KNOWN: Rate at which radiation is intercepted by each of three surfaces (see (Example 12.1).
FIND: Irradiation, G[W/m ], at each of the three surfaces.
ANALYSIS: The irradiation at a surface is the rate at which radiation is inci
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 to make use of tables or charts. The approach involves u
KNOWN: Tabulated values of density for water and definition of the volumetric thermal expansion
FIND: Value of the volumetric expansion coefficient at 300K; compare with tabulated values.
PROPERTIES: Table A-6, Water (300
KNOWN: Water at 1 atm with Ts Tsat = 10C.
FIND: Show that the Jakob number is much less than unity; what is the physical significance of the
result; does result apply to other fluids?
ASSUMPTIONS: (1) Boiling situation, Ts > Tsat .
KNOWN: Initial overall heat transfer coefficient of a fire-tube boiler. Fouling factors following one
FIND: Whether cleaning should be scheduled.
ASSUMPTIONS: (1) Negligible tube wall conduction resistance, (2) N
KNOWN: Flowrate and temperature of water in fully developed flow through a tube of prescribed
FIND: Maximum velocity and pressure gradient.
ASSUMPTIONS: (1) Steady-state conditions, (2) Isothermal flow.
KNOWN: Temperature and velocity of fluids in parallel flow over a flat plate.
FIND: (a) Velocity and thermal boundary layer thicknesses at a prescribed distance from the leading
edge, and (b) For each fluid plot the boundary layer thicknesses
KNOWN: Steady-state, one-dimensional heat conduction through an axisymmetric shape.
FIND: Sketch temperature distribution and explain shape of curve.
ASSUMPTIONS: (1) Steady-state, one-dimensional conduction, (2) Constant properties
KNOWN: One-dimensional, plane wall separating hot and cold fluids at T,1 and T ,2 ,
FIND: Temperature distribution, T(x), and heat flux, q , in terms of T,1 , T,2 , h1 , h 2 , k
ASSUMPTIONS: (1) One-dimensiona
KNOWN: Method of separation of variables (Section 4.2) for two-dimensional, steady-state conduction.
FIND: Show that negative or zero values of , the separation constant, result in solutions which
cannot satisfy the boundary conditions.
KNOWN: Variation of hx with x for laminar flow over a flat plate.
FIND: Ratio of average coefficient, h x , to local coefficient, hx, at x.
ANALYSIS: The average value of hx between 0 and x is
h x dx = x -1/2dx
KNOWN: Electrical heater attached to backside of plate while front surface is exposed to
convection process (T,h); initially plate is at a uniform temperature of the ambient air and suddenly
heater power is switched on providing a constant q .