The material (Co = 460 J/kg°C, p = 7600 kg/m) has initally
uniform temperature of 100 °C. The material has placed to a
convection environment (h = 100 W/m2°C, T. = 20 °C). The
material has a heat generation rate of 90e+3 kW/m while the
right face of the material is maintained to be 100 °C. Calculate
the temperature of the indicated nodes after 10 seconds.
Answers
Answer:
For each of the following cases, determine an appropriate characteristic length Lc and the
corresponding Biot number Bi that is associated with the transient thermal response of the solid
object. State whether the lumped capacitance approximation is valid. If the temperature information is
not provided, evaluate properties at T = 300 K. a. A toroidal shape of diameter D = 65 mm and cross-
sectional area = 72
is of thermal conductivity k = 2.3 W/mK. The surface of the torus is
exposed to a coolant corresponding to a convection coefficient of h = 50 W/m2K.
b. A long, hot AISI 302 stainless steel bar of rectangular cross-section has dimensions w = 5 mm,
W = 7 mm, and L = 150 mm. The bar is subjected to a coolant that provides a heat transfer coefficient
of h = 10 W/m2K at all exposed surfaces.
c. A long extruded aluminum (Alloy 2024) tube of diameter of inner and outer dimensions w = 25 mm
and W = 30 mm, respectively, is suddenly submerged in water, resulting in a convection coefficient of
h = 40 W/m2K at the four exterior tube surfaces. The tube is plugged at both ends, trapping stagnant
air inside the tube.
d. An L = 300-mm-long solid stainless steel rod of diameter D = 13 mm and mass M = 0.328 kg is
exposed to a convection coefficient of h = 30 W/m2K.
f. A long cylindrical rod of diameter D = 20 mm, density, specific heat cp = 1750 J/kgK, and thermal
conductivity k = 16 W/mK is suddenly exposed to convective conditions with. The rod is initially at a
uniform temperature of T = 100℃ at t = 225 s.
g. Repeat part (f) but now consider a rod diameter of D = 200 mm.
Answer:
It is your answer hope it is correct.
