DOCSLIB.ORG

Measurement Method of Thermal Diffusivity of the Building Wall for Summer and Winter Seasons in Poland

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Measurement Method of Thermal Diffusivity of the Building Wall for Summer and Winter Seasons in Poland energies Article Measurement Method of Thermal Diffusivity of the Building Wall for Summer and Winter Seasons in Poland Mariusz Owczarek 1,† , Stefan Owczarek 1,†, Adam Baryłka 2,† and Andrzej Grzebielec 3,*,† 1 Faculty of Civil Engineering and Geodesy, Military University of Technology, 00-908 Warsaw, Poland; [email protected] (M.O.); [email protected] (S.O.) 2 Building Research Center, 01-434 Warsaw, Poland; [email protected] 3 Institute of Heat Engineering, Faculty of Power and Aeronautical Engineering, Warsaw University of Technology, 00-665 Warsaw, Poland * Correspondence: [email protected]; Tel.: +48-602-277-873 † These authors contributed equally to this work. Abstract: The thermal diffusivity of building materials is an extremely important parameter influenc- ing the subsequent thermal comfort of building users. By definition, thermal diffusivity describes how quickly heat from a hot source can flow through a material. Therefore, this parameter includes both the thermal conductivity and the heat capacity of the material. This parameter is often neglected in heat-related calculations which, in the case of dynamic problems, leads to unreliable results. It should be taken into account that heat flows through all materials at a finite speed. On the other hand, knowing the correct thermal diffusivity value of building materials, it is possible to accurately determine the internal parameters in rooms over time. There are several methods for determining thermal diffusivity, most of which are destined to determine this property in laboratories. The aim of the present research is to show how the thermal diffusivity of materials can be determined in existing buildings. The presented method can be used to determine more real thermal parameters used for Citation: Owczarek, M.; Owczarek, thermal calculations in buildings, for example, during energy audits or when calculating the demand S.; Baryłka, A.; Grzebielec A. for cooling for air conditioning or heat for space heating. This research presents the results for a Measurement Method of Thermal Diffusivity of the Building Wall for 60 cm brick wall. Thermal diffusivity was determined for specific summer and winter days—most Summer and Winter Seasons in representative of the whole year. This research has shown that the applied method should be used in Poland. Energies 2021, 14, 3836. the summer period, due to the fact that the wall has greater temperature fluctuations. The obtained https://doi.org/10.3390/en14133836 results are comparable with the previously mentioned laboratory methods. However, due to the fact that the materials analyzed on the spot, the results are more reliable, and also take into account Academic Editor: Luisa F. Cabeza changes in the value of thermal diffusivity resulting from the use of binders, inaccuracies in joining and external layers made of other materials. Received: 20 May 2021 Accepted: 22 June 2021 Keywords: thermal diffusivity measurements; temperature distribution in building element; two Published: 25 June 2021 dimensional approximation; Ångström method Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- 1. Introduction iations. Building materials comprise a large group of substances. Among them are thermal insulations with a thermal conductivity of l = 0.02 W/(m·W), materials that conduct heat well, such as metals with a conductivity coefficient of several hundred W/(m·K) and intermediate materials. The cp—specific heat value also covers a wide range from 200 to Copyright: © 2021 by the authors. 1000 J/(kg·K). Licensee MDPI, Basel, Switzerland. In turn, the coefficient of thermal diffusivity is a parameter that determines the speed of This article is an open access article distributed under the terms and heat propagation in the body in the way of conduction [1,2]. It depends on the conductivity conditions of the Creative Commons but also on the heat capacity of the material. Thermal conductivity characterizes the flow of Attribution (CC BY) license (https:// conducted heat, and capacity characterizes the amount of energy that must be supplied by creativecommons.org/licenses/by/ or received from a given part of the sample to change its temperature by a certain amount. 