...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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...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 move to the hand and cause burns. The second method of heat...
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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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...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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...ABSTRACT Thermodynamics is the science of heat and temperature and, in particular, of the laws governing the conversion of thermal energy into mechanical, electrical, or other forms of energy. It is a central branch of science that has important applications in chemistry, physics, biology, and engineering. What makes thermodynamics such a powerful tool? It is a completely logical discipline and can be applied without any sophisticated mathematical techniques. The immense practical value of thermodynamics lies in the fact that it systematizes the information obtained from experiments performed on systems and enables us to draw conclusions, without further experimentation, about other aspects of the same systems and about similar aspects of other systems. It allows us to predict whether a certain reaction will proceed and what the maximum yield might be. Thermodynamics is a macroscopic science concerning such properties as pressure, temperature, and volume. Unlike quantum mechanics, thermodynamics is not based on a specific molecular model, and therefore it is unelected by our changing concepts of atoms and molecules. Indeed, the major foundations of thermodynamics were laid long before detailed atomic theories became available. This fact is one of its major strengths. Furthermore, thermodynamics helps us predict the direction and extent of chemical reactions; it tells us nothing about the rate of a process. First Law of Thermodynamics Introduction The first law of conservation...
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...Heat Transfer Course Paper Name Institution Date Introduction To explore and work in space, the astronauts must carry their environment because there is no oxygen and atmospheric pressure to sustain life. The spacesuit is more than clothes an astronaut puts on in space. It’s really a small spacecraft. Its main work is to protect the astronaut when in space. Astronauts needs to put on spacesuits at any time they leave a spacecraft and are exposed to the surrounding space. In space, air to breath and air pressure is not available. Space has dangerous radiation and is extremely cold so without protection, an astronaut would rapidly die in space. The design of spacesuits is such that it protect astronauts from the radiation, cold and low pressure in space and furthermore provide air to breathe. Wearing a spacesuit permits an astronaut to be able survive and work in space. They also keep the astronaut from getting hurt by the space dust. The space dust always travel at a very high speed and may cause hurt to the astronaut. Moreover the suits holds drinking water for the astronaut. The spacesuit is made up of many parts that perform different roles. One of the parts protect the chest, another part covers the arms and connects to gloves and the helmet protects the head. The last part of this suit covers the astronaut’s feet and legs. Other parts of this suits are made up of many layers of material. The layers each performs different roles; some protect the astronaut from space...
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...HEAT TRANSFER IN VAROIUS MATERIALS. To find the best insulator of heat from various materials. Insulators are materials that impede the free flow of electrons from atom to atom and molecule to molecule, they generally restricts movement only around the atom they are attached to. They can move from one side of the atom to the other but are unable to leave the atom. Conductors are materials that permit electrons to flow freely from particle to particle. An object made of a conducting material will permit charge to be transferred across the entire surface of the object. AIM The aim of this experiment is to find out which material is best is used as an insulator when using copper as conductor and using either wool, paper box, plastic bubble wrap or steel glass wool as insulators. Hypothesis Copper is the best material to use as a conductor because it doesn't corrode and has a high melting point and also when you heat one end of a piece of copper, the other end will quickly reach the same temperature while wool is best material to use as an insulator because fibres in the wool trap pockets of air to create an insulating layer in between the fibres. The three main methods of heat transfer are conduction, convection and radiation. Conduction is the transfer of heat between substances that are in direct contact with each other. The better the conductor, the more rapidly heat will be transferred. Metal is a good conduction of heat. Convection occurs...
