...needed to be optimized in building envelop. Extended Research Task Temperature Control in Homes ---- Windows Extended Research Task Temperature Control in Homes ---- Windows Temperature Control in Homes --- Windows 1. Abstract: The window insulation always plays an important role in building design and thermal comfort, it is one of the main parts needed to be optimized in building envelop. Window insulation is a basic element which can decide the insulation capacity. The large heat loss from the window is the main part of wasting energy, and simultaneously, there is also difficult to explore the new energy source and to improve the current heat generation device efficiency. Therefore, building a proper insulated window system is a good approach to keep an acceptable indoor climate as well as to reduce energy use and negative climate effects. The aim of this extended research task is to introduce readers to different ways of windows insulation that can efficiently reduce heat loss in an average household during Tasmanian winter. 2. Introduction Tasmania has cold temperature climate with four distinct seasons, with the most distinctive season during the winter month between June and July. During the winter season Tasmania become the wettest and coolest state in Australia with most high lying areas receiving considerable snowfall. Winter maximums are 12 °C (54 °F) on average along coastal areas and 3 °C (37 °F) on the Central Plateau, thanks to a series of...
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...The most important concept to understand within the fire phenomena is heat transfer. Heat transfer is everywhere within the aspects of fire, such as fire development. Before the three types of heat transfer can be explained, a few more things need to be understood. Such as heat is the transfer of energy based on a temperature difference between two objects. Also that temperature is a measure of kinetic energy of the molecules in an object. Now the three types of heat transfer and first up is Conduction which is the transfer of energy in the form of heat by direct contact through excitement of molecules with driven by a temperature difference. Energy travels from a high to a low and the same thing happens with heat. When the high temperature molecules collide with the low temperature molecules, a transfer of energy occurs from the hot, more energetic molecules to the colder, less energetic molecules and this is recognized as conduction. Conduction is most prevalent in solids but it can also be found in liquids and gases. The rate at which heat is transmitted through a material by conduction depends on thermal conductivity which is a characteristic of a material and its mass. The easiest way to think of conduction is to hold a metal rod by one end and put the other over a fire. Eventually the hot energetic molecules from the fire will transfer to the cold, less energetic molecules of the metal rod and slowly creep up the rod to the cold end where it is being held and then...
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...HEAT TRANSFER Essay 1 Heat is one of many forms of energy that can be transformed into each other in accordance with the First Law of Thermodynamics. However, it is important to note that the energy contained within any substance cannot be regarded as heat. In fact, heat only exists when it is transferred between two media and then only due to a temperature difference between those media. There are many misuses of the word “heat”. It is not uncommon to describe the temperature in an oven as being 350 degrees of heat. Also, the energy contained in a medium is sometimes said to be the heat contained within that medium. These uses, as well as other misuses, are excluded by the definition: heat is energy in transit due to a temperature difference. Heat transfer is one of the most ubiquitous processes in nature. It is also commonly encountered in virtually all devices, machines, instruments, and living creatures. With such a broad range of application, heat transfer becomes a key part of the engineering knowledge base. Like most undergraduate subjects, the subject matter taught in heat transfer courses represents the academic view of the topic. That view is highly sanitized and drastically simplified compared with reality. The homework problems in the typical undergraduate course are also contrived to be solvable by use of the knowledge base that is conveyed in standard textbooks and in the classroom. Expertise in solving such problems is misleading because those problems...
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...HEAT TRANSFER Modes of Transferring Heat Heat is always transferred when a temperature difference exists between two bodies. There are three basic modes of heat transfer: Conduction involves the transfer of heat by the interactions of atoms or molecules of a material through which the heat is being transferred. Convection involves the transfer of heat by the mixing and motion of macroscopic portions of a fluid. Radiation or radiant heat transfer, involves the transfer of heat by electromagnetic radiation that arises due to the temperature of a body. CONDUCTION Conductive Heat transfer takes place as conduction if there is a temperature gradient in a solid or fluid Conduction will take place if there exist a temperature gradient in a solid (or stationary fluid) medium. Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occurs in direction of the decreasing temperature since higher temperatures are associated with higher molecular energy. Fourier's Law expressed conductive heat transfer as: q = k A dT / s Where q = heat transfer (W, J/s, Btu/s)A = heat transfer area (m2 , ft2)k =thermal conductivity of the material(W/m.K or W/m℃, Btu/(hroF ft2/ft))dT = temperature difference across the material (K oroC,oF)s = materialism thickness (m, ft) Example of Heat Transfer by Conduction is A plane wall constructed of solid iron with thermal conductivity 70 W/m℃, thickness 50 mm...
