Summary: convection

Convection is the flow of heat energy from a region of high temperature to a region of low temperature by movement of a fluid.
Convection only occurs in fluids - liquids and gases.
- When part of a liquid or gas is heated it expands, becomes less dense and rises.
- It is replaced by the cooler, denser fluid.
- This liquid or gas is in turn heated, expands becomes less dense and rises.
- This sets up a convection current.
Wall heaters (“radiators”) heat mainly by convection.
Trapped air prevents heat loss by conduction and convection.

Heat transfer - CCEASummary: convection