PROBLEM 1.8
KNOWN: Net power output, average compressor and turbine temperatures, shaft dimensions and
thermal conductivity.
FIND: (a) Comparison of the conduction rate through the shaft to the predic
PROBLEM 1.40
KNOWN: Width, surface emissivity and maximum allowable temperature of an electronic chip.
Temperature of air and surroundings. Convection coefficient.
2
1/4
FIND: (a) Maximum power dissip
PROBLEM 1.39
KNOWN: Hot and cold reservoir temperatures of an internally reversible refrigerator. Thermal
resistances between refrigerator and hot and cold reservoirs under clean and dusty conditions.
PROBLEM 1.38
KNOWN: Hot and cold reservoir temperatures of an internally reversible refrigerator. Thermal
resistances between refrigerator and hot and cold reservoirs.
FIND: Expressions for modified C
PROBLEM 1.37
KNOWN: Flow of water in a vertical tube. Tube dimensions. Mass flow rate. Inlet pressure and
temperature. Heat rate. Outlet pressure.
FIND: (a) Outlet temperature, (b) change in combined
PROBLEM 1.36
KNOWN: Inlet and outlet conditions for flow of water in a vertical tube.
FIND: (a) Change in combined thermal and flow work, (b) change in mechanical energy, and (c)
change in total energ
PROBLEM 1.35
KNOWN: Resistor connected to a battery operating at a prescribed temperature in air.
&
FIND: (a) Considering the resistor as the system, determine corresponding values for Ein ( W ) ,
&
&
PROBLEM 1.34
KNOWN: Vacuum enclosure maintained at 77 K by liquid nitrogen shroud while baseplate is
maintained at 300 K by an electrical heater.
FIND: (a) Electrical power required to maintain basepl
PROBLEM 1.33
KNOWN: Exact and approximate expressions for the linearized radiation coefficient, hr and hra,
respectively.
FIND: (a) Comparison of the coefficients with = 0.05 and 0.9 and surface tempe
PROBLEM 1.32
KNOWN: Hot plate suspended in vacuum and surroundings temperature. Mass, specific heat, area
and time rate of change of plate temperature.
FIND: (a) The emissivity of the plate, and (b) T
PROBLEM 1.31
KNOWN: Spherical shaped instrumentation package with prescribed surface emissivity within a
large space-simulation chamber having walls at 77 K.
FIND: Acceptable power dissipation for ope
PROBLEM 1.30
KNOWN: Diameter and emissivity of spherical interplanetary probe. Power dissipation
within probe.
FIND: Probe surface temperature.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2)
PROBLEM 1.29
KNOWN: Air and wall temperatures of a room. Surface temperature, convection coefficient
and emissivity of a person in the room.
FIND: Basis for difference in comfort level between summer
PROBLEM 1.28
KNOWN: Length, diameter, surface temperature and emissivity of steam line. Temperature
and convection coefficient associated with ambient air. Efficiency and fuel cost for gas fired
furna
PROBLEM 1.27
KNOWN: Upper temperature set point, Tset, of a bimetallic switch and convection heat
transfer coefficient between clothes dryer air and exposed surface of switch.
FIND: Electrical power f
PROBLEM 1.26
KNOWN: Chip width and maximum allowable temperature. Coolant conditions.
FIND: Maximum allowable chip power for air and liquid coolants.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state condition
PROBLEM 1.25
KNOWN: Length, diameter and calibration of a hot wire anemometer. Temperature of air
stream. Current, voltage drop and surface temperature of wire for a particular application.
FIND: Air
PROBLEM 1.24
KNOWN: Dimensions of a cartridge heater. Heater power. Convection coefficients in air
and water at a prescribed temperature.
FIND: Heater surface temperatures in water and air.
SCHEMATIC:
PROBLEM 1.23
KNOWN: Width, input power and efficiency of a transmission. Temperature and convection
coefficient associated with air flow over the casing.
FIND: Surface temperature of casing.
SCHEMATIC
PROBLEM 1.22
KNOWN: Hot vertical plate suspended in cool, still air. Change in plate temperature with time at the
instant when the plate temperature is 225C.
FIND: Convection heat transfer coefficient
PROBLEM 1.21
KNOWN: Long, 30mm-diameter cylinder with embedded electrical heater; power required
to maintain a specified surface temperature for water and air flows.
FIND: Convection coefficients for
PROBLEM 1.20
KNOWN: Inner and outer surface temperatures of a wall. Inner and outer air temperatures and
convection heat transfer coefficients.
FIND: Heat flux from inner air to wall. Heat flux from w
PROBLEM 1.19
KNOWN: Power required to maintain the surface temperature of a long, 25-mm diameter cylinder
with an imbedded electrical heater for different air velocities.
FIND: (a) Determine the conve
PROBLEM 1.18
KNOWN: Hand experiencing convection heat transfer with moving air and water.
FIND: Determine which condition feels colder. Contrast these results with a heat loss of 30 W/m2 under
normal
PROBLEM 1.17
KNOWN: Heat flux and convection heat transfer coefficient for boiling water. Saturation
temperature and convection heat transfer coefficient for boiling dielectric fluid.
FIND: Upper surf
PROBLEM 1.16
KNOWN: Dimensions and thermal conductivity of a chip. Power dissipated on one surface.
FIND: Temperature drop across the chip.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2) Con
PROBLEM 1.15
KNOWN: Thickness, diameter and inner surface temperature of bottom of pan used to boil
water. Rate of heat transfer to the pan.
FIND: Outer surface temperature of pan for an aluminum and
PROBLEM 1.14
KNOWN: Expression for variable thermal conductivity of a wall. Constant heat flux.
Temperature at x = 0.
FIND: Expression for temperature gradient and temperature distribution.
SCHEMATIC:
PROBLEM 1.13
KNOWN: Masonry wall of known thermal conductivity has a heat rate which is 80% of that
through a composite wall of prescribed thermal conductivity and thickness.
FIND: Thickness of masonr
PROBLEM 1.12
KNOWN: Dimensions and thermal conductivity of food/beverage container. Inner and outer
surface temperatures.
FIND: Heat flux through container wall and total heat load.
SCHEMATIC:
ASSUMPT