Improve Insulation Performance Research Articles

Incorporation of specific defects through ion bombardment for better ferroelectrics

AbstractIncorporating specific defects into complex oxides facilitates the exploration of exotic phenomena and novel functionalities based on the intricate coupling between the defects and lattice/charge. However, methods for maximizing the density of specific defects while enhancing the desired properties have been rarely explored. In this study, the effect of N+ ion bombardment‐driven specific defects on the properties of bismuth ferrite (BFO) thin films was investigated. Furthermore, atomic structure characterization and computational processing revealed the displacement and orientation of the Fe atoms, which are linearly related to the degree of polarization. The ion bombardment introduced deep‐level trap states within the lattice, leading to a significant reduction in the leakage current and improved insulation performance of the films. By precisely engineering the defect content through N+ ion bombardment, the pure BFO thin films with remarkable and stable ferroelectric properties (remnant polarization, Pr = ∼116.8 µC·cm−2; leakage current, J = ∼1.5 × 10−8 A·cm−2) were fabricated. This innovative defect engineering‐based approach enables the customization and optimization of local ferroelectric order parameters, thereby establishing a solid foundation for designing functionalities across various functional material systems.

Effect of Silica and Alumina Nanoparticles Addition on the Dielectric and Rheological Properties of Shea Oil Methyl Ester

Study’s Excerpt/Novelty This study introduces a novel green nanofluid by incorporating shea methyl ester (SME) with surface-modified Al2O3 and SiO2 nanoparticles, addressing the environmental concerns associated with mineral-based transformer oils. The research highlights that SiO2 nanoparticles significantly enhance the dielectric properties of the base oil while minimally impacting its viscosity, suggesting improved insulation performance. This innovative approach offers a sustainable alternative with superior electrical characteristics, potentially transforming the application of transformer oils in the industry. Full Abstract The increasing environmental and utility concerns of mineral-based transformer oils have impelled research into alternative insulation liquids. This study developed a green nanofluid using a two-step approach, incorporating shea methyl ester (SME) derived from shea butter oil and surface-modified Al2O3 and SiO2 nanoparticles. The dynamic viscosity at 25 °C and dielectric properties of the developed nanofluid were investigated in the frequency range of 0.1–15 kHz. Adding nanoparticles into the SME noticeably increased the oil's viscosity, with SiO2 nanoparticles having the least effect on the base liquid's viscosity. The addition of 0.6 wt% of Al2O3 nanoparticles increased the dielectric loss of the SME at all frequencies (0.1–15 kHz), while the addition of 0.6 wt% SiO2 filler nanoparticles reduced the loss of the base oil at frequencies beyond 4 kHz indicative of an improved electrical property. Adding Al2O3 and SiO2 to the base SME oil obtained higher relative permittivity values. This study successfully developed an SME and single nanoparticle-based nanofluid, incorporating a 0.6 wt% weight fraction of surface-modified Al2O3 and SiO2 nanoparticles. The addition of these nanoparticles increased the dynamic viscosity of the base methyl ester oil, with approximately 43% and 36% increases, respectively. The nanofluid developed by incorporating SiO2 nanoparticles showed promising dielectric performance for its application as an insulation liquid.

Vertically aligned and conformal BN-coated carbon fiber to achieve enhanced thermal conductivity and electrical insulation of a thermal interface material

Due to excellent thermal conductivity, high aspect ratio, and low density, mesophase pitch-based carbon fibers (MPCFs) are highly desired in electronic packaging. However, their thermal conductivity is hard to present in the polymer matrix because of the disordered stacking and low filling. Moreover, few researches are focused on the enhancement of the electrical insulation performance for MPCFs. Herein, we report vertically aligned and insulating boron nitride (BN) coated carbon fiber (CF) powders as significant fillers for polymer composites, endowing markedly improved thermal conductivity and electrical insulation. The high-quality BN coating layer on the surface of the CF is produced by a cooling precipitation method and high-temperature treatment with ingenious use of solubility properties, exhibiting a conformal, dense, and highly crystalline structure. This preparation method overcomes the limitations of coating thickness and particle agglomeration, resulting in a 31-fold enhancement of the electrical resistivity of the CF powders. After orientation treatment in a silicone rubber matrix, such CF@BN-filled pads exhibit good thermal conductivity, significantly improved insulation performance, and excellent mechanical properties. Among them, the optimized pad achieves a thermal conductivity of 12.06 W m−1 K−1, a volume resistivity of 50 × 108 Ω cm and a breakdown voltage of 3100 V mm−1, exceptional flexibility, and a favorable compression ratio (@45 psi) of 41.7 %. This work provides unique insights into constructing carbon fiber fillers as well as the preparation of high thermal conductivity composites, thereby expanding the application scenarios of carbon fiber powder in electronic packaging.