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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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...10, 2014 INTRODUCTION Heat conduction (or thermal conduction) is the transfer of internal energy by microscopic diffusion and collisions of particles or quasi-particles within a body due to a temperature gradient. The microscopically diffusing and colliding objects include molecules, electrons, atoms, and phonons. They transfer disorganized microscopic kinetic and potential energy, which are jointly known as internal energy. Conduction can only take place within an object or material, or between two objects that are in direct or indirect contact with each other. Conduction takes place in all forms of ponderable, such as solids, liquids, gases and plasmas. Whether by conduction or by thermal radiation, heat spontaneously flows from a hotter to a colder body. In the absence of external drivers, temperature differences decay over time, and the bodies approach thermal equilibrium. In conduction, the heat flow is within and through the body itself. In contrast, in heat transfer by thermal radiation, the transfer is often between bodies, which can be spatially separate. Also possible is transfer of heat by a combination of conduction and thermal radiation. In convection, internal energy is carried between bodies by a material carrier. In solids, conduction is mediated by the combination of vibrations and collisions of molecules, of propagation and collisions of phonons, and of diffusion and collisions of free electrons. In gases and liquids, conduction is due to the collisions...
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...behavior. Principal one is the fire triangle or Tetrahedron. The fire triangle consists of having heat, fuel, and oxygen. Removing one of these elements from the triangle and the fire will eventually die out. Principal two is method of heat transfer. Therefore, if heat is transfer from direct contact, liquid or air. A fire of some sort could arise. Methods such as convection, conduction, and radiation. Which is known to be the number one cause of any fire exposure. Principal three in stages and fire growth. This talks about the stages of a fires lowest point of ignition...
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...Revision Checklist AQA GCSE Core Science & Physics 1 TRANSFER(OF(ENERGY(IN(HEATING( ! State!what!infrared!radiation!is!and!that!objects!emit!and!absorb!it.!! Describe!how!the!amount!of!infrared!radiation!can!vary.! Describe!how!different!surfaces!vary!in!their!absorption!of!infrared!radiation.!! Describe!how!different!surfaces!vary!in!their!reflection!of!infrared!radiation.! Describe!the!particle!arrangement!and!different!levels!of!energy!in!the!states!of!matter.!! Explain!the!different!energy!states!using!the!kinetic!theory.!! Describe!the!bonds!between!particles!in!the!different!states!of!matter! Describe!what!is!meant!by!conduction,!in!terms!of!particles,!including!the!role!of!free!electrons.! Describe!what!is!meant!by!convection,!in!terms!of!particles,!including!explaining!changes!in!density.! Describe!how!energy!is!transferred!in!evaporation!and!condensation!and!factors!affecting!each.! Describe!the!factors!that!affect!the!rate!of!heat!transfer!from!an!object.! State!the!use!of!U@values.!! Describe!how!solar!panels!work.! Describe!what!is!meant!by!specific!heat!capacity!and!use!the!equation.! Describe!how!energy!is!wasted!and!what!happens!to!it.! Construct!and!Read!information!from!a!Sankey!diagram! Calculate!the!efficiency!of!a!device!using!the!equation.! Describe!payback!time!and!calculate!it.! Describe!energy!transfers!in!everyday!electrical!appliances.! Link!the!amount!of!energy!transferred!to!the!power!and!the!amount!of!time!switched!on.! Calculate!the!energy!transferred...
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...2. BASICS OF ENERGY AND ITS VARIOUS FORMS Syllabus Basics of Energy and its various forms: Electricity basics - DC & AC currents, Electricity tariff, Load management and Maximum demand control, Power factor. Thermal basics -Fuels, Thermal energy contents of fuel, Temperature & Pressure, Heat capacity, Sensible and Latent heat, Evaporation, Condensation, Steam, Moist air and Humidity & Heat transfer, Units and conversion. 2.1 Definition Energy is the ability to do work and work is the transfer of energy from one form to another. In practical terms, energy is what we use to manipulate the world around us, whether by exciting our muscles, by using electricity, or by using mechanical devices such as automobiles. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. 2.2 Various Forms of Energy There are two types of energy - stored (potential) energy and working (kinetic) energy. For example, the food we eat contains chemical energy, and our body stores this energy until we release it when we work or play. 2.2.1 Potential Energy Potential energy is stored energy and the energy of position (gravitational). It exists in various forms. Chemical Energy Chemical energy is the energy stored in the bonds of atoms and molecules. Biomass, petroleum, natural gas, propane and coal are examples of stored chemical energy. Nuclear Energy Nuclear energy is the energy stored in the nucleus of an atom - the energy that holds...
