Methods of Heat Transfer Flashcards
3 Methods of Heat transfer
Conduction
Convection
Radiation
- the process where heat is transferred thru a material without any movement of the material
- the direct flow of heat thru a material resulting from physical contact
Conduction
in conduction, objects are ________
in contact with each other
it often happens when energetic molecules bump into less energetic cool molecules
Conduction
refers to the materials that conduct heat well ( best examples for this are metals)
Thermal conductors
refers to the materials that conduct heat poorly ( best examples for this are wood, plastic, glass)
Thermal insulators
2 ways to create good insulators:
- small k and big d
- ratio d/k called R factor (higher R factor, better insulator)
other insulators like ___________ and _________ work by trapping air in small spaces where convection currents arise
goose down
styrofoam
- refers to the flow of heat due to the movement of matter
- heat transfer between surface and adjacent fluid and any by the flow of fluid from one place to another, induced by temperature
Convection
Difference in densities of fluids with different temperatures (WARM air RISES, COLD air FALLS) fall under this type of convection
Natural convection
2 types of convection
- Artificial
- Natural
Circulatory system (pumps blood) and Radiator pump (antifreeze) are under this type of convection
Artificial convection
CONVECTION OR RADIATION.
heat from the sun reaches Earth without contact
Radiation
CONVECTION OR RADIATION.
Movement of a Fluid
Convection
Energy is transferred by __________
electromagnetic waves
- refers to the transfer of energy via electromagnetic waves
- includes radio waves, microwaves, x-rays, infrared, and visible light
Radiation
ice cubes emit ______________ radiation
very little
TRUE/FALSE.
All bodies (objects) continually emit radiation
TRUE
warm bodies, like human bodies emit ______
infrared radiation
when the temperature of the body reaches 1000K, it starts to emit ___________
visible dull red light
when the the temperature of the body reaches 1700K, it starts to emit ___________
white-hot light
TRUE/FALSE/
Different objects react the same to radiation
FALSE. reacts differently
-what color absorbs most of radiation
- a good absorber of radiation
Black
what color absorbs little radiation
Silver, white, light colors
an object that absorbs all radiation and hits it
blackbody
TRUE/FALSE.
All objects emit and absorb radiation continually
TRUE
good absorbers = _______
good emitters
- no transfer medium required
- refers to the transfer of thermal energy thru matter of space by electromagnetic waves
Radiation
Conduction: via __________
direct contact
Convection: via __________
fluid
Radiation: via ____________
electromagnetic radiation
