Chapter 8: Internal Forced Convection

More documents

Recommendations

Info

• The temperature difference between the fluid and the surface decaysexponentially in the flow direction, and the rate of decay depends onthe magnitude of the exponenthAsmc p• This dimensionless parameter iscalled the number of transferunits (NTU).–Large NTU value – increasing tubelength marginally increases heattransfer rate.–SmallNTU value – heat transfer increasessignificantly with increasing tube length.
• Solving Eq. 8–29 for mc p giveshAsmc p=(8-31)ln ⎡⎣( Ts −Te) ( Ts −Ti)⎤⎦• Substituting this into Eq. 8–15Q= mc T −T (8-32)Q = hA∆T( ) (W)p e islnwhereT −T ∆T −∆T∆ Tln= =ln ⎡⎣s e s i ⎦ei e e i( T −T ) ( T −T) ⎤ ln[ ∆T∆T]i(8-33)∆Τ ln is the logarithmic mean temperature difference.
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 20 and 21: Constant Surface Temperature• The
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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?