Introduction
Conduction, convection, and radiation are all types of heat transfer in which heat is transferred from a system to its surroundings. As humans, we are in the presence of, and manipulate these heat transfers all the time. Heat transfer is very important to our every day lives as we try to live in a world where the temperature outside is not comfortable and we want our food cooked. Some people go out of their way to get more radiation to get a tan, or use convection while siting in a sauna. In this paper, I will discuss the physics behind these three heat transfer methods, their equations, and some everyday examples.
Conduction
Conduction is an energy transfer process that is associated with temperature difference. As an object
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There are two types of convection, natural and forced. In natural convection, the temperature difference results in a difference in density. The difference in density is what drives convection and convection transfers energy by actually moving the substance. When a heat source heats a gas or a liquid, it causes it to become less dense and the kinetic motion of the particles is greater. This less dense area will rise, cool off, and then sink back down to become heated again. Convection is a cycle; this cycle can be very small to very large. Forced convection does not occur naturally but happens when the substance is forced to move by a fan or pump (Serway and Vuille, …show more content…
The Earth is not near enough for heat to be gained through conduction or convection as well as there is no medium for heat to travel through either, but Earth still receives heat from the Sun. This is because of the massive amount of heat radiating out from the Sun. The Earth absorbs this radiation and re-radiates some back out. One way to manipulate the heat you feel from the Sun on your body is to wear either dark or light clothing. On a summer day, you would want to wear lighter colors as they reflect more radiation, while on a winter day, a black color will help you absorb the heat to make you feel warmer. Another example of radiation is sitting by a fire. Earlier we talked about convection, but that was only when the hand was over the fire. When you are sitting close to the fire but are not over it, the heat you are feeling is from
Thermodynamics is essentially how heat energy transfers from one substance to another. In “Joe Science vs. the Water Heater,” the temperature of water in a water heater must be found without measuring the water directly from the water heater. This problem was translated to the lab by providing heated water, fish bowl thermometers, styrofoam cups, and all other instruments found in the lab. The thermometer only reaches 45 degrees celsius; therefore, thermodynamic equations need to be applied in order to find the original temperature of the hot water. We also had access to deionized water that was approximately room temperature.
Materials of different types will exhibit varied changes in temperature when transferred the same amount of heat. This variation is a result of the difference in properties displayed from one material to another, known as "heat capacity." Every substance has a variable, positive valued heat capacity that represents the amount of heat required to initiate a specific temperature change. (Hechinger, page 1) For ideal gases, there are heat capacities at constant volume and constant pressure given by:
When there is a heat exchange between two objects, the object’s temperature will change. The rate at which this change will occur happens according to Newton’s Law of heating and cooling. This law states the rate of temperature change is directly proportional between the two objects. The data in this lab will exhibit that an object will stay in a state of temperature equilibrium, unless the object comes in contact with another object of a different temperature. Newton’s Law of Heat and Cooling can be understood by using this formula:
There are three different types of ways heat can be transferred, and that is conduction, convection, and radiation. Radiation is a heat transfer that involves heat absorption such as the sun producing heat and the Earth absorbing the heat. Second is conduction, which is the process of heat being transferred through metal. an example of this would be heating up one end of a metal pipe and the other end of the pipe will begin to get hotter. Lastly is convection, which is heat transf...
Convection is a transfer of internal energy into or out of an object by the physical movement of a surrounding fluid that transfers the internal energy along with its mass. According to Oxford Dictionary, convection is the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder or denser material to sink under gravity's influence, that results in transfer of heat. Two fluids are liquid and gas.The fluid above a hot surface expands, becomes less dense, and rises.This applies to objects such as steam from a hot cup of coffee turning cool, ice melting like heat moving to ice from the air, or frozen material becoming raw like how frozen food thaws more quickly under cold running water. When
In this project, we use three principles which are focusing sunlight to evacuated tube, converting light energy to heat energy and trapping heat energy.
Conduction, convection and radiation are the three methods through which heat can be transferred from one place to another. The (www.hyperphysics.com) first method is the conduction through which heat can be transferred from one object to another object. This process is defined as the heat is transmitted from one to another by the interaction of the atoms and the molecules. The atoms and the molecules of the body are physically attached to each other and one part of the body is at higher temperature to the other part or the body, the heat begins to transfer. A simple experiment through which conduction can be understood easily is as follows. First of all, take a metallic rod of any length. Hold the rod in the hand or at any stand made up of the insulator so that the heat does not transfer to the stand. Heat up the one end of the rod with the help of the spirit lamp. After sometime, touch the other end of the end, the other end of the becomes heated too and the temperature of the other end of the rod has also increased. Although only one end of the rod is heated with the spirit lamp, but the other end of the rod has also been heated. This is represents that the heat has been transferred from one end of the rod to the other end of the rod without heating it from the other end. So, the transformation of the heat is taking place. This process is called the conduction. Conduction is a process which is lead by the free electrons. As the conduction happens occurs only in the metallic materials, the reason for it is that the metals has the free electrons and they can move freely from one part of the body to another part of the body. These electrons are not bounded by the nucleus so, they can move easily. And when the temperature of the ...
