What is the definition of convective heat transfer?

Convective heat transfer is defined as the transfer of heat through the movement of a fluid medium, which can be either a liquid or a gas. In this process, heat is carried away from one surface and distributed throughout the fluid as it flows. For example, in coffee roasting, hot air can circulate around the coffee beans, transferring heat to them through convection. This is crucial for achieving an even roast and ensuring that the beans are heated uniformly.

The fluid medium plays an essential role in convective heat transfer because the movement of the fluid enhances the efficiency of heat transfer compared to conduction (which occurs through direct physical contact) or radiation (which involves heat transfer through electromagnetic waves). In cases where heat is transferred through a solid material, it falls under conduction rather than convection. Understanding the mechanism of convective heat transfer is fundamental for processes like roasting, where controlling heat distribution significantly impacts the final product quality.