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.

Finite Element Analysis of Uniaxial Compression of Glazed Hollow Bead of Recycled Concrete Short Columns

2014 ◽  
Vol 898 ◽  
pp. 399-402
Author(s):  
Heng Sun ◽  
Bai Shou Li
Keyword(s):  
Finite Element ◽  
Uniaxial Compression ◽  
Recycled Concrete ◽  
Intensity Level ◽  
Concrete Wall ◽  
Element Analysis ◽  
Ordinary Concrete ◽  
Ansys Simulation ◽  
Finite Element Software ◽  
Short Columns

For traditional ordinary concrete wall column prone to thermal bridges, posted outside the insulation board short life than the life of the building，in the glazed hollow bead of recycled concrete foundation with good thermal conductivity test and compressive strength of the proposed ,use glazed hollow bead of recycled concrete exterior wall column instead of the traditional ordinary concrete wall column ,and using the finite element software ANSYS simulation analysis the uniaxial compression of glazed hollow bead of recycled concrete short columns and ordinary concrete short columns. Comparative analysis showed the same intensity level glazed hollow bead of recycled concrete ultimate compressive bearing capacity of an analog value the same as ordinary concrete short columns. To validate the ANSYS simulation of concrete short columns under uniaxial compression condition .

The Study on the Impact of Recycled Fine Aggregate and Powder on the Mechanics and Thermal Performance of Recycled Concrete Hollow Blocks

2012 ◽  
Vol 509 ◽  
pp. 119-122
Author(s):  
Wei Zhou ◽  
Ling Huan Lu ◽  
Zhen Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Performance ◽  
High Strength ◽  
Recycled Concrete ◽  
Fine Aggregate ◽  
Ordinary Concrete ◽  
Recycled Fine Aggregate ◽  
The Impact ◽  
The Heat Transfer Coefficient

The impact of recycled fine aggregate and powder on the mechanics and thermal performance of recycled concrete hollow blocks was discussed in this paper. The results showed that 30% recycled fine aggregate and powder have slight affect on the strength of recycled concrete hollow blocks. But the strength reduced significantly when the replacement is above 50%. The impact of recycled fine aggregate and powder on the performance of concrete hollow blocks with high strength grade is notable . The heat transfer coefficient of recycled concrete hollow blocks with 30% recycled fine aggregate and powder was equivalently to ordinary concrete hollow blocks.

scholarly journals Change in Conductive–Radiative Heat Transfer Mechanism Forced by Graphite Microfiller in Expanded Polystyrene Thermal Insulation—Experimental and Simulated Investigations

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2626
Author(s):  
Aurelia Blazejczyk ◽  
Cezariusz Jastrzebski ◽  
Michał Wierzbicki
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Insulation ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Expanded Polystyrene ◽  
Transfer Mechanism ◽  
Total Thermal Conductivity ◽  
Heat Transfer Mechanism

This article introduces an innovative approach to the investigation of the conductive–radiative heat transfer mechanism in expanded polystyrene (EPS) thermal insulation at negligible convection. Closed-cell EPS foam (bulk density 14–17 kg·m−3) in the form of panels (of thickness 0.02–0.18 m) was tested with 1–15 µm graphite microparticles (GMP) at two different industrial concentrations (up to 4.3% of the EPS mass). A heat flow meter (HFM) was found to be precise enough to observe all thermal effects under study: the dependence of the total thermal conductivity on thickness, density, and GMP content, as well as the thermal resistance relative gain. An alternative explanation of the total thermal conductivity “thickness effect” is proposed. The conductive–radiative components of the total thermal conductivity were separated, by comparing measured (with and without Al-foil) and simulated (i.e., calculated based on data reported in the literature) results. This helps to elucidate why a small addition of GMP (below 4.3%) forces such an evident drop in total thermal conductivity, down to 0.03 W·m−1·K−1. As proposed, a physical cause is related to the change in mechanism of the heat transfer by conduction and radiation. The main accomplishment is discovering that the change forced by GMP in the polymer matrix thermal conduction may dominate the radiation change. Hence, the matrix conduction component change is considered to be the major cause of the observed drop in total thermal conductivity of EPS insulation. At the microscopic level of the molecules or chains (e.g., in polymers), significant differences observed in the intensity of Raman spectra and in the glass transition temperature increase on differential scanning calorimetry(DSC) thermograms, when comparing EPS foam with and without GMP, complementarily support the above statement. An additional practical achievement is finding the maximum thickness at which one may reduce the “grey” EPS insulating layer, with respect to “dotted” EPS at a required level of thermal resistance. In the case of the thickest (0.30 m) panels for a passive building, above 18% of thickness reduction is found to be possible.

