At 03:36 PM 6/21/2011, Jed Rothwell wrote:
Abd ul-Rahman Lomax wrote:
Look, Abd, you need to get real. I honestly have no idea how these
meters work.
That's right. I can tell you this: the brochure is quite specific
as to what is measured, and it ain't enthalpy.
What are you talking about? The brochure says that it measures,
quote: "Enthalpy" (kcal/kg)
http://www.deltaohm.com/ver2010/uk/st_airQ.php?str=HD37AB1347
That's a calculated value, not a measurement. Please understand the
issue. The page you cited does *not* state that it measures
"enthalpy." Read more carefully! You should know better, I'm not
entirely dim, not dead yet.
The instrument simultaneously measures several parameters: [CO2, CO,
temperature, relative humidity], and calculates others, and enthalpy
is in that second list.
The main application seems to be HVAC. The manual is at
http://www.deltaohm.com/ver2010/uk/manuali/HD37AB1347_M_15-12-2010_uk.pdf
The device is described as being intended to measure "indoor air quality."
The enthalpy of what? Hot molten salt? (seriously, not that, the
temperature is too high. But obviously the meter needs to know what
substance is being measured!)
Steam, obviously. There is no significant enthalpy in humid air.
Nobody wants to measure that, in any case.
You may if you are checking an evaporative cooler, I'd think. HVAC.
No, the big market for these meters is HVAC, in fact. You think
people doing cold fusion calorimetry are a big market?
Jed, read the manual. Page 6 of the manual seems to contradict me. I
think that there, they simply did not discriminate between what is
measured and what is calculated.
By the way, I think I erred when I reported the "operating range" as
up to 85% RH, non-condensation. That was referring to the unit
itself, not to the probe.
Look at page 59, a probe specified for enthalpy measurements. It has
a temperature limit of 60 degrees. Obviously this probe isn't
intended to measure steam enthalpy!
On page 60, there are probes rated for 150 C. But the probe operating
temperature is given as only up to 80 C.!
Jed, I've looked, not just here, and I'm not seeing the slightest
clue, anywhere, that these devices, these RH meters, are sold and
intended to be used as steam quality instruments. Much more complex
stuff is sold for that purpose, there are consulting services you can
hire to make these measurements, and if an RH meter could hack it,
wouldn't they be touting this? There are papers on the internet
describing what's needed to measure steam quality and it's pretty complex.
You are right you would not use it to measure the enthalpy of hot
water. Bingo! Wet steam is, partly, hot water! It is not a uniform
material, it will separate out into hot water and water vapor. I
don't think the probe is measuring the hot water at all.
If the probe does not correctly take into account the fraction of
steam that is hot water, it would not work correctly. It would be useless.
Useless for measuring steam quality. Not "useless." These devices are
sold primary for measuring air quality. Like, the stuff people breath
and live in.
I don't see that these probes are intended to work in steam at all.
From the specs, you may be able to stick this thing in steam up to
150 C., without it breaking, but that's not operating temperature.
It's looking like someone screwed up, royally. However, there is this
possibility: someone really does know what they are doing, knows how
to use an RH meter to measure steam quality. It would involve more
than just sticking the thing in, I'd expect.
But there is no sign of the more sophisticated process we'd expect.
Jed, you got stuck on this for some reason, a while back. Drop it.
You screwed up, that's all. This need not change the overall
conclusions about Rossi, it doesn't make your additional information
wrong. It does increase the worry factor a little, I'd say, that's about it.