Heat transfer from high temperature heated surfaces finds considerable application in engineering. Because of its large number of applications in industries, considerable efforts have been made by researchers to investigate various aspects of the heat transfer and its fundamental principles involved. Fluid flow problems involving heat transfer viz. in presence of convention and radiation represents an idealization of many meaningful problems in engineering practice. Due to the presence of higher level of temperature required in many system like boiler, nuclear reactor; the effect of radiation heat transfer increases. So, there becomes a need of including radiative effect of the participating medium and also their boundary conditions. Keeping this in mind, an attempt was made to investigate the heat transfer in the Indian Pressurized Heavy Water Reactor (IPHWR) during Loss of Coolant Accident (LOCA) with low steam flow. This study will help in estimating the safe working limits for the heat dissipation in the reactor.
laws are drawn from reflection steady heating under three temperatures low, intermediate and high representing the most common heating conditions on a production line.
The heat makes the molecules in the mixture expand and move slower than when they are in colder temperatures (source 1). The molecules are like people when it comes to how they react to heat and coldness. When the molecules are cold, they like to be very close to one another and the molecules move fast because they are “shivering” (source 2).This is just a one of many examples and comparisons that I am going make throughout this paper. Some of the examples will be very cheesy. I am going to give a warning. When the molecules are hot, they like to be far apart from one another (source 1). They even might start to sweat like humans, too. The molecules have some energy too, but the molecules just do not have as much energy when they are hot. They like to be lazy like many humans do in hot weather (source 1).
Works Cited Although heat and temperature are correlated terms in daily speech, there is a crucial difference in their definitions in the study of physics. In specific, heat is a form of thermal energy that can be transformed from one object to another; whereas temperature is a measurement of the average kinetic energy of the particles in a sample of matter (“Methods of Heat Transfer”, n.d.). Heat transfer indicates the movement of heat energy from one place to another caused by the difference in temperature (“Chapter 16: Heat Transfer”, n.d.). Heat will always move from the hotter object to the cooler one, until they both reach the same temperature, indicating thermal equilibrium (“Chapter 16: Heat Transfer”, n.d.). There are three primary mechanisms for heat transfer, including convection, conduction, and radiation.
The physics properties of conduction, convection, and radiation are apparent and vital to our everyday life. The transfer of heat, a form of kinetic energy, can be described as the movement of a higher temperature to a lower temperature area. This movement of heat from one substance to the other can be used through the processes of conduction, convection, and radiation. There are many examples involving these principles within our common everyday activities. An example of conduction would be the an ice cube melting in your hand, or touching a hot stove and being burned. Convection can be exemplified through hot air rising, cooling, and then falling. Lastly, radiation is observed through anything warmer than it’s surrounds like fire, the sun,
When you go outside on a sunny day, you can feel the heat from the sun
Again, it is the most common means of energy transfer and by understanding exactly what conduction means, we can identify it in some of the simple things we do. For instance, think of a pot placed on the stove, on a hot burner. The burner and the bottom of the pot are obviously touching, therefore the pot begins to heat up and get hot as well. As physical contact is the key element in heat transfer through conduction, we can see how important a role it plays in this situation. Now, say that your food is done, you turn the burner off and grab the handle of the pot, only to find that it is extremely hot as well. Again, we can thank conduction for this- as the heat was transferred through the bottom of the pot to the handle. Another example of conduction can be seen through ironing. We plug in and heat up the iron prior to placing it on the clothing in which we wish to smooth out. Once the iron has heated up, we place it on top of the article of clothing and it then heats up the clothing as well. Again, physical contact between the iron and the shirt show us that conduction plays the role of heat transfer in this scenario too. For a final example of heat transfer through conduction, let’s imagine a child, playing outside in the snow on a rather cold day. Once outside for a bit, he is freezing and decides to come inside. He takes off his snow gear, cuddles up to his father and begins to warm up
The word thermal in thermal energy means heat and temperature, so all together means heat that comes from energy. Conduction, convection, and radiation are the types of thermal energy. Conduction is when two molecules collide. An example of conduction is a pot on a stove with boiling water. Convection is heat transferred to another object. An example of convection is a pot on a stove with boiling water and bubbles forming. Radiation is energy from the sun. A man standing outside in the sun and the sun rays are hitting the man and he start to sweat.