Wall Panels with Improved Thermal Properties on KBR's Porous Fillers

2018 ◽  
Vol 931 ◽  
pp. 243-246 ◽  
Author(s):  
Valery K. Khuranov ◽  
Aues S. Tsipinov ◽  
Muzarib I. Bjakhov
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Characteristics ◽  
Engineering Calculation ◽  
Wall Panel ◽  
Structural Concrete ◽  
External Wall ◽  
Constructive Solution ◽  
Coefficient Of Thermal Conductivity ◽  
Wall Panels

The article describes the design of buildings for multi-apartment houses 139 series, designed for construction in the conditions of the Kabardino-Balkaria Republic (KBR). An analysis of existing wall panel variants based on their thermal characteristics was carried out and a new constructive solution was proposed using porous fillers of KBR. The coefficient of thermal conductivity of the proposed structural concrete is determined analytically and the heat engineering calculation of the external wall panel is presented.

Determination of the Thermal Properties of a PCB by Coupled Numerical and Experimental Approach

2020 ◽  
Author(s):  
Yener Usul ◽  
Mustafa Özçatalbaş
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Numerical Analysis ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Analyses ◽  
Analysis Model ◽  
Linear Temperature ◽  
Coefficient Of Thermal Conductivity

Abstract Increasing demand for usage of electronics intensely in narrow enclosures necessitates accurate thermal analyses to be performed. Conduction based FEM (Finite Element Method) is a common and practical way to examine the thermal behavior of an electronic system. First step to perform a numerical analysis for any system is to set up the correct analysis model. In this paper, a method for obtaining the coefficient of thermal conductivity and specific heat capacity of a PCB which has generally a complex composite layup structure composed of conductive layers, and dielectric layers. In the study, above mentioned properties are obtained performing a simple nondestructive experiment and a numerical analysis. In the method, a small portion of PCB is sandwiched from one side at certain pressure by jaws. A couple of linear temperature profiles are applied to the jaws successively. Unknown values are tuned in the analysis model until the results of FEM analysis and experiment match. The values for the coefficient of thermal conductivity and specific heat capacity which the experiment and numerical analysis results match can be said to be the actual values. From this point on, the PCB whose thermal properties are determined can be analyzed numerically for any desired geometry and boundary condition.

scholarly journals Thermal Behavior and Measures to Prevent Condensation of a Newly Developed External Wall Panel

2019 ◽  
Vol 11 (3) ◽  
pp. 912 ◽  
Author(s):  
Goopyo Hong ◽  
Suk-Won Lee ◽  
Ji-Yeon Kang ◽  
Hyung-Geun Kim
Keyword(s):  
Surface Temperature ◽  
Thermal Performance ◽  
Simulation Analysis ◽  
Thermal Characteristics ◽  
Weather Conditions ◽  
Building Envelope ◽  
Unsteady State ◽  
Wall Panel ◽  
External Wall ◽  
Thermal Transmittance

An external wall panel (EWP) as a novel alternative to provide spatial flexibility and improve the performance of external walls was developed. The purpose of this study was to analyze the thermal performance of this EWP. A simulation analysis was carried out to scrutinize whether it was vulnerable to condensation, considering South Korea’s weather conditions, and find countermeasures to prevent this. Results indicated that the indoor surface temperature with the measures of added insulation materials and an inserted thermal-breaker was over 16.5 °C and that these methods could prevent condensation. In addition, this study assessed unsteady-state thermal characteristics, linear thermal transmittance, and the effective thermal transmittance of EWP. Effective thermal transmittance was estimated in consideration of the heat transmittance of EWP and the linear thermal transmittance of its slabs and its connection parts. The thermal characteristics of the building envelope are needed to analyze effective thermal transmittance and linear thermal transmittance-associated thermal bridges.

