Tag Archives: thermal conductivity

923–934 G. Bambi, P.F.P Ferraz, G.A.S. Ferraz, P. Pellegrini and H. Di Giovannantonio
Measure of thermal transmittance of two different infill wall built with bamboo cultivated in Tuscany
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Measure of thermal transmittance of two different infill wall built with bamboo cultivated in Tuscany

G. Bambi¹, P.F.P Ferraz², G.A.S. Ferraz², P. Pellegrini¹ and H. Di Giovannantonio¹

¹University of Florence, Department of Agriculture, Food, Environment and Forestry, Via San Bonaventura 13, IT50145 Firenze, Italy
²University Federal of Lavras, Department of Engineering, Federal University of Lavras, BR37200-000 Lavras -Minas Gerais, Brasil
*Correspondence: gianluca.bambi@unifi.it

Abstract:

Bamboo is used in different scenarios of application, its physical and mechanical characteristics guarantee a high flexibility of use especially in the buildings constructions. The experience gained in civil constructions demonstrates that bamboo can be considered a sustainable material able to replace wood in many constructive elements with structural functions. The applications of bamboo aimed at carrying out structural functions are thoroughly studied. For this reason the present research focuses on the thermal insulation performance. To ensure an approach focused on the sustainability of potential exploitation, the research examined only local material coming from three bamboo fields located in the Tuscany region (Italy). The material harvested and suitably treated was utilized for the realization of two different kind of wall, undergone later to experimental tests in compliance with the ISO 9869 standard for the calculation of the transmittance values. The measure of transmittance enabled to know the characteristics of thermal conduction of bamboo walls. The first wall was made of cut throw longitudinal axis bamboo culms; the second one was made of cut throw longitudinal axis bamboo culms coated in internal face with a sustainable mortar. The test was carried out using insulating thermal box with internal temperature under control.
The calculation of the transmittance in place was compared with the images captured by thermal camera. Thermal imagine allowed to highlight the behaviour of the material subjected to a thermal stress induced by the experimental test.

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1191–1198 T. Schnabel, H. Huber, A. Petutschnigg and A. Jäger
Analysis of plant materials pre-treated by steam explosion technology for their usability as insulating materials
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Analysis of plant materials pre-treated by steam explosion technology for their usability as insulating materials

T. Schnabel¹*, H. Huber¹, A. Petutschnigg¹² and A. Jäger³

¹Salzburg University of Applied Sciences. Department of Forest Products Technology & Timber Constructions. Marktstraße 136a, AT5431 Kuchl, Austria
²BOKU University of Natural Resources and Life Sciences, Konrad Lorenz-Straße 24, AT3430 Tulln, Austria
³University of Applied Sciences Upper Austria, Faculty of Engineering, Department of Bio & Environmental Technology, Stelzhamerstr. 23, AT4600 Wels, Austria
*Correspondence: thomas.schnabel@fh-salzburg.ac.at

Abstract:

Raw materials of annual plants fibres are not easily usable for industrial production applications. Pre-treatment of the annual plant fibres is necessary to increase the homogeneity of the material and to improve the material properties. This study deals with the influence of steam explosion treatment on the quality of annual plant fibres used as insulating material.
Maize and wheat straw were selected for production of insulating panels. To clarify the changes within the structure of the plants due to the pre-treatment process material analysis was carried out using FT-IR spectroscopy and raster electron microscope. Furthermore, the bulk density and the thermal conductivity were analysed as important values for insulating materials.
The results showed that the pre-treatment process homogenizes the materials and the processes could be used for the production of bulk insulation.

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1077-1084 P. Kic and P. Neuberger
Thermal properties of historic rural building materials in Czechia
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Thermal properties of historic rural building materials in Czechia

P. Kic¹* and P. Neuberger²

¹Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
²Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: kic@tf.czu.cz

Abstract:

Due to the different natural conditions, various local natural building materials were used for the construction of rural residential and farm buildings in various locations in the Czech Republic. Currently, it is often a requirement for the modernization of relatively old buildings. The buildings were built with different technologies. Very often only locally available material was used. In many cases, the properties of old materials are not available in the literature. However, it is necessary to know the thermal properties of building materials for the preparation of a reconstruction design. Thermal properties of materials are the basis for determination of heat losses of buildings useful for design of heating systems. The aim of this paper is to compare the research results focused on the thermal conductivity of different old construction materials (stones and rocks) and to show examples of preserved historical agricultural buildings. The results presented in this paper are based on the measurements by the portable instrument Isomet 2104. Authors recognised significant differences between tested materials. The mean values of thermal conductivity λm of tested materials: gaize 1.49 W m-1 K-1, artificial marble 1.80 W m-1 K-1, gneiss 2.36 W m-1 K-1, proterozoic shale 2.68 W m-1 K-1, granite 3.66 W m-1 K-1 and quartz sandstone 6.15 W m-1 K-1. Differences between thermal conductivity values of stones and rocks should be respected in calculation of heat balance of new or reconstructed buildings to avoid the problems of the formation of thermal bridges.

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1033–1040 A. Kešner,, R. Chotěborský and M. Linda
Determining the specific heat capacity and thermal conductivity for adjusting boundary conditions of FEM model
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Determining the specific heat capacity and thermal conductivity for adjusting boundary conditions of FEM model

A. Kešner¹,*, R. Chotěborský¹ and M. Linda²

¹ Department of Material Science and Manufacturing Technology Faculty of
Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ165 21 Prague – Suchdol, Czech Republic
² Department of Electrical Engineering and Automation, Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, CZ165 21 Prague – Suchdol, Czech Republic
*Correspondence: kesner@tf.czu.cz

Abstract:

One of modern way of the heat treatment process of agricultural tools such as chisels or tines is FEM modelling. FEM models needs the accurate boundary conditions for successful solution. Specific heat capacity and thermal conductivity are important parameters for the design of the physical properties of heat treatment. These parameters are used for the formation of the temperature field during the cooling process at the heat treatment. More accurate parameters allow you to better estimate the final microstructure in the entire cross-section of the material. Specific heat capacity and thermal conductivity are known from material sheets, but they are stated as constant values. This is the reason why this work is focused on the determination of specific heat capacity and thermal conductivity of steel during the quenching. For the experiment in this work was chosen material 25CrMo4. The values of specific heat capacity and thermal conductivity were determined by comparing the experimentally measured cooling curves and cooling curves generated by the mathematical model. The dependences of specific heat capacity and thermal conductivity were compared in temperature, so that the relationships of cooling curves were statistically significant under alfa level 0.05.

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