KNOWN: Radiation from a diffuse radiant source A1 with intensity I1 = 1.2 10 W/m sr is
incident on a mirror Am, which reflects radiation onto the radiation detector A2.
FIND: (a) Radiant power incident on Am due to emission from the sourc
Sketch a schematic of the each of the following systems with labeled arrows identifying the
relevant heat transfer processes. Write an energy balance for the system in terms of the
transport laws of each heat transfer mode, and state any
ENF P 3 12
1. A composite spherical shell of inner radius r1 = 0.25 m is constructed from lead of outer radius
r2 = 0.30 m and A181 302 stainless steel of outer radius r3 = 0.31 m. The cavity is lled with radioactive
Introduction to Fluid Mechanics
1) [25 points] Mark all of the following statements as true (T) or false (F).
2 2 a). Extensive properties are independent of the amount of material considered.
2 2 b). The velocity
Introduction to Fluid Mechanics
Midterm I; Part I: closed books and closed notes
1a) [10 points] Mark all of the following statements as true (T) or false (F).
2 2 a). Within a constant density fluid that is stationary the pre
As part of the academic integrity code practiced at the University of
Maryland, please copy the statement below on the space provided, and
three nodal points of a block with thermal conductivity
of 1 Wm-K are shown in the figure. Calculate the temperature at node 1 , 2 and 3 when
the top and bottom surfaces are insulated and the right side is exposed to ambient air.
1. The steady state tempe
1.) Calculate the following:
a. The velocity boundary layer thickness over an isothermal at plate at 12 cm
downstream of the leading edge. The freestream velocity is 2 m/s and the
kinematic viscosity is 2><10'5 mZ/s.
KNOWN: Right-circular cylinder of diameter D, length L and the areas A1, A2, and A3 representing
the base, inner lateral and top surfaces, respectively.
FIND: (a) Show that the view factor between the base of the cylinder and the inner latera
KNOWN: Small flat plate maintained at 400 K coated with white paint having spectral absorptivity
distribution (Figure 12.22) approximated as a stairstep function. Enclosure surface maintained at 3000 K
with prescribed spectral emissivity dis
KNOWN: Surface temperatures of a steel wall and temperature of water flowing over the
FIND: (a) Convection coefficient, (b) Temperature gradient in wall and in water at wall
ASSUMPTIONS: (1) Steady-state conditions, (
KNOWN: Surface temperatures of two parallel pipe lines buried in soil.
FIND: Heat transfer per unit length between the pipe lines.
ASSUMPTIONS: (1) Steady-state conditions, (2) Two-dimensional conduction, (3)
Constant properties, (
KNOWN: One-dimensional wall, initially at a uniform temperature, Ti, is suddenly exposed
to a convection process (T, h). For wall #1, the time (t1 = 100s) required to reach a specified
temperature at x = L is prescribed, T(L1, t1) = 315C.
KNOWN: Heat flux and surface temperatures associated with a wood slab of prescribed
FIND: Thermal conductivity, k, of the wood.
ASSUMPTIONS: (1) One-dimensional conduction in the x-direction, (2) Steady-state
KNOWN: Composite wall of a house with prescribed convection processes at inner and
FIND: (a) Expression for thermal resistance of house wall, R tot ; (b) Total heat loss, q(W); (c)
Effect on heat loss due to increase in outsid
1. A plane wall with k = 0.12 W/m-K and thickness La = 0.3 m separates two uids at
temperatures Ti = 27C and T 0=5C. The convective heat transfer coefcients between the wall
and each uid is h = 50 W/mz-K, and ho = 5 W/m2-1<.
Conceptual short answer questions
2 or 3 problems
Equation sheets, tables of thermophysical
properties, and values of mathematical
functions will be provided. You will not need
to interpolate any table values.