Effective heat conductivity of Honeycomb (porous) composite panel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Cletus Matthew Magoda ◽  
Jasson Gryzagoridis ◽  
Kant Kanyarusoke
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Composite Material ◽  
Thermal Properties ◽  
Heat Conductivity ◽  
Composite Panel ◽  
Porous Composite ◽  
Content Type ◽  
One Dimensional ◽  
Coefficient Of Thermal Conductivity

Purpose The purpose of this paper is to validate an assumption of what to use as an effective (steady state) heat transfer coefficient of thermal conductivity for the honeycomb core sandwiched by Fiberglass face sheets composite. A one-dimensional model based on Fourier law is developed. The results are validated experimentally. Design/methodology/approach The results were obtained from the one-dimensional mathematical model of an overall or effective heat conductivity of the Honeycomb composite panel. These results were validated experimentally by applying heat flux on the specimen under controlled environment. The surface temperatures at different voltages were recorded and analysed. The skin of the sandwich composite material used in the investigation was Fiberglass sheet with a thickness of 0.5 mm at the bottom and 1.0 mm at the top surface. Both skins have a stacking sequence of zero degrees. Due to the presence of air cells in the core (Honeycomb), the model considers the conduction, convection and radiation heat transfer, across the thickness of the panel, combined as an effective conduction mode, whose value may be predicted by using the coefficient of thermal conductivity of the air based on the average temperature difference between the two skins. The experimental results for the heat transfer through the thickness of the panel provide validation of this assumption/prediction. Both infrared thermography and conventional temperature measurement techniques (thermocouples) were used to collect the data. Findings The heat transfer experiment and mathematical modeling were conducted. The data obtained were analyzed, and it was found that the effective thermal conductivity was temperature-dependent as expected. The effective thermal conductivity of the honeycomb panel was close to that of air, and its value could be predicted if the panel surface temperatures were known. It was also found that as temperature raised the variation between experimental and predicted effective air conduction raised up. This is because there was an increase in molecular diffusion and vibration. Therefore, the convection heat transfer increased at high temperatures and the air became an insulator. Originality/value Honeycomb composite panels have excellent physical and thermal properties that influence their performance. This study provides an appropriate method in determining thermal conductivity, which is one of the critical thermal properties of porous composite material. This paper also gives useful and practical data to industries that use or manufacture honeycomb composite panels.

scholarly journals EFFECT OF ALUMINUM DROSS AND RICE HUSK ASH ON THERMAL AND MOULDING PROPERTIES OF SILICA SAND

2017 ◽  
Vol 36 (3) ◽  
pp. 794-800
Author(s):  
EF Ochulor ◽  
HOH Amuda ◽  
SO Adeosun ◽  
SA Balogun
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Thermal Characteristics ◽  
Silica Sand ◽  
Cast Part ◽  
Solidification Kinetics ◽  
Moulding Sand

Moulding properties of foundry sand should be controlled so as to minimize casting defects. Its thermal characteristics are vital in defining the solidification kinetics of a cast part,  evolving microstructure and mechanical properties. Modification of the thermal properties of the moulding sand mix is important in achieving desired structure and mechanical properties in the cast component. This study investigates the incorporation of 2-12 wt. % aluminium dross (AlDr) and 1-6 wt. % rice husk ash (RHA) in silica sand on moulding and thermal properties of the resulting sand mix. Results show that RHA significantly reduced thermal conductivity of the moulding sand from 1.631-1.141 W/m. K (a 30% reduction).However, AlDr increased its thermal conductivity from 1.631-1.787 W/m.K for 1-6 wt. % AlDr, which later dropped progressively from 1.753-1.540 W/m.K for 8-12 wt. %. The moisture content increased abruptly from 4.0-4.2 % for 6-8 wt. % AlDr addition but decreased from 4.0-2.8% for0-6 wt. % RHA addition in the moulding sand mix. http://dx.doi.org/10.4314/njt.v36i3.19

scholarly journals Metamorphism and thermal properties of fresh snow (study in the Moscow region)

2016 ◽  
Vol 56 (2) ◽  
pp. 199-206 ◽  
Author(s):  
R. A. Chernov
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Temperature Gradient ◽  
Negative Temperature ◽  
Average Temperature ◽  
The North ◽  
Coefficient Of Thermal Conductivity ◽  
European Part Of Russia ◽  
Snow Conditions

