1. HEAT TRANSFER
Final Review
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2. Final Review Session
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3. Viscous Flow The Navier-Stokes Equations
Nonlinear, second order, partial differential equations.
Couette Flow, Poiseuille Flow.
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4. Convection Basic heat transfer equation
Primary issue is in getting convective heat transfer coefficient, h
h relates to the conduction into the fluid at the wall
average heat transfer coefficient
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5. Convection Heat Transfer Correlations
Key is to fully understand the type of problem and then make sure you apply the appropriate convective heat transfer coefficient correlation
External Flow
For laminar flow over flat plate
For mixed laminar and turbulent flow over flat plate y
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6. External Convection Flow
For flow over cylinder
Overall Average Nusselt number
Table 7.2 has constants C and m as f(Re)
For flow over sphere
For falling liquid drop
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7. Convection with Internal Flow
Main difference is the constrained boundary layer
Different entry length for laminar and turbulent flow
Compare external and internal flow:
External flow: Reference temperature: T is constant
Internal flow: Reference temperature: Tm will change if heat transfer is occurring!
Tm increases if heating occurs (Ts > Tm )
Tm decreases if cooling occurs (Ts < Tm ) ro
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8. Internal Flow (Cont’d)
For constant heat flux:
For constant wall temperature
Sections 8.4 and 8.5 contain correlation equations for Nusselt number T x T x
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9. Free (Natural) Convection
Unstable, Bulk fluid motion
Stable, No fluid motion
Grashof number in natural convection is analogous to the Reynolds number in forced convection
Natural convection can be neglected
Natural convection dominates
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10. Free (Natural) Convection
Rayleigh number: For relative magnitude of buoyancy and viscous forces
Review the basic equations for different potential cases, such as vertical plates, vertical cylinders, horizontal plates (heated and cooled)
For horizontal plates, discuss the equations (P513)
Please refer to problem 9.34.
For vertical surface, transition to turbulence at Rax  109
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11. Heat Exchangers Example: Shell and Tube: Cross-counter Flow
Two basic methods discussed:
LMTD Method
-NTU Method
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12. Discussion on the U Notice! Example 11.1 Equation 11.5
For the unfinned, concentric, tubular heat exchangers.
When the inner tube surface area is the reference calculating area.
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13. Discussion on the problems
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