Difference Between Conduction, Convection, and Radiation (With Table)

The transmission of energy between things of various temperatures is known as heat. The kinetic energy of objects fluctuates when they warm-up or cool down. Temperature is a measure of the average kinetic energy of the particles in an object. The energy of motion is known as kinetic energy. The energy of motion increases as the temperature rises. 

Conduction, convection, and radiation are the three methods through which heat can be transmitted. In this article, we have distinguished all three forms of heat transfer.

Conduction vs Convection vs Radiation

The main difference between conduction, convection, and radiation is determined by the medium. Conduction is the transmission of heat across objects via direct touch, whereas convection is the transmission of heat across items via the flow of a medium like air or water. Heat is delivered through radiation without any physical contact between objects.

Example of conduction: When we make tea, heat from the stove is transferred to the steel pan due to direct contact, resulting in conduction. Heat energy is transmitted from ironed clothing when they are ironed.

Example of convection: When we heat a pot of water, the water particles at the surface heat up first; we know that heat causes particles to travel faster, therefore these particles move randomly and a relatively empty space is formed. Particles from far locations migrate here to fill the space. Again, these particles require heat energy and go away, and the process repeats itself, resulting in hot water from cold water.

Example of radiation: When boiling water on the stove, heat conducts from the stove to the pot because it is directly in contact. Due to convection, all the water particles receive heat. You will feel hot if you raise your hand closer to the pot’s side; this is caused by the pot’s radiation.

Comparison Table Between Conduction, Convection and Radiation

Parameters of ComparisonConductionConvectionRadiation
MediumConduction of heat requires the presence of a medium.For heat transfer by convection, a medium is required.The use of a medium is not required for radiant heat transmission.
VacuumIn a vacuum, conduction is not possible.In a vacuum, convection is not possible.In a vacuum, radiation can happen.
Effects on mediumThe medium particles do not deviate from their average location. They dissipate heat by vibrating around their centre of gravity.The medium particles leave their average position and migrate upward, transporting heat from the source.The medium is unaffected in any way.
Direction of heatHeat can be transferred in any direction.The only way for heat to be transferred is vertically upward.Heat is transferred in all directions in a straight line.
Time takenThe process is slow.The process is faster than conduction.The process is the fastest and the transfer of heat takes place with the speed of light.

What is Conduction?

The process of heat transfer in which heat is transmitted from one portion of the body at a higher temperature to another area of the body at a lower temperature without the molecules moving from one place to another is known as conduction.

Conduction occurs most commonly in solids as a result of temperature differences. It happens as a result of free electron energy transfer and molecular lattice vibrational energy transmission.

Free electrons are responsible for 70% of heat transfer, whereas vibration is responsible for the remaining 30%. When one end of a metal rod is heated, the other end eventually becomes heated as well.

What is Convection?

Convection unlike conduction occurs in liquids and gases. It is the transfer of heat through the movement of particles. Warm particles rise, cool particles fill in space below, so this is a circular motion.

Natural, forced, gravitational, granular, or thermomagnetic convection are all possible classifications.

When we heat a pot of water, the water particles at the surface heat up first; we know that heat causes particles to travel faster, therefore these particles move randomly and a relatively empty space is formed. Particles from far locations migrate here to fill the space. Again, these particles require heat energy and go away, and the process repeats itself, resulting in hot water from cold water.

What is Radiation?

Heat energy can also be transported without the use of particles, allowing it to pass across a vacuum. This occurs when energy is delivered through radiation, specifically infrared wavelengths.

All objects are capable of both absorbing and emitting radiation at the same time. The hotter something is, the more radiation it emits.

This is why putting your hand over a grill, even if you aren’t touching it, feels hot. Infrared radiation is emitted by the extremely hot metal and coal, which is absorbed by your hand. When we look at infrared radiation in the context of the electromagnetic spectrum, we can see how it is.

Main Differences Between Conduction, Convection and Radiation

  1. The presence of a medium is required for heat conduction and convection. Radiative heat transfer, on the other hand, does not require the usage of a medium.
  2. Conduction and convection are impossible in a vacuum, but radiation is feasible.
  3. In conduction, heat can be moved in any direction, whereas in convection, heat can only be transferred vertically upward. Radiation is a method of transferring heat in a straight line in all directions.
  4. Conduction is a slow process, whereas convection is quicker than conduction, and the process is the quickest, with heat transfer occurring at the speed of light in case of radiation.
  5. Conduction requires heated solids, while convection necessitates the use of fluids, and radiation necessitates the use of electromagnetic waves as a medium.

Conclusion

Heat is carried via conduction from a hot item or region to a cold object or area, whereas heat is transported by convection through the flow of fluid currents, and heat is transported sans any medium by radiation.

In thermodynamics, the modes of heat transmission, such as conduction, convection, and radiation, are important topics.

References

  1. https://www.sciencedirect.com/science/article/pii/0142727X94000144
  2. https://asmedigitalcollection.asme.org/heattransfer/article-abstract/85/4/318/414710