Propylene Glycol Solution as a cooling media

[Mike4chemic]

We have a question about design a cooling system with Propylene Glycol solution 52/48 at various temp and hence various viscosity values. System description: Propylene Glycol solution 52/48 will use as a cooling media at a Generator cooler. The Propylene Glycol will cool the hot air circulation at the Generator. Hot Propylene Glycol will be cooled by a dedicated air cooler consists of several fans and circulation pump.
The system is designed for 80F where 52/48 solution viscosity is around 3 cps. However min ambient temp at the area is around -30F with solution viscosity of about 250 cps.
Our concern is about start up of this system at a cold day (-30 F). Do we have to design the circulation pump for Propylene Glycol solution at -30F with 250 cps? Maybe we could circulate only small amount of Propylene Glycol solution at start up in order to reduce viscosity of the solution? Does any body have experience with such sys? What about the circulation pump motor? Does it need a heater or to be over sized?

Thanks in advance

 

[elguero]

Check with the pump manufacturer for operation at higher viscosity. Some manufacturers catalogues have such information. Also the Cameron manual, by Ingersol Rand has data for derating pumps at higher viscosities. Make a complete diagram of your proposed scheme. Do pressure drop calculations for all the possibilities. See August 2005 cover story in Chemical Engineering magazine for an excellent article on sizing cetrifugal pumps.

 

[MJCronin]

Mike....

Suggest that you consider a more dilute PG solution. (By 52/48 do you mean 52% PG to 48% water ?) What is setting your percent PG ?

I have designed systems using a 42% PG solution that offers adequate "freeze solid" protection at very low temperatures. The additional benefit is that your heat exchangers can become smaller due to the change in film coefficent.

Where is this facility to be located and what is the coldest 1 day temperature ?

Dow Chemical has some ecellent information on PG system design.....

http://www.dow.com/propyleneglycol/index.htm

http://www.dow.com/PublishedLiterat...ycol/pdfs/noreg/117-01682.pdf&fromPage=GetDoc

good Luck !!

-MJC