scholarly journals Effect of textile woven fabric parameters on its thermal properties

2019 ◽  
Vol 70 (01) ◽  
pp. 15-20 ◽  
Author(s):  
HALAOUA SABRI ◽  
ROMDHANI ZOUHAIER ◽  
JEMNI ABDELMAJID
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Conduction ◽  
Fiber Type ◽  
Thermal Characteristics ◽  
Woven Fabric ◽  
Surface Mass ◽  
Weave Structure ◽  
Fabric Construction ◽  
The Relationship

This paper aims to investigate the relationship between fabric construction properties and its thermal properties. For this aim three basic weave structures, three fiber compositions, five surface mass and four thicknesses were used. The thermal convection resistance RCV, thermal conduction resistance RCD, adiathermic power and thermal conductivity of all fabric samples were determined. In this research the plain weave structure showed the highest thermal properties while the twill and satin weave depicted the lowest thermal characteristics. The fiber type affects deeply different thermal properties. The increase of the surface mass and thickness was directly bound to the adiathermic power, thermal resistance and the thermal conductivity.

Shaped Seamless Woven Garments

2014 ◽  
Vol 18 (2) ◽  
pp. 96-107
Author(s):  
Abdel-Fattah M. Seyam ◽  
Sanaa S. Saleh ◽  
Mamdouh Y. Sharkas ◽  
Heba Z. AbouHashish
Keyword(s):  
Woven Fabrics ◽  
Woven Fabric ◽  
Weft Yarn ◽  
Additional Parameter ◽  
Yarn Tension ◽  
Differential Shrinkage ◽  
Fabric Construction ◽  
The Relationship

A range of intricate finished seamless shaped garments have been developed with the aim to fit predetermined sizes. The shape is created by using woven tubular fabrics with differential shrinkage in the same garment. The differential shrinkage is obtained by altering the fabric construction parameters at strategic locations along the length of the garment. The construction arameters include different weaves (plain, 2/2 basket, 1/3 twill, 2/2 twill, and crowfoot), weft densities, weft yarn counts, and weft yarns with different shrinkages (cotton, cotton that contains spandex, and cotton/polyester yarns). The weft yarn tension is used as an additional parameter to influence fabric shrinkage. A total of thirty-three woven fabrics are formed to establish the relationship between the construction parameters, weft tension, and shrinkage of the finished woven fabric. The relationship is used to produce a range of intricate garments with inherent shapes and predetermined sizes.

Temperature Gradient of Concrete Pavement Slab Overlaid with Asphalt Surface Course

2000 ◽  
Vol 1730 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Tatsuo Nishizawa ◽  
Shigeru Shimeno ◽  
Akinori Komatsubara ◽  
Masashi Koyanagawa
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Stress ◽  
Temperature Gradient ◽  
Numerical Simulations ◽  
Structural Design ◽  
Concrete Slab ◽  
Concrete Pavement ◽  
Reduction Effect ◽  
The Relationship

In the structural design of composite pavement with a concrete pavement slab overlaid with an asphalt surface course, it is very important to estimate the temperature gradient in the concrete slab. An asphalt surface course reduces the temperature gradient in an underlaid concrete slab, resulting in the reduction of thermal stress of the concrete slab. This effect was investigated by temperature measurement in model pavements and by thermal conductivity analysis. Thermal properties were estimated by a backanalysis by using measured temperatures over 1 year. From the numerical simulations varying the thickness of asphalt surface and concrete slab, the relationship between the reduction effect and the asphalt thickness was derived as a function of the thickness of asphalt surface course, which can be used in the structural design of the composite pavement.

Research on the Relationship between Thermal Conductivity and Porosity during Carbonation of Cement Materials

2014 ◽  
Vol 1065-1069 ◽  
pp. 1838-1841
Author(s):  
Son Tung Pham
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Cement Mortar ◽  
Total Porosity ◽  
Accelerated Carbonation ◽  
Experimental Campaign ◽  
Hydrostatic Weighing ◽  
Specific Material ◽  
The Relationship ◽  
Microstructural Studies

The objective of this work was to examine the relationships that may exist between porosity and thermal conductivity with particular reference to normalized cement mortar which is most commonly found in civil engineering. Samples were prepared and subjected to accelerated carbonation at 20°C, 65% relative humidity and 20% CO2 concentration. We investigated the evolution of the total porosity measured by hydrostatic weighing and of the thermal properties measured by Hotdisk method. This experimental campaign allowed relating the total porosity and the thermal conductivity before and during carbonation. These results can be used for further studies which can propose models predicting the thermal conductivity if changes in porosity are known. Moreover, the results indicated that the thermal conductivity of a cement material is directly related to the density and inversely related to porosity. Finally, this study showed that a characteristic coefficient can be deduced for two states of material: non-carbonated and carbonated. This coefficient is therefore proper to a specific material and can be used not only for modeling the relationship between porosity and thermal properties but also for other microstructural studies of cement materials.

