Heat Transfer Flashcards
4 methods of heat transfer
Conduction
Convection
Evaporation
IR radiation
Where does conduction occur
Solids and liquids
Where does convection occur
Fluids (gases and liquids
Where does evaporation occur
Surfaces of liquids
IR
A type of energy invisible to eyes, we sense it from heat.sun and fire are sources and no particles are involved
What is conduction particle theory
Particles with more energy collide with other particles, transferring some heat energy across
Convection particle theory
Hot fluid rises and particles move a lot more and get further apart making the fluid less dense
IR RADIATION particle theory
Waves of thermal energy get omitted from hot objects e,g sun and fire
Evaporation particle theory
When hot gases escape from a liquid it lowers the overall temperature
What prevents conduction
Conduction cannot happen in a vacuum as particles must be present
What prevents convection
It can only happen in fluids and currents transfer more heat when this is more fluid so if the fluid does not cover a large surface area not a lot of heat will be transferred
How to stop IR
Aluminium wrap
How to prevent evaporation
Cover the body of water so no evaporated fluid can escape
Why would a pocket of air not be good for convection and conduction
Convection happens best in large spaces so not a lot of heat will be transferred by convection as the pocket is small
Bad for conduction as conduction does not work as well in gases