Calculation of Thermal Conductivity in Nanofluids From Atomic-Scale Simulations

2005 ◽  
Author(s):  
Xuan Wu ◽  
Ranganathan Kumar ◽  
Parveen Sachdeva
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Enhancement ◽  
Pure Water ◽  
Research Work ◽  
Atomic Scale ◽  
Heat Current ◽  
Transfer Enhancement ◽  
Atomic Interactions ◽  
Time Autocorrelation Function

Nanofluids that consist of nanometer sized particles and fibers dispersed in base liquids have shown the potential to enhance the heat transfer performance. Although three features of nanofluids including anomalously high thermal conductivities at very low nanoparticle concentrations, strongly temperature dependent thermal conductivity and significant increases in critical heat flux have been studied widely, and layering of liquid molecules at the particle-liquid interface, ballistic nature of heat transport in nanoparticles, and nanoparticle clustering are considered as the possible causations responsible for such kind of heat transfer enhancement, few research work from atomic-scale has been done to verify or explain those fascinating features of nanofluids. In this paper, a molecular dynamic model, which incorporates the atomic interactions for silica by BKS potential with a SPC/E model for water, has been established. To ensure the authenticity of our model, the position of each atom in the nanoparticle is derived by the crystallographic method. The interfacial interactions between the nanoparticle and water are simplified as the sum of interaction between many ions. Due to the electrostatic interaction, the ions on the nanoparticle’s surface can attract a certain number of water molecules, therefore, the effect of interaction between the nanoparticle and water on heat transfer enhancement in nanofluids is studied. By using Green-Kubo equations which set a bridge between thermal conductivity and time autocorrelation function of the heat current, a model which may derive thermal conductivity of dilute nanofluids that consist of silica nanoparticles and pure water is built. Several simulation results have been provided which can reveal the possible mechanism of heat enhancement in nanofluids.

A Review on the Thermal Conductivity and Viscosity Models of Nanofluids: Impact on Convection Coefficient Calculations

2014 ◽  
Author(s):  
I. P. Koronaki ◽  
M. T. Nitsas ◽  
V. Papaefthimiou
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Nusselt Number ◽  
Base Fluid ◽  
Research Work ◽  
Nanometer Scale ◽  
Convection Coefficient ◽  
Viscosity Models ◽  
Effective Dynamic ◽  
Liquid Suspensions

Recent advances in technology have given the opportunity of developing structures of nanometer scale suitably dispersed in base fluids. The term nanofluids, introduced by Stephen U.S Choi, describes the liquid suspensions which contain these structures (nanoparticles, nanotubes, nanodroplets etc). Even though the branch of nanotechnology, where nanofluids can be categorized, is in its infancy the growth of research work in terms of engineering applications that has been done already indicates the interest of researchers in nanofluids. As mentioned above a lot of research work, both experimental and computational, has been done in the field of nanofluids. As far as heat transfer is concerned, all researchers reach the same conclusion: heat transfer is enhanced while using nanofluids as means of cooling or heating due to the improved, among others, thermal conductivity of nanofluids compared to the conductivity of the base fluid which in most cases is water. The purpose of this review is to present the research that has been done on heat transfer calculations as well as the basic properties of the nanofluids. For this reason the structure of the review is divided into two topics. In the first topic models of calculating the effective thermal conductivity and the effective dynamic viscosity of nanofluids are presented. The aforementioned models have derived from both theoretical and experimental analysis. The second section concentrates on summarizing the correlations which calculate the Nusselt number and thus the convection coefficient.

