35 minutes ago, Bernie said:The heat transfer is conduction (even though the air/steam is moving the heat is being transferred from the gas to the food and the gas is moved on by gravity (it bubbles to the surface) and is replaced by new hotter steam. That is not convection
Convection occurs when the medium circulates around a body because of differences in the temperature of the medium itself, which is not what the gas/oil does.
There IS convection happening while the oil is being heated but that is within the oil itself.
Maybe there are a few terms used too loosely here:
Convection is heat transfer by a liquid or gaseous medium. It consists of mainly two different underlying processes:
Conduction is heat transfer by thermal diffusion, thus two media in contact with each other try to equilibrate their temperature.
Advection is the heat transfer by movement of bulk medium (this is what you refer to here as convection in the last paragraph).
Convection encompasses the two processes above and is the correct term to describe both deep frying and air frying.
