For each of the following cases, determine an appropriate characteristic length Lc and the corresponding Biot Bi number that is associated with the transient thermal response of the solid object. Say if the global capacitance approximation is va lid. If temperature information is not provided, evaluate properties T = 300K a)oroidal shape with diameter D = 50mm and cross-sectional area AC = 5 mm², with thermal conductivity k = 2.3W / (mK) The surface of the toroid is exposed to a refrigerant corresponding to a convective coefficient eta = 50 W/( m2.k)
For each of the following cases, determine an appropriate characteristic length Lc and the corresponding Biot Bi number that is associated with the transient thermal response of the solid object. Say if the global capacitance approximation is va lid. If temperature information is not provided, evaluate properties T = 300K
a)oroidal shape with diameter D = 50mm and cross-sectional area AC = 5 mm², with thermal conductivity k = 2.3W / (mK) The surface of the toroid is exposed to a refrigerant corresponding to a convective coefficient eta = 50 W/( m2.k)
b)A long stainless steel heated bar (AISI 304), with rectangular cross section, and dimensions w = 3mm , W = 5mm and L = 100mm . the bar issubjected to a refrigerant that provides a heat transfer coefficient of h =15 W/(m2 K) on all exposed surfaces.
c)A long extruded aluminum tube (2024 Alloy) with internal dimensions and external w = 20 mm and W = 24 mm , respectively, suddenly submerged in water, with a convective coefficient of h = 37 W/(m2 K) on the four surfaces outside of the tube. The tube is closed at its ends, which keeps stagnant air inside.
d)A solid rod, with length L = 300 mm, stainless steel with diameter D = 13 mm and mass M = 0.328 kg is exposed to a convective coefficient h = 30 W/(m2 - K).
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