Pressure rise due to liquid thermal expansion - query 2

[chemks2012]

Dear all,
I have a coil within a reactor. Coil is used for reactor heating/cooling pupose.
It’s a 3inch stainless steel, schedule 40 coil, 70m long coil with volume of 0.3m3. However, as I am assuming ZERO leak in the equation provided in the web link below i.e. the term, ‘ qt/v ‘ becomes ZERO.

With that zero leak assumption, the equation gives of 6.8bar per 1deg C rise for water. Is this possible? See attached calcs.

Has anybody used this equation in past and know the reference for the origin of this equation please?

http://www.chemkb.com/process/flare-and-vent-systems/relief-systems/thermal-expansion-relief-valves/

Thanks.

 

[LittleInch]

Check out this:

http://www.eng-tips.com/faqs.cfm?fid=1339

That sounds highly possible, but I haven't checked your calculation.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[zdas04]

I've seen several blocked in pipes fail from the sun shining on them. I've seen hydrostatic tests where we had to bleed liquid for the whole test. I didn't open your link, but the number I've always used is 100 psi/1F, so you are certainly in the ballpark of that rule.

David Simpson, PE
MuleShoe Engineering

Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat

 

[bimr]

I don't know the source of the equation, but the thermal expansion of water is 12.4 bar/°C without accounting for the affects of elastic deformation which at small ΔT will relieve some of the overpressure caused by thermal expansion.

http://abiquim.org.br/congresso/cong_cd/fullpapers/P171757.pdf

I would ignore the affects of elastic deformation and estimate the expansion as 12.4 bar/°C.

Since water is nearly incompressible, it does not take much water to increase pressure. For example, if you had an 8 inch water main, 1,000 feet long and all of the air was removed or purged from the water line, it would only take about one cup of water to bring the pressure up to 150 PSI.

 

[25362]

It appears that the developed pressure depends on the water temperature level, as obtained upon dividing the thermal expansivity by the isothermal compressibility. Using tabulated values, I found for liquid water:

°C bar/°C
20 4.5
30 6.8
40 8.7
50 10.4
60 11.8
70 12.9
80 13.9

 

[Latexman]

I've had a reply by 25362 archived for about 8 years. Take a look:

thread124-171158

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[chemks2012]

Thank you all for your input.

Regards,
KS