Thermal energy is a term that we use to describe the level of activity of molecules in an object. One way or another, increased excitement is associated with an increase in temperature, while atoms in cold objects move much slower.
Examples of heat transfer can be found everywhere - in nature, technology and everyday life.
Examples of heat transfer
The biggest example of heat transfer is the sun, which warms the planet Earth and everything on it. In everyday life you can find a lot of such options, only in a much less global sense. So, what examples of heat transfer can be observed in everyday life?
Here is some of them:
- A gas or electric stove and, for example, a frying pan for frying eggs.
- Automotive fuels, such as gasoline, are sources of thermal energy for the engine.
- The included toaster turns a piece of bread into a toast. This is due to the radiant thermal energy of the toast, which draws moisture from the bread and makes it crispy.
- A hot cup of steaming cocoa warms your hands.
- Any flame, starting from a match flame and ending with massive forest fires.
- When ice is placed in a glass of water, thermal energy from the water melts it, that is, the water itself is a source of energy.
- A radiator or heating system in the house provides heat for long and cold winter months.
- Conventional ovens are sources of convection, as a result of which the food product placed in them is heated, and the cooking process is started.
- Examples of heat transfer can be observed in your own body, taking a piece of ice in your hand.
- Thermal energy is even inside the cat, which can warm the owner’s knees.
Heat is movement
Heat flows are in constant motion. The main methods of their transmission can be called convention, radiation and conductivity. Let's look at these concepts in more detail.
What is conductivity?
Perhaps many have noticed more than once that in the same room the sensations of touching the floor can be completely different. It is pleasant and warm to walk on the carpet, but if you enter the bathroom with bare feet, a noticeable coolness immediately gives you a feeling of vivacity. Just not in the case where there is floor heating.
So why does the tiled surface freeze? This is all due to thermal conductivity. This is one of three types of heat transfer. Whenever two objects of different temperatures are in contact with each other, thermal energy will pass between them. Examples of heat transfer in this case can be given as follows: holding on to a metal plate, the other end of which will be placed above the flame of a candle, you can feel burning and pain over time, and when you touch the iron handle of a pot of boiling water, you can get a burn.
Conductivity Factors
Good or poor conductivity depends on several factors:
- The type and quality of the material from which the items are made.
- The surface area of two objects in contact.
- The temperature difference between the two objects.
- Thickness and size of items.
In the form of an equation, this is as follows: the rate of heat transfer to the object is equal to the thermal conductivity of the material from which the object is made, multiplied by the surface area in contact, multiplied by the temperature difference between the two objects and divided by the thickness of the material. Everything is simple.
Conductivity Examples
Direct heat transfer from one object to another is called conductivity, and substances that conduct heat well are called conductors. Some materials and substances cope poorly with this task, they are called insulators. These include wood, plastic, fiberglass and even air. As you know, insulators do not actually stop the flow of heat, but simply slow it down to one degree or another.
Convection
This type of heat transfer, such as convection, occurs in all liquids and gases. You can find such examples of heat transfer in nature and in everyday life. When the liquid heats up, the molecules in the lower part gain energy and begin to move faster, which leads to a decrease in density. Warm fluid molecules begin to move up, while a cooler (denser liquid) begins to sink. After the cool molecules reach the bottom, they again receive their share of energy and again tend to the top. The cycle continues as long as there is a heat source at the bottom.
Examples of heat transfer in nature can be cited as follows: using a specially equipped burner, warm air, filling the space of a balloon, can raise the entire structure to a sufficiently high height, the fact is that warm air is lighter than cold.
Radiation
When you sit in front of a bonfire, the heat emanating from it warms you. The same thing happens if you bring your palm to a burning light bulb without touching it. You will also feel warm. The largest examples of heat transfer in everyday life and nature are led by solar energy. Every day, the heat of the sun passes through 146 million km of empty space right up to the Earth itself. This is the driving force for all the forms and systems of life that exist on our planet today. Without this mode of transmission, we would be in great trouble, and the world would be completely different from the way we know it.
Radiation is the transfer of heat through electromagnetic waves, whether it is radio waves, infrared, x-rays or even visible light. All objects emit and absorb radiant energy, including the person himself, but not all objects and substances cope with this task equally well. Examples of heat transfer in everyday life can be considered using a conventional antenna. As a rule, what radiates well is also good and absorbs. As for the Earth, it receives energy from the sun, and then gives it back to space. This radiation energy is called terrestrial radiation, and this is what makes life on the planet possible.
Examples of heat transfer in nature, everyday life, technology
Energy transfer, in particular thermal, is a fundamental area of research for all engineers. Radiation makes the Earth habitable and provides renewable solar energy. Convection is the basis of mechanics, responsible for the flow of air in buildings and air exchange in houses. Conductivity allows you to heat the pan, just by putting it on fire.
Numerous examples of heat transfer in technology and nature are obvious and are found everywhere in our world. Almost all of them play a large role, especially in the field of engineering. For example, when designing a building's ventilation system, engineers calculate the heat transfer of a building in its vicinity, as well as the internal heat transfer. In addition, they choose materials that minimize or maximize heat transfer through individual components to optimize efficiency.
Evaporation
When atoms or molecules of a liquid (such as water) are exposed to a significant volume of gas, they tend to spontaneously enter a gaseous state or evaporate. This is because the molecules are constantly moving in different directions at random speeds and collide with each other. During these processes, some of them receive kinetic energy sufficient to repel from the heat source.
However, not all molecules have time to evaporate and become water vapor. It all depends on the temperature. So, water in a glass will evaporate more slowly than in a pan heated on a stove. Boiling water significantly increases the energy of molecules, which, in turn, accelerates the evaporation process.
Basic concepts
- Conductivity is the transfer of heat through matter through direct contact of atoms or molecules.
- Convection is the transfer of heat through the circulation of gas (for example, air) or liquid (for example, water).
- Radiation is the difference between the absorbed and reflected amount of heat. This ability is highly dependent on color, black objects absorb more heat than light ones.
- Evaporation is a process in which atoms or molecules in a liquid state receive enough energy to become gas or vapor.
- Greenhouse gases are gases that trap the heat of the sun in the Earth’s atmosphere, producing a greenhouse effect. There are two main categories - water vapor and carbon dioxide.
- Renewable energy sources are endless resources that are quickly and naturally replenished. These include the following examples of heat transfer in nature and technology: winds and solar energy.
- Thermal conductivity is the speed at which a material transfers thermal energy through itself.
- Thermal equilibrium is a state in which all parts of the system are in the same temperature regime.
Practical application
Numerous examples of heat transfer in nature and technology (pictures above) indicate that these processes should be well studied and served for the good. Engineers apply their knowledge of the principles of heat transfer, research new technologies that are associated with the use of renewable resources and are less damaging to the environment. The key point is the understanding that energy transfer opens up endless possibilities for engineering solutions and more.