Good Insulation Effect Research Articles

Design Of Pluggable Solar Greenhouse

Original design of a plug-in assembly type solar greenhouse, good insulation effect, plug and pull, can change the height and length of the wall according to production needs. This new type of solar greenhouse adopts plug-in heat preservation wall. This kind of wall adopts standardized module, which can be industrialized mass production. It has the advantages of low cost, convenient disassembly, assembly and transportation, and protection of land and environment.

Impact of aeration and deaeration of switchable vacuum insulations on the overall heat conductivity using different core materials and filling gases

Investigating switchable vacuum insulation panels might lead to a new type of insulation, which can be switched on to enable a low heat flow when a good insulation effect is desired and switched off when exchange with the environment is requested, during a cold summer night, for example. For this reason, different core materials for vacuum insulations as typical silica powder were investigated as well as silica agglomerates and silica gel. These materials were checked for the necessary time of aeration and evacuation and the corresponding change of heat conductivity along with the change of gas-pressure. Silica gel in combination with helium as filling gas showed best results corresponding to a high difference of the heat conductivities evacuated and aerated. Beside the solid backbone structure of the silica gel, this is caused by the high heat conductivity and small kinetic atomic diameter of the helium gas. Silica agglomerates decreased the aeration time as well as the deaeration time, but the improvement was neglected because of a lower change of heat conductivity during pressure drop or rise. Nevertheless, a good switchable vacuum insulation can be produced using silica gel and helium, for example.

Dynamic characteristics and stability of pipe-in-pipe system conveying two-phase flow in thermal environment

Pipe-in-pipe (PIP) systems are utilized widely in modern petroleum industry owing to their good insulation effect. In present work, a novel mathematical model for the free vibration of the fluid-conveying cantilevered PIP system considering thermal effect and two-phase flow is proposed. The insulation layer connecting two concentric pipes is simplified as the distributed springs and dampers here. The governing equation of the pipe system is then derived using Hamilton's principle based on Euler-Bernoulli beam theory. Then the Galerkin method is applied to the free vibration analysis. In the numerical section, parametric analysis is performed to elucidate the effects of different physical factors, such as environment temperature, equivalent stiffness and damper of the insulation layer, structural damping, two-phase flow, and axial load on the dynamic characteristic and stability of the PIP system through the forms of Argand diagram, stability map, and time history diagram. The results show that the PIP system has an advantage over a single fluid-conveying pipe in terms of stability considering thermal effect, axial load, and structural damping. Besides, different from single pipe, two different frequencies are found for each vibration mode, and two-pipe coupled flutter instability occurs to the PIP system as the fluid velocity exceeds the critical fluid velocity. The theoretical work is helpful to improve the analysis and design of the PIP system with consideration of internal two-phase flow and environmental temperature.

Study on the performance of inflatable decelerator under hypersonic aerodynamic load

In order to understand the influence of hypersonic aerodynamic force and aerodynamic heat on the performance of flexible structure of inflatable decelerator, a unidirectional thermal-fluid-structure three field coupling model under the extreme conditions of reentry trajectory is established in this paper. The temperature distribution of thermal protection structure (TPS) and structure response are obtained. The numerical results show that the TPS has a good insulation effect, and the cooling contribution of insulation layer in TPS is up to 80.90%. The stress is concentrated at the contact position between the flexible structure and the blunt head. The stress of TPS layer fluctuates greatly.

Mechanical Properties of Phenolic Foam Modified Insulation Board by Urethane Oligomer

In this paper, the major research contents include improving the properties of phenolic foams through making urethane oligomer modifiers. Various characterization methods were adopted to analyze the properties and microstructure of phenolic foams. Finally, a new type of phenolic foam, which has good insulation effect and excellent mechanical properties, has been made. The results have shown that this new phenolic foam has the following features: good insulation effect (thermal conductivity is 0.030W/m•K), good hardness (apparent density can reach 40-60kg/m3), and high toughness (the flexural strength can reach to 4.0N/cm2, and the compression strength can be improved by 16% and reach to 0.134Mpa). The phenolic foams can be widely used in construction field of external wall insulation, which is significant in energy conservation

Simulation and experimental investigation on micro electrochemical drilling of micro-holes with ultra short pulse voltage

This paper introduces an electrochemical drilling process which is efficient in fabricating micro-holes, in order to study the influences of ultra short pulse voltage and high speed spiral micro electrode on the machining accuracy and machining efficiency of micro electrochemical drilling, the simulation of the gap electric field and the gap flow field are carried out. Firstly, the model of ultra short pulse gap electric field was established, by simulating the process of the drilling, the shape change of the anode workpiece surface was analysed and predicted with the ultra short pulse voltage. The results show that the ultra short pulse voltage can greatly improve the machining accuracy. Secondly, by using CFX to simulate the gap flow field, with the increase of the electrode rotating speed, the gas film generated with good insulation effect can greatly reduce the taper of the micro-holes. Finally, the simulation results above were verified by the experiments, a series of micro-holes was fabricated successfully; the diameter of the micro-holes was less than 200 μm, which proved that the micro electrochemical drilling for fabricating micro-holes has a widespread application prospect. [Submitted 3 November 2016; Accepted 5 December 2017]

Simulation and experimental investigation on micro electrochemical drilling of micro-holes with ultra short pulse voltage

