Theory and Design for Mechanical Measurements
6th Edition
ISBN: 9781118881279
Author: Richard S. Figliola, Donald E. Beasley
Publisher: WILEY
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Chapter 5, Problem 5.42P
A thermocouple is a temperature sensor made of two electrical conductors each of different materials. The conductors are electrically connected at two points, called junctions, each junction exposed to a different temperature. The thermocouple generates a voltage relative to the temperature gradient between junctions. Table 8.6 lists values of voltage as a function of temperature relative to one junction maintained at 0 °C for a thermocouple made from joining an iron wire with a constantan (chrome- nickel) wire. Estimate the sensitivity of the wire at 1 (X) “C (one junction) relative to 0 °C (one junction).
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X The sum of the second derivatives is zero
for some values of a and b.
The partial differential equation for two-
dimensional steady-state conduction assuming no
volumetric thermal energy generation and
constant properties is
+
= 0
dx?
dy?
The following temperature distribution is valid
under the stated conditions.
T = ax + by
True.
False.
True if a = -b.
O It is not possible to determine whether
the profile is valid.
II
A J- type thermocouple is used to measure the temperature in a heating process. Sheath material used is SS316. The length of the sheath is 10mm and thickness is 0.2mm. Find the time constant of the sheath.
Material
Q(kg/m3)
s(J/Kg - oc)
K(W/m-k)
Platinum
21450
130
71.6
SS304
8030
500
21.4
SS316
7990
500
21.4
SS410
7750
460
24.9
Air
1.20
1005
0.025
MgO Powder
3580
877
26.8
Silicon compound
3210
800
3
Time constant of the bare material is, T=
Answer
two kinds of bacteria are found in a sample of tainted food. it is found that the population size of type 1, N1 and of type 2, N2 satisfy the equation
dn/dt=-0.3/N1
dn/dt=0.4/N2
N1 is equal to 1500 at time equal to zero, while N2 is equal to 30 at time equal to zero. then the population sizes are equal
N1 = N2 at what time?
(4 decimal places)
Chapter 5 Solutions
Theory and Design for Mechanical Measurements
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