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frutty [35]
3 years ago
9

A 4 cm diameter sphere of copper is initially at a temperature of 95 °C. It is placed in a very large water bath at time t- 0. T

he water bath is initially at a uniform temperature of 25 °C. The heat transfer coefficient is estimated to be 400 watts / (m2 °C). The specific heat of copper is 0.385 Joule (gram °C) and its density is approximately 9 gram per cc. Estimate the time at which the average temperature of the sphere will be 35 °C.
Engineering
1 answer:
avanturin [10]3 years ago
4 0

Answer:112.376 s

Explanation:

Given

T_i=95^{\circ}C

T_f=35^{\circ}C

T_\infty \left ( ambient\right )=25^{\circ}C

h=400 watts/\left ( m^{2}^{\circ}C\right )

c=0.385 J/\left ( m^2^{\circ}C\right )

\rho =9 gm/cm^{3}

Using Newton's law of cooling

\frac{T_i-T_{\infty}}{T-T_{\infty}}=e^{\frac{ht}{\rho L_{c}c}}

\frac{95-25}{35-25}=e^{\frac{400\times 3\times 10^{-4}\times t}{9\times 2\times 0.385}}

7=e^{1.7316\times 10^{-2}\times t}

Taking log both side

t=112.376sec

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See explanation below

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Ferrite has a higher tensile strength than cementite but cementite is harder.

Considering that hypoeutectoid steel contains ferrite at grain boundaries and pearlite inside grains whereas hypereutectoid steel contains a higher amount of cementite, the following properties are obtainable:

Hypo-eutectoid steel has higher yield strength than Hyper-eutectoid steel

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When making a knife or axe blade, I would choose Hyper-eutectoid steel alloy because

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7 0
3 years ago
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Thermal energy storage systems commonly involve a packed bed of solid spheres, through which a hot gas flows if the system is be
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C) attached below

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Given data :

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<u>A) Determine how long it takes a sphere near the inlet of the system to accumulate 90% of the maximum possible energy and the corresponding temperature at the center of sphere</u>

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attached below is a detailed solution of the given problem

<u>B) The physical properties are copper</u>

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It has an advantage over Aluminum

C<u>) Determine how long it takes a sphere near the inlet of the system to accumulate 90% of the maximum possible energy and the corresponding temperature at the center of sphere</u>

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