PROBLEM 7.90
KNOWN: Surface temperature and geometry of a tube bank. Velocity and temperature of air in cross
flow.
FIND: (a) Total heat transfer, (b) Air flow pressure drop.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2) Negligible radiation an

PROBLEM 9.19
KNOWN: Room and ambient air conditions for window glass.
FIND: Temperature of the glass and rate of heat loss.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2) Negligible temperature gradients in the glass, (3)
Inner and outer surface

PROBLEM 9.35
KNOWN: Surface temperature of a long duct and ambient air temperature.
FIND: Heat gain to the duct per unit length of the duct.
SCHEMATIC:
ASSUMPTIONS: (1) Surface radiation effects are negligible, (2) Ambient air is quiescent.
-6 2
PROPERTIE

PROBLEM 9.52
KNOWN: Horizontal rod immersed in water maintained at a prescribed temperature.
FIND: Free convection heat transfer rate per unit length of the rod, qconv
SCHEMATIC:
ASSUMPTIONS: (1) Water is extensive, quiescent medium.
3
PROPERTIES: Table A

PROBLEM 9.75
KNOWN: Horizontal tubes of different shapes each of the same cross-sectional area transporting a
hot fluid in quiescent air. Lienhard correlation for immersed bodies.
FIND: Tube shape which has the minimum heat loss to the ambient air by free

PROBLEM 9.16
KNOWN: Interior air and wall temperatures; wall height.
FIND: (a) Average heat transfer coefficient when T = 20C and Ts = 10C, (b) Average heat
transfer coefficient when T = 27C and Ts = 37C.
SCHEMATIC:
ASSUMPTIONS: (a) Wall is at a uniform t

PROBLEM 9.13
KNOWN: Square aluminum plate at 15C suspended in quiescent air at 40C.
FIND: Average heat transfer coefficient by two methods using results of boundary layer similarity
and results from an empirical correlation.
SCHEMATIC:
ASSUMPTIONS: (1) Un