Heat Transfer By Conduction – Meaning, Types, Difference Between Conduction And Convection, And 7 Examples Of Conduction

In my previous post, I discussed convection and provided some examples. Today, I will be discussing conduction, another heat transfer method.

Although conduction and convection are both methods of heat transfer and may appear similar, I will explain their differences in detail. Additionally, I will provide examples of conduction to help illustrate this heat transfer method.

What Is Conduction?

Conduction is transferring thermal or electrical energy from one location to another. This process is initiated by colliding adjacent atoms or molecules within a solid or liquid medium.

The conduction process is more noticeable in substances with tightly packed particles than those with widely dispersed particles. This occurs when high-energy particles collide with lower-energy particles, causing them to move faster or vibrate more intensely.

To put it differently, conduction refers to the movement of energy from particles with higher energy levels to those with lower energy levels within a substance, which is caused by the interaction between the particles.

Types Of Conduction

The three main conduction types are Ionic, Electric, and Lattice/thermal conduction.

1. Ionic Conduction

   Conduction of this nature takes place in substances containing ions, such as salts and acids.

   Ionic conduction refers to the transfer of ions from one location to another, which is facilitated by defects in the lattice structure of a solid or an aqueous solution. These defects create vacancies which allow the ions to move in response to an electric field.

   High ionic conductivity is desirable in solid-state electronics like computers and mobile phones and in normal and rechargeable batteries and fuel cells. Ionic salts can also be dissolved in a solution, allowing the ions to become nomadic and conduct an electric current.

   Unlike solid salts, which lack mobile charge carriers, ions in a solution are electrically charged and mobile, making them effective charge carriers. Ions move through the material, transferring energy as they collide with other particles.

2. Electrical Conduction

   In this form of conduction, energy is transferred as electrons traverse a material, exchanging energy through collisions with other particles.

   In metals, electrical conductivity occurs due to the movement of electrically charged particles. The atoms in a metal possess valence electrons, which are electrons located in the outer shell of each atom.

   These valence electrons are free to move throughout the structure. The ability of these electrons to move is referred to as being delocalized, enabling the metal to conduct electric current. Without external influences, these electrons move randomly throughout the structure. This type of conduction is frequently observed in metals.

3. Lattice/thermal Conduction

   This form of conduction takes place in solids, wherein energy is transferred through particles’ vibrations within the material’s lattice structure. This mode of conduction is frequently observed in non-metallic materials.

   Heat conduction or thermal conduction is the transfer of kinetic energy from rapidly moving particles to their adjacent particles, leading to the movement of heat from a higher to a lower temperature region.

   The rate of heat conduction is influenced by four key factors, namely the temperature gradient between the regions, the length and cross-sectional area of the region, and the material in which the process occurs. Metallic solids are the most proficient conductors of heat, while gases are the least effective.

   This is due to the proximity of particles in solid states, which leads to a high probability of a collision and transfer of thermal energy. The excellent thermal conductivity of solids is also linked to their electrical conductivity, and the denser the solid, the more efficient it is in conducting thermal energy.

Differences Between Conduction And Convection

Examples Of Conduction

• Feeling the heat from a hot pan handle as it transfers to your hand through touch.
• Heat is conducted from the soup to the handle of a metal cooking spoon when stirring hot soup.
• Sitting on a metal chair on a sunny day causes it to become warm through conduction.
• The heat from your hand melts an ice cube through conduction when holding it.
• Feeling the coldness of a windowpane when touching it due to heat being conducted from your hand to the glass.
• Walking barefoot on hot sand at the beach causes the heat to be conducted from the sand to your feet.
• The coldness of a metal railing on a cold winter day can be felt when touching it with your hand.

Conclusion

Heat tends to be transferred when there is a temperature difference between two points. Heat can be transmitted through various means, such as convection, conduction, and radiation. Each method has its unique way of transferring heat and uses different mediums. Understanding these differences can help in properly utilizing and applying these methods.