Calculation Method on the Cooling Roller of Waterless Offset Press

2013 ◽  
Vol 312 ◽  
pp. 196-199
Author(s):  
Lin Jin ◽  
Yan Li ◽  
Xiao Zhang ◽  
Miao Liu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Contact Area ◽  
Calculation Method ◽  
The Other

In order to control the temperature of the ink, a cooling roller is used to cool down the temperature of the blanket cylinder. The calculation of the heat transfer on cooling roller is divided into two parts: One part is the exchange heat with the air through the cooling roller and the blanket cylinder, the other part is the heat conduction of the cooling roller and the blanket cylinder on the contact area. The heat conduction on the contact area is divided into the thermal conductivity generated by the friction and the heat conduction from blanket to the cooling roller.

scholarly journals Influence of the color of the refrigeration body on its thermal parameters

2018 ◽  
Vol 19 (12) ◽  
pp. 589-592
Author(s):  
Karolina Perz ◽  
Łukasz Mamoński ◽  
Aleksandra Rewolińska
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Expanded Polystyrene ◽  
The Body ◽  
Thermal Parameters ◽  
Body Colour ◽  
The Impact

The article discusses the issue of the impact of the color of refrigeration bodies on the thermal parameters of insulation. The tests of the density of heat flux flowing through metal claddings were carried out, and then their heat transfer coefficient was calculated on their basis. In the further part of the article, the influence of the body colour on the thermal conductivity of a three-layer wall consisting of an insulating core (expanded polystyrene) and two external claddings of different colour was analyzed. On the basis of the obtained results, it can be stated that the colour of the body affects the value of heat that passes through it.

scholarly journals The influence of climatic conditions on the thermal state of frame partitions insulated with loose fiber materials

2019 ◽  
Vol 282 ◽  
pp. 02038
Author(s):  
Piotr Kosiński ◽  
Aneta Skoratko
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Building Materials ◽  
Thermal State ◽  
Operating Temperature ◽  
Climatic Conditions ◽  
Laboratory Results ◽  
Simulation Results ◽  
Fiber Materials

The paper focus of the influence of the climatic conditions on thermal state and heat transfer of the frame partitions insulated with loose wood wool. While it is well known that building materials change thermal conductivity depending on the operating temperature, the always question is how much it influences on the whole element. The paper presents the laboratory results from the hot box chamber investigation of the frame partition. These results are compared with the simulation results.

Numerical Analysis on Hollow EPSRC Block and its Thermal Insulation Wall

2013 ◽  
Vol 724-725 ◽  
pp. 1526-1530 ◽  
Author(s):  
Xiao Sen Fan ◽  
Yan Li Chen ◽  
Xiao Ling Niu ◽  
Xian Cong Wang ◽  
Chao Feng Liang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Analysis ◽  
Thermal Insulation ◽  
Masonry Wall ◽  
Expanded Polystyrene ◽  
Recycled Concrete ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Insulation Wall

A new building material named expanded polystyrene recycled concrete (EPSRC) has been experimental studied not long ago by authors in this paper. Now, numerical analysis was further carried out on hollow EPSRC block and its thermal insulation wall based on thermodynamic principles. The results showed that the average thermal resistance of E45 and E60 EPSRC blocks are 0.616 and 0.823 (m2·K)/W, and the average heat transfer coefficient of E45 and E60 EPCRC masonry wall are 1.473 and 1.280 W/(m2·k). Therefore, the EPSRC blocks can be widely applied to the non load-bearing lightweight insulation masonry by suitable design.

Modeling of Heat Transfer in Low-Density EPS Foams

2005 ◽  
Vol 128 (6) ◽  
pp. 538-549 ◽  
Author(s):  
R. Coquard ◽  
D. Baillis
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Structural Characteristics ◽  
Expanded Polystyrene ◽  
Radiative Properties ◽  
Cell Diameter ◽  
Low Density ◽  
Equivalent Thermal Conductivity ◽  
Numerical Resolution ◽  
Steady State Heat Transfer

Expanded polystyrene (EPS) foams are one of the most widely used thermal insulators in the building industry. Owing to their very low density, both conductive and radiative heat transfers are significant. However, only few studies have already been conducted in the modeling of heat transfer in this kind of medium. This is due to their complex porous structure characterized by a double-scale porosity which has always been ignored by the previous works. In this study, we present a model of one-dimensional steady state heat transfer in these foams based on a numerical resolution of the radiation-conduction coupling. The modeling of the conductive and radiative properties of the foams takes into account their structural characteristics such as foam density or cell diameter and permits us to study the evolution of their equivalent thermal conductivity with these characteristics. The theoretical results have been compared to equivalent thermal conductivity measurements made on several EPS foams using a flux-meter apparatus and show a good agreement.

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