The Playground

"... is an Alumina 'boat' which could be used to hold a fuel sample."

The same from AR [unconfirmed leak].

Thanks for the info Alan, really nice. I love the parts list, really affordable practical research

If I have time whilst the students are away, I'll try something similar.

Re: Hotter on the inside..., unfueled alumina tube with coil on outside of tube.

Quote from Sherlock Holmes

What are you afraid of, Fanboy? Skepticism is not contagious and it's only dangerous to scammers.

Sure. But M.Y. and Jed look more then fundamentalist and fanatic rather then skeptic......

Not really nice people to stay with.

Quote from Paradigmnoia

Hotter on the inside..., unfueled alumina tube with coil on outside of tube.

You are discovering the obvious. The inside of the pipe is obviously hotter..... so what ?

Quote from maryyugo

Eric, are you kidding? Zeus is a never-ending source of comedy. Tragi-comedy perhaps, but comedy nonetheless.

Also you Mary. More sadness then comedy I would say. Haw many years ago you started your battle Mary ? More then ten as far I can remember.

Let's see: according to Kirk, Jed is basically a fanatical believer. According to Ele, Jed is a fanatical skeptic. I guess the guy just can't win.

Quote from ele

You are discovering the obvious. The inside of the pipe is obviously hotter..... so what ?

Clearly I "discovered" this a couple of years ago.

How hot would the heater coils in the Lugano device be, if the outside surface was 1410 C?

And, how hot is the Lugano thermocouple in it's fairly central Cap position?

In my plot, the inner thermocouple was only 2 mm below the outer coils, on the other side of the alumina.

Quote from Paradigmnoia

How hot would the heater coils in the Lugano device be, if the outside surface was 1410 C?

And, how hot is the Lugano thermocouple in it's fairly central Cap position?

First a remark concerning your statement that the fins on the Lugano device contribute little to the overall cooling.

The area of the central tube of the Ecat is 0.0125 square meter without fins.
The area of the central tube with the fins present is about 0.0263 square meter
If we assume a view factor of the fins of .9 the effective area with fins is 0.9 x 0.0263 = 0.0237 square meter.
The ratio of the areas with and without fins is 0.0125/0.0237 = 0.53
According to the Stephan-Bolzmann law the temperature of the central tube thus will be lowered by the forth root of 0.53 or 0.85.
Thus the temperature of the central part, disregarding convection, would be 15 % lower with the fins present.

I consider this not being little.

Now about the question if the outside surface was 1410 C?

As a consequence of using the correct fin area when calculating radiated power for the Lugano device you have to calculate with an area of 0.0237 square meters instead of the 0.0125 meters.
Now with this area of 0.0237 square meters you can with the data in the Lugano report calculate back what the average emissivity of the central part must have been.
If we look at the data of the first actual run, then the calculated emissivity becomes 0.215 for the reported temperature of 1260 degree C. When using the Nasa emissivity curve (Which is about the same for high temperatures as the curve given in the report) the emissivity should have been .402. The error being 46 % !!!
For me this is an indication that something must have been wrong. Possibly the temperature due to the emissivity error the dear professors are said to have been made or that the body temperatures in table 6 of the report was wrongfully reported in degree K instead of degree C and thus 273.15 has to be extracted from those values.
The curious thing is that both type of corrections leads to temperatures which are close.
If we assume that the values in the second column of table 6 where wrong (But assuming all other temperature where reported correctly) , the real temperature would have been 987 degree C. Now if we for this temperature calculate back the emissivity we arrive at a value of .472 and the value according to the Nasa curve is also .472
This is a strong indication that indeed the real temperature must have been 987 degree C.

Note that these lower temperatures makes the use of Kantal A1 possible as the heating wire used in the Lugano device.

Quote from LDM

First a remark concerning your statement that the fins on the Lugano device contribute little to the overall cooling.

The area of the central tube of the Ecat is 0.0125 square meter without fins.
The area of the central tube with the fins present is about 0.0263 square meter
If we assume a view factor of the fins of .9 the effective area with fins is 0.9 x 0.0263 = 0.0237 square meter.
The ratio of the areas with and without fins is 0.0125/0.0237 = 0.53
According to the Stephan-Bolzmann law the temperature of the central tube thus will be lowered by the forth root of 0.53 or 0.85.
Thus the temperature of the central part, disregarding convection, would be 15 % lower with the fins present.

I consider this not being little.

Now about the question if the outside surface was 1410 C?

As a consequence of using the correct fin area when calculating radiated power for the Lugano device you have to calculate with an area of 0.0237 square meters instead of the 0.0125 meters.
Now with this area of 0.0237 square meters you can with the data in the Lugano report calculate back what the average emissivity of the central part must have been.
If we look at the data of the first actual run, then the calculated emissivity becomes 0.215 for the reported temperature of 1260 degree C. When using the Nasa emissivity curve (Which is about