1C Heat Transfer Flashcards
Heat Transfer
THE NET FLOW OF HEAT FROM A HOTTER (HIGHER TEMPERATURE) SYSTEM TO A COLDER (LOWER TEMPERATURE) SYSTEM. THIS OCCURS FASTER WHEN THE DIFFERENCE IN TEMPERATURE BETWEEN THE SYSTEMS IS GREATER
Heat
thermal energy that flows from one system to another
measured in joules
Thermal Equilibrium
once two systems reach the same temperature, they are in thermal equilibrium. there is no net heat transfer between systems in thermal equilibrium
Thermal Conduction
a form of heat transfer due to the collision of particles
When does Thermal Conduction occur?
- when they are in physical contact
- when they are at different temperatures
- in solids, liquids, and gases, but is particularly effective in solid metals
Thermal Convection
the transfer of heat through the movement of fluids (liquids or gases)
When does Thermal Convection occur?
it occurs when warmer, less dense fluid rises, and cooler, denser fluid sinks. this results in a continuous cycle called a convection current.
Convection Currents
1 a heat source warms up part of the fluid
2 as the fluid heats up, it becomes less dense and rises
3 when the fluid reaches a cooler area, it becomes less dense and rises
4 this creates a continuous cycle
Thermal Radiation
the transfer of heat through electromagnetic waves, primarily in the infrared spectrum, without the need for a medium
Based on what do objects emit thermal radiation?
based on their temperature. hotter objects emit more radiation than colder objects
What form is Radiation in ?
mostly in the form of infrared waves, but very hot objects can emit visible light, e.g. glowing hot metal
How do Objects absorb thermal Radiation ?
they absorb from their surroundings and emit their own radiation simultaneously. when an object absorbs thermal radiation its temperature increases
Where does Conduction Happen ?
in solids, liquids or gases at different temperatures in contact with each other
Where does Convection Happen ?
In Fluids
Where does Radiation Happen ?
All objects above 0 K emit radiation, but the emission is more significant in hotter objects
How Does Conduction transfer heat ?
Particles collide transferring kinetic (thermal) energy
How Does Convection transfer heat ?
Particles in the fluid rise and fall due to different densities
How Does Radiation transfer heat ?
through electromagnetic waves, primarily in the infrared spectrum, without the need for a medium.
