As part of a heat treatment process, cylindrical, 304 stainless steel rods of 100-mm diameter are cooled from an initial temperature of 500 ° C by suspending them in an oil bath at 30 ° C . If a convection coefficient of 500 W/m 2 ⋅ K is maintained by circulation of the oil, how long does it take for the centerline of a rod to reach a temperature of 50 ° C, at which point it is withdrawn from the bath? If 10 rods of length L = 1 m are processed per hour, what is the nominal rate at which energy must be extracted from the bath (the cooling load)?
As part of a heat treatment process, cylindrical, 304 stainless steel rods of 100-mm diameter are cooled from an initial temperature of 500 ° C by suspending them in an oil bath at 30 ° C . If a convection coefficient of 500 W/m 2 ⋅ K is maintained by circulation of the oil, how long does it take for the centerline of a rod to reach a temperature of 50 ° C, at which point it is withdrawn from the bath? If 10 rods of length L = 1 m are processed per hour, what is the nominal rate at which energy must be extracted from the bath (the cooling load)?
Solution Summary: The author explains that the heat removal rate from bath is calculated as 140.5s. The calculated Biot number is greater than (0.1) due to which one cannot use the lumpe
As part of a heat treatment process, cylindrical, 304 stainless steel rods of 100-mm diameter are cooled from an initial temperature of
500
°
C
by suspending them in an oil bath at
30
°
C
.
If a convection coefficient of
500
W/m
2
⋅
K
is maintained by circulation of the oil, how long does it take for the centerline of a rod to reach a temperature of
50
°
C,
at which point it is withdrawn from the bath? If 10 rods of length
L
=
1
m
are processed per hour, what is the nominal rate at which energy must be extracted from the bath (the cooling load)?
A composite plane wall consisting of materials, 1.5-in steel (k = 312 BTU-in/HR.ft2.0F) and 2-in aluminum (k = 1400 BTU-in/HR.ft2.0F), separates a hot gas at Ti = 2000F, hi = 2 BTU/HR.ft2.0F, from cold gas at To = 80 deg F, ho = 5. If the hot fluid is on the aluminum side, find: a) Transmittance, U; b) The heat through 100 sq. ft of the surface under steady state condition and c) The interface temperature at the junction of the metals.
Indirect Cooling With Liquid Nitrogen. You are designing a system to cool an insulated silver plate of dimensions 2.00 cm × 2.00 cm × 0.60 cm. One end of a thermally insulated copper wire (diameter D = 2.70 mm and length L = 18.0 cm) is dipped into a vat of liquid nitrogen (T = 77.2 K), and the other end is attached to the bottom of the silver plate.(a) If the silver plate starts at room temperature (65.0 °F), what is the initial rate of heat flow between the plate and the liquid nitrogen reservoir?(b) Assuming the rate of heat flow calculated in part (a), estimate the temperature of the silver plate after 30.0 seconds.
3. A food product with 73% moisture content in a 10 cm diameter can wants to be frozen. The density of the product is 970 kg / m³, the thermal conductivity is 1.2 W / (m K), and the initial freezing temperature is -2 ° C. After 14 hours in the freezing medium -30 ° C, the product temperature becomes -10 ° C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder.
h = Answer
W / (m² K).
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