Hi Ed,

You need to look at a 13% increase in delta T.  If Delta T is in the
range of 20 to 50 deg., the increase is only 2.6 to 6.5 deg.  I don't
remember report of lesser temperature, but the increase wouldn't be
that great.

Bob W.


On Sat, 4 Feb 2006 20:56:49 -0500
"Ed Anderson" <eanderson@carolina.rr.com> wrote:

Hi Al,

Appreciate your (anybody else welcome also) views on one other thing that is still bothering me about the use of NPG.

Given that NPG+ has a specific heat of 0.66 at 212F or  20% less than the 0.82 for the 50/50 mixture and given that NPG+ is  approx 7% more dense than the 50/50 - then that for the same flowrate for both it would seem that NPG still has a 13% lesser overall capacity for heat transfer (at the same temps 212F and flow rates).

Also assume that the engine is produce the same heat load (Q),lets take alook at what temperature we might see with NPG+ compared to the 50/50 solution.  We have from the oldie but goody Q = c*M*DeltaT the ability to solve for the temperature increase, DeltaT.

Delta T = Q/cM, now if the combined effects of c and m  provide 13% less heat transfer capability than the 50/50 mixture that would indicated that to carry away the same Q at the same flow rate, the delta T of NPG+ would need to increase by 13%.  So if I were getting 180F with the 50/50 for the same Q load (and flow rate) then with NPG+,  I would expect 180 *1.13 = 203F.  Yet, if I understood correct we have reports  that lesser temperatures results noted by users of NPG - this leaves me a bit puzzled.

If my assumption is correct thus far, then I am at a loss to understand the reports of lesser cooling temps when using NPG+, it would seem just the opposite would happen, that is - the coolant  temperature would increase.

Now,  If the coolant temp with NPG+ actually does  remain  the same (or decreased) for the same Q and flow rate,  then it could indicate the engine heat load is not being carried away as well as with the 50/50.  IF the reports of lesser cooling temps occurs when switching to NPG+  are correct, then it would appear to me that the engine must then be operating under a higher heat load (i.e heat not being transfer to the radiators as effectively) .  This doesn't even take into consideration the possibly lesser flow rate of NPG+ for the same pump speed as the 50/50 due to its higher 3 times higher viscosity (at 212F).

 Yes, I have no problem understanding that boil-over has been eliminated - but, is NPG actually cooling as well as coolant temps may lead one to believe? I mean with NPG, I could have a excessive block temperature and still not have boil-over - but my rotary engine would likely have suffered damage.

 What am I missing? Inquiring minds (even old ones) want to know {:>)

Ed A

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