Chapter 8: Internal Forced Convection

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Average Velocity• The value of the average velocity is determined fromthe conservation of mass principle (8-1)m ρV A ρu r dA= =∫( )avg C CA• For incompressible flow in a circular pipe of radius RVavgρu r dA∫ ( )RC= ρu( r)πrdrAc= ∫0=Cc2 2ρA ρπR R2 2R∫0u r rdr( )(8-2)
Average Temperature• It is convenient to define the value of the meantemperature T m from the conservation ofenergy principle.• The energy transported by the fluid through across section in actual flow must be equal tothe energy that would be transported throughthe same cross section if the fluid were at aconstant temperature T mE = mcT = ∫cT( r) δm = ∫ ρcT( r) u( rVdA ) (8-3)fluid p m p p cmAc
Page 1: Chapter 8:Internal Forced Convectio
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 20 and 21: Constant Surface Temperature• The
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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