Thermal Metrics for High Performance Enclosure Walls: the Limitations of R-Value
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Causal Heat Conduction Contravening the Fading Memory Paradigm
entropy Article Causal Heat Conduction Contravening the Fading Memory Paradigm Luis Herrera Instituto Universitario de Física Fundamental y Matematicas, Universidad de Salamanca, 37007 Salamanca, Spain; [email protected] Received: 1 September 2019; Accepted: 26 September 2019; Published: 28 September 2019 Abstract: We propose a causal heat conduction model based on a heat kernel violating the fading memory paradigm. The resulting transport equation produces an equation for the temperature. The model is applied to the discussion of two important issues such as the thermohaline convection and the nuclear burning (in)stability. In both cases, the behaviour of the system appears to be strongly dependent on the transport equation assumed, bringing out the effects of our specific kernel on the final description of these problems. A possible relativistic version of the obtained transport equation is presented. Keywords: causal dissipative theories; fading memory paradigm; relativistic dissipative theories 1. Introduction In the study of dissipative processes, the order of magnitude of relevant time scales of the system (in particular the thermal relaxation time) play a major role, due to the fact that the interplay between this latter time scale and the time scale of observation, critically affects the obtained pattern of evolution. This applies not only for dissipative processes out of the steady–state regime but also when the observation time is of the order of (or shorter than) the characteristic time of the system under consideration. Besides, as has been stressed before [1], for time scales larger than the relaxation time, transient phenomena affect the future of the system, even for time scales much larger than the relaxation time. -
FHF02SC Heat Flux Sensor User Manual
Hukseflux Thermal Sensors USER MANUAL FHF02SC Self-calibrating foil heat flux sensor with thermal spreaders and heater Copyright by Hukseflux | manual v1803 | www.hukseflux.com | [email protected] Warning statements Putting more than 24 Volt across the heater wiring can lead to permanent damage to the sensor. Do not use “open circuit detection” when measuring the sensor output. FHF02SC manual v1803 2/41 Contents Warning statements 2 Contents 3 List of symbols 4 Introduction 5 1 Ordering and checking at delivery 8 1.1 Ordering FHF02SC 8 1.2 Included items 8 1.3 Quick instrument check 9 2 Instrument principle and theory 10 2.1 Theory of operation 10 2.2 The self-test 12 2.3 Calibration 12 2.4 Application example: in situ stability check 14 2.5 Application example: non-invasive core temperature measurement 16 3 Specifications of FHF02SC 17 3.1 Specifications of FHF02SC 17 3.2 Dimensions of FHF02SC 20 4 Standards and recommended practices for use 21 4.1 Heat flux measurement in industry 21 5 Installation of FHF02SC 23 5.1 Site selection and installation 23 5.2 Electrical connection 25 5.3 Requirements for data acquisition / amplification 30 6 Maintenance and trouble shooting 31 6.1 Recommended maintenance and quality assurance 31 6.2 Trouble shooting 32 6.3 Calibration and checks in the field 33 7 Appendices 35 7.1 Appendix on wire extension 35 7.2 Appendix on standards for calibration 36 7.3 Appendix on calibration hierarchy 36 7.4 Appendix on correction for temperature dependence 37 7.5 Appendix on measurement range for different temperatures -
Convective Heat Flux Explained.Indd
Convective heat flux explained Theory Thermal convection is one of the three mechanisms of heat transfer, besides conduction and thermal radia- tion. The heat is transferred by a moving fluid (e.g. wind or water), and is usually the dominant form of heat transfer in liquids and gases. Convection can be divided into natural convection and forced convection. Generally, when a hot body is placed in a cold envi- rameters like velocity of the fluid, material proper- ronment, the heat will flow from the hot body to the ties etc. For example, if one blows air over the tea cup, cold surrounding until an equilibrium is reached. the speed of the fluid is increased and thus the heat Close to the surface of the hot body, the surrounding transfer coefficient becomes larger. This means, that air will expand due to the higher temperature. There- the water cools down faster. fore, the hot air is lighter than the cold air and moves upwards. These differences in density create a flow, Application which transports the heat away from the hot surface To demonstrate the phenomenon of convection, the to the cold environment. This process is called natu- heat flux of a tea cup with hot water was measured ral convection. with the gSKIN® heat flux sensor. In one case, air was When the movement of the fluid is enhanced, we talk blown towards the cup by a fan. The profile of the about forced convection: An example is the cooling of a hot body with a fan: The fluid velocity is increased and thus the device is cooled faster, because the heat transfer is higher. -
