REFLECTOR:Re: NPG+

John Dibble reflector@tvbf.org
Sun, 18 Apr 2004 18:24:46 -0500


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The few psig of the sealed system simply raises the boiling point by a
few degrees - boiling still occurs, just at a higher temp.  I'm simply
not buying the "insulation by the steam layer" concept.  The steam layer
is part of the boiling process, specifically when the boiling rate is
very high.  I question if a steam layer exists in an engine cooling
system, but if it does, it indicates a very high rate of heat transfer.
If insulation did happen, the steam generation would slow and the steam
layer would collapse.  A non-boiling coolant will have a much lower heat
transfer rate and that translates to a higher temperature at the
cylinder jacket wall.
The only way the NPG+ makes sense is if water-cooled engines have much
lower CHTs/EGTs than air-cooled and it is desirable to increase them.

John

Chuck Jensen wrote:

> John,I can't pass up an opportunity to show my ignorance (and there
> are many!), but I thought the reason for keeping the water coolant
> under pressure was so it would not boil against the cylinder jacket.
> As we know, water has a higher boiling point under pressure, so the
> few psig of the sealed coolant system keeps the water from boiling
> when it hits the hot engine components.  When we take the cap
> off...every so carefully...that relieves the pressure and the hot
> water near-instantly boils; spitting like a cobra into the face of the
> unwary. The NPG+ article talks about how it won't "boil" and leave a
> layer of steam against the hot metal.  Steam is actually quite a good
> insulator so the engine metal will get even hotter if a layer of steam
> is present.  NPG+ says, since their solution won't boil, there will
> never been a steam layer that thermally insulates the engine metal and
> thus the heat will be conducted away more efficiently; reducing the
> potential for knock/predetonation.I got lost in the issue about the
> engine running hotter with NPG+.  Unless they mean the whole engine
> can run hotter while critical components are kept cooler, which will
> reduce the potential for mechanical damage from predetonation while
> enjoying the ever so slight improvement of a hotter engine?  Measuring
> such gains probably falls in the realm of the new
> "Nanotechnology."With all that said, some of their claims leave me
> thinking about the 'ole West Medicine Wagon and their medicinal
> potions.  When the claims start filling up a half-page, I start
> thinking about half-truths.Chuck

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The few psig of the sealed system simply raises the boiling point by a
few degrees - boiling still occurs, just at a higher temp.&nbsp; I'm simply
not buying the "insulation by the steam layer" concept.&nbsp; The steam
layer is part of the boiling process, specifically when the boiling rate
is very high.&nbsp; I question if a steam layer exists in an engine cooling
system, but if it does, it indicates a very high rate of heat transfer.&nbsp;
If insulation did happen, the steam generation would slow and the steam
layer would collapse.&nbsp; A non-boiling coolant will have a much lower
heat transfer rate and that translates to a higher temperature at the cylinder
jacket wall.
<br>The only way the NPG+ makes sense is if water-cooled engines have much
lower CHTs/EGTs than air-cooled and it is desirable to increase them.
<p>John
<p>Chuck Jensen wrote:
<blockquote TYPE=CITE><style></style>
<span class=031475220-18042004>John,</span><span class=031475220-18042004></span><span class=031475220-18042004>I
can't pass up an opportunity to show my ignorance (and there are many!),
but I thought the reason for keeping the water coolant under pressure was
so it would not boil against the cylinder jacket.&nbsp; As we know, water
has a higher boiling point under pressure, so the few psig of the sealed
coolant system keeps the water from boiling when it hits the hot engine
components.&nbsp; When we take the cap off...every so carefully...that
relieves the pressure and the hot water near-instantly boils; spitting
like a cobra into the face of the unwary.&nbsp;</span><span class=031475220-18042004></span><span class=031475220-18042004>The
NPG+ article talks about how it won't "boil" and leave a layer of steam
against the hot metal.&nbsp; Steam is actually quite a good insulator so
the engine metal will get even hotter if a layer of steam is present.&nbsp;
NPG+ says, since their solution won't boil, there will never been a steam
layer that thermally insulates the engine metal and thus the heat will
be conducted away more efficiently; reducing the potential for knock/predetonation.</span><span class=031475220-18042004></span><span class=031475220-18042004>I
got lost in the issue about the engine running hotter with NPG+.&nbsp;
Unless they mean the whole engine can run hotter while critical components
are kept cooler, which will reduce the potential for mechanical damage
from predetonation while enjoying the ever so slight improvement of a hotter
engine?&nbsp; Measuring such gains probably falls in the realm of the new
"Nanotechnology."</span><span class=031475220-18042004></span><span class=031475220-18042004>With
all that said, some of their claims leave me thinking about the 'ole West
Medicine Wagon and their medicinal potions.&nbsp; When the claims start
filling up a half-page, I start thinking about half-truths.</span><span class=031475220-18042004></span><span class=031475220-18042004>Chuck</span></blockquote>

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