RE: Thermal Energy and Heat

James :

You are not doing so badly, understanding these differences... but I must clarify some things :

When you are talking about thr mechanisms of heat transfer you cannot say that only one occurs. In most cases convection, conduction and radiation all occur together. For example, in a solar heater - it receives the sun's radiation, radiation that is transferred by conduction to the pipes, and finally convection in the water inside the pipe.

So you cannot talk about heat transfer mechanisms separately in many cases.

Let me analyze a little more the questions that you sent...

a) Ice forms on the inside of a window:

You said that there is a conduction here and it is not wrong at all. The main heat transfer mechanism is convection because there is cold air outside the house.

The air presents a lower temperature than the temperature inside the house, so the cold air "steals" heat from the window that is more or less the same temperature as that inside the house, and then heat flow by conduction by the glass reduces the temperature inside the glass, taking the temperature to zero celsius and the water in the air condenses and goes to ice.

b) You are right, the main heat transfer mechanism is conduction.

c) In this case conduction also occurs.

d) Radiation is the main mechanism. Solar collectors are painted black because the radiation absorbed by a body depends on its color. The black color is the one that absorbes the most energy.

e) When you are talking of curents, you refer to air above the radiator, so the main mechanism is convection that takes heat from the hot surface of the radiator.

f) You are right that it is mainly conduction.

I hope that clarifies you dudes about heat transfer.
If you have more questions I can help you.

just write to me: jarango@janua.upb.edu.co

Juan Felipe Arango Valencia.
Departament of Mechanical engineering
Universidad Pontificia Bolivariana
Medellin Colombia 
South America.