scholarly journals An Approach to the Simple Calculation Method of Steady Thermal Conductivity of Semitransparent Material

Netsu Bussei ◽  
2018 ◽  
Vol 32 (4) ◽  
pp. 151-156 ◽  
Author(s):  
Kazuya Hosono ◽  
Tsuyoshi Nishi ◽  
Hiromichi Ohta
Keyword(s):  
Thermal Conductivity ◽  
Calculation Method ◽  
Simple Calculation ◽  
Semitransparent Material

A Simple Calculation Method of Flashover Characteristics for Long Air Gaps under Various Discharge Conditions

1993 ◽  
Vol 113 (3) ◽  
pp. 252-258
Author(s):  
Kiyoto Nishijima ◽  
Itaru Tsuneyasu ◽  
Hiraku Nakahodo ◽  
Masaharu Minakami
Keyword(s):  
Calculation Method ◽  
Simple Calculation ◽  
Air Gaps

scholarly journals Comparison of the thermal performance between conventional and cob building

2019 ◽  
Vol 111 ◽  
pp. 03003
Author(s):  
Kaoutar Zeghari ◽  
Hasna Louahlia ◽  
Malo Leguern ◽  
Mohamed Boutouil ◽  
Hamid Gualous ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Behaviour ◽  
Calculation Method ◽  
Building Materials ◽  
Residential Building ◽  
Local Heat ◽  
Energy Performance ◽  
Stationary Regime ◽  
Thermal Regulation ◽  
Climate Data

The appliance of sustainable development approach in building has urged construction industry to adopt proper measurements to protect environment and reduce residential building energy consumption and CO2 emissions. Thus, an increasing interest in alternative building materials has developed including the use of bio-based materials such as cob which is studied in this paper. In the previous work, many experimental and numerical studies have been carried out to characterize thermal behaviour of earth buildings, reduce its thermal conductivity and water content. In this paper, an experimental study is carried out to determine the thermal properties and energy performance of cob building. Cob samples within different soil and fiber contents are studied using an experimental set up instrumented with flux meters and micro-thermocouples in order to evaluate the local heat flux and thermal conductivity during stationary regime. The results are analysed and compared to deduce the performant mixes in terms of thermal behaviour while respecting the French thermal regulation. A static thermal simulation based on RT 2012 calculation method (the official French calculation method for the energy performance of new residential and commercial buildings according to France thermal regulation) is used to compare energy performance between conventional and cob building using the French climate data base .

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

scholarly journals Heat Transfer Dynamic Analyses for Recycled-Concrete Wall Combined with Expanded Polystyrene Template

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Jianhua Li ◽  
Wenjing Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Calculation Method ◽  
Research Work ◽  
Shear Wall ◽  
Climatic Conditions ◽  
Expanded Polystyrene ◽  
Recycled Concrete ◽  
Concrete Wall ◽  
Ordinary Concrete

Due to the benefits of pollution reduction, energy saving, and recycling of resources associated with the recycled concrete, together with the apparent thermal storage thermal insulation yield of expandable polystyrene (EPS) template, the heat transfer dynamics of their combination has become a contemporary study topic. In this research work, an investigation of the heat transfer coefficient (U) of EPS template recycled-concrete shear wall has been carried out. Four different concrete mixtures shear wall samples having different insulation types were developed for the purpose of quantifying their thermal outputs. Both temperature (T) and humidity (H) affection to thermal conductivity coefficient (λ) of reinforced concrete and the EPS template were investigated, correspondingly. The λ0°C (relative variation for a 0°C of temperature variation in T) of cement mortar, recycled-concrete shear wall, and ordinary concrete shear wall were measured being 0.7526, 1.2463, and 1.3750 W·m−1·K−1, respectively. And the λ calculation of EPS was carried out being 0.0396 W·m−1·K−1. A corrected calculation method was put forward to application in practical work that could reflect the real U value in a more precise manner. These results brought to light the fact that the heat preservation output of recycled-concrete shear wall posed to be comparatively more improved than that of ordinary concrete shear wall. We put forth the suggestion for the use of corrected calculation method in the calculation and analysis of U of EPS template recycled-concrete composite shear wall in the climatic conditions of Beijing. The results revealed the fact that the U of EPS template recycled-concrete shear wall was dominantly controlled by the change of thermal conductivity changes of EPS template. The monthly mean U increased with increasing Tout and decreased with decreasing Tout. The smaller the U of the enclosure wall was, the better the thermal stability of the wall was experienced.

