Heat transfer by conduction is generally lower than heat transfer by convection. Conduction is the process of heat transfer through direct contact between materials or particles, where heat flows from regions of higher temperature to regions of lower temperature. It occurs primarily in solids and to a lesser extent in liquids.
Convection, on the other hand, involves the transfer of heat through the movement of fluids (liquids or gases). In natural convection, heat is transferred as a result of the buoyancy-driven flow of fluid due to temperature differences. Forced convection occurs when a fluid is forced to flow over a surface, typically facilitated by a fan or pump. Convection is generally more efficient at transferring heat compared to conduction because the fluid movement enhances the transfer process.
In practical scenarios, convection is often the dominant mode of heat transfer. For example, when you feel a breeze on a hot day, the transfer of heat from your body to the surrounding air is primarily through convective heat transfer. However, there are cases where conduction may still play a significant role, such as in solid materials with high thermal conductivity or in situations where there is limited fluid motion for convection to occur.
It's important to note that the relative effectiveness of conduction and convection depends on the specific circumstances, materials involved, and the temperature gradients present.