RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
Department of Mechanical and Aerospace Engineering
650:481 HEAT TRANSFER
MIDTERM EXAM
OPEN BOOK AND NOTES
March 21, 2012
80 Mins.
NOTE: All questions carry
PROBLEM 12.3
KNOWN: Thickness and temperature of aluminum plate. Irradiation. Convection conditions.
Absorptivity and emissivity.
FIND: Radiosity and net radiation heat flux at top plate surface, rate
PROBLEM 7.3
KNOWN: Velocity and temperature of air in parallel flow over a flat plate.
FIND: (a) Velocity boundary layer thickness at selected stations. Distance at which boundary layers
merge for pla
PROBLEM 6.2
KNOWN: Form of the velocity and temperature profiles for flow over a surface.
FIND: Expressions for the friction and convection coefficients.
SCHEMATIC:
ANALYSIS: The shear stress at the w
PROBLEM 4.2
KNOWN: Two-dimensional rectangular plate subjected to prescribed uniform temperature boundary
conditions.
FIND: Temperature at the mid-point using the exact solution considering the first
PROBLEM 3.5
KNOWN: Thermal conductivities and thicknesses of original wall, insulation layer, and glass layer.
Interior and exterior air temperatures and convection heat transfer coefficients.
FIND: H
PROBLEM 1.2
KNOWN: Thickness and thermal conductivity of a wall. Heat flux applied to one face and
temperatures of both surfaces.
FIND: Whether steady-state conditions exist.
SCHEMATIC:
L = 10 mm
T2 =
Lecture 16
Flow over Bluff Objects
March 11, 2011
Cylinder in Cross Flow
The Cylinder in Cross Flow
Conditions depend on special features of boundary layer development, including
onset at a stagnatio
PROBLEM 8.2
KNOWN: Temperature and mean velocity of water flow through a cast iron pipe of
prescribed length and diameter.
FIND: Pressure drop.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2)
PROBLEM 9.1
KNOWN: Thickness and thermal conductivity of plane wall. Fluid temperatures.
FIND: Expected minimum and maximum steady-state heat fluxes through the wall for (a) free
convection in gases,
PROBLEM 13.1
KNOWN: Various geometric shapes involving two areas A1 and A2.
FIND: Shape factors, F12 and F21, for each configuration.
ASSUMPTIONS: Surfaces are diffuse.
ANALYSIS: The analysis is not t
RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
School of Engineering
Department of Mechanical and Aerospace Engineering
650:481 HEAT TRANSFER (3 Cr)
Tentative Schedule:
Week
Topic
Chapter
1
2
3
4
5
6
7
8
Lecture 17
Internal Flow:
General Considerations
March 23, 2011
Entrance Conditions
Entrance Conditions
Must distinguish between entrance and fully developed regions.
Hydrodynamic Effects: Assume la
Lecture 18
Internal Flow:
Heat Transfer Correlations
March 25, 2011
Fully Developed Flow
Fully Developed Flow
Laminar Flow in a Circular Tube:
The local Nusselt number is a constant throughout the fu
Lecture 19
Free Convection:
General Considerations
and Results for
Vertical and Horizontal Plates
March 30, 2011
General Considerations
General Considerations
Free (natural) convection refers to flui
Review
Review
Be familiar with the expressions of various
familiar with the expressions of various
thermal resistances (Table 3.3, p. 126)
Thermal circuit: steady state, no
circuit: steady state no
Lecture 6
Extended Surfaces
& Fins Problem
02/04/11
Nature and Rationale
Nature and Rationale of Extended Surfaces
An extended surface (also know as a combined conduction-convection system
or a fin)
Lecture
Lecture 7
Single Fins and Fin Arrays
02/09/11
Review
Review
Essential function of fins: Enhancement of
function of fins: Enhancement of
Heat Transfer
Thin Fin Approximation:
Fin Approximatio
Lecture 8
2-D Steady-State Conduction
02/11/11
General Considerations
General Considerations
Two-dimensional conduction:
Temperature distribution is characterized by two spatial coordinates,
e.g., T
Lecture 9
Transient Conduction:
The Lumped Capacitance Method
02/16/11
Transient Conduction
Transient Conduction
A heat transfer process for which the temperature varies with time.
It is initiated w
Lecture 13
Introduction to Convection
Chapter 6 and Appendix D
03/03/11
Boundary Layers: Physical Features
Velocity Boundary Layer
A consequence of viscous effects
associated with relative motion
be
Lecture 14
The Reynolds Analogy
03/04/11
The Principle of Similarity
Review
VL VL
=
the Reynolds Number
v
cp v
Pr
= the Prandtl Number
k
Re L
s
2 u *
Cf
=
V 2 / 2 Re L y*
h=
k f T / y
y =0
Ts T
y