Towards sustainable building solutions: Development of hemp shiv-based green insulation material

There is currently a growing need for sustainable and environmentally friendly materials. One promising candidate is hemp shiv, which is considered waste material. hemp shiv exhibits lightweight properties and high insulation capabilities. This study focuses on the development of a material based in hemp shiv, recycled cardboard fibers is used as binder material, with the addition of a vegetable coating (colophony and arabic gum) for moisture protection and citric acid to enhance cellulose crosslinking. Thermal insulation properties were assessed measuring the heat transfer through the material. Acoustic insulation properties were evaluated using a Kundt tube within a frequency range of 100–6500 Hz. Mechanical tests, including compression, shear, and bending, were performed to assess the material’s strength. Additionally, moisture and fire resistance properties, as well as microstructure analysis, were examined. The influence of citric acid in the cellulose crosslinking was verified using FTIR-ATR spectroscopy. Results demonstrated that a higher percentage of hemp shiv content led to improved insulation performance, achieving attenuation values greater than 0.85–0.95 dB/dB and a thermal conductivity of 0.02–0.03 W/m K. These findings indicate a great performance compared to commercial materials. The coating shields the material from external factors. It was observed that the citric acid does not react with hemp shiv.

Development of a 3 MV coaxial peaking capacitor for large-scale electromagnetic pulse simulator.

Coaxial peaking capacitor is a key component in high-altitude electromagnetic pulse (EMP) simulators with fast front pulse output. It poses significant technical and engineering challenges in limiting radiation field amplitude and test space. This paper presents the design and testing of a 180 pF, 3 MV coaxial peaking capacitor with improved insulation performance. In the insulation design, the length of the dielectric film is extended to reduce the background electric field on the flashover path. The electric field threshold obtained from image diagnosis is used as a reference. During capacitor testing, the insulation characteristics are diagnosed using both direct and indirect methods. The voltage measured by a D-dot probe, the output waveform of the Marx generator in the primary source, and the radiation field waveform are analyzed to understand the flashover characteristics of the capacitor and to improve the reliability of the test results. The experimental results demonstrate that the peaking capacitor can operate stably at 3.0 MV. If flashover occurring on the dropping edge of the pulse is permitted, the operating voltage can be greater than 3.7 MV without significantly affecting the radiation field waveform. The analysis on the surface flashover morphology of the peaking capacitor reveals that the flashover mainly occurs at the dropping edge of the capacitor's waveform, indicating that the damage to the film is not serious. This research significantly increases the working voltage of coaxial peaking capacitors and contributes to the development of high-altitude EMP simulation technology.

Discharge Randomness and Attraction Process of Epoxy Surface on Discharge Channel in SF6 Gas Under Uniform Electric Field

It is generally believed that due to the electric field distortion effect and the photoemission process of the solid surface, the discharge channel near the solid surface trends to develop along the surface than that in bulk gas. One way to improve insulation performance is to avoid the solid surface from participating in the gas discharge process. However, the mechanism of the solid surface’s effect on the gas discharge process is still unclear. In this paper, we recorded high-speed framing pictures of the discharge process in SF6 gas near the epoxy surface under lightning impulse voltage in the uniform electric field. The arc pictures show that the attraction effect of the solid surface to the discharge channel is related to the surface shape, gas gap height, and distance from the discharge channel to the solid surface. Besides, discharge randomness also plays a role, which is more obvious in the cylinder insulator than in the conical insulator, for the surface with conical shape could easily attract and arrest the discharge channel to its surface. According to the pictures of discharge process near the cylinder surface, we found that the photoemission process occurs in the streamer stage but has little effect on the attraction effect. The leader initiates after the streamer bridges the gas gap, and its random stepped walk could induce the attraction effect from the solid surface: only when the random stepped leader deflects close to the solid surface, the discharge channel could be further attracted to the solid surface by the electrostatic force, especially its normal component. The result indicates that there are three points to prevent the solid surface from participating in the gas discharge process and further improve insulation performance: choose a cylinder shape (avoid a conical shape), keep the surface away from the high electric field area where discharge may start, and reduce the normal component of the surface electric field.