scholarly journals The thermal conductivity of gas mixtures

1929 ◽  
Vol 123 (791) ◽  
pp. 134-142 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Calibration Curve ◽  
Bridge Circuit ◽  
Simple Calculation ◽  
Gas Analysis ◽  
Heat Losses ◽  
Gas Mixture ◽  
Metallic Conduction ◽  
Copper Lead

The action of the katharometer as an instrument for gas analysis depends essentially upon the thermal conductivity of the gas mixture examined. One method of calibration for a given pair of gases is to make a number of mixtures of known composition by volume, and to obtain from them a curve showing how the deflection θ of the galvanometer in the bridge circuit of the instrument depends upon the composition of the mixture which surrounds one of the fine platinum helices. By reference to this curve, any other mixture of the two gases can be analysed when its deflection is known. A typical calibration curve is shown in fig. 1, which is for mixtures of helium and argon. The direction of the galvanometer deflection depends on whether the gas is a better or worse conductor than air. A useful convention is to regard the deflection for gases which are better conductors than air as positive. Daynes has examined the nature of the heat losses in the katharometer cell, which are due to ( a ) radiation, ( b ) convection, ( c ) conduction by the gas, ( d ) cooling of the platinum helix by metallic conduction along the copper lead. Even at the highest temperature used in the katharometer, the effect of ( a ) is very small, and will not be influenced directly by the nature of the gas surrounding the wire. Experiments have shown that the effect of ( b ) is also small. The effect of ( c ) on the temperature of the helix is large, and will depend upon the nature of the gas. The effect of ( d ) is also considerable, and will depend upon the temperature of the helix. This effect will consequently vary with the nature of the gas under examination, but the magnitude of the effect in the steady state which is reached depends upon the effect of ( c ) (the small effects of convection and radiation will similarly depend upon the effect of ( c )). Thus in practice, the thermal conductivity of the gas controls the temperature of the helix, and the instrument will give the same reading for all gases or mixtures having the same thermal conductivity. Owing to the complicated design of the katharometer cell, it is not possible to make a simple calculation of the heat loss due solely to the conductivity of the gas, or to devise a method of converting katharometer readings directly into thermal conductivities. It should be noticed also that the calibration curves for different instruments are not all of quite the same form, owing to small differences in the winding of the helix, or of its position in the cell.

The Study about Flexural Performance of GFRP Bar Reinforced Concrete Beams Based on Numerical Calculation Method

2010 ◽  
Vol 29-32 ◽  
pp. 1350-1356
Author(s):  
Qing Guo Yang ◽  
Yu Wei Zhang ◽  
Zhi Zhong Tu
Keyword(s):  
Reinforced Concrete ◽  
Numerical Calculation ◽  
Bearing Capacity ◽  
Calculation Method ◽  
Concrete Beams ◽  
Simple Calculation ◽  
Reinforced Concrete Beams ◽  
Displacement Curve ◽  
Gfrp Bar ◽  
Numerical Calculation Method

Replacing the steel bar with GFRP (Glass Fiber Reinforced Plastics) bar can improve the durability of concrete structure in the corrosive environment. Different ratios of GFRP bar lead huge difference performance of GFRP reinforced concrete beams; therefore, to reduce the workload, it is very necessary to study GFRP reinforced concrete beams’ performance with suitable numerical calculation method. In the study, first, GFRP reinforced concrete beams’ mechanical behavior and failure characteristics were researched through the flexural experiments of GFRP reinforced concrete beams with different ratio of GFRP bar; Second, the numerical calculation model of GFRP reinforced concrete beams was built according to experimental results which contain the load-displacement curve and the phenomenon that concrete in compression zone are crushed, then the calculation criterion of obtaining the beam’s bearing capacity was proposed. Lastly, the bending bearing capacity of GFRP bar reinforced concrete beams with different ratio of GFRP is obtained through the finite element calculation, and the practical and simple calculation formula is acquired.

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