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...Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy and heat between physical systems. As such, heat transfer is involved in almost every sector of the economy.[1] Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species, either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system. Heat conduction, also called diffusion, is the direct microscopic exchange of kinetic energy of particles through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described by the second law of thermodynamics. Heat convection occurs when bulk flow of a fluid (gas or liquid) carries heat along with the flow of matter in the fluid. The flow of fluid may be forced by external processes, or sometimes (in gravitational fields) by buoyancy forces caused when thermal energy expands the fluid (for example in a fire plume), thus influencing its own transfer...
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...Chapter 1 INTRODUCTION The project ‘Heat Transfer Studies on a 7.5 Watt LED Lighting Load using Finite Element Analysis’ is mainly concerned with the heat generated by an LED lighting load and its dissipation to the surrounding such that the LED junction temperature is maintained low. The LED chosen for this project is 7.5 Watt, which has a maximum operating temperature of around 80°C, exceeding which the LED will fail. The LED is best operated at room temperature conditions and may be just above. The project implements a specific method of cooling or rather maintaining the LED junction temperature as low as possible by using a Thermo Electric Cooling device, more specifically known as the Peltier device. The project looks into the various methods by which a Peltier cooler can be implemented such as, with or without a fan or simply a fan would provide sufficient cooling for the LED module. A Heat sink is a necessary component which is always associated with cooling electronic components. Before getting into the depth of the project detailing we will look into the basic components that have been used in the project setup which include: a. LED Module b. Peltier Cooler c. Heat Sink d. Cooling Fan 1.1 Light Emitting Diode: Light-emitting diodes (LEDs) are small but powerful devices in terms of their diverse applications. LED lights assume greater significance in the context of need for electrical energy conservation and pollution control world over. LED is basically...
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...Heat Transfer: Conduction, Convection, & Radiation 1 Heat Transfer Basics Tami L. Donnell Humanities 300, History and Methods of Science Professor Datte February 7, 2007 Heat Transfer: Conduction, Convection, & Radiation 2 Heat Transfer Basics What is Heat Transfer? Heat Transfer is the movement of energy due to a temperature difference. In my paper I will discuss Heat Transfer Basics and will address three physical mechanisms of the movement of heat. The three modes are conduction, convection, and radiation. I will offer examples of the three in hopes that you will gain a better understanding of what each one means. By the end of my essay paper you will have gain the knowledge, skills and abilities to define and understand how heat transfer occurs in our daily living. I will begin by given some small information about heat. Heat as some of you may know flows from an area of higher temperature to a region of lower temperature. Heat can also be made to flow from a cooler area to a hotter area in order to do this function; heat is controlled via a system such as a heat pump. Heat is basically made up of molecules as most anything. Molecules are constantly moving so the hotter something maybe the faster the molecules are moving. Eventually, they move at the same speed which means that any object that is hot will become cold. As mentioned previously heat moves from one object to another in three ways: conduction, convection...
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...This page intentionally left blank SEVENTH EDITION Fundamentals of Heat and Mass Transfer THEODORE L. BERGMAN Department of Mechanical Engineering University of Connecticut ADRIENNE S. LAVINE Mechanical and Aerospace Engineering Department University of California, Los Angeles FRANK P. INCROPERA College of Engineering University of Notre Dame DAVID P. DEWITT School of Mechanical Engineering Purdue University JOHN WILEY & SONS VICE PRESIDENT & PUBLISHER EXECUTIVE EDITOR EDITORIAL ASSISTANT MARKETING MANAGER PRODUCTION MANAGER PRODUCTION EDITOR DESIGNER EXECUTIVE MEDIA EDITOR PRODUCTION MANAGEMENT SERVICES Don Fowley Linda Ratts Renata Marchione Christopher Ruel Dorothy Sinclair Sandra Dumas Wendy Lai Thomas Kulesa MPS Ltd. This book was typeset in 10.5/12 Times Roman by MPS Limited, a Macmillan Company and printed and bound by R. R. Donnelley (Jefferson City). The cover was printed by R. R. Donnelley (Jefferson City). Founded in 1807, John Wiley & Sons, Inc. has been a valued source of knowledge and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Our company is built on a foundation of principles that include responsibility to the communities we serve and where we live and work. In 2008, we launched a Corporate Citizenship Initiative, a global effort to address the environmental, social, economic, and ethical challenges we face in our business. Among the issues we are addressing...
