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Unformatted text preview: Heat Transfer: Heat Transfer: Physical Origins Physical Origins and and Rate Equations Rate Equations Chapter One Chapter One Sections 1.1 and 1.2 Sections 1.1 and 1.2 Heat Transfer and Thermal Energy • What is heat transfer ? Heat transfer is thermal energy in transit due to a temperature difference. • What is thermal energy ? Thermal energy is associated with the translation, rotation, vibration and electronic states of the atoms and molecules that comprise matter. It represents the cumulative effect of microscopic activities and is directly linked to the temperature of matter. Heat Transfer and Thermal Energy (cont.) Quantity Meaning Symbol Units Thermal Energy + Energy associated with microscopic behavior of matter Temperature A means of indirectly assessing the amount of thermal energy stored in matter Heat Transfer Thermal energy transport due to temperature gradients Heat Amount of thermal energy transferred over a time interval t 0 Heat Rate Thermal energy transfer per unit time Heat Flux Thermal energy transfer per unit time and surface area or U u J or J/kg T K or °C Q J q W q ′′ 2 W/m + Thermal energy of system Thermal energy per unit mass of system U u → → DO NOT confuse or interchange the meanings of Thermal Energy , Temperature and Heat Transfer Modes of Heat Transfer Conduction: Heat transfer in a solid or a stationary fluid (gas or liquid) due to the random motion of its constituent atoms, molecules and /or...
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 Spring '08
 Kuznetsov
 Thermal Energy, Heat Transfer, Tsur

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