As a result of laboratory tests were obtained values of the coefficient thermal conductivity (Keff) of new snow for different types of the solid precipitation: plates, needles, stellars, graupels. Snow samples were collected during a snowfall and placed in the freezer. For all types of sediment thermal conductivity of snow is equal to 0.03–0.04 W/m·°C. Transformation of new snow occurs within 10 days at average temperature −10 °C and the gradient temperature of 50–60 °C/m. Under these conditions, the metamorphism leads to an increase the density of snow, size of grains and rounded snow particles. At the beginning of the experiment, the thermal conductivity of snow is linearly increased in proportion to the density of the snow. However, after 3–5 days Keff stabilized at about 0.08–0.09 W/m·°C, although the density of the snow and size of grains continued to increase. This effect occurs with the appearance of faceted crystals and loosening of snow. In the future, while maintaining a negative temperature coefficient of thermal conductivity remained unchanged. Thus, the temperature gradient metamorphism affect to the thermal conductivity snow, which plays an important role in maintaining the thermal insulation properties of snow cover. The article describes the formula to calculate the thermal conductivity of the snow conditions in the temperature gradient metamorphism. Such conditions are characteristic of the vast expanses of the north and northeast of the European part of Russia. On the basis of long-term observations in Moscow shows the average minimum and maximum values for the density of the snow woods and fields on the basis of which can be calculated for the thermal properties of the snow.

Rice husk incorporated foam concrete wall panels as a thermal insulating material in buildings

2019 ◽  
Vol 29 (5) ◽  
pp. 721-729 ◽  
Author(s):  
NR Aravind ◽  
Dhanya Sathyan ◽  
K M Mini
Keyword(s):  
Thermal Conductivity ◽  
Energy Consumption ◽  
Fly Ash ◽  
Rice Husk ◽  
Bending Test ◽  
Wall Panel ◽  
Foam Concrete ◽  
Durability Properties ◽  
Thermal Insulating ◽  
Wall Panels

The major segment for energy consumption is found in industry, transport, agricultural, residential and commercial sector. The main part of the energy consumption in residential and commercial buildings is due to the use of mechanical devices to maintain a comfortable indoor environment. Thermal conductivity of building materials is one of the factors which influence the heat transfer in buildings. Thermal conductivity can be reduced by the use of materials with low density. The present paper reports the development of a sustainable thermal insulating external wall panel and its mechanical, thermal and durability properties. The wall panel was prepared using foam concrete and rice husk and replacing the cement by fly ash. Strength of panel was tested by conducting in plane bending test and compressive strength test. Thermal conductivity was tested using guarded hot plate apparatus. Durability properties were tested by conducting water absorption test, drying shrinkage and acid resistance test. The test results showed that the rice husk and fly ash content had a major influence on the thermal conductivity and durability properties of the developed wall panels.

The Method Analysis of Using Finite Element Method to Determine the Bemding Moment Formula of Precast Reinforced Concrete Composite Thermal Insulation of External Wall

2012 ◽  
Vol 204-208 ◽  
pp. 3682-3685
Author(s):  
Ying Wang ◽  
Yan E Sui
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Calculation Method ◽  
Engineering Application ◽  
Wall Panel ◽  
External Wall ◽  
Wall Panels ◽  
Sandwich Type ◽  
Method Analysis ◽  
Element Method

This paper describes the calculation method and steps of compound insulation external wall panels who's whole board with openings. Using Finite Element Method to simulate and analysis the result,For in the engineering application of the sandwich type wall panel provides the basis.