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...Heat Transfer Conduction When we place one end of an iron rod in a fire, the other end also heats up after a while. We say heat has been conducted along the rod from the hot end. Conduction is the process by which heat is transmitted through a medium from one particle to another. The heat is transmitted from the hot to the cold end. Most metals are good thermal conductors. A metal surface feels colder than a cement surface although they are both at the same temperature. This is because e metal conducts heat away form the hand more quickly than cement which is a poor conductor. Generally, substances which are liquids at ordinary temperatures are poor conductors. One exception is mercury which is a good conductor. Mercury is a metal in the liquid state at room temperature and pressure. The thermal conductivity of gases is even lower than that of liquids. How conduction works Conduction takes place when heat energy is transferred from one particle to the next. When one end of a rod is heated, the particles at this end of the rod gain energy and vibrate more vigorously. These particles collide with their less energetic neighbours. Some of their energy is transferred to these neighbouring particles which in turn gain kinetic energy. In this way, heat energy is passed along the rod by the vibrating particles. Conduction of heat in metals is far better than in other solids. The ‘free’ electrons in a metal are responsible for its superior thermal conductivity....
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...thermal contact. Figure. Layers in a composite furnace wall. The temperature T0 on the inside of the refractory is 1370oC, while the temperature T3 on the outside of the steel plate is 37.8oC. The heat loss through the furnace wall is expected to be 15800 W/m2. Determine the thickness of refractory and insulation that results in the minimum total thickness of the wall. Given thermal conductivities in W/(m K): Layer k at 37.8oC k at 1093oC Refractory 3.12 6.23 Insulation 1.56 3.12 ________________________________________ Solution. Click here for stepwise solution Click here for stepwise solution Step. Thermal resistance representation for composite furnace wall Step. Thermal resistance representation for composite furnace wall In general, the heat flow is given by Q = T/Rth and the thermal resistance for a rectangular slab is Rth = x/(kA), where T is the temperature driving force (thermal potential difference), x is the slab thickness, k is the thermal conductivity, and A is the cross-sectional area of the slab. The thermal resistances for the three layers are in series as shown in the figure below. Figure. Thermal resistance representation of composite furnace wall. Based on the thermal resistance representation for the composite furnace wall, the heat flux q is (1) In the refractory and insulation, the thermal conductivity k varies with temperature. If a linear variation is assumed, then the arithmetic mean is to be used for the thermal...
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...BENSON KILONZO MBITHI MECHANISMS OF HEAT TRANSFER IN ROCKS THERMAL CONDUCTIVITY OF ROCKS Thermal conductivity of a rock (������) is defined as the heat flow across a surface per unit area per unit time when a particular temperature difference exists in a unit length perpendicular to the surface. It depends on following factors:- Chemical composition of the rocks (rocks are aggregates of minerals) 1. Water content of the rock 2. Temperature 3. Pressure 4. Radioactive decay (if any) etc. Thermal conductivity has units of W/(m℃) Heat is transported through a saturated porous medium in a combined mechanism: by conduction through its solid matrix and liquid in its pores as well as by convection of the moving liquid. By applying the law of conservation of energy to a control volume, an equation for heat transfer in the saturated porous medium can be expressed as: ρc∂t∂τ+ ρwcwV·∇t =∇ · (k∇t) (2) where k denotes the effective thermal conductivity of the porous medium; ρc is the volumetric specific heat of the porous medium, including both the solid matrix and water in its pores, ρwcw the volumetric specific heat of water. Note in the equation that heat is stored and conducted through both the water and soil matrix, but only water takes part in convection of heat here. The average linear groundwater velocity V over a cross-section of the medium may be determined by the hydraulic head distribution according to the Darcy’s law if the hydraulic...
