Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
(OP)
I am witnessing a customer system failure when they capture 20°F chilled 30% glycol between two ball valves, and allow the captured solution to heat up as much as 70°F. I realize that an expansion tank is in order, but I need to calculate the pressure change to justify it to them. There are many tools to calculate the volume change, but I have not found anything to calculate the pressure generated. Any and all help is most greatly appreciated.





RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
Idiots.
Mike Halloran
Pembroke Pines, FL, USA
RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
TTFN
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RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
Mike's answer is much simpler.
RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
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RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
A thin-walled steel system with bends may be more suitable.
RE: Pressure generated by a 30% Ethylene Glycol on a closed thermal sys?
pipe volume is the original volume x it's expansion coefficient x 3. The water volume is the original volume x the bulk thermal expansion coefficient, expansion for liquids is defined in that manner (the linear expansion coefficient is already multiplied by 3).
2.) calculate the net change in volume, the volume of glycol-water should be greater, so that indicates that it will be compressed back into the now expanded volume of the pipe.
3.) Take the difference between the two,
4.) Now squeeze the glycol-water mix (compress it) back to the now expanded volume of pipe.
5.) Calculate the pressure increase using the mix's bulk modulus at 70F.
The above is actually considering the expansion effects only due to temperature, neglecting the expansion of the pipe volume with pressure, but you could include that for even more accruacy.
That expansion due to pressure at yield/per unit length of pipe = Area1 * (1+2*SMYS/E).
SMYS is the specified minimum yield stress of the pipe.
E is Young's modulus
Area1 is the original pipe area.
We are more connected to everyone in the world than we've ever been before, except the person sitting next to us. Lisa Gansky