4.0/). Energies 2021, 14, 3836. https://doi.org/10.3390/en14133836 https://www.mdpi.com/journal/energies Energies 2021, 14, 3836 2 of 11 Thus, diffusivity is an essential parameter in the analysis of non-stationary heat conduction. Thermal diffusivity is defined as [3] l a = , (1) r · cp where: a is thermal diffusivity (m2/s), l is thermal conductivity (W/m·K), r is density 3 (kg/m ) and cp is specific heat (J/(kg·K)). Usually, materials with high thermal conduc- tivity also have a high density, which limits the variability of thermal diffusivity. Com- paring the most insulating materials with the best heat-conducting materials, a thermal diffusivity value of a = 1.54 × 10−7 m2/s can be obtained for aerogel insulation [4], and a = 1.00 × 10−4 m2/s for steel [5]. However, the lowest diffusivity value should not be pre-assigned to the best insulation and the highest should not be pre-assigned to the best heat conductor. This article deals with the measurements of the thermal diffusivity of a wall made of mineral materials such as bricks and concrete. Based on the results of the works [6–8], the thermal diffusivity of concrete covers the range 5.090 × 10−8–1.283 × 10−5 m2/s. Concrete is a material with a large variety of components and as such it has wide range of possible values of this parameter [9,10]. The thermal diffusivity of a brick wall, obtained from [11–13] is in the range of 0.35 × 10−6–3.34 × 10−6 m2/s. Knowledge of thermal diffusivity values can also be used to evaluate other physical properties. By measuring the thermal diffusivity, it is possible to determine the hardness of steel [5] or the physical properties of new nanomaterials [14]. For building materials, thermal diffusivity often depends on moisture saturation [15,16]. For concrete, the ability to absorb water depends not only on the composition but also on the proportion of ingredients [17]. For bricks, the change of moisture saturation causes a 200% change in the value of the thermal conductivity coefficient and a 70% change in thermal effusivity [18]. Most of the methods for determining the thermal diffusivity coefficient consist of mea- suring the temperature of the tested sample during variable heat flow. The phenomenon of changing the heat flux is forced artificially in the laboratory or is the result of natural processes. Many methods compare the change in the measured temperature on the surface of the sample material with the change in temperature obtained as a result of calculations for known boundary conditions. A review of the methods based on the periodic boundary condition is presented in publication [19]. The Ångstrom method [20–22] is the most popu- lar in this case. For this application, the measurement of two parameters characterizing non-stationary heat transfer is required; phase shift and amplitude decay with distance from the periodic boundary condition [23,24]. By analyzing the response of the sample to periodic extortion, it is even possible to determine the thermal properties of a multi-layer material [25–28]. The method based on the stepwise variability of the boundary condition was discussed in publications [11,29]. The next group of methods for determining thermal diffusivity is the use of variable natural conditions. In these studies, it was decided to use this method. This solution allows the obtaining of the thermal diffusivity in the place where the sample is located and where the heat flow directly influences the conformation of a building’s users. In the experiment, the outside wall’s temperature is influenced by solar radiation, air tempera- ture, air humidity, wind speed and the occurrence of rainfall. In this study, the method for determining thermal diffusivity based on the approximation of the temperature measured in the wall has been presented. It was assumed that the approximating function satisfies the Fourier equation and the thermal diffusivity was determined by solving the inverse problem. Calculations were made for the selected summer and winter day. This parameter was then determined using the Ångström method. This method is based on measurements of amplitude and temperature phase difference. The advantages of this method are its simplicity of use, and its well-established correct operation, confirmed by many works. Based on the measurements made, this method could be directly applied. The Ångström Energies 2021, 14, 3836 3 of 11 method uses the entire month of August for summer and January for winter as the measur- ing time. The results of both methods were convergent. Finally, a summary is provided and conclusions are drawn. 2. Method Description The method described in [30] was used to measure the thermal diffusivity for a selected wall over a period of six months. Figure1 shows the procedure for the used method. Figure 1. Method procedure. The measuring apparatus described in detail in [30,31] was used. Temperature sensors were placed in the wall of the existing building. The wall was 0.6 m thick and made of bricks. The distance of the wall temperature sensors from the side walls, ceiling and floor was so large that the heat flow was assumed to be one dimensional. The outer surface of the tested wall was exposed to natural weather conditions. In the experimental study, Pt1000 temperature sensors were used. The stand is shown in Figure2. external side examined wall 0.6 PC T1, x=0.35T1, T2, x=0.30T2, T3, x=0.25 T3, T4, x=0.20 T4, T5, x=0.15 T5, internal side data logger Figure 2.
