|
Marvin, From what I can see
looking at the characteristic of the NPG is that whatever advantages it
conveys, it has a reduced specific heat (heat carrying capability)
compared to water or a 50/50% mix. Lower by approx 29-34% than water
and 13 -20% less than the traditional 50/50 mix. That being the
case, the NPG must operate at a higher temperature (assuming flow rate is
unchanged) to carry away the same amount of heat per unit time out of
the engine. For example if water carried
away 100 BTU of heat per unit time at say 200F, then at the same
flow rate the NPG temp would probably
need to be closer to 230F to carry away to same heat quantity at the same
flow rate. So I am not surprised to see
elevated temps over water or 50/50 mix.
Interesting to see that its
viscosity is much higher than water - any affect on pump energy
required??Flow rates?
So for your project (recip
engine?) which can with stand a higher
operating temperature than the rotary, it may be suitable
particularly if concerned about corrosion of the magnesium- but you will
see higher coolant temps. So what you are seeing in temps is
probably not unreasonable.
Thats my take on it.
Ed
Ed Anderson
COMPARISON OF COOLANT
PARAMETERS |
| |
|
Water |
50/50 EGW |
Evans NPG |
Evans NPG+ |
| |
|
|
|
|
|
| Boiling Point |
|
121° C (250° F)
(1 atm plus 15
psig) |
129° C (264° F)
(1 atm plus 15
psig) |
187° C (369° F)
(1 atm plus 0
psig) |
191° C (375° F)
(1 atm plus 0
psig) |
|
| Viscosity |
|
|
|
|
|
| 10° C (50°
F) |
cp |
1.2 |
5.0 |
115 |
58 |
| 80° C
(176° F) |
cp |
.37 |
1.0 |
4.5 |
3.7 |
| 100° C (212°
F) |
cp |
.28 |
0.7 |
2.8 |
2.3 |
|
| Density |
|
|
|
|
|
| 20° C (68°
F) |
spec grav |
1.00 |
1.066 |
1.038 |
1.091 |
| 20° C (68°
F) |
lbs/gal |
8.32 |
8.87 |
8.64 |
9.08 |
|
| Specific Heat |
|
|
|
|
|
| 80° C
(176° F) |
Btu/lb/°F |
1.00 |
0.81 |
0.68 |
0.64 |
| 100° C (212°
F) |
Btu/lb/°F |
1.01 |
0.82 |
0.71 |
0.66 |
|
| Heat of Vaporization |
cal/mole |
9,700 |
9,800 |
12,500 |
12,050 |
|
| Vapor Pressure |
|
|
|
|
|
| 80° C
(176° F) |
mm Hg |
360 |
270 |
8 |
6 |
| 80° C
(176° F) |
kPa |
475 |
360 |
11 |
8 |
|
| Surface Tension |
|
|
|
|
|
| 25° C (77°
F) |
dyn/cm |
72 |
56 |
36 |
44 |
| 
Ed Anderson
RV-6A N494BW Rotary
Powered
Matthews, NC
----- Original Message -----
Sent: Thursday, August 12, 2004 2:28
AM
Subject: [FlyRotary] coolant
temps
> I've got a question regarding coolant temps I hope some of you can
help with.
> We've been running the Eagle540 recently, getting
ready for that impending
> first flight. Our installed
instrumentation on the coolant side is located on
> the higher pressure,
high temp engine outlet side of the coolant circuit...
> the flow comes
out of the top rear of the engine to the thermostat housing.
> Temp
sensor is installed in the t-stat housing. From there it goes through
> the firewall and down to the radiator, then returns back through the
firewall
> and on to the water pump. The water pump forces the
coolant into the block
> and the circuit is complete. We are not
running 50/50 water/anti-freeze
> because of the magnesium components...
we are running straight Evans NPG.
> During recent runs (engine RPM
about 2000RPM, the rev limiter is set at 3800,
> so we're just over 50%)
we're seeing the high temp side over 230 degrees. NPG
> doesn't
boil until somewhere around 400, but we obviously don't have any
> desire
to operate at that kind of temperature. For those of you who are
>
instrumented both before and after the radiator (evap cores, whatever) what
> kind of temperature spread are you seeing? I suspect I'll
eventually be
> instrumenting the cool side of the circuit, but would
like to know what to
> expect on the hot side. If we're seeing a 40
degree delta across the radiator
> (I imagine) is 250-260 considered too
hot as a redline for the hot side? (Our
> oil temps are very well
behaved, we still haven't exceeded 150 on the oil cool
> side and TITs
are running 1350-1400 at these reduced power levels... sounds ok
> to me,
but what do I know?) TIA for any info you're willing to share.
>
> <Marv>
>
>
> >> Homepage: http://www.flyrotary.com/
>
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
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