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Clothing and Insulation

Clothing and Insulation. Question:. If you stand in front of an open refrigerator, too far away for any cold air to reach you, would you feel colder than you would facing a wall in your home?. Retaining Heat. Heat flows from hot to cold Three major heat transfer mechanisms: Conduction

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Clothing and Insulation

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  1. Clothing and Insulation

  2. Question: If you stand in front of an open refrigerator, too far away for any cold air to reach you, would you feel colder than you would facing a wall in your home?

  3. Retaining Heat • Heat flows from hot to cold • Three major heat transfer mechanisms: • Conduction • Convection • Radiation • To minimize heat flow, impede all three

  4. Conduction • Conductive heat flow depends on • Temperature difference • Thermal conductivity • Proximity (inverse length) • To minimize conductive heat flow, minimize all three items

  5. Convection • Convective heat flow depends on • Temperature difference • Mobility of fluid • Heat capacity of fluid • Convection cell formation • To minimize convective heat flow, minimize all four items

  6. Radiation • Radiative heat flow depends on • Temperature difference • Absolute temperatures of surfaces • Emissivity of surfaces • To minimize radiative heat flow, minimize all three items

  7. Question: If you stand in front of an open refrigerator, too far away for any cold air to reach you, would you feel colder than you would facing a wall in your home?

  8. Human Adaptations • Thermally insulating skin • Hair • Counter-current exchange • Evaporative cooling

  9. Sound Insulation • To minimize sound transmission • Block the passage of sound waves • Cause sound waves to reflect

  10. Electric Insulation • To minimize current flow • Immobilize electric charges • Many other issues are also involved

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