Heat energy is the manifestation of energy in the form of heat. In all materials, the atoms that make up their molecules are in continuous movement, either moving or vibrating. It is also called thermal energy.
This movement of the particles implies that the atoms and molecules have a certain kinetic energy that we call heat, thermal energy, or heat energy. In a way, heat energy is the internal energy of a body. If kinetic energy increases the particles move faster.
The internal energy of a thermodynamic system can be changed in two ways: by doing work on the system and by exchanging heat with the environment. The energy that the body receives or loses in the process of heat exchange with the environment is called the amount of heat or simply heat.
Energy is measured in Joules (J) according to the international system. Although when it comes to heat energy, calories (lime) are also often used.
Examples of heat energy
Caloric energy is often linked to other types of energy. Here are some examples of heat energy:
- Nuclear energy. In the process of nuclear fission of uranium atoms, a large amount of energy is released in the form of heat.
- Chemical energy. In a chemical reaction. Exothermic reactions generate heat.
- Electric power. The passage of electrons through a resistance generates heat.
- Geothermal energy. It is the use of heat from the interior of the Earth.
- Fossil fuels. In the combustion of fossil fuels. Heat engines, etc.
Thermal Energy Transfer
This form of energy can be transmitted from one body to another following the laws of thermodynamics in three different ways:
- Radiation heat transmission.
- Transmission of thermal energy by conduction.
- Convection heat energy transmission.
Heat travels by conduction and radiation in solids and by convection in fluids like air and water.
The transfer of heat by conduction is experienced when a hot body is in physical contact with a cooler body. Energy is always transmitted from the hot body to the cold body. If both bodies are at the same temperature there is no energy transfer. When we touch a piece of ice with our hand, part of the thermal energy from our hand is transferred to the ice, so we feel cold.
On the other side, if we touch a warm object we feel heat because its temperature is higher than our corporal temperature. Since the thermal equilibrium is not achieved we will keep feeling cold or hot.
For example, in the gas state, when a fast moving particle collides with a slower moving particle, it transfers some of its energy to the slower moving particle, increasing the speed of that particle. The more heat dispensed the higher temperatures.
The transmission of thermal energy by convection occurs when hot molecules are moved from one side to the other. This would be the case of the wind, capable of moving molecules with a certain heat energy from one side to the other.
Heat energy in phase changes
If thermal energy is supplied to a body, increase its heat and temperature. On the other hand, if heat energy is transferred outside, it cools down. This happens as long as this body is not changing phase. That is, during the transformation from solid to liquid, from liquid to gas and vice versa, the variation of heat does not imply a change in temperature until the transformation is complete. When it is completed temperature rises again.
The energy required for the phase transition of a unit mass of a substance is called the specific heat of the phase transformation.
Water phase changes
If liquid water is supplied with heat, it increases the temperature to 100 degrees Celsius. Then boiling. From this temperature the energy transfer is used to change the liquid state to a gas (water vapor).
At this time the temperature will remain constant until all the water is steam. When all the water is steam, the temperature can continue to rise. That is because of latent heat.
Latent heat is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process.