(20pts) A thermocouple junction, which may be approximated as sphere, is to be used for temperature measurement in a gas stream.
The convection coefficient between the junction surface and the gas is h = 400 W/m2·K and the junction thermophysical properties are k = 20 W/m·K, c = 400 J/kg·K and rho = 8500 kg/m3. Determine the junction diameter needed for the thermocouple to have a time constant of 2 s. If the junction is at 25 °C and is placed in a gas stream that is at 200 °C, estimate the temperature of the junction after 10 minutes.
1 answer:
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Answer:
L= 312.75 mm
Explanation:
given data
elastic modulus E = 106 GPa
cross-sectional diameter d = 3.9 mm
tensile load F = 1660 N
maximum allowable elongation ΔL = 0.41 mm
to find out
maximum length of the specimen before deformation
solution
we will apply here allowable elongation equation that is express as
ΔL = ....................1
put here value and we get L
L =
solve it we get
L = 0.312752 m
L= 312.75 mm