasonable layout of the insulator, especially the composite insulator, can effectively increase the field strength at the cathode tip and the plasma density.
基金financially supported by Natural Science foundation of Hebei Province (E2017209164) and (E2023209035)。
文摘To expand the application of multi-layer graphene in water-based systems, modified multi-layer graphene was prepared by vacuum impregnation with silica sol and carbon-embedded heat treatment at 300, 500 or 700 ℃ for 3 h. The phase composition, microstructure and wettability of the modified multi-layer graphene heat treated at different temperatures were studied. The results show that the water wettability of the modified multi-layer graphene is improved after vacuum impregnation with silica sol and carbon-embedded heat treatment;the optimum heat treatment temperature is 300 ℃, and the modified multi-layer graphene has the water wetting angle of 64.7°.
基金supported by National Natural Science Foundation of China(No.51577011)
文摘To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation characteristics of plasma of the electrode are investigated, effects of diameter of insulating sleeve, variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed. Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions. Moreover, the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve. The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.
基金Supported by the National Natural Science Foundation of China (51074205)Corporate Research Centre for Greenhouse Gas Technology Foundation in Australia
文摘In order to solve the water issues when 13X zeolite was applied to capture CO 2 from wet flue gas by vacuum swing adsorption process, multi-layered adsorption system was considered regarding activated alumina F200 and silica gel based Sorbead WS as pre-layer materials. LBET (extended Largmuir-BET) model and extended CMMS (cooperative multimolecular sorption) equation were simulated respectively to describe water loading on F200 and Sorbead WS. The two equations can be well added into our in-house simulator to simulate double-layered CO 2 -VSA (vacuum swing adsorption) process. Results indicated that water can be successfully stopped in pre-layers with a good CO 2 capture performance.