Analysis and Impact of Activated Carbon Incorporation into Urea-Formaldehyde Adhesive on the Properties of Particleboard

Nowadays, the particleboard industry cannot meet the market’s demand. Therefore, filler materials have started to be used both to conserve raw materials and to enable the use of wood-based boards in different areas. This study investigates the effects of incorporating different ratios of activated carbon (0%, 1.5%, 4.5%, 7.5%) on the properties of particleboards. The physical properties were examined, including density, moisture content, thickness swelling, and water absorption. The results reveal that the density increased with increasing activated carbon content while the moisture content decreased, indicating improved dimensional stability and water resistance. Additionally, the color properties were influenced by activated carbon, leading to a darker appearance with decreased lightness and yellow-blue components. The mechanical properties, such as internal bond strength, modulus of rupture, and modulus of elasticity, showed significant enhancements with the addition of activated carbon, indicating improved bonding and increased strength. Moreover, the thermal conductivity decreased with increasing activated carbon content and improved insulation performance. Scanning electron microscope analysis confirmed the uniform distribution of activated carbon within the particleboard matrix, without agglomeration, positively impacting the mechanical performance. According to the thermogravimetric analysis results, the addition of activated carbon led to a decrease of up to 6.15% in mass loss compared to the control group. The incorporation of activated carbon at a ratio of 4.5% in particleboards confers notable enhancement to their physical, mechanical, and thermal characteristics. These findings contribute to understanding the potential benefits and considerations of using activated carbon as an additive in particleboard production.

Effective Thermal Conductivity Model of Micron Hollow Sphere or Phase Change Material/Opacifier-SiO2 Aerogel Composites

Abstract Pure SiO2 aerogel has a strong light transmittance in the infrared wavebands from 3.0 to 8.0 μm, and an opacifier could efficiently reduce aerogel's radiative thermal conductivity (λr), especially at high temperatures (>400 K). Consequently, the λr of different core/shell structured opacifiers is proposed, including micron hollow sphere opacifier (MHSOP), i.e., hollow carbon black/SiC/TiO2, and phase change material (PCM)/opacifier, i.e., VO2/SiO2, and Ge2Sb2Te5/SiC; further, their conductive λ model has also been established. The results showed that MHSOP could reduce MHSOPs-SiO2 aerogel composite's λ compared to traditional solid structure opacifiers; the effect of MHSOPs with a certain core–shell ratio on suppressing thermal radiation is equivalent to their solid structure opacifier at high-temperature. Adding SiC MHSOPs reduces aerogel composites' weight and thermal conductivity by 42.19 and 26.29%, while the shading effect of a core–shell ratio of over 0.75 is equivalent to the solid structure. Specifically, rutile-phased VO2/SiO2's λr is smaller than TiO2 MHOSP, and crystalline Ge2Sb2Te5/SiC doped aerogel exhibits good thermal insulation. The proposed micron hollow sphere opacifier and PCM/opacifier provide a novelty, lightweight, and high-efficiency method to restrain aerogel's infrared radiation and improve insulation performance at high temperatures.

Experimental-based energy performance evaluation of low-cost retrofit strategy for aging low-rise residential building for carbon neutrality

The CO2 reduction policy has driven the remodeling policy to reduce the energy consumption of buildings, which can be implemented by insulating and replacing windows to reduce the energy consumption of buildings. However, due to energy poverty, many residents have limited opportunities for these projects. Therefore, economically accessible technologies were evaluated in this study. Specifically, practical technologies were applied and evaluated in practice, and a survey of 107 households was conducted to analyze the behavior of energy consumption behavior in the residential areas with buildings. The airtight performance of the window was improved by approximately 15% without replacing it, and energy consumption was reduced by 25%. In the case of electric energy consumption, the use of high-efficiency lighting showed the most direct reduction. However, the introduction of renewable energy into buildings that are not insulated can contribute to relative climate-dependent reductions, but whether direct reductions are possible needs to be examined more closely. Relatively inexpensive technologies have improved insulation performance and have a shorter payback period compared to window replacement, further solidifying economic feasibility.

Review of the Performance of High-Voltage Composite Insulators.

