Thermal energy is the term we use to describe the level of activity of molecules in an object. Increased excitation is, one way or another, associated with an increase in temperature, while in cold objects, atoms move much more slowly.
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 similar options, only in a much less global sense. So, what are some examples of heat transfer in everyday life?
Here are some of them:
- Gas or electric stove and, for example, a frying pan for frying eggs.
- Automotive fuels such as gasoline provide thermal energy to the engine.
- The included toaster turns a piece of bread into toast. It is associated with radiantthe thermal energy of the toast, which draws moisture out of the bread and makes it crispy.
- A hot cup of steaming cocoa warms hands.
- Any flame, from match flames to massive forest fires.
- When ice is placed in a glass of water, the thermal energy from the water melts it, that is, the water itself is a source of energy.
- The radiator or heating system in your home provides warmth during the long, cold winter months.
- Conventional ovens are sources of convection, as a result of which the food placed in them is heated and the cooking process starts.
- 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 conduction. 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 from touching the floor can be completely different. It is pleasant and warm to walk on the carpet, but if you go into the bathroom with bare feet, a noticeable coolness immediately gives a feeling of cheerfulness. Not where there is underfloor heating.
So why does the tiled surface freeze? It's all becausethermal conductivity. It 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 include the following: holding on to a metal plate, the other end of which is placed over the flame of a candle, over time, you can feel burning and pain, and at the moment you touch the iron handle of a pot of boiling water, you can get burned.
Conductivity factors
Good or bad conductivity depends on several factors:
- The type and quality of the material from which the objects are made.
- The surface area of two objects in contact.
- Temperature difference between two objects.
- Thickness and size of items.
In equation form, it looks like this: The rate of heat transfer to an object is equal to the thermal conductivity of the material from which the object is made, times the surface area at the contact, times the temperature difference between the two objects, and divided by the thickness of the material. It's simple.
Examples of conductivity
The direct transfer of heat from one object to another is called conduction, and substances that conduct heat well are called conductors. Some materials and substances do not cope well with this task, they are called insulators. These include wood, plastic, fiberglass and even air. As you know, isolators do not actually stop the flow.heat, but simply slow it down to one degree or another.
Convection
This type of heat transfer, like convection, occurs in all liquids and gases. You can find such examples of heat transfer in nature and in everyday life. As the liquid heats up, the molecules at the bottom gain energy and move faster, resulting in a decrease in density. The warm fluid molecules begin to move upward while the coolant (the 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 given as follows: with the help of a specially equipped burner, warm air, filling the space of a balloon, can raise the entire structure to a sufficiently high height, the thing is that warm air is lighter than cold air.
Radiation
When you sit in front of a fire, you are warmed by the warmth emanating from it. 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 all the way to the Earth itself. It is the driving force behind all forms and systems of life that exist on our planet today. Without this mode of transmission, we would be in big trouble, and the world would not be the same as we are.we know him.
Radiation is the transfer of heat using electromagnetic waves, be it 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 at absorbing. 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 it is what makes life on the planet possible.
Examples of heat transfer in nature, everyday life, technology
Transmission of energy, in particular thermal, is a fundamental area of study for all engineers. Radiation makes the Earth habitable and provides renewable solar energy. Convection is the basis of mechanics, is responsible for air flow in buildings and air exchange in houses. Conductivity allows you to heat a pot by simply putting it on fire.
Numerous examples of heat transfer in technology and nature are obvious and are found throughout our world. Almost all of them play an important role, especially in the field of mechanical engineering. For example, when designing a building's ventilation system, engineers calculate the heat transfer from the building around it, as well as internal heat transfer. In addition, they select materials that minimize or maximize heat transfer.through individual components to optimize efficiency.
Evaporation
When the 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 themselves from the heat source.
However, not all molecules have time to evaporate and become water vapor. Everything depends on the temperature. So, water in a glass will evaporate more slowly than in a pan heated on the stove. Boiling water greatly increases the energy of the molecules, which in turn speeds up the evaporation process.
Basic concepts
- Conductivity is the transfer of heat through a substance by direct contact of atoms or molecules.
- Convection is the transfer of heat through the circulation of a gas (such as air) or a liquid (such as water).
- Radiation is the difference between the amount of heat absorbed and reflected. This ability is highly color dependent, black objects absorb more heat than light objects.
- Evaporation is the process by which atoms or molecules in a liquid state gain enough energy to become a gas or vapor.
- Greenhouse gases are gases that trap the sun's heat in the Earth's atmosphere, producing a greenhouse gas. Effect. There are two main categories - water vapor and carbon dioxide.
- Renewable energy sources are limitless resources that replenish quickly and naturally. These include the following examples of heat transfer in nature and technology: winds and solar energy.
- Thermal conductivity is the rate 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 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 destructive to the environment. The key is to understand that energy transfer opens up endless possibilities for engineering solutions and more.
