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If you find any info to support your points, let me know will you? What
do you mean by "you can't have pressure without a spring"? Why do you
assume coolant is boiled? Why does coolant pushed out have to result in
vapor?
I always thought that pressure always increased in closed systems when
you heat a fluid. This because the molecules get excited and move farther
apart. The volume tries to increase, but can't due to sys being closed,
so pressure must rise.
Here's another cool site...or hot and cool site.
http://science.howstuffworks.com/stirling-engine1.htm
-al wick
On Sun, 26 Jun 2005 23:21:55 -0400 "Ian Dewhirst" <ianddsl@magma.ca>
writes:
> Sorry Al, I think you are incorrect on the no vapor theory. While it
> is
> true that in many big three cooling solutions the level in the
> overflow
> reservoir will change as the engine is cycled from cold to hot back
> to cold
> again, the cooling system is never all liquid. There has to be
> vapor
> before you start. I am sure that we both agree on the following
> points: An
> automobile cooling system needs to be pressurized to operate above
> the
> boiling point of water. You can't have pressure without a spring in
> a
> closed system. The spring used is compressed vapor. If you don't
> start out
> with vapor, you will push out coolant until you create some vapor,
> this
> vapour is the result of coolant that has boiled in the block
> somewhere. A
> rad cap is a pressure relief device not an accumulator; it is open
> or
> closed. For a spring loaded to opperate as an accumulator you need
> an
> unlimited supply of coolant/air/oil/etc. to flow through at a rate
> high
> enough that you can create back pressure, much like the spring
> loaded
> pressure regulator on an engine lubrication system.
>
> Your radiator may look like it is full but the filler neck likely
> extends
> down past the top of the tank or it is on the side of in the case of
> a cross
> flow radiator, either way the cooling system is not 100% liquid
> filled.
>
> Since we are all building hybrid cooling systems, we need to
> remember to
> leave some vapour in the system ( as you are doing ) to make sure
> that we
> are operating with a pressurized system "before" we start to expel
> coolant
> from the system.
>
> George mentioned the fact that a good many vehicles have systems
> that never
> vent coolant through the cap unless over heating, I would agree with
> him
> that this is the best solution; usually it involves a combination
> expansion
> tank / swirl pot and a pressure cap that is vented to the ground.
> Cheers -
> Ian
>
>
> -----Original Message-----
> From: Rotary motors in aircraft
> [mailto:flyrotary@lancaironline.net]On
> Behalf Of al p wick
> Sent: Sunday, June 26, 2005 8:02 PM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Coolant Leak
>
>
> Actually, I think the opposite is true. I understand the auto
> approach is
> to NOT have any air in the cooling system. I don't recall the
> details of
> their reasoning. In my experience, the safety advantage of cup-o-air
> is
> much more significant.
> BTW, it's probably more like 2 cups. The goal is to have enough air
> cushion to prevent pressure from reaching cap rating. When you
> include
> coolant temp, fluid level, and pressure info, it really improves
> your
> understanding of how your system is behaving.
>
> If you ever open your car radiator and find air at top, it indicates
> a
> problem with your cooling system.
>
>
>
> -al wick
> Artificial intelligence in cockpit, Cozy IV powered by stock Subaru
> 2.5
> N9032U 200+ hours on engine/airframe from Portland, Oregon
> Prop construct, Subaru install, Risk assessment, Glass panel design
> info:
> http://www.maddyhome.com/canardpages/pages/alwick/index.html
>
>
>
> On Sun, 26 Jun 2005 13:15:14 -0400 "Ian Dewhirst"
> <ianddsl@magma.ca>
> writes:
> > Al, your experience with the value of having an air cushion is
> > supported by
> > every automotive cooling system that I have ever seen (many).
> > Typically
> > autos use either a pressure cap and expansion tank that is not
> > filled to the
> > top, or an overflow bottle into which coolant is expelled and
> > recovered. I
> > get the impression that some people assume that these overflow
> style
> > systems
> > contain no vapour when cold, I don't think that assumption is
> > correct. The
> > overflow systems all have expansion capacity built into the top
> of
> > the
> > radiator, or some other part of the cooling system they are never
> > completely
> > filled with coolant. The bigger the cooling system the greater
> the
> > volume
> > of vapour stored cold.
> >
> > -- Ian
> >
> > (GM, Chrysler, and Ford are not trying to piss you off with those
> > side
> > mounted radiator caps.. ;-)
> >
> >
> >
> >
> > -----Original Message-----
> > From: Rotary motors in aircraft
> > [mailto:flyrotary@lancaironline.net]On
> > Behalf Of al p wick
> > Sent: Sunday, June 26, 2005 11:58 AM
> > To: Rotary motors in aircraft
> > Subject: [FlyRotary] Re: Coolant Leak
> >
> >
> > My focus is on flight safety. I found great value to having appx.
> 1
> > cup
> > of air at the top of my cooling system....
> >
> >
> >
> > >> Homepage: http://www.flyrotary.com/
> > >> Archive: http://lancaironline.net/lists/flyrotary/List.html
> >
> >
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
>
-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
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