In the present literature survey, we focused on the performance of polymeric materials encompassing silicone rubber (SiR), ethylene propylene diene monomer (EPDM) and epoxy resins loaded with micro, nano, and micro/nano hybrid fillers. These insulators are termed as composite insulators. The scope of the added fillers/additives was limited to the synthetic inorganic family. Special attention was directed to understanding the effect of fillers on the improvement of the thermal conductivity, dielectric strength, mechanical strength, corona discharge resistance, and tracking and erosion resistance performance of polymeric materials for use as high-voltage transmission line insulators. The survey showed that synthetic inorganic fillers, which include silica (SiO2) and hexagonal boron nitride (h-BN), are potential fillers to improve insulation performance of high-voltage insulators. Furthermore, nano and micro/nano filled composites performed better due to the better interaction between the filler and polymer matrix as compared to their only micro- or nano filled counterparts. Finally, some aspects requiring future work to further exploit fillers are identified and discussed.

Evaluation of the applicability of high insulation fire door with vacuum insulation panels: Experimental results from fire resistance, airtightness, and condensation tests

High insulation fire door (HIFD) was designed using the design process of vacuum insulation panels (VIPs) and frames to improve the insulation performance of fire doors. To improve the insulation and airtightness performance of HIFDs, the frame was designed using a 3D heat transfer program. The thermal performance of the HIFD could be improved through ceramic board application, gasket positioning, and frame design for cavity applications. The final designed HIFD exhibited a heat transmittance value of 0.872 W/m 2 K. To assess the applicability of the HIFD to buildings, tests were conducted using the test object produced for the optimal design derived from the simulation data. The tests included fire resistance, airtightness, and condensation tests. Despite the high insulation performance, a fire resistance performance of more than 60 min was achieved. Due to the application of graphite covering tapes, fire resistance and airtightness improved, and the exhibited condensation performance could be applied in the −20 °C area. • Evaluation of the insulation performance of the VIP-applied fire door. • Improvement of the fire door frame to improve insulation performance. • Fire resistance performance evaluation of VIP-integrated high insulation fire door. • Insulation, airtightness, and condensation evaluation of high insulation fire door.

Review of interface tailoring techniques and applications to improve insulation performance

Interfaces between different materials, for instance, electrode–dielectrics and vacuum/air/SF6-insulators and oilpaper, are universal in high-voltage insulation systems. Targeted tailoring of the interfacial properties, e.g. chemical structures, micro-/nanoscale morphology, the charge injection barrier, trap states, and surface conductivity, is thought to be an effective approach to improve insulation properties such as breakdown and flashover strength, corona/tracking resistance, and wettability. In this article, the authors review recent progress in interface tailoring methods and their application to improve various insulation properties. The potential application scenarios of interface tailoring in different facilities are first summarised, and the desired insulation properties of various applications are highlighted. Interface tailoring methods are classified as physical/chemical surface modification and surface coating (inorganic, organic and composite), and the features of different techniques are described in detail. The structure–property relationships between interfacial states and various microscopic parameters such as charge injection barrier, trap distribution and surface conductivity are discussed together with the tailoring mechanisms for different insulation properties. Finally, the future development prospects of interface tailoring methods and their applications, e.g. multifunctional coating and stimuli–response smart coating, are presented.

Optimal Design of Functionally Graded Power Cable Joint Utilizing Silicone Rubber/Carbon Nanotube Composites

Functionally graded materials (FGMs) used in electrical insulation have spatially inhomogeneous dielectric properties (i.e., permittivity or conductivity), which can be applied to relieve localized electric field (E-field) intensification and improve insulation performance. However, previous research shows some limitations in inadequate considerations on the material feasibility, and insufficient universality on material grading type and voltage form. In this study, a material study of silicone rubber (SiR) nanocomposites containing carbon nanotubes (CNTs) is conducted to determine the practical variation range of dielectric properties (both permittivity and conductivity) in joint insulation materials. Then, the optimal design of both multilayer and pointwise FGM joint insulation is investigated under both AC and DC voltage, in which the lower and upper limits of permittivity and conductivity were derived from the experimental results. Experimental results on SiR/CNT nanocomposites indicate that low-amount doping of the CNTs (0-0.5% wt%) can effectively increase the permittivity and conductivity of joint insulation materials. The successive simulation study indicates that compared to uniform joints, cable joints employing optimally designed FGM insulation show a considerable increase in the E-field utilization factor (from 0.08-0.17 to 0.23-0.56), indicating elevated E-field uniformity. Finally, the optimal range of CNT doping ratios is determined to be 0-0.3 wt% from both experimental and simulation results. This study systematically verifies the applicability of FGMs in enhancing the performance of power cable accessories, which can show some guidance to the design and fabrication of advanced power cable systems.

