FLUID TEMPERATURE: FORMULA TO CALCULATE TEMPERATURE 1

[XISCOGUA]

FIRST ALL, HI TO EVERYBODY THIS IS AN EXCELLENT FORUM THAT HAS INFORMATION OF MUCH AID AND QUALITY FOR THE PROFESSIONAL.

I NEED YO KNOW IF EXIST A FORMULA THAT CALCULATES THE TEMPERATURE OF THE FLUID THAT IS IN THE INTERIOR OF THE PIPE , ONLY WITH THE EXTERNAL MEASURE OF TEMPERATURE OF THE PIPE.

THANKS FOR YOUR HELP

 

[JStephen]

With only the information, given, no.

There are correlations for heat loss from pipe. You should be able to work some of them backwards to find an estimate of the fluid temperature. But you would need more information, like flow rate, heat loss or temperature drop along the pipe, etc.

 

[hacksaw]

not with any reasonable accuracy

 

[iainuts]

I'd agree with the above responces, as they directly answer the question. However, a strap on thermocouple or other temperature measuring device are widely used in industry.

The best solution is to put some insulation around the thermocouple to prevent heat transfer to the environment, and get a more accurate reading of the fluid itself. So if you put a thermocouple on the outside of your line, and then insulate it for a few inches upstream and downstream of the thermocouple, you should get a reasonably accurate measurement (ie: within 10 degrees F) of the fluid inside the pipe.

 

[sailoday28]

The best solution is to get a better input to the problem.Wall thickness, material, etc. Also define what is meant by Temperature--bulk???. What if the flow is laminar. Temp at pipe center will be different than temp at wall.
Again a better definition of problem is needed.
Regards

 

[dcasto]

Humm, looks like a problem in the pipeline industry, How do I get a good flowing temperature without having a therwell in the line which would not allow a pigg to get by. Skin temperature with some insulation, becareful of under insulation corrosion, there are always drawbacks.

 

[JStephen]

From the way the question was posed, I assume it meant that the temperature of the pipe contents was expected to be different from the pipe outside. Which means it's heating up or cooling off as it goes or maybe you have transient effects.

If flow is steadystate with no great heat flow down the line, you should be able to insulate the line and just measure outside temperature as noted.

I guess you could put a couple of taps up and down the line, run tubing between them, and measure temperature in the tubing rather than the mainline.

 

[magicme]

you should heed all the comments made previously, especially regarding insulation.

here is a link to notes i use in my heat transfer course with all the equations thru a laminated pipe. there is a javascript calculator at the bottom. if you play with that and tweak the T's and k's, that should put you in the ballpark.

you can read the page source to review the script commands and verify that you agree with how i did it.

http://www.tikmark.com/javacalcs/heatransfer/pipelaminated.html

regards

magicme


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"not all that glitters is gold"

 

[pmover]

magicme,

applaud your efforts!

bear in mind of the difference between bulk temperature (what OP requested) and film temps (at pipe wall).

again, with information given by OP, the answer is NO.

good luck!
-pmover

 

[magicme]

<pmover>

I was thinking to combine several of the previous comments about insulating the pipe for several diameters up and dowstream of the thermocouple and using the mass flow rate to estimate internal HTC.

treat the insulation (radially) as a layer of the laminated pipe and guess at an external HTC (forced? natural?)

from that, as someone else commented, you could use the equations to 'back out' an estimated fluid temperature.

Obviously, lots of estimating here reduces your confidence in the answer, but it's an option.

regards

magicme

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"not all that glitters is gold"