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...included. Signature: Date: August 18, 2014 Acknowledgments The author would like to acknowledge the use of the Queen’s University On-line Library for access to Research Journals. Abstract Global warming is one of the most potentially disastrous issues facing mankind in the early 21st century, considered to be caused by man-made greenhouse gas emissions. Approximately 30% of the man-made carbon dioxide (CO2) emissions causing global warming is created by the burning of fossil fuels to produce electricity or used as a direct energy source. The use of solar energy to pre-heat water for industrial, commercial and institutional and residential purposes can reduce electricity usage by up to 2% to 6% in southern Ontario. Adding the emissions from using natural gas directly to heat water a figure of 5% to 17% reduction in CO2 emissions can be derived by the use of solar energy to pre-heat water. This report details the equipment necessary for such a domestic solar hot water system (DSHW). The information has been used in a design matrix to create a viable system for southern Ontario from the many alternatives available. Table of Contents Declaration of Sole Authorship ii Acknowledgments iii Abstract...
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...ENGINEERING COLLEGE HEAT & MASS TRANSFER LAB MANUAL ENGINEERING SCIENCES DEPARTMENT HEAT & MASS TRANSFER LAB MANUAL ENGINEERING SCIENCES DEPARTMENT LAB INSTRUCTIONS 1. No late submissions 2. If you miss the submission time, you will be marked zero in that lab 3. If cheating or plagiarism is observed in the lab report, zero will be marked in that lab. 4. Detailed calculations should be shown. 5. Neat work will earn good marks. 6. Graphs should be made by hands. MS excel graphs will not be accepted. LAB MARKS DISTRIBUTION LAB REPORT/ ATTENDENCE | 50% | LAB PERFORMANCE | 10% | MID TERM ASSESMENT/QUIZES | 10% | FINAL LAB ASSESMENT | 30 % | TOTAL | 100% | TABLE OF CONTENTS S.NO | DATE | OBJECTIVE | PAGE NO | SIGNATURE | 1. | | To show that the intensity of radiation on a surface is inversely proportional to the square of the distance of the surface from the source of radiation | | | 2. | | To show the intensity of radiation various as fourth power of source. | | | 3. | | Determination of barrier temperature gradient between two different metals in end to end pressure contact. | | | 4. | | To perform energy balance on air flowing throw a duct heated by cylindrical rod | | | 5. | | To perform energy balance on air flowing throw a duct heated by cylindrical rod using DAQ | | | 6. | | Determination of a mean surface heat transfer coefficient for tubes in...
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...Turbulence 10 References 13 Abstract The fires problem is one of the hazard pose a threat to life and property. Flames behave differently under various conditions which include: the oxygen available, combustible material, orientation of surfaces, etc. this a complex phenomena which is influenced by multiple factors that includes ignition, heat release rate, flame spread and the generation of different products of combustion like carbon IV oxide and carbon II oxide. The research was performed by studying various sources in the library and in the internet and also performing experiments to simulate a real life situation. Introduction The Fire Problem The flammability of a material is a complex event which is influenced by multiple factors that includes ignition, heat release rate, flame spread and the generation of different products of combustion like carbon IV oxide and carbon II oxide. In order to better protect the people and property from risk posed by the unwanted fires, it become necessary to understands all these factors under different conditions. Babrauskas and Vytenis 1992 suggested that heat release rate is the main variable in fire hazard; but Kashiwagi and Ito argued effectively that, the flame spread over the surface of combustible material such a wall and a floor is the main variable responsible for the growth of fire at the initial stages of fire. In addition, the angle of orientation of the combustible material has been found to contribute...
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