Simultaneous enhancement of polarization and breakdown strength in lead-free BaTiO3-based ceramics

Lead-free dielectric ceramic capacitors have garnered extensive attention owing to their excellent dielectric and energy storage characteristics. However, most currently reported lead-free dielectric ceramics have limitations, including an unclear local phase structure, and inverse correlation between polarization and dielectric breakdown strength. These issues can be well solved by establishing the relationship between structure and performance. Herein, we enhanced both the polarization and dielectric breakdown strength of BaTiO3-based ferroelectric ceramics by tailoring the temperature corresponding to the maximum dielectric permittivity to room temperature and decreasing the grain size. We confirmed the existence of a tetragonal phase structure in the relaxor BaTiO3-based ferroelectric ceramics. The simultaneously enhanced polarization and breakdown strength can be derived from the distortion of octahedral [TiO6] in the lattice and improved insulation performance. Finally, an ultrahigh recoverable energy density (Wrec) of 4.23 J/cm3 and efficiency (η) of 93.40% with decent stability (variation of Wrec ≤ 9.76% over 20–190 °C, Wrec ≤ 2.25% in 1–100 Hz, and Wrec ≤ 1.78% after 5000 cycles) were simultaneously achieved in the novel BaTiO3-based ceramics. This study may provide a feasible and paradigmatic approach to develop high performance dielectrics for energy storage applications.

Development and calibration of reduced-size plate thermometer for measuring incident heat flux

This study proposes a new reduced-size plate thermometer with a modified shape and improved insulation performance in order to resolve problems commonly found when using conventional plate thermometers to measure incident heat flux in fire environments, for example, a low spatial resolution caused by the large plate area and a non-uniform temperature distribution on the plate. The main results of this study showed that the new plate thermometer exhibits high spatial temperature uniformity, and that the plate thermometer can be reduced in size to 30 mm. Moreover, it was found that the relative error of the incident heat flux of the plate thermometer was substantially reduced compared to that of a heat flux meter using a conduction correction factor expressed as a third-order polynomial function of heat flux, rather than using an average empirical constant calculated from measurement over a wide range of heat fluxes. Finally, it was confirmed that the incident heat flux measured by the new reduced-size plate thermometer in a heptane pool fire was in good agreement with the heat flux meter measurements during the rapid-fire growth, fully developed and decay phases of a fire.

Effect of different surface treatment agents on the physical chemistry and electrical properties of polyethylene nano‐alumina nanocomposites

Generally, the electrical properties of nanocomposite are affected by the type, size, filling concentration and surface treatment process of the nanoparticle. In this study, nanocomposites of polyethylene (PE) with varying filling contents of nano-alumina particles were prepared by the melting blending method and three different kinds of coupling agents were applied for surface modification properties of the nanoparticles. Two of them were silane based and the other was titanate based. The effect of different coupling agents on the dielectric properties was studied. Fourier-transform infrared spectroscopy and thermo-gravimetric analysis were used to verify their compositions. Scanning electron microscope and polarised optical microscopy were used for morphology study. Dielectric permittivity, direct current (DC) volume resistivity and DC breakdown strength characterised their improved insulation performance with nano-alumina as filler. Thermal stimulated current results revealed that adding nano-alumina particles into low-density PE could provide more deep traps and increase DC resistivity.