Heat Flux Measurement Practical Applications for Electronics
Heat Flux Measurement Practical Applications for Electronics Heat flux sensors are practical measurement tools which are component may be known, as well as the resistance of the useful for determining the amount of thermal energy passed board and solder connections; the resistance at the interface through a specific area per unit of time. Heat flux can be of the component and board to the ambient are not easily thought of as the density of transferred power, similar to known and are dependent on the flow characteristics. While current through a wire or water through a pipe. Measuring analytical or CFD methods can at best predict the heat heat flux can be useful, for example, in determining the transfer coefficient at a particular area, often for complex amount of heat passed through a wall or through a human systems with uneven or sparsely populated components body, or the amount of transferred solar or laser radiant these methods are not accurate and may not be useful. For energy to a given area. In a past article [1] we learned how those components which generate power, but may not need heat flux sensors operate and how they can be calibrated. But the use of a separate heatsink, the heat flux gage can be how can heat flux sensors be used for electronics design? experimentally used to determine the heat transfer coefficient This article highlights several practical uses of the heat flux on the component surface or the compact thermal response sensor in the design of electronics systems. See Figure 1 for on the board (e.g. -
Thermal Conductivity 1 Thermal Conductivity
Thermal conductivity 1 Thermal conductivity In physics, thermal conductivity, , is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat conduction. Thermal conductivity is measured in watts per kelvin-meter (W·K−1·m−1, i.e. W/(K·m) or in IP units (Btu·hr−1·ft−1·F−1, i.e. Btu/(hr·ft⋅F). Multiplied by a temperature difference (in kelvins, K) and an area (in square meters, m2), and divided by a thickness (in meters, m), the thermal conductivity predicts the rate of energy loss (in watts, W) through a piece of material. In the window building industry "thermal conductivity" is expressed as the U-Factor [1], which measures the rate of heat transfer and tells you how well the window insulates. U-factor values are generally recorded in IP units (Btu/(hr·ft⋅F)) and usually range from 0.15 to 1.25. The lower the U-factor, the better the window insulates. The reciprocal of thermal conductivity is thermal resistivity. Measurement There are a number of ways to measure thermal conductivity. Each of these is suitable for a limited range of materials, depending on the thermal properties and the medium temperature. There is a distinction between steady-state and transient techniques. In general, steady-state techniques are useful when the temperature of the material does not change with time. This makes the signal analysis straightforward (steady state implies constant signals). The disadvantage is that a well-engineered experimental setup is usually needed. The Divided Bar (various types) is the most common device used for consolidated rock samples. -
RULES CERTIFICATE Department of Commerce
Clearinghouse Rule 96-144 RULES CERTIFICATE Department of Commerce TO ALL TO WHOM THESE PRESENTS SHALL COME, GREETINGS : i, William McCoshen Secretary of the Department of Commerce, and custodian of the official records of said department, do hereby certify that the annexed rule(s) relating to Energy Conservation and Ventilation (Subject) were duly approved and adopted by this department . further certify that said copy has been compared by me with the original on file in the department and that the same is a true copy thereof, and of the whole of such original , SDI IN TESTIMONY WHEREOF, I have hereunto set my hand at D~,ci:it ~ sgs Csr~~l5 81k~~a.i in the city of Madison, this -J day of IL- A D.. 19 Secretary q - / " 97 ORDER OF ADOPTION Department of Commerce 101 .02 (1) and (15) Pursuant to authority vested in the Department of Commerce by section(s) Stats ., the Department of Commerce I x I creates; I x , amends; repeals and recreates ; a repeals and adopts rules of Wisconsin Administrative Code chapter(s) : ILHR 2 Fee Schedule ILHR 50 to 64 Building and Heating, Ventilating and Air Conditioning ILHR 66 Uniform Multifamily Dwellings ILHR 72 Intermittent Ignition Devices ILHR 82 Design, Construction, Installation, Supervision and Inspection of Plumbing (number) (Title) The attached rules shall take effect on April 1 , 1997 pursuant to section 227 ..22, Stats„ Adopted at Madison, Wisconsin this date„ "t / 6- I'i DEPARTMENT OF COMMERCE Secretary - ~ I . State of Wisconsin. \ Department of Commerce RULES in FINAL DRAFT FORM As Adopted with Germane Modificat ions December 5, 1996 C ~Zu~C-s 3 z i t z 0 I 23 ~ t& C.LA Rule No . -
Quantification of Fourth Generation Kapton Heat Flux Gauge Calibration Performance
