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Velocity field fully developed ”Heat balance” for an element dxdr2?r Heat conduction in radial direction Enthalpy transport in x-direction
CHAPTER 6 HEAT TRANSFER APPLICATIONS The principles of heat transfer are widely used in food processing in many items of equipment
Heat transfer due to a superposition of energy transport by the random motion of the molecules (diffusion), and by the bulk motion of the fluid
The egg is cooled by transferring heat by convection to the air and by radiation to the surrounding surfaces Disregarding heat transfer by radiation, the
Velocity boundary layer: surface shear stress: local friction coeff : Thermal boundary layer: local heat flux: local heat transfer coeff :
Page 1 Vol 2 Chapter 6 – Heat Transfer Page 2 Page 3 Page 4 Page 5 Page 6 Page 7
Although consideration of these means is deferred to Chapter 6, convection heat transfer will frequently appear as a boundary condition in the solu-
6 1 Absorbing and Losing Heat ?In this section you will investigate how different materials absorb heat at different rates This is referred to as
Convective Heat Transfer (6) heat transfer Introduction of heat transfer coeficient: Heat conduction in the fluid (calulating the heat flow as in chapter 1) Qd
Velocity boundary layer: surface friction and friction coefficient C f ▫ Thermal boundary layer: convection heat transfer and heat transfer convection coefficient h
gies between momentum and heat transfer 333 CHAPTER 6 CONTENTS 6–1 Physical Mechanism on Convection 334 6–2 Classification of Fluid Flows
The particles (atoms and/or molecules) cease vibrating No movement occurs Page 4 Heat Transfer ▫ Always trying to reach Thermodynamic Equilibrium