Chapter 8: Internal Forced Convection

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Constant Surface Temperature• The energy balance on a differential control volumeδ Q = mc dT = h T −T dA (8-27)( )p m s m s• Since the mean temperature of the fluid T m increases in the flowdirection, the heat flux decays with x.• The surface temperature is constant (dT m =-d(T s -T m )) anddA s =pdx, therefore,−d( T ) sTmhp=− dxT −T mc s m p(8-28)
• Integrating Eq. 6-28 from x=0 (tube inletwhere T m =T i ) to x=L (tube exit where T m =T e )givesT −T hAln s e =−sTs −Ti mc p• Taking the exponential of both sides andsolving for T e(8-29)• orT = T − T −T −hpL mc ( ) exp( )e s s i pT x T T T hpx mc( ) = −( − ) exp( − )m s s i p x 度(8-30)
Page 1: Chapter 8:Internal Forced Convectio
Page 4 and 5: Average Velocity• The value of th
Page 6 and 7: • For incompressible flow in a ci
Page 8 and 9: The Entrance Region• A fluid ente
Page 10 and 11: Thermal Entrance Region• Consider
Page 12 and 13: • Surface heat flux can be expres
Page 14 and 15: Entry Lengths ()- HydrodynamicLamin
Page 16 and 17: General Thermal Analysis• In the
Page 18 and 19: • In the fully developed region,
Page 22 and 23: • The temperature difference betw
Page 24 and 25: Laminar Flow in TubesAssumptions:
Page 26 and 27: • Taking the limit as dr, dx 0 g
Page 28 and 29: • Combining the last two equation
Page 30 and 31: • A pressure drop due to viscous
Page 32 and 33: • Or∂T1 ∂Qu =−( )∂ x ρc
Page 34 and 35: • Separating the variables and in
Page 36 and 37: Constant Surface temperature (circu
Page 38 and 39: - HydrodynamicLaminar flowLh,lamina
Page 40 and 41: Turbulent flow in Tubes• Most cor
Page 42: Moody Diagram

Chapter 8: Internal Forced Convection

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