In situ electric field driven assembly to construct adaptive graded permittivity BaTiO3/epoxy resin composites for improved insulation performance

The applications of dielectric functionally graded materials in high-voltage systems have emerged as a potential strategy to obtain superior insulation performance in recent years. However, the existing preparation methods mainly rely on simple lamination or centrifugal force intervention, and cannot adapt to the complex electric field spatial distribution. In this work, we developed low partial discharge (PD), high flashover voltage barium titanate/epoxy resin (BT/ER) insulation composites with graded permittivity, which were assembled by the in situ electric field. Our approach involves (a) the migration and deposition of BT in high electric field strength regions, driven by in situ electrophoretic forces in the BT/ER suspension (dispensable), (b) the alignment of BT in high electric field strength regions, driven by in situ dielectrophoretic forces in the BT/ER suspension, and (c) the “freezing” of the composite structure by curing. The insulation performance of the samples after this electric field structuring was assessed by PD measurements and flashover tests. The PD of the samples with 2.0 vol% BT and electric field treatment was significantly reduced, and the flashover voltage was increased by 31.8% compared with the pure ER sample. Optical microscope images, scanning electron microscope (SEM) images and finite element simulations also verify that this type of electric field structuring can effectively reduce the electric field non-uniform coefficient. We believe that the strategy of electric field assembly to prepare graded permittivity materials (GPMs) is promising candidate for high performance insulation applications.

Effects of TiO2 nanoparticles and electrodes surface-modified by low-temperature plasma on impulse breakdown voltage of propylene carbonate

Insulating and energy-storage materials, such as propylene carbonate, require high dielectric strength. To improve insulation performance of propylene carbonate, we surface treated a copper electrode with a low-temperature plasma based on liquid nanometer modification technology. Thus, a TiO 2 nano-modified liquid was prepared and the surface of the copper electrode was modified by sputtering a TiO 2 film. The surface morphologies of the electrode surface before and after modification and the impulse breakdown voltages and space charge distributions of pure and nano-modified propylene carbonate were studied. These results indicate that the TiO 2 film deposition on the surface of the copper electrode markedly reduced the surface roughness. Furthermore, after the surface modification, the breakdown voltage of pure propylene carbonate and nano-modified propylene carbonate increased by 9.4 and 14.3%, respectively. We analyzed the effects of the electrode surface modification and nanoparticles on the breakdown voltage of propylene carbonate from the perspective of space charge. The nanoparticles introduced shallow traps, which increased the rate of charge dissipation. Furthermore, surface modification of the electrodes inhibited charge injection into the liquid, which affected the generation and development of streamers in the liquid, thereby further improving the breakdown performance of the propylene carbonate.

Composite foamed alkali-activated concrete with slag and steel slag

Thermally expandable foaming microspheres (FMS) are used as a foaming agent in many different fields due to their excellent dimensional stability and elastic properties. In this study, lightweight thermal insulation materials were prepared by adding FMS to foamed concrete containing alkali-activated steel slag and blast-furnace slag. The dry bulk density, cube strength, thermal conductivity and drying shrinkage of samples with different compositions were investigated and their microstructure was analysed using scanning electron microscopy and X-ray diffraction. With the addition of FMS, foamed materials with a dry bulk density of 625 kg/m3 and 40 mm cube strength of 3·6 MPa could be obtained. The 28 d drying shrinkage was 0·8 mm/m and the thermal conductivity was 0·102 W/m.K (thermal inertia index of 4·66). The results showed that FMS can be used as an organic foaming agent to prepare lightweight thermal insulation materials with improved insulation performance and mechanical properties.

Modeling and optimization of composite thermal insulation system with HGMs and VDMLI for liquid hydrogen on orbit storage

The passive thermal insulation system for liquid hydrogen (LH2) on orbit storage mainly consists of foam and variable density multilayer insulation (VDMLI) which have been considered as the most efficient and reliable thermal insulation system. The foam provides main heat leak protection on launch stage and the VDMLI plays a major role on orbit stage. However, compared with the extremely low thermal conductivity of VDMLI (1 × 10−5 W/(m·K)) at high vacuum, the foam was almost useless. Recently, based on hollow glass microspheres (HGMs) we have proposed the HGMs-VDMLI system which performs better than foam-VDMLI system. In order to improve insulation performance and balance weigh and environmental adaptability of passive insulation system, the HGMs-VDMLI insulation system should be configured optimally. In this paper, the thickness of HGMs and the number and arrangement of spacers of VDMLI were configured optimally by the “layer by layer” model. The effective thicknesses of HGMs were 25 mm for 60 layers MLI and 20 mm for 45 layers VDMLI. Compared with 35 mm foam and 45 layers VDMLI system, the heat flux of 20 mm HGMs and 45 layers VDMLI system was reduced by 11.97% with the same weight, or the weight of which was reduced by 9.91% with the same heat flux. Moreover, the effects of warm boundary temperature (WBT) and vacuum pressure on thermal insulation performance of the system were also discussed.