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

The Effect of β-SiC Nanowires on the Properties of Al2O3 Composites

2016 ◽  
Vol 690 ◽  
pp. 240-245
Author(s):  
Wasana Khongwong ◽  
Chumphol Busabok
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Flexural Strength ◽  
Bending Test ◽  
Matrix Composites ◽  
Sic Nanowires ◽  
Four Point Bending ◽  
Four Point Bending Test ◽  
Cold Pressed ◽  
The Relationship

To investigate the effect of adding b-SiC nanowires on the properties of the Al2O3 matrix composites, four different amounts of SiC nanowires, 0.05, 0.1, 0.2 and 0.25 wt% were mixed with Al2O3 powder. All mixtures were ball-milled and dried in an oven at a temperature of 120°C. The Al2O3-SiC mixtures were uniaxially pressed into pellets under 5 MPa and were then isostatically cold-pressed (CIP) under a pressure of 200 MPa. Specimens (13 mm in diameter and 2.5 mm in thickness) were sintered in a tube furnace at the temperature of 1400°C for 1 h in Ar atmosphere. Physical and thermal properties of pellet composites were characterized. The bar shape specimens with dimension of 3 mm x 4 mm x 35 mm were prepared for four-point bending test. The relationship between thermal conductivity and flexural strength versus grain connection of composites have been investigated. The results showed that the composites with adding SiC nanowires at 0.05-0.2 wt% possessed lower thermal conductivity than those monolithic Al2O3 specimens. However, the thermal conductivity of the composite specimens with 0.25 wt% SiC nanowires became higher than those of monolithic Al2O3 specimens. The flexural strengths of the composites gradually decreased with the increasing amount of SiC nanowires.

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

Measurements of Thermal Properties of Gaskets for the Design of Bolted Flange Joints Under Thermal Conduction Conditions

2006 ◽  
Author(s):  
Takahiro Ohmura ◽  
Kanji Hanashima ◽  
Junichi Nyumura ◽  
Toshiyuki Sawa
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Effective Thermal Conductivity ◽  
Linear Thermal Expansion ◽  
Absolute Temperature ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Bolted Flange ◽  
The Relationship

In this study, the thermal properties of the gaskets, which were used for designing the bolted flange joints, such as effective thermal conductivity, specific heat, linear thermal expansion coefficient and so on were measured. Especially, the effective thermal conductivities were measured by using the heat flow method. The relationship between the gasket structure and the thickness was shown by using an equivalent thermal resistance, and an empirical equation of effective thermal conductivity, which was related to the bulk density and absolute temperature, was proposed by deriving the heat conduction in solid, radiation and gas. Also, in the measurement of the linear thermal expansion coefficients of the gaskets, the measured values were shown to change substantially below 150 °C, and to depend on the heating rate and the load applied on the gasket sample.

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.

scholarly journals The Thermal Parameters of Mortars Based on Different Cement Type and W/C Ratios

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4258
Author(s):  
Agata Stolarska ◽  
Jarosław Strzałkowski
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Point Of View ◽  
Thermal Parameters ◽  
Cement Type ◽  
Water Absorbability ◽  
The Relationship ◽  
Total Specific Surface Area

This study examines the thermal parameters of mortars based on different cement type and water-cement W/C ratios. The presented relationships are important from the point of view of thermal insulation of the entire building component, of which the mortar is a part. The thermal properties of the mortar, and in particular its dependence on the degree of moisture, is important information from the point of view of hygrothermal simulations of building components. The moisture effect on the thermal properties was tested using nine mortar types. The study consisted of producing nine types of mortar on the basis of three cements (CEM I 42.5R, CEM II A-S 52.5N, CEM III A 42.5N). For each cement type, three variants of specimens were prepared which differed according to their water/cement ratio (0.50, 0.55 and 0.60). The main research of thermal parameters was carried out using a non-stationary method based on the analysis of changing heat flux readings. The thermal conductivity, volume-specific heat and thermal diffusivity values were analyzed. The tests performed allowed for determination of the density of specimens, water absorbability and thermal parameters in three water saturation states: dry, natural and wet. Additional microstructural tests were performed using mercury intrusion porosimetry. The obtained parameters were used to determine the relationship between the measured properties. An adverse effect of dampness on the thermal insulation of the studied materials was confirmed. In extreme cases, the increase in thermal conductivity due to material high moisture was 93%. The cement used affects the relationship between the total specific surface area and the W/C ratio. As expected, the total porosity of specimens was higher for mortars with higher W/C ratios. A strong correlation has been demonstrated between the total surface area and thermal conductivity. The opposite results were obtained when assessing the relationship between the total specific surface area and water absorbability. In case of specimens CEM II A-S 52.5N, the relation was the proportional, and in specimens CEM III A 42.5N, the relationship was inversely proportional to the W/C ratio.

Sign in / Sign up

Export Citation Format

Share Document