设计:徐志明
Chapter 10
Heat Exchangers
换热器热
10-1 Introduction
Three modes of heat transfer
conduction
convection
radiation
We study separately
Integrated application
Technical analysis
Economic gain
Sustainable development
definition of the overall heat transfer coefficient
10-2 The overall heat transfer coefficient
a plane wall
h1 and h 2 are calculated with the method in previous sections
Combined Heat Transfer (Radiation heat transfer)
1). Calculation of heat transferred by radiation qr
4). Total heat flow rate
3). then
2). Defining
tubes
The overall heat transfer coefficient based on inside area of the tube
The overall heat transfer coefficient based on outside area of the tube
fin-wall combinations
open wall
10-3 Fouling factors
Fouling (污垢)---The coating of various deposit on heat transfer surfaces
Fouling provides an additional thermal resistance which is called fouling thermal resistance or Fouling Factor.
An alternative definition
Plane wall
Outside surface of a tube
induction period(诱导期)
linear
falling
渐进
渐进污垢热阻
asymptotic fouling
resistance

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