Quantification of Fourth Generation Kapton Heat Flux Gauge Calibration Performance A THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Matthew Paul Hodak B.S. Graduate Program in Mechanical Engineering The Ohio State University 2010 Master’s Examination Committee: Dr. Charles W. Haldeman, Advisor Dr. Michael G. Dunn Copyright by Matthew Paul Hodak 2010 ABSTRACT Double sided Kapton heat flux gauges which are used routinely by the Ohio State University Gas Turbine Laboratory are driven by two main calibrations, the sensors temperature as a function of resistance and the material properties of Kapton. The material properties separate into those that govern the steady-state response of the gauge and those that influence the transient response. The steady-state response, as it forms the key to data processing, will be the topic of this investigation and is based on the thermal conductivity divided by the thickness (k/d). Calibration accuracies for the heat flux gauge sensors reached levels on the order of +-.05 °C and were well within the target accuracy of +- 0.1 °C over a 100 °C calibration range. Time degradation of the gauges did occur and for these cases and a single point calibration method is introduced that maintains the accuracy to ±0.4 °C instead of the ± 3 °C that would have resulted from the resistance shift due to erosion. This method will allow for longer use of the gauges in the turbines. Various calibration methods for k/d were investigated and performed. -
Heat Flux Sensors.Cdr
Heat Flux Sensor A heat flux sensor is a transducer that generates an electrical signal proporonal to the total heat rate applied to the surface of the sensor. The measured heat rate is divided by the surface area of the sensor to determine the heat flux. careful design, rugged quality construcon and versale mounng configuraons. Each transducer will provide a self- generated 10-millivolts (nominal) output at the design heat flux level. Heat Flux gauge absorb heat in a thin metallic circular foil and transfer the heat radially (parallel to the absorbing surface) to the heat sink welded around the periphery of the foil. The emf output is generated by a single differenal thermocouple between the foil center temperature and foil edge temperature. Technical Parameters Parameters Cooled Uncooled Heat Flux (maximum) 10, 30 W/cm² 10, 30 W/cm² Sensor Output Linear output, 10mv nominal at full range Linear output, 10mv nominal at full range Over Range 25% of Rated Heat Flux 25% of Rated Heat Flux Accuracy ±5% or Better ±5% or Better Repeatability 1% 1% Measurement Duration 60s for 10 W/cm² 60s for 10 W/cm² Sensor Differential Thermocouple Differential Thermocouple Dimension Diameter 25mm, Length 25mm Diameter 25mm, Length 25mm Mounting Flange Flange Standard Features Ÿ Linear Output Ÿ Output Proporonal to Heat Transfer Rate Ÿ Accurate, Rugged, Reliable Ÿ Convenient Mounng Ÿ Measure Total Heat Flux Ÿ Measure Radiant Heat Flux www.tempsens.com Heat Flux Sensor Standard configuraon of cooled/uncooled models Ÿ The sensor is provided with or without provision for water cooling of transducer body. -
Examination of Heat Flux Through a Surface Using Digital Image Processing of Infrared Images
University of Tennessee at Chattanooga UTC Scholar Student Research, Creative Works, and Honors Theses Publications 5-2015 Examination of heat flux through a surface using digital image processing of infrared images Nicholas D. true University of Tennessee at Chattanooga, [email protected] Follow this and additional works at: https://scholar.utc.edu/honors-theses Part of the Mechanical Engineering Commons Recommended Citation true, Nicholas D., "Examination of heat flux through a surface using digital image processing of infrared images" (2015). Honors Theses. This Theses is brought to you for free and open access by the Student Research, Creative Works, and Publications at UTC Scholar. It has been accepted for inclusion in Honors Theses by an authorized administrator of UTC Scholar. For more information, please contact [email protected]. Examination of Heat Flux Through a Surface Using Digital Image Processing of Infrared Images Nicholas True Departmental Thesis The University of Tennessee at Chattanooga Mechanical Engineering Project Director: Dr. Charles Margraves, Ph. D. Examination Date: March 4, 2015 Committee Members: Dr. Gary McDonald, Ph. D. Dr. Trevor Elliott, Ph. D. Dr. Linda Frost, Ph. D. Signatures: __________________________________________________________________ Project Director __________________________________________________________________________________ Department Examiner __________________________________________________________________________________ Department Examiner ___________________________________________________________________________________ -
Fundamentals of Heat Transfer in Thermal Interface Gap Filler Materials