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...Methods of heat transfer Steve Strittmatter Conduction, Convection, and Radiation: Methods of heat transfer. Abstract There are three different types of heat transfer we often discuss in physics. This paper uses example of each type of heat transfer; conduction, convection, and radiation. When breaking down conduction we understand it is the physical transfer of heat. Two objects are touching and the heat from one object transfers to the other object to warm it. In convection we understand it is the flow of matter that moves the heat. Matter is warmed, moves away from the heat source and then other matter that has not been warmed moves closer to the heat source to be warmed. This creates a current allowing the flow of hot matter away and cool matter toward the heat source. Radiation is the other type of heat transfer we discuss; this type of heat transfer takes no matter at all and uses electromagnetic waves to transfer energy (heat) from one object to another. Conduction, convection and radiation are all methods in which heat is transferred from one object to another or from a heat source to an object. In each of these methods heat moves from the higher temperature to the lower temperature until a thermal equilibrium is established. It is the differences of each type of heat transfer that will be discussed in this paper. Before I explain each type of heat transfer I will discuss heat transfer in general. Heat is a form...
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...Horizontal Shell and Tube Heat Exchanger Table of Contents: Nomenclature. Pg. 3 Introduction and Background Pg. 4 Experimental Methodology Equipment and Apparatus Pg. 6 Experimental Procedures Pg. 7 Results Pg. 8 Analysis and Discussion……………………………………………………………………..Pg. 11 Summary and Conclusions Pg. 12 References Pg. 13 Appendices Pg. 14 Nomenclature Symbol | Term | Units | A | Heat transfer surface area for the tubes | Inches2 (in2) | Cp | Heat Capacity | J/(mol*K) | F | Correction Factor | __ | | Heat | W | c | Cold Side Heat Duty | W | H | Hot Side Heat Duty | W | Shell Side | Hot Side | __ | T | Temperature | Celsius | ∆T | Change in Temperature | Celsius | Tube Side | Cold Side | __ | ∆Tlm | Log mean temperature difference | Kelvin (K) | U | Heat Transfer Coefficient | W/(K*in2) | V | Volume | L | ṁH | Hot water flow rate | L/min | ṁC | Cold water flow rate | L/min | 1.0 Introduction and Background A heat exchanger is a device designed to efficiently transfer thermal energy from one fluid to another fluid, which can be a liquid or a gas [1]. These fluids do not mix or come into direct contact with each other. Even though all heat exchangers do the same job of passing heat from fluid to fluid, there are various types that work in many different ways. The two most common types of heat exchangers are the shell-and-tube...
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...The Teachers of Promise study (2005-2011) is a longitudinal study of 57 promising new primary and secondary teachers from their third to seventh years of teaching. The research aimed to uncover the factors that sustained and developed the commitment of a group of highly “promising” teachers over time — from their initial teacher education programmes, throughout their induction period and the following six years of teaching. Teachers shared their perspectives on the factors that helped them make a good start (or otherwise) in their careers and assisted them to build their teaching expertise and that of their colleagues. We chose to focus on this period because: •provisionally registered teachers have been, and are currently the focus of other studies •this is the period when teachers typically make critical decisions about their careers such as whether to stay in teaching, to advance up the career ladder, or to continue with professional learning; and •research demonstrates that teachers play a critical role in students' enjoyment and engagement in school, and their success as learners, so it matters how well teachers are prepared, mentored and supported as early career teachers. Participants were interviewed in 2005, 2006 and 2011, and surveys were undertaken in the same years. The surveys from 2006 onwards included versions for those who had left teaching or who were teaching overseas. We asked them to reflect on: • the reasons they decided to become teachers • their...
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...CHAPTER – 1 Introduction:- Heat exchangers are very helpful in chemical process, engineering application and also in daily use applications, such as, dairy industry, chemical industry, environment engineering, power production, air conditioning and also in food industry. Shell & Tube heat exchanger is commonly used in energy industries and petrochemical industry. Plate Heat Exchanger is commonly used in a wide range of chemical process and so many industrial functions. So many effort have been made to increase the heat transfer of heat exchanger, reduce the heat transfer time and also increase the energy utilization. The mixture of fluid (base liquid) and Nanoparticles (nanometer sized) are called 'nanofluid'. Latest technology gives benefit...
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