This paper introduces an electrochemical drilling process which is efficient in fabricating micro-holes, in order to study the influences of ultra short pulse voltage and high speed spiral micro electrode on the machining accuracy and machining efficiency of micro electrochemical drilling, the simulation of the gap electric field and the gap flow field are carried out. Firstly, the model of ultra short pulse gap electric field was established, by simulating the process of the drilling, the shape change of the anode workpiece surface was analysed and predicted with the ultra short pulse voltage. The results show that the ultra short pulse voltage can greatly improve the machining accuracy. Secondly, by using CFX to simulate the gap flow field, with the increase of the electrode rotating speed, the gas film generated with good insulation effect can greatly reduce the taper of the micro-holes. Finally, the simulation results above were verified by the experiments, a series of micro-holes was fabricated successfully; the diameter of the micro-holes was less than 200 μm, which proved that the micro electrochemical drilling for fabricating micro-holes has a widespread application prospect. [Submitted 3 November 2016; Accepted 5 December 2017]

Design of thermal insulation energy-saving coatings for exterior wall

Thermal insulation coatings can effectively prevent coatings and substrate from solar radiation under the condition of zero-energy consumption, which could improve the working conditions and reduce the energy consumption. A kind of thin layer thermal insulating energy-saving coatings with high performance was designed by synergistic effect of thermal insulation mechanisms during the process of light and heat transfer. The excellent performance of coatings had characterized with low thermal conductivity, good insulation effect, high reflectivity, and so on. Moreover, double insulation system as an optimized thermal insulation coating structural model was proposed and designed. The reflection-insulation type thermal insulation coating was used as the top-coat to form reflection-insulation layer, and the radiation-insulation type thermal insulation coating was used as the intermediate-coat to form radiation-insulation layer. The double system had advantages of good thermal insulation and convenient process, and it is also easy to rush, save energy and reduce energy consumption. Some issues of insulation coatings were explored and explained, such as coating strength, filler arrangement and coating thickness.

Thermal Simulation Analysis of Insulation of the New Heat-Insulation Bricks

Using the ANSYS thermal analysis module to do steady thermal analysis of given heat-insulating bricks. The results show that this kind of bricks can achieve better insulation in both sides; when the thermal conductivity of the heat insulating material in the hole space are less than 0.3 W/(m·K), the bricks can obtain the good insulation effect; the smaller the heat conductivity coefficients of the bricks materials and filling materials are, the better insulation bricks can achieve.

Temperature field simulation of complex structures in fire environment

In this paper, the typical model of the system of dangerous goods – steel – wood composite structure including components of explosives is used as the research object. Using MARC program, the temperature field of the structure in the fire environment is simulated. Radiation, conduction and convection heat transfer within the gap of the structure are taken into account, contact heat transfer is also considered. The phenomenon of thermal decomposition of wood in high temperature is deal with by equivalent method. The results show that the temperature of the explosives is not high in the fire environment. The timber inside the composite structure has played a very good insulation effect of explosives.

인산염 피막처리 분말을 사용한 Fe-6.0 wt%Si 합금 압분자심의 자기적 특성

가스분무법으로 제조한 <TEX>$35\~180\;{\mu}m$</TEX> 크기의 <TEX>$Fe-6.0wt\%Si$</TEX> 합금분말에 대하여 인산염계 절연물질을 피막처리하고 <TEX>$600\~900^{\circ}C$</TEX>에서 1시간 동안 열처리한 후 압축성형한 압분자심(분말코아)의 자기적 성질 및 기계적 특성을 조사하였다. 대체적으로 열처리온도가 증가할수록 압축강도가 감소하였으며, 자심손실 또한 낮아졌다. <TEX>$800^{\circ}C$</TEX>에서 열처리한 경우 압축성형강도가 15 kgf, 100 kHz에서 실효투자율은 74, 품질계수는 26, 50 Oe의 직류자장 하에서 퍼센트투자율은 78 정도의 값을 나타내었으며, 50 kHz-0.1 T에서 자심손실은 <TEX>$750\;mW/cm^3$</TEX>였다. 그리고 투자율-주파수 곡선 상에서의 cut-off 주파수는 거의 200 kHz 이상에 이르는 것으로 나타났다. <TEX>$Fe-6.0wt\%Si$</TEX> 합금 압분자심의 이러한 제반 특성은 인산염 피막의 양호한 전기절연효과와, 고규소농도에 따른 합금의 결정자기이방성 및 포화자기변형의 감소, 전기비저항의 증대 등 기초 물성의 변화에 기인하는 것으로 사료되었다. Dust cores (compressed powder cores) of <TEX>$Fe-6.0wt\%Si$</TEX> alloy with a size of <TEX>$35\~180\;{\mu}m$</TEX> in diameter have been prepared by phosphate coatings and annealings at <TEX>$600\~900^{\circ}C$</TEX> for 1 h in nitrogen atmosphere. Further the magnetic and mechanical properties of the powder cores were investigated. As a general trends, the compressive strength and core loss decreased with the increase in annealing temperature. When annealed at <TEX>$800^{\circ}C$</TEX>, the compressive strength was 15 kgf, the permeability and quality factor were 74 and 26, respectively. Moreover the core loss at 50 kHz and 0.1 T induction was <TEX>$750\;mW/cm^3$</TEX>, and the percent permeability under the static field of 50 Oe was estimated to be about 78. In addition, the cut-off frequency in the cure representing the frequency dependence of effective permeability was measured to be around 200 kHz. These properties of the <TEX>$Fe-6.0wt\%Si$</TEX> alloy dust cores could be considered to be due to the good insulation effect of iron-phosphate coats, the decrease in magnetocrystalline anisotropy and saturation magnetostriction and the increase in electric resistivity.