Heat Energy (Thermal energy) is a form of energy that is associated with the movement and vibrations of atoms and molecules of a substance. It manifests itself as heat transferred from one body to another due to a temperature difference. Heat Energy is the result of the internal energy of a substance caused by the movement of its elementary particles.
Key aspects of heat energy
- Transfer mechanism – Heat Energy is transferred from a body with a higher temperature to a body with a lower temperature. This process can be carried out in three ways: conduction (transfer through direct contact), convection (transfer through the movement of liquid or gas) and radiation (transfer through electromagnetic waves).
- Heat Energy sources – It can be produced by various sources such as solar radiation, geothermal sources, chemical reactions, electrical resistances and heat engines.
- Application – Heat Energy is widely used to provide warmth and comfort in domestic conditions (heating houses, heating water), in industry for heating and cooling processes, and in the production of electricity through thermal power plants .
Heat energy value
It plays an important role in everyday life and industry, providing the necessary heat energy for various processes and satisfying the basic needs of humanity for warmth and comfort. Its efficient use helps reduce energy costs and save the environment.
In heating systems, energy saving is ensured by a boiler (containing a heating element or heat exchanger ), a buffer tank or a heat accumulator .
How heat energy is used?
Heat Energy is a form of energy that is generated as a result of the movement of particles that make up an object.
Today, various methods of obtaining heat energy are used in the world:
- Incineration of organic waste materials
- Using ground heat
- Use of solar heat energy
- Obtaining heat from natural chemical reactions
- Use of bioreactors
In the case of burning organic materials, heat energy is one of the products of the combustion process. Heat energy obtained in this way can be converted into electrical energy at special combined heat and power plants (CHP) and thermal power plants (TPP). Most often, coal or gas is used as a consumable. Various biomasses can also be used for these purposes. Oil is practically not used to obtain heat energy and convert it into electrical energy. Traditional methods of obtaining heat energy, although the most common, are still actively criticized in modern society. The criticism is based on the postulates of the need for a careful attitude to nature and the inadmissibility of depleting natural resources.
Using the heat directly from the Earth is a fairly environmentally friendly way to produce heat energy. There are two types of geothermal sources:
- Natural
- Artificial
In the process of obtaining heat energy, steam turbines and other heat engines are used.
Getting heat from the sun’s rays has not become popular on a global scale. However, work in this direction continues, and engineers actively cooperate with architects and ecologists in creating energy-producing houses and other structures.
Obtaining heat as a result of natural chemical reactions (rotting, fermentation, etc.), as well as obtaining heat energy using bioreactors, have not yet gained significant popularity in the world. The amount of heat obtained as a result of such production is extremely small in comparison with other methods of obtaining thermal energy.
The source of heat energy is a special power plant. To increase heat energy, friction force can be used in various ways.
The “life cycle” of heat energy looks like this:
- production
- broadcast
- consumption
If heat energy is not converted into electrical energy, it is used for the following needs:
- Heating of residential and non-residential premises
- Hot water supply
The unit of measurement of heat energy is the gigacalorie (Gcal).
To calculate the heat energy used for heating purposes, the following formula is used:
Q = V * ( T1 – T2 ) / 1000
Q – amount of heat energy
V – amount of hot water used (in cubes)
T1 – hot water temperature
T2 – cold water temperature
Examples of Heat Energy in Everyday Life
The hotter an object is, the more heat energy it will radiate. To better explain this phenomenon, we have collected some of the best examples of heat energy that you see in everyday life.
Solar Energy
Heat Transfer Type: Radiation The Sun is a nearly perfect sphere of hot plasma that converts hydrogen into helium through billions of chemical reactions that ultimately produce intense amounts of heat. Instead of staying close to the Sun, the heat radiates away from the star and into space. A small portion of this energy (heat) reaches Earth as light. It mainly contains infrared, visible, and ultraviolet light. The transfer of heat energy in this way is called thermal radiation. While some of the heat energy penetrates the Earth’s atmosphere and reaches the ground, some of it is blocked by clouds or reflected off other objects. Sunlight that reaches the Earth’s surface heats it. According to the University of Oregon, the entire Earth receives an average of 164 watts per square meter over the course of a 24-hour period. This means that the entire planet receives 84 terawatts of energy.
Melting Ice
Heat energy always flows from regions of higher temperature to regions of lower temperature. For example, when you add ice cubes to a drink, heat moves from the liquid to the ice cubes. The temperature of the liquid drops as heat moves from the drink to the ice. Heat continues to move to the coldest region of the drink until it reaches equilibrium. The loss of heat causes the temperature of the drink to drop.
Fuel cells
Heat Transfer Type: depends on the type of fuel cell Fuel cells are electrochemical devices that convert the chemical energy of a fuel and oxidizer into electrical energy. When a fuel cell operates, a significant portion of the input energy is used to generate electrical energy, with the remainder converted into heat energy, depending on the type of fuel cell. The heat produced during this process is used to improve energy efficiency. In theory, fuel cells are much more energy efficient than conventional processes: if the waste heat is captured in a cogeneration scheme, efficiencies of up to 90% can be achieved.
