Heat Transfer Flashcards

Conduction

• Occurs primarily in solids.
• Heat transfer mechanism: Atoms vibrate due to a heat source.
• Vibrations propagate through the solid, transferring energy to cooler regions.
• Metals vs. Wood/Plastics:
  • Metals are better conductors because they possess free mobile electrons.
  • These electrons facilitate heat energy transfer.
  • Wood and plastics are insulators (poor conductors).
  • Examples of insulators: fiberglass and wool.

Convection

• Occurs in fluids (liquids and gases).
• Fluids as Conductors: Fluids are generally poor conductors due to large interatomic spacing.
• Mechanism of Convection:
  • Warmer fluid particles exhibit faster movement and increased separation.
  • This leads to decreased density.
  • Lower density fluid rises above cooler, higher density fluid.
• Circulation:
  • Convection establishes fluid circulation.
  • This results in natural mixing and heat distribution.

Radiation

• Nature of Radiation: Infrared radiation is perceived as heat.
• Wave Properties:
  • Travels as a transverse wave.
  • Speed: Speed of light (approximately 300 \times 10^6 m/s).
• Absorption and Transmission:
  • Dark objects are good absorbers and transmitters.
  • Objects with large surface area, especially "matte dark" surfaces, maximize absorption/transmission.
• Reflection:
  • White and silver surfaces are poor absorbers and transmitters of infrared radiation.