ME 323
Quiz 4
Name_____SOLUTION______
1.
The dimensionless parameter that characterizes natural convection is the
A.
Reynolds number
B.
Peclet number
C.
Biot number
D.
Grashoff number
2.
Natural convection occurs in heat transfer because
A.
Heat naturally flows from a hot body to cold body
B.
Fluid density decreases with an increase in temperature
C.
Sometimes the pumps necessary for forced convection are impractical
D.
The conservation equations are too difficult to solve
3.
The radiation view factor F ij
is defined as the fraction of radiation that surface i emits that is received by surface j. True or false?
A.
True
B.
False
4.
Thermal radiation is emitted continuously from a body unless its surface temperature is less than that of its surroundings. True or false?
A.
True
B.
False
5.
Which of the following is not true of radiation view factors?
A.
A i
B.

F
F ij
= A j
F ji ij
= 1
C.
F ii
= 0
D.
0 < F ij
< 1

6.
Consider two very long concentric cylinders. The inner one, surface 1, has diameter D; the outer one, surface 2, diameter 2D. What is the radiation view factor from outer to inner cylinder, F
21
?
A.
¼
B.
½
C.
¾
D.
1
7.
The transmissivity of glass tends to be high for short wave thermal radiation but low for long wave thermal radiation. True or false?
A.
True
B.
False
8.
The units for a convective heat transfer coefficient are
A.
W/m K
B.
W/m
2
K
C.
m
2
/s
D.
J/kg K
9.
Which of the following is NOT a fundamental heat transfer mechanism?
A.
Conduction
B.
Convection
C.
Radiation
D.
Latent Heat
10.
My favorite class at PSU has been
A.
Heat Transfer
B.
Heat Transfer
C.
Heat Transfer
D.
Heat Transfer