30% Propelyene Glycol/Water Mixture

[RJB32482]

I am trying to find the specific heat of a 30% Propylene Glycol/Water mixture. Is the heat transfer capability lower or higher than just pure water? If the heat transfer is lower, why are solutions like this used instead of just water in heat exchange systems (corrosion?)?

Thanks.

 

[monaco8774]

30% Glycol is used as an antifreeze to stop it freezing water on its own is a better choice if your ambient temperature stays above freezing for cost and heat transfer

 

[TD2K]

http://www.dow.com/PublishedLiterat...rans/pdfs/noreg/180-01330.pdf&fromPage=GetDoc

 

[TBP]

My table shows the specific as 0.955.

Lots of systems can be out of service - either intentionally or by accident - in sub freezing weather. Water filled systems will freeze and split.

 

[thermcool]

30% Ethylene Glycol and water mixture is preferably used if the working temperature is below zero

Beside this, ethylene glycol mixture has higher boiling point than the water which allow for the working of the radiator at higher temperature.

 

[willard3]

The specific heat of prop glycol/water mix is less than pure water (around 0.9 at 100F) , ie, it carries less heat per gallon.

The kinematic viscocity is also higher than water and has a pump energy penalty.

 

[Mattysdad]

you can get from sizing software @ flatplate"

http://www.flatplate.com/software.htm

 

[jmw]

Ice water slurries probably yield the best heat capcaity (latent heat):

http://www.cemagref.fr/english/ex/agri-food/Cold/Cold-example.htm

JMW

http://www.ViscoAnalyser.com

 

[25362]

http://www.chemistrystore.com/ChemicalMSDS/Dowfrost.pdf

 

[speco]

RJB32482,

The specific heat varies with both concentration and temperature. According to the old program I have from Dow, the specific heat of 30% propylene glycol is:

.901 @ 10 F

.933 @ 100 F

.969 @ 200 F

The heat transfer properties of propylene glycol are slightly less than those of water, (or ethylene glycol for that matter). The reasons are (1) lower specific heat (2) lower thermal conductivity, and (3) higher viscosity.

Glycols are usually used to prevent freezing. However, it appears that the freezing point of 30% propylene glycol is around 8 deg F.

Regards,

Speco

 

[chicopee]

Specific heat of water is 1 btu/lbm-F I dont know of routinely used water based mixtures that can beat that.

 

[25362]

I'm not 100% sure but aqueous ammonia might, although by a small margin.