# What is Conduction Heat Transfer?

By Mohit Uniyal|Updated : June 16th, 2022

Conduction Heat Transfer or Thermal conduction is the transfer of internal energy within a body through tiny particle collisions and electron mobility. When molecules, atoms, and electrons collide, they transfer disordered tiny kinetic and potential energy, which is known as internal energy. Conduction heat transfer occurs in all stages, including solids, liquids, gases, and plasma.

As per the Conduction heat transfer, heat naturally moves from a hotter to a cooler body. For example, heat is transferred from the hotplate of an electric stove to the bottom of a saucepan that is in contact with it. Conduction heat transfer explains the reason that temperature variations within a body or between bodies diminish with time in the absence of an opposing external driving energy source, and thermal equilibrium is approached, with temperature becoming more uniform.

## What is Conduction Heat Transfer?

Thermal energy is transferred from one location with greater kinetic energy to another with lower kinetic energy. When high-speed particles collide with slow-moving particles, the slow-moving particles' kinetic energy is increased. Conduction heat transfer is a common method of heat transfer that involves physical contact. The term "conduction" is sometimes referred to as "thermal" or "heat" conduction.

“The process of energy transmission from one medium particle to another with the particles in direct touch with one another.”

Thermal contact conductance is the study of energy transfer between solid bodies in contact. At the interface between the two surfaces in contact, a temperature drop is generally observed. The presence of thermal contact resistance between the contacting surfaces is thought to be the cause of this phenomenon.

## Fourier Law of Conduction Heat Transfer

According to Fourier's law, the area at right angles to the gradient through which the heat flows is proportional to the negative gradient of temperature and the time rate of heat transfer. The law of heat conduction is also known as Fourier's law.

### Differential Form Of Fourier’s Law:

Fourier's law is expressed in differential form as follows:

q=-k▽T

Where,

• q is the local heat flux density in W.m2
• k is the material's conductivity in W.m-1.K-1
• ▽T is the temperature gradient in K.m-1

### Integral Form:

∂Q/∂t = -k∮∮s▽T.dS

Where,

• ∂Q/∂t is the amount of heat transferred per unit of time
• dS is the surface area element

## Common Examples of Conduction Heat Transfer

The terms heat conduction and thermal conduction are similar. When molecules heat up, they start to vibrate, transferring kinetic energy to other molecules they come into contact with. The following are the common examples of conduction in everyday life.

• You can warm up your back muscles using a heating pad. The pad delivers heat to the part of your body it is in contact with as it heats up.
• The heat from a hot beverage also heats up the cup. If you pick up a cup of hot coffee or tea, the cup will be hot, and your hands will feel it.
• If you are cold and someone holds your hand to warm you, heat is transferred from their body to yours.
• If you hold a chocolate candy in your palm long enough, it will melt. Your hand's heat is transferred to the chocolate.
• The iron is hot when ironing a piece of cloth, and the heat is transferred to the cloth.
• If you use poker to stoke a fire in the fireplace and then leave it in the flames, the poker will become extremely hot.
• Sand has the ability to conduct heat. Walking on the beach on a hot summer day will warm your feet in this way.
• When walking on scorching asphalt or concrete, it's critical to protect your dog's paws. They transfer heat to your pet's feet in the same way that they do to yours.
• Heat is produced by light bulbs. Your hand will be burned if you touch a light bulb that is turned on.

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## FAQs on Conduction Heat Transfer

• Heat is transported within a material via molecular excitation rather than bulk motion in conduction heat transfer. In gases and liquids, conduction heat transmission is caused by the collisions and diffusion of molecules during their random motion.

• Conduction, convection, and radiation are the three modes of heat transfer. Heat is normally transferred in a combination of these three forms, with each type occurring only infrequently on its own. Solid materials, liquids and gases, and electromagnetic waves are all used to transport heat.

• The process of heating a pan on a stove is an example of conduction heat transfer. The heat from the burner is transferred directly to the pan's surface.

• No, Because air is a poor thermal conductor unless you stick your hand in the fire, you won't get much heat from the campfire by conduction. Assuming you're seated several feet away from the campfire, conductive heat transmission can be ignored.

• Boiling water involves both conduction and convection. Heat is carried from the heat source to the water at the bottom of the container by conduction, and heat is moved within the water via convection.

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