Need help to find Volumatic flow rate of water in pipe 1

[Subhash28]

Hello,

I need to find the Volumatic flow rate of the water. The inside diameter of the aluminum pipe is 0.006 meter. The inside temp of pipe is 75 °c. The water temp is 25°c while entering into pipe. The water temp is 50 °c when it comes out of the pipe. The pipe length is 1.3 meter.

Have to assume other value for the calculation. Please help.

 

[Artisi]

Rub the discharge into a bucket, calculate the volume and time the rate to fill it.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[LittleInch]

So a 6mm ID pipe?

If you use a power equation of 40W/m2/K you're probably not far off.

Use the mid temp difference.

Work out the heat power in your 1.5m

Then calculate how much volume of water you get for that power to heat up from 25 to 50C.

Then you have your volume/sec.

Then check the velocity. My guess for that temp is is about 0.5m/sec?

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[1503-44]

This is a homework problem.

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[Subhash28]

Thank you all for your response.

Based on the response.

I did attached the calculation. I believe, I did something wrong. the water volumetric flow rate should be between 6-12 gallon/min. May I am wrong.

Can someone check the calculation?

I really appreciate all the help.

 

[LittleInch]

Well your units are all over the place for startes.

I don't know where you got 1000W/m2/K from??

Your inputs differ from your OP.

Is this a pipe in a bath of water at 75C or 50C or what? I can't make any sense of what this thing is.

I don't understand why you've added 273 to the heat flow equation. all you need is the difference in temp in C or K.

Your low answer is about 13 m/sec by my calcualtion. That's too fast to raise the temperature

Is this homework???

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Subhash28]

I assume the heat transfer rate is 1000 w/m2 c.

No, It is part Electronic unit. I am trying to cool down the electronic unit with water cooling systems.

The Aluminum pipe gets the heat by condensation process. I assume that pipe inside temp is 75 °c

The only thing, I know is water temp at the out of pipe 50°c. For that, I need to find the volumetric flow rate.

I have attached the calculation excel sheet for your reference.

I added 273 in the heat flow question to convert the °c to °k.

Can you share your calculation for my reference about velosity 13 m/sec?

 

[LittleInch]

But then your calc has only 30C at the outlet.

Delete the +273.

All you're finding is the delta so it is (Ti+273) - (To+273) so the +273 cancels out.

You seem to be using the calculation for a water to water heat exchanger? Just keep it simple.

All I meant was 6 (US) gpm in a 6mm ID pipe has a velocity of 13 metres/second. So your water would be in there for 1/10th of a second. There is no way with that delta T that the water could raise in temperature 25 degrees.

I think it will need to be in the pipe for maybe 10 seconds? so a flowrate of 0.06 gpm?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[saplanti]

Whatever the amount (mass flow rate) comes in, the same amount (mass flow rate) comes out since the water is incompressible (do not go into compressibility of water and bulk modulus if you do not need a scientific applications).[tt][/tt] This is the Bernoulli basic information. The only change occurs in the density which may not be very significant for most of the processes. But you may find the values in the books for those temperatures. The other change will be in the velocity since the volumetric flow rate might change with the change of the density. The rest is the mathematics.
I guess you can figure it out all these.