Load more

Recommended publications
  • Thermal Conductivity of Selected Materials, Part 2
    . A11105 14bD4fl & TECH R,c NSfflDS-NBS 1 THT f /NSRDS-NBS * 46040 16 ' :2:196e G' 1 NBS~ piir-^ 19 . : . NBS PUBLICATIONS UNITED STATES DEPARTMENT OF COMMERCE Alexander B. Trowbridge, Secretary NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director Thermal Conductivity of Selected Materials Part 2 C. Y. Ho,* R. W. Powell,*fC and P. E. Liley' *This report was prepared under contract at the Thermophysical Properties Research Center Purdue University, 2595 Yeager Road West Lafayette, Indiana 47906 NSRDS-NBS 16 National Standard Reference Data Series- National Bureau of Standards—16 (Category 5—Thermodynamic and Transport Properties) Issued February 1968 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $2 National Bureau of Standards SEP 4 151382 QC IOO ,U573 ® n • ! (p doty X Foreword The National Standard Reference Data System is a government-wide effort to give to the technical community of the United States optimum access to the quantitative data of physical science, critically evaluated and compiled for convenience. This program was established in 1963 by the President’s Office of Science and Technology, acting upon the recommendation of the Federal Council for Science and Technology. The National Bureau of Standards has been assigned responsibility for administering the effort. The general objective of the System is to coordinate and integrate existing data evaluation and compilation activities into a systematic, comprehensive program, supplementing and expanding technical coverage when necessary, establishing and maintaining standards for the output of the participating groups, and providing mechanisms for the dissemination of the output as required.
    [Show full text]
  • 3.37 (Class 4) Question: Thermal Diffusivity? • Thermal Diffusivity
    3.37 (Class 4) Question: thermal diffusivity? • Thermal Diffusivity (alpha) = Thermal Conductivity (k) / (density * heat capacity) • Combined, or derived parameter • From Fourier’s 1st law and 2nd law (diffusion equation) • deltaH = Cp*deltaT Question: Cold welding of semiconductors, is it gold-to-gold? Typically yes, gold pad Discussion about World Trade Center and Pentagon: • Why collapse? Structural members, lose part of the group, place more stress on the others, heat from the fire softens the steel, unzipping, once they let go then they bring down the other floors by impact loading from floors above • Why no tipping? Not really any force that would create tipping. Building has a large inertia. • Defense against terrorist attacks like this? o Dealing with people who are willing to die for what they believe o Have to be willing to pay the same price, have just as strongly held beliefs as this person. o Goes back many years: Why British not able to defeat the colonials? Same about Vietnam. Afghanistan like Vietnam to Soviets. Fighting for homeland. • People have a harder time dealing with man-made disasters than natural disasters. Review: • Contamination, rough surfaces and interfacial voids limit the strength of many joints • Liquids are often used to overcome surface roughness (adhesive bonding, soldering, brazing, fusion welding) • Interfacial shear is required for mechanically produced joints • Langmuir is 10^-8 atm*sec • pressure*time product for one monolayer of atoms to strike the surface • (also need to account for sticking factor, probability that stays when hits, for oxygen and metal this will be quite high, say 0.8) Contact are under normal loading never exceeds 1/3 apparent area Story: In 1980 working with test lab (guy inherited business from father, had a correspondence degree).
