- #1
zippycorners
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Hello, I'm not actually asking a homework question. I'm working at an internship and have been asked a practical question about how long it will take a steel rod to change temperatures.
Because it's not a problem from a textbook, I may not have all the required data, but I can certainly try to find it.
We have a steel rod at 41°F. It is in a room that is 68°F The rod is 3/4" in diameter, and 6" long. How long will it take for the pipe to reach 68°F?
I've been using these numbers:
The Specific Heat (Cρ) of Carbon Steel is: 0.49 (kJ/kg K), 0.12 (kcal/kg°C), or 0.12 (Btu/lbm°F)
I got those numbers from this website.
I also calculated the area of the rod to be A = .84375∏ inches cubed.
I haven't taken a Heat Transfer course yet, but I've spent the past several hours reading about it on the internet (haha). I've been plugging in numbers into all sorts of equations, trying to find an answer. These are the equations I've been using are:
Rate = k•A•(T1 - T2)/d
Q = h*A*(Ts-T∞) (where T∞ is the temperature of the air)
(Q_dot) = (m_dot)*(c_p)(T1-T2)
Because I haven't taken a Heat Transfer course yet, and I honestly have never seen these equations before, I don't think I did anything right. I think I am very close, but need a little guidance. I know that Q is going to be power, and I think that I can use Watt*second for that, but I'm still having a hard time relating these equations to time.
Can someone give me a hand?
Homework Statement
Because it's not a problem from a textbook, I may not have all the required data, but I can certainly try to find it.
We have a steel rod at 41°F. It is in a room that is 68°F The rod is 3/4" in diameter, and 6" long. How long will it take for the pipe to reach 68°F?
I've been using these numbers:
The Specific Heat (Cρ) of Carbon Steel is: 0.49 (kJ/kg K), 0.12 (kcal/kg°C), or 0.12 (Btu/lbm°F)
I got those numbers from this website.
I also calculated the area of the rod to be A = .84375∏ inches cubed.
Homework Equations
I haven't taken a Heat Transfer course yet, but I've spent the past several hours reading about it on the internet (haha). I've been plugging in numbers into all sorts of equations, trying to find an answer. These are the equations I've been using are:
Rate = k•A•(T1 - T2)/d
Q = h*A*(Ts-T∞) (where T∞ is the temperature of the air)
(Q_dot) = (m_dot)*(c_p)(T1-T2)
The Attempt at a Solution
Because I haven't taken a Heat Transfer course yet, and I honestly have never seen these equations before, I don't think I did anything right. I think I am very close, but need a little guidance. I know that Q is going to be power, and I think that I can use Watt*second for that, but I'm still having a hard time relating these equations to time.
Can someone give me a hand?