부산대학교현규

부산대학교 화공생명공학부현 규 (Kyu Hyun)

유체역학및열전달

Chapter 11. Principles of Heat Flow in Fluids

-열교환기

유체역학및열전달 1

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Heat-Exchange Equipment – Using latent heat

-In this text the symbol ΔT is used to signify a temperature difference between two objects or two fluids

유체역학및열전달 2

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Heat-Exchange Equipment – Using sensible heat

l Countercurrent flow (or counter flow) 향류

l Parallel flow (or counter flow) 병류

Parallel flow is used in special situations èTo change the temperature of fluid rapidly

유체역학및열전달 3

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Energy Balances (1)

- Heat loss (cool down)

- Heat gain (heat up)

유체역학및열전달 4

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Energy Balances (2)

유체역학및열전달 5

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Heat flux and Heat-transfer coefficients (1)

-Tubular exchanger = Pipe shape-Plate type heat exchanger = Both side areas are same, only one U Value

유체역학및열전달 6

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Heat flux and Heat-transfer coefficients (2)

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Heat flux and Heat-transfer coefficients (3)

유체역학및열전달 8

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Heat flux and Heat-transfer coefficients (4)

l LMTD is not always valid -ΔT is not a linear function of q

-Cooling and condensing superheated vapor

-Temperature patterns in Jacketed tubular reactor

유체역학및열전달 9

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Individual heat-transfer coefficient (1)

유체역학및열전달 10

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Individual heat-transfer coefficient (2)

-Turbulent flow effect on the temperature profile (forced convection)

-Newton’s cooling law유체역학및열전달 11

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Individual heat-transfer coefficient (3)

-Tubular pipe

유체역학및열전달 12

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Individual heat-transfer coefficient (4)

-Eq. 10.15

유체역학및열전달 13

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Individual heat-transfer coefficient (5)

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Individual heat-transfer coefficient – Nusselt Number

Tube diameter

유체역학및열전달 15

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Overall heat-transfer coefficient

유체역학및열전달 16

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Individual heat-transfer coefficient -Plate

유체역학및열전달 17

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Heat conduction through composite walls – Plate (1)

-Newton’s cooling law

-q0 (heat flux) = constant

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Heat conduction through composite walls – Plate (2)

유체역학및열전달 19

Individual heat transfer coefficient

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Heat conduction through composite walls - Pipe

-r0q0 (heat flux) = constant