    [Show full text]
  • Effect of Testing Conditions on the Diffusivity Measurements of Nuclear Fuels Via the Flash Method C
    Effect of testing conditions on the diffusivity measurements of nuclear fuels via the flash method C. Duguay, M. Soulon, L. Sibaud To cite this version: C. Duguay, M. Soulon, L. Sibaud. Effect of testing conditions on the diffusivity measurements of nuclear fuels via the flash method. ECerS2017 - 15th Conference and Exhibition of the European Ceramic society, Jul 2017, Budapest, Hungary. ECerS2017 - 15th Conference and Exhibition of the European Ceramic society, 2017. hal-02417740 HAL Id: hal-02417740 https://hal.archives-ouvertes.fr/hal-02417740 Submitted on 18 Dec 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Christelle DUGUAY, Mathias SOULON and Laurène SIBAUD Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA), DEN/DEC Centre de Cadarache , 13108 Saint-Paul-Lez-Durance Cedex, France, E-mail : [email protected] Context and objectives Thermal conductivity of the nuclear fuel : λλλ ρρρ A key parameter to understand the performance of the fuel under irradiation (T) = a(T).C p(T). (T) Highly dependent on microstructure,
    [Show full text]
  • Thermal Diffusivity and Volumetric Specific Heat Measurements Using Heat Flow Meter Instruments for Thermal Conductivity 29 / Thermal Expansion 17 Conference *
    Title: Thermal Diffusivity and Volumetric Specific Heat Measurements Using Heat Flow Meter Instruments for Thermal Conductivity 29 / Thermal Expansion 17 Conference * Authors: Akhan Tleoubaev Andrzej Brzezinski * not published in the Proceedings because of late submission ABSTRACT Heat Flow Meter Method (ASTM C518, ISO 8301, EN 1946-3, etc.) instruments are the most widely used steady-state type of devices for thermal conductivity measurements. In computerized systems the heat flow meters’ (transducers’) signals can be recorded versus time. The recorded signals can give additional information about other important thermal properties of the samples – volumetric specific heat and thermal diffusivity. Volumetric specific heat can be calculated simply from amount of the heat flow per square area absorbed by sample after switching instrument’s plates’ temperature set points from one (after reaching thermal equilibrium condition) to another (until reaching new thermal equilibrium condition) . For thermal diffusivity calculations two unsteady state thermal problems solutions should be used: 1) with boundary conditions of 1st kind (so-called ideal thermal contact, i.e. when thermal contact resistance is negligible) - for samples of low thermal conductivity, and 2) with boundary conditions of 3rd kind (in presence of thermal contact resistance) - for samples of moderate thermal conductivity. After reaching so-called “regular regime” thermal diffusivity of the specimen can be calculated using slopes of the graphs of logarithms of the heat-flow meters’ signals versus time (slopes of their linear part) during the process of the system’s exponential relaxation toward the final thermal equilibrium. Experimental checks using several materials - Expanded Polystyrene, 1450b and 1450c NIST Standard Reference Materials, Pyrex 7740, Vespel SP1, Perspex, Pyroceram 9606 were done.
    [Show full text]
  • Elastic and Thermal Properties of Free-Standing Molybdenum Disulfide Membranes Measured Using Ultrafast Transient Grating Spectr
    Elastic and thermal properties of free-standing molybdenum disulfide membranes measured using ultrafast transient grating spectroscopy Taeyong Kim, , Ding Ding, , Jong-Hyuk Yim, , Young-Dahl Jho, and , and Austin J. Minnich Citation: APL Materials 5, 086105 (2017); doi: 10.1063/1.4999225 View online: http://dx.doi.org/10.1063/1.4999225 View Table of Contents: http://aip.scitation.org/toc/apm/5/8 Published by the American Institute of Physics APL MATERIALS 5, 086105 (2017) Elastic and thermal properties of free-standing molybdenum disulfide membranes measured using ultrafast transient grating spectroscopy Taeyong Kim,1,a Ding Ding,2,a Jong-Hyuk Yim,3 Young-Dahl Jho,3,b and Austin J. Minnich1,c 1Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA 2Singapore Institute of Manufacturing Technology, 2 Fusionopolis Way, Singapore 138634, Singapore 3School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju 61005, South Korea (Received 25 April 2017; accepted 2 August 2017; published online 21 August 2017) Molybdenum disulfide (MoS2), a member of transition-metal dichalcogenide family, is of intense interest due to its unique electronic and thermoelectric properties. How- ever, reports of its in-plane thermal conductivity vary due to the difficulty of in-plane thermal conductivity measurements on thin films, and an experimental measurement of the in-plane sound velocity has not been reported. Here, we use time-resolved transient grating spectroscopy to simultaneously measure the in-plane elastic and thermal prop- erties of free-standing MoS2 membranes at room temperature. We obtain a longitudinal acoustic phonon velocity of 7000 ± 40 m s 1 and an in-plane thermal conductivity of 74 ± 21 W m 1K 1.