Fundamentals of Heat Transfer in Thermal Interface Gap Filler Materials Introduction This paper focuses on the primary function of a thermal gap filler – its ability to transfer heat from one surface to another. The selection process for a gap filler can sometimes be confusing because most thermal considerations are left to the end of the design cycle when the selection process must be performed under a tight schedule. This paper will describe steps to making the selection process simpler. Figure 2. In a basic thermal solution in electronic assembly, the most common thermal resistances are the case of the component, the thermal gap filler (TIM), and the heat sink. Terms and Units Prior to beginning a discussion on heat transfer in as thermal resistance, whether in °C2/Watt or °C/Watt. thermal interface gap filler materials, a number of terms These are just temperature gradients per power; the and units require definition. The most common term is absolute temperature is more a function of the ambient. thermal resistance. This is the reciprocal of conductivity Watts/mK do not include contact resistance when that includes contact resistance. It is not just thermal discussing TIMs. Just like ASTM 5470, for example, the resistance of the bulk material, but also contact resistance delta of the thermal resistance and the change in thickness between the hot and cold sides. are used to calculate conductivity. Thermal resistance or Thermal gap fillers are a particular type of thermal thermal impedance is shown in values of °C2/Watt or as interface material (TIM) used to fill in gaps between cold °C/Watt if the geometry is called out explicitly. -
The Effects of Temperature on Insulation Performance: Considerations for Optimizing Wall and Roof Designs
The Effects of Temperature on Insulation Performance: Considerations for Optimizing Wall and Roof Designs Chris Schumacher and John Straube, PEng Building Science Consulting, Inc. 167 Lexington Court, Unit 6, Waterloo, Ontario N2J 4R9 Phone: 519-342-4731 • Fax: 519-885-9449 • E-mail: [email protected] Lorne Ricketts, EIT, and Graham Finch, PEng RDH Building Engineering, Ltd. 224 W. 8th Avenue, Vancouver, British Columbia V5Y 1N5 Phone: 604-873-1181 • Fax: 604-873-0933 • E-mail: [email protected] 3 1 ST R C I I NTE R NAT I ONAL C ONVENT I ON AND T R ADE S HOW • M A rc H 10-15, 2016 S C HU M A C HE R ET AL . • 1 6 5 Abstract Recent research into the real-world performance of insulation materials in roofs and walls has shown that the industry’s reliance on R-value at a standard temperature does not always tell the whole story. This paper will present measurements from several field- monitoring studies across North America that demonstrate how insulated roofs and walls exhibit thermal performance that is different than assumed by designers. Specifically, results show that insulation properties vary with temperature (i.e., performance changes at high or low temperatures). This is important because of peak energy demand, annual heat- ing and cooling costs, occupant comfort, and durability considerations. Speakers Chris Schumacher — Building Science Consulting, Inc. CHRISTOPHER SCHUMACHER is a principal with Building Science Consulting, Inc. (BSCI), a consulting firm specializing in design facilitation, building enclosure commis- sioning, forensic investigation, and training and communications. Its research division, Building Science Laboratories (BSL), provides a range of research and development services. -
Thermal Properties of Rocks
UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY THERMAL PROPERTIES OF ROCKS by Eugene C. Robertson 1 Open-File Report 88-441 This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. 1 Reston, Virginia 1988 CONTENTS Page Abstract- 1 Introduction 1 Units------------------- 3 Symbols 4 Thermal conductivity 5 Introduction 5 Solidity 5 Thermal impedance 5 Calculation of composite models - 6 Porefluid - - 8 Quartz, olivine, pyroxene, amphibole, and clay content 8 Rock conductivity at 300 K 10 Introduction 10 Mafic igneous rocks, air in pores 11 Mafic igneous rocks, water in pores 13 Felsic igneous rocks, air or water in pores 14 Limestone, air or water in pores - 16 Dolostone, air or water in pores - 18 Sandstone, air in pores 20 Sandstone, water in pores - 22 Shale, water in pores 24 Shale, air in pores 26 Soils, air in pores - - ~ 28 Anhydrite, gypsum, air in pores 30 Selected rocks 31 Conductivity anisotropy of metamorphic rocks 32 Rock conductivity change with temperature 34 Introduction 34 Basalt and other mafic rocks - 34 Felsic igneous rocks 35 Carbonate rocks 36 Quartz-bearing rocks - 37 Ultramafic rocks - 39 Rock glasses - 40 Mineral conductivity change with temperature 41 Introduction - - 41 Quartz - - - 41 Feldspar - - 42 Plagioclase 43 Mafic silicate minerals 44 Olivine - 46 Calcite and aragonite 47 Halite 48 Mineral conduction mechanisms 49 Phonon and imperfection conductivity 49 Radiative conductivity 49 Analysis of mechanisms - - - . - 50 Miscellaneous thermalconductivities 58 Pressure effect on thermal conductivity 59 Thermal conductivity under vacuum - 62 Thermal expansion and density of minerals - - 65 11 Specific heat of rock 71 Introduction 71 Calculation of specificheat-- -- - - - - - 85 Diffusivity and thermal inertia 88 Calculation ofparameters 88 Heat transfer coefficients 91 Radioactive heat generation in rocks - 96 Appendix I.