Heat Transfer (I guess eng question)

Thought this would be the most appropriate forum to ask for help

Air flows through a copper inside tube and is heated by saturated steam condensing on the outside of the tube.

1. Determine the rate of heat transfer to the air at 3 different flow rates of the air (rotameter readings 10, 20 and 30).
For each air flow rate:
2. Experimentally determine the overall heat transfer coefficient based on the outside area of the pipe.
3. Estimate the inside (air) film heat transfer coefficient assuming that the resistances of the copper wall and steam film are small compared to the resistance of the air film.
4. Predict the film heat transfer coefficient using the Dittus-Boelter equations.
5. Compare the film heat transfer coefficients from the experiments with those calculated from the Dittus-Boelter equation. Comment on the comparison.
6. Estimate the steam consumption, stating assumptions.

The schematic is attached.

The dimensions of central copper tube are:
Length: L = 300 mm
Inside diameter: di = 4.5 mm
Outside diameter: do = 6.3 mm

Just wondering what the best way to approach this is, and how to answer all the questions, what measurements to make etc?

Any links or straight out advice?

Thanks very much

If you are new in thermodynamics and heat transfer engineering, you would better ask some body specialized in the field, unless you are lucky enough and find a website such as this one:

http://www.efunda.com/formulae/heat_...e/overview.cfm

which, unfortunately, doesn´t provide a straight answer to your problem, but may be a beginning.

Otherwise it will take you ages to understand and master the subject.

I don´t think you will find qualified respondants to this question of yours in this particular forum.

This might be a good forum for the question.
It's down right now, for some reason.

http://www.eng-tips.com/threadminder.cfm?pid=391


I hope the link hasn't been redirected to a dead server...

When I took heat tran a few years ago, I bought a solutions manual for an older edition of my book. Most of the problems had been changed, but the general methods for solving the problems were the same. I found it on half.com I think and the person sent me a link and password to download it from his site. I wish I could still remember heat tran, but I forgot most of it.

This might also help:

http://www.livstek.lth.se/People_lis...htm#individual

All I did was a Google search on 'Dittus-Boelter equations'. This is pretty hard core stuff. You must be taking a mechanical or chemical engineering class.

Well, let's see what we know:

- temperature of the outside of the pipe (hint: condensing steam)
- air flow through the pipe
- pipe geometry

Here's how I would approach it:

1. Find the film heat transfer coefficient using the Dittus-Boelter equations. My guess is that all you need is reynolds number (should be able to calculate from air flow rate and geometry)

2. Find heat transfer rate from condensing steam to the air flowing inside the pipe using standard convective heat transfer equations. Should also be able to get temp of air inside the pipe at each flow rate.

3. Find steam consumption using thermodynamic properties of condensing steam and the heat transfer (energy transfer) rate from 2.

4. Experimental measurements would be air temp inside the pipe at each flow rate, amount of steam consumption (measure the rate of liquid water accumulation)

still working on this?

Quote:

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5. Compare the film heat transfer coefficients from the experiments with those calculated from the Dittus-Boelter equation. Comment on the comparison.

---

Nu = (.024Re^.8)*Pr^.4

h=Nu*k/d

That should get you started....