Geothermal Energy
Heat Transfer Type: Mantle Convection Geothermal energy is heat produced in the Earth’s interior. It is contained in liquids and rocks beneath the crust and can be found deep in the Earth’s hot molten rock, or magma. It is produced by the radioactive decay of materials and the continuous loss of heat from the formation of the planet. Temperatures and pressures at the core-mantle boundary can reach over 4,000°C and 139 GPa, causing some rocks to melt and the solid mantle to behave plastically. This causes parts of the mantle to convect upward (since the molten rock is lighter than the surrounding solid rock). Steam and/or water carry the geothermal energy to the planet’s surface, where it can be used for cooling and heating, or can be used to generate clean electricity.
Heat Energy in the Ocean
Heat Transfer Type: Convection and Conduction For decades, the oceans have absorbed more than 9/10 of the atmosphere’s excess heat from greenhouse gas emissions. According to a study, the ocean has been warming at a rate of 0.5-1 watt of energy per square meter over the past ten years. Oceans have incredible potential for storing heat energy. Since their surfaces are exposed to direct sunlight for long periods of time, there is a huge difference between the temperatures of shallow and deep sea areas. This temperature difference can be used to run a heat engine and generate electricity. This type of energy conversion, known as ocean heat energy conversion, can operate continuously and can support various spin-off industries.
Solar Cooker
Heat Transfer Type: Radiation and Conduction A solar cooker is a low-tech, low-cost device that uses the energy of direct sunlight to heat, cook or pasteurize beverages and other food materials. On a sunny day, it can reach temperatures of up to 400°C. All solar cookers work on three basic principles: Concentrate sunlight: The device has a mirror surface to concentrate sunlight into a small cooking area. Convert light energy into heat energy. When light hits the receiver material (the pan), it converts the light into heat, and this is what we call conduction. Trap heat energy: The glass cover isolates the air inside the cooker from the outside air, minimizing convection (heat loss).
Rubbing your hand
Heat Transfer Type: Conduction When you rub your hands together, friction converts mechanical energy into heat energy. Mechanical energy refers to the movement of your hands. Since friction occurs due to the electromagnetic attraction between charged particles on two surfaces in contact, rubbing your hands together results in an exchange of electromagnetic energy between the molecules in your hands. This results in thermal excitation of the molecules in your hands, which ultimately produces energy in the form of heat.
Heat Engine
Heat Transfer Type: Convection A heat engine converts heat energy into mechanical energy, which can then be used to perform mechanical work. An engine takes energy from heat (compared to the surroundings) and turns it into motion. Depending on the type of engine, different processes are used, such as using the energy of nuclear processes to generate heat (uranium) or igniting a fuel through combustion (coal or gasoline). In all processes, the goal is the same: to convert heat into work. Everyday examples of heat engines include a steam locomotive, an internal combustion engine, and a thermal power plant. All are powered by the expansion of heated gases.
Burning candle
Heat Transfer Type: Conduction, Convection, Radiation Candles make light by producing heat. They convert chemical energy into heat. The chemical reaction is called combustion, where the candle wax reacts with oxygen in the air to form a colorless gas called carbon dioxide, along with a small amount of steam. The steam is produced in the blue part of the flame, where the wax burns cleanly with plenty of oxygen. But since no wax burns perfectly, they also produce a little smoke (aerosol) in the bright, yellow part of the flame. Throughout the process, the wick absorbs the wax and burns to produce light and heat energy.
Electric Toasters
Heat Transfer Type: Radiant Thermal An electric toaster takes electrical energy and converts it into heat very efficiently. It is made up of rows of thin wires (filaments) that are spaced far enough apart to toast the entire surface of the bread. When electricity flows through the wire, energy is transferred from one end to the other. This energy is carried by electrons. Throughout the process, the electrons collide with each other and with the atoms in the metal wire, generating heat. The greater the electrical current and the thinner the wire, the more collisions there are and the more heat is generated.
Modern Home Heating Systems
Heat Transfer Type: Convection Two common types of heating systems installed in buildings are hot air and hot water heating systems. The first uses heat energy to heat air and then circulates it through a system of ducts and registers. The warm air is blown out of the ducts and circulated throughout the rooms, displacing the cold air. The second uses heat energy to heat water and then pumps it throughout the building in a system of pipes and radiators. The hot radiator radiates heat energy into the surrounding air. The warm air then moves throughout the rooms in convection currents.
Processors and other electrical components
Heat Transfer Type: Convection and conduction The processor, graphics processor, and system on a chip dissipate energy as heat through resistance in electronic circuits. GPUs in laptops/desktops consume and dissipate significantly more power than mobile processors due to their higher complexity and speed. Various types of cooling systems are used to maintain optimal temperatures for microprocessors. For example, a typical desktop CPU cooling system is designed to dissipate up to 90 watts of heat without exceeding the maximum junction temperature for a desktop CPU.