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Unformatted text preview: 9/8/2010 1 Transient Conduction: The Lumped Capacitance Method The Lumped Capacitance Method Chapter Five Sections 5.2 thru 5.3 Class 7 What kind of situation is transient conduction? • A solid experiences a sudden change in its thermal environment – Quenching Charging – Charging • Lumped capacitance – Assume temperature is spatially uniform at any instant during the transient process – Therefore we assume no temperature gradients For this situation, what is the energy balance? g out in st st E E E t dE E & & & & + − = ≡ I II III IV a) I and II b) I and III c) I, II and III d) I and IV e) II, III and IV How do we use the energy balance to find our lumped capacitance approach? 9/8/2010 2 Define a thermal time constant: Define a thermal time constant: What will happen if we increase R t ? a) A solid will respond more slowly to changes in its thermal environment b) A solid will respond more quickly to changes in its thermal environment c) The R t does not affect the response – only the lumped thermal...
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This note was uploaded on 11/12/2010 for the course CHEN 3320 at Colorado.