Analysis of Grinding Temperatures by Energy Partitioning

1996 ◽  
Vol 210 (6) ◽  
pp. 579-588 ◽  
Author(s):  
W B Rowe ◽  
S C E Black ◽  
B Mills ◽  
H S Qi
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Cubic Boron Nitride ◽  
Thermal Characteristics ◽  
Theoretical Models ◽  
Relative Magnitude ◽  
Partition Ratio ◽  
Energy Partitioning ◽  
Grinding Wheel ◽  
Effective Thermal Properties

The partitioning of heat between two sliding bodies depends strongly on the relative magnitude of the thermal characteristics of each body. Grinding with the superabrasive CBN (cubic boron nitride) gives the favourable condition of a high thermal conductivity wheel, allowing increased heat to be carried away by the grinding wheel. This reduces the temperatures experienced by the workpiece. In this paper different methods of theoretical partitioning in grinding are reviewed. The partition ratio is the proportion of the total grinding energy that enters the workpiece. The partition ratio in surface grinding was measured using a thermocouple technique. Theoretical models for predicting the partition ratio were correlated with measured results to establish the effective thermal properties of CBN and aluminium oxide abrasives. The effective thermal conductivity of CBN was found to be considerably lower than the reported theoretical value. The findings provide the basis for improved prediction of workpiece temperatures in grinding.

scholarly journals Impact of point thermal bridges on thermal properties of building envelopes

2020 ◽  
Vol 24 (3 Part B) ◽  
pp. 2181-2188 ◽  
Author(s):  
Jolanta Sadauskiene ◽  
Juozas Ramanauskas ◽  
Algimantas Vasylius
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Characteristics ◽  
Insulation Layer ◽  
Geometrical Properties ◽  
Thermal Transmittance ◽  
Energy Efficient Buildings ◽  
Thermal Bridge ◽  
Thermal Bridges ◽  
Bearing Layer

During the design of energy-efficient buildings with a ventilated fa?ade systems, the evaluation of point thermal transmittance is complicated. It requires additional theoretical knowledge, special software and skills to use it. Because of that, point thermal transmittance is often ignored in practice. The dependence of point thermal transmittance, which is appearing because of aluminum fixing elements used in the insulated wall with ventilated fa?ade system, from the thermal and geometrical properties of construction layers are analyzed in this paper. Research has shown, that thermal properties of the supporting wall, where fixing element is located, had the biggest influence on the point thermal transmittance. When thermal conductivity of the supporting wall was increasing, as well as a thickness of the insulation layer, a value of thermal bridge was increasing in a non-linear way. For this reason, the thermal transmittance coefficient of all construction could increase up to 35%. When the thickness of the supporting wall and thermal conductivity of the insulation layer was increased, the value of point thermal bridge was decreasing. The tests revealed strong dependency of the point thermal bridge on the thermal conductivity of bearing layer material and the thickness of the bearing layer of wall. For this reason, thermal bridges should receive greater consideration. It is not enough to use the diagrams of typical fasteners that very often do not take into account the exact thickness and thermal characteristics of materials

THERMAL PERFORMANCE OF PANELS WITH HIGH DENSITY, RANDOMLY ORIENTED STRAW BALES

2018 ◽  
Vol 13 (1) ◽  
pp. 31-55 ◽  
Author(s):  
Sarah Seitz ◽  
Kyle Beaudry ◽  
Colin MacDougall
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Heat Flow ◽  
Experimental Error ◽  
High Density ◽  
Normal Density ◽  
Wall Panels ◽  
Lime Plaster ◽  
Straw Bale ◽  
Measured Thermal Conductivity

This paper describes the hot-box testing (based on ASTM C1363-11) of seven straw bale wall panels to obtain their thermal conductivity values. All panels were constructed with stacked bales and cement-lime plaster skins on each side of the bales. Four panels were made with traditional, 2-string field bales of densities ranging from 89.5 kg/m3–131 kg/m3 and with the bales on-edge (fibres perpendicular to the heat flow). Three panels were made with manufactured high-density bales (291 kg/m3–372 kg/m3). The fibres of the manufactured bales were randomly oriented. The key conclusion of this paper is that within the experimental error, there is no difference in the thermal conductivity value for panels using normal density bales and manufactured high density bales up to a density of 333 kg/m3. However, because of lack of precision of the hot-box, no conclusions can be made on the true thermal conductivity of the high density bale panels. In addition, the panels tested were found to have significant voids between bales, and this is believed to have contributed to higher measured thermal conductivity values compared to those reported in the literature for normal density bale panels. Thermal properties may be affected for bales with higher densities than 333 kg/m3, therefore further testing is suggested.

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