3 Types of Thermal Energy Transfer Explained
Types of thermal energy transfer are; conduction, convection and radiation.
It must be noted that the types of thermal energy transfer are usually also described as the methods of thermal energy transfer.
This article discusses the types of thermal energy transfer, as follows;
1). Conduction (as one of the Types of Thermal Energy Transfer)
One of the three ways thermal energy can be transferred is through conduction.
Conduction is a physicochemical process whereby heat is transferred across a material through collisions between excited molecules in contact with each other [4].
An alternative term used to describe conduction is heat diffusion; because it involves the migration of heat from a point of higher energy concentration to a point of lower energy concentration.
The peculiarity of conduction as a type of thermal energy transfer is based on the fact that it requires physical contact between bodies. In order for conduction to be effective, the heat from one body or material zone must be physically absorbed into the molecular lattice of another body or zone, so that the absorbent molecules become energized as temperature rises.
Also, the effectiveness of conduction depends on the thermal conductivity of materials involved.
Materials which can be involved in thermal conduction are mainly solids, although fluids can also conduct thermal energy.
In order for thermal conduction to be energy-efficient, the rate of energy waste that occurs across a conductor from one point to another, must be minimal, so that a significant proportion of heat that enters at one end is received at another.
For practical purposes, energy waste is minimized using non-conductive materials called insulators, which may surround the conductors and prevent loss of heat.
The concept of conduction is very important, as it explains other phenomena like electromagnetism and the generation as well as flow of electricity.
An example of thermal energy conduction is the flow of heat from a hot metal to a cold metal when both materials are in contact. Heat flow from one end of a metal to another is another simple example of conduction.
2). Convection
Convection thermal transfer or convective heat transfer, is the transfer of thermal energy from one point to another in a fluid-dominated medium, by the movement of fluid masses under the influence of temperature and density differences.
In convection, fluid masses absorb heat and become less-dense, so that they rise above adjacent fluid masses of lower temperature and higher density [2].
The high-density, cool fluid masses (gas or liquid) at the bottom may also absorb heat and rise, as formerly-hot masses lose temperature and descend. This dynamic generates a continuous loop of circulating fluid that distributes heat across a medium.
An example of thermal energy transfer by convection is the conveyance of geothermal heat through hydrothermal fluids in the subsurface. Other examples include the mechanism of boiling in a metal pot, ocean thermal energy circulation, and the distribution of heat in the gas chambers of a large electric generator.
3). Radiation (as one of the Types of Thermal Energy Transfer)
Radiation transfers thermal energy in the form of electromagnetic waves that are capable of traveling through space from one point to another, without the need for an intermediate conductor material [3].
Thermal energy by radiation is possible from any hot body. A good example of a hot body that emits thermal energy by radiation is the Sun, whose solar thermal energy is transmitted across space to the Earth as electromagnetic waves [1].
Radiation is a very important type of thermal energy transfer which is needed in cases where there is no material medium for heat conduction or convection. It is behind technologies and applications like solar collector systems and space heating.
Conclusion
Types of thermal energy transfer are;
1. Conduction
2. Convection
3. Radiation
References
1). Arnold, K.; Stewart, M. (2008). "Surface Production Operations. Design of Gas-Handling Systems and Facilities, Volume 1." Available at: https://doi.org/10.1016/B978-0-7506-7853-7.X5001-7. (Accessed 8 February 2023)..
2). Buonomo, B.; Cascetta, F.; Lauriat, G.; Manca, O. (2018). "Convective heat transfer in thermally developing flow in micro-channels filled with porous media under local thermal non-equilibrium conditions." Energy Procedia 148:1058-1065. Available at: https://doi.org/10.1016/j.egypro.2018.08.054. (Accessed 8 February 2023).
3). Nanda, M. K. (2018). "Energy Heat Transfer." Project: e-PGPathshala in the subject- Environmental Sciences, paper-Atmospheric Processes, under MHRD, Govt. of India. Available at: https://www.researchgate.net/publication/325115895_Energy_Heat_Transfer. (Accessed 8 February 2023).
4). Shahidian, A.; Ghassemi, M. (2020). "Bio-Engineering Approaches to Cancer Diagnosis and Treatment." Available at: https://www.sciencedirect.com/book/9780128178096/bio-engineering-approaches-to-cancer-diagnosis-and-treatment. (Accessed 8 February 2023).