    [Show full text]
  • Investigation of the Optical, Thermal, and Mechanical Properties of a Bulk Polymer Using the Surface Thermal Lensing Technique Bushra Hussain
    Eastern Michigan University DigitalCommons@EMU Master's Theses, and Doctoral Dissertations, and Master's Theses and Doctoral Dissertations Graduate Capstone Projects 2005 Investigation of the optical, thermal, and mechanical properties of a bulk polymer using the surface thermal lensing technique Bushra Hussain Follow this and additional works at: http://commons.emich.edu/theses Part of the Physics Commons Recommended Citation Hussain, Bushra, "Investigation of the optical, thermal, and mechanical properties of a bulk polymer using the surface thermal lensing technique" (2005). Master's Theses and Doctoral Dissertations. 114. http://commons.emich.edu/theses/114 This Open Access Thesis is brought to you for free and open access by the Master's Theses, and Doctoral Dissertations, and Graduate Capstone Projects at DigitalCommons@EMU. It has been accepted for inclusion in Master's Theses and Doctoral Dissertations by an authorized administrator of DigitalCommons@EMU. For more information, please contact [email protected]. INVESTIGATION OF THE OPTICAL, THERMAL, AND MECHANICAL PROPERTIES OF A BULK POLYMER USING THE SURFACE THERMAL LENSING TECHNIQUE By Bushra Hussain Thesis Submitted to the Department of Physics and Astronomy Eastern Michigan University In partial fulfillment of the requirements For the degree of MASTER OF SCIENCE in Physics August 23, 2005 Ypsilanti, Michigan DEDICATION To my Brother, Syed Intesar Hussain ii ACKNOWLEDGEMENTS I feel great pleasure to express my sincere gratitude to my thesis advisor Professor Marshall Thomsen for initiating this research topic and for his constructive criticism, encouragement, guidance, support, and patience throughout the length of this investigation. I would also like to thank Professor Donald Snyder of the Chemistry Department, who collaborated with Professor Marshall Thomsen, for his support and guidance whenever I needed it.
    [Show full text]
  • Analytical Modeling of Temperature Distribution, Peak
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Available online at www.sciencedirect.com ScienceDirect Procedia Materials Science 6 ( 2014 ) 821 – 834 3rd International Conference on Materials Processing and Characterisation (ICMPC 2014) Analytical Modeling of Temperature Distribution, Peak Temperature, Cooling Rate and Thermal Cycles in a Solid Work Piece Welded By Laser Welding Process K.Suresh Kumara,b* a Research Scholar,University of Madras, Chennai,Tamil Nadu,600005,India bP.T.LeeChengalvaraya Naicker College of Engineering and Technology,Kanchipuram,Tamil Nadu,631502,India Abstract Generalized theoretical prediction of temperature distribution, peak temperature, cooling rate and thermal cycles in a solid work piece welded by laser welding process, where no melting is occurs, i.e., from the boundary of fusion zone to the end of heat affected zone. With the moving point or line heat source may be considered for the analysis that indicates the temperature gradient ahead of the heat source is much higher than that behind, increasing welding velocity elongates the isotherms surrounding the heat source, higher thermal conductivity of materials make the isotherm more circular, reducing the temperature gradient in front of the heat source. The peak temperature experienced throughout the workpiece, determine the size of the heat affected zone (HAZ). The peak temperature at a given point is experienced by the point shortly after it is passed by the heat source. The size of the HAZ increases with the net energy input. The cooling rates experienced by a material, determines the grain structure and phases that are formed.
    [Show full text]
  • A Method for Indirect Measurements of Thermal Properties of Foods
    SIK-rapport 2002, No. 703 A Method for Indirect Measurements of Thermal Properties of Foods Eva Olsson, Hans Janestad, Lilia Ahrné SIK-rapport 2002, No. 703 A Method for Indirect Measurements of Thermal Properties of Foods Eva Olsson, Hans Janestad, Lilia Ahrné Göteborg, 2002 ISBN 91-7290-223-X ABSTRACT A method has been developed for the simultaneous estimation of thermal diffusivity, thermal conductivity, volumetric heat capacity and the heat transfer coefficient for foods heated/cooled by convection. The method uses experimental time-temperature data of the food and the medium, which are used in a parameter estimation procedure based on the conduction heat transfer equation in one dimension for an infinite cylinder. To increase the accuracy in the results the estimations are performed in a number of sub-steps under varied model conditions, for example is an inner fictive cylinder used. The suggested method estimated the thermal diffusivity, the heat conduction and the volumetric heat capacity with a maximal relative error in the interval 6-9%. This study shows the well known difficulty of separating the thermal conductivity and the volumetric heat capacity in the expression for the thermal diffusivity, caused among other things by the uncertainty in the estimation of the heat transfer coefficient. TABLE OF CONTENTS INTRODUCTION.............................................................................................................................. 2 MATERIALS AND METHODS..........................................................................................................
    [Show full text]
  • Measurements of Thermophysical Property of Thin Films by Light Pulse Heating Thermoreflectance Methods T
    MEASUREMENTS OF THERMOPHYSICAL PROPERTY OF THIN FILMS BY LIGHT PULSE HEATING THERMOREFLECTANCE METHODS T. Baba, K. Ishikawa, T. Yagi, N. Taketoshi To cite this version: T. Baba, K. Ishikawa, T. Yagi, N. Taketoshi. MEASUREMENTS OF THERMOPHYSICAL PROP- ERTY OF THIN FILMS BY LIGHT PULSE HEATING THERMOREFLECTANCE METHODS. THERMINIC 2006, Sep 2006, Nice, France. pp.151-156. hal-00171371 HAL Id: hal-00171371 https://hal.archives-ouvertes.fr/hal-00171371 Submitted on 12 Sep 2007 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Nice, Côte d’Azur, France, 27-29 September 2006 MEASUREMENTS OF THERMOPHYSICAL PROPERTY OF THIN FILMS BY LIGHT PULSE HEATING THERMOREFLECTANCE METHODS Tetsuya Baba, Kazuko Ishikawa, Takashi Yagi, Naoyuki Taketoshi National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology AIST Tsukuba Central 3, Umezono 1-1-1, Tsukuba, Ibaraki, 305-8563, Japan Kimiaki Tamano, Tetsuro Ohtsuka, Hiroshi Watanabe, Yuzo Shigesato Department of Chemistry School of Science & Engineering Aoyama Gakuin University, Fuchinobe, Sagamihara, Kanagawa, 229-8558 Japan ABSTRACT [4]. Thermal diffusivity of submicrometer thin films per- pendicular to the surface was calculated from the cooling Thermoreflectance methods by picosecond light pulse rate of the surface temperature and the penetration depth heating and by nanosecond light pulse heating have been of the heating light.
    [Show full text]
  • Measurement of Thermal Conductivity Anddiffusivity in Situ
    FI9900089 POSIVA 99-01 Measurement of thermal conductivity and diffusivity in situ: Literature survey and theoretical modelling of measurements Mmo Kukkonen Ilkka Suppala Geological Survey of Finland 30-17 January 1999 POSIVA OY Mikonkatu 15 A. FIN-OO1OO HELSINKI. FINLAND Phone (09) 2280 30 (nat). ( + 358-9-) 2280 30 (int.) Fax (09) 2280 3719 (nat.). ( + 358-9-) 2280 3719 (int.) ISBN 951-652-056-1 ISSN 1239-3096 The conclusions and viewpoints presented in the report are those of author(s) and do not necessarily coincide with those of Posiva. ti - POSiva Report Raportintunnus- Report code POSIVA 99-01 Mikonkatu 15 A, FIN-00100 HELSINKI, FINLAND Julkaisuaika - Date Puh. (09) 2280 30 - Int. Tel. +358 9 2280 30 January 1999 Tekija(t) - Author(s) Toimeksiantaja(t) - Commissioned by Ilmo Kukkonen Ilkka Suppala Posiva Oy Geological Survey of Finland Nimeke - Title MEASUREMENT OF THERMAL CONDUCTIVITY AND DIFFUSIVITY IN SITU: LITERATURE SURVEY AND THEORETICAL MODELLING OF MEASUREMENTS Tiivistelma - Abstract In situ measurements of thermal conductivity and diffusivity of bedrock were investigated with the aid of a literature survey and theoretical simulations of a measurement system. According to the surveyed literature, in situ methods can be divided into 'active' drill hole methods, and 'passive' indirect methods utilizing other drill hole measurements together with cutting samples and petrophysical relationships. The most common active drill hole method is a cylindrical heat producing probe whose temperature is registered as a function of time. The temperature response can be calculated and interpreted with the aid of analytical solutions of the cylindrical heat conduction equation, particularly the solution for an infinite perfectly conducting cylindrical probe in a homogeneous medium, and the solution for a line source of heat in a medium.
    [Show full text]
  • Polymer Processing Modeling and Simulation
    Tim Osswald Juan P. Hernández-Ortiz Polymer Processing Modeling and Simulation Sample Chapter 2: Processing Properties ISBNs 978-1-56990-398-8 HANSER 1-56990-398-0 Hanser Publishers, Munich • Hanser Publications, Cincinnati CHAPTER 2 PROCESSING PROPERTIES Didyou ever considerviscoelasticity? —Arthur Lodge 2.1THERMAL PROPERTIES The heat flowthrough amaterial can be definedbyFourier’s lawofheat conduction. Fourier’s lawcan be expressedas ∂T q = − k (2.1) x x ∂x where q x is theenergy transport perunitarea in the x direction, k x thethermal conductivity and ∂T/∂x thetemperaturegradient. At theonset of heating, thepolymerresponds solely as aheat sink, and theamount of energy per unit volume, Q ,stored in thematerialbefore reaching steady state conditions can be approximated by Q = ρCp ∆ T (2.2) where ρ is thedensity of thematerial, C p the specific heat, and ∆ T thechange in temperature. Thematerial properties found in eqns.(2.1) and(2.2) areoften written as onesingleproperty, 38 PROCESSING PROPERTIES Table2.1: ThermalPropertiesfor Selected Polymeric Materials Polymer Specific Specific Thermal Coeff. Thermal Max gravity heat conduc. therm. diffusivity temp. expan. kJ/kg/KW/m/K µ m/m/K(m 2 /s)10− 7 o C ABS1.04 1.47 0.3901.7 70 CA 1.28 1.50 0.15 100 1.04 60 EP 1.9 -0.23 70 -130 PA66 1.14 1.67 0.24 90 1.01 90 PA66-30% glass1.38 1.26 0.52 30 1.33 100 PC 1.15 1.26 0.2 65 1.47 125 PE-HD0.95 2.3 0.63 120 1.57 55 PE-LD 0.92 2.3 .33200 1.17 50 PET 1.37 1.05 0.24 90 -110 PF 1.4 1.3 0.35 22 1.92 185 PMMA 1.18 1.47 0.2 70 1.09 50 POM 1.42 1.47 0.2800.7 85
    [Show full text]
  • Characteristic Temperature Curves for Aluminum Alloys During Friction Stir Welding
    Hamilton et al Supp Sept 2010layout:Layout 1 8/12/10 10:49 AM Page 189 Characteristic Temperature Curves for Aluminum Alloys during Friction Stir Welding An empirically derived relationship between temperature and weld energy is used to predict maximum friction stir welding temperatures in aluminum alloys BY C. HAMILTON, S. DYMEK, AND A. SOMMERS Ulysse (Ref. 7) studied the impact of vary- ABSTRACT ing weld parameters on the temperature distribution in 7050-T7451 plate. Also, Review of published friction stir welding (FSW) data across numerous aluminum Khandkar et al. (Refs. 8, 9) introduced a alloys demonstrates that a characteristic relationship between the temperature ratio heat input model based on the torque of (the maximum welding temperature divided by the solidus temperature of the alloy) the FSW tool and successfully applied the and the energy per unit length of weld exists. When the temperature ratio is plotted as model to friction stir welded aluminum a function of the energy per unit length of weld, a linear relationship whose slope is de- 6061-T651 plate. pendent on the thermal diffusivity of the alloy is revealed. Utilizing these characteris- A commonality to each of these ap- tic curves, the maximum welding temperatures were estimated for Sc-modified Al-Zn- proaches, however, is the need to develop Mg-Cu alloy extrusions joined through FSW at 225, 250, 300, and 400 rev/min (all other a computer simulation to satisfactorily weld parameters held constant). The characteristic curves successfully predict the max- solve the heat transfer equation for the imum weld temperatures at the lower energy weld conditions, i.e., 225 and 250 rev/min, alloy and welding conditions of interest, but for the high-energy welds, 300 and 400 rev/min, the curves overpredict the maxi- and to calculate the thermal profile and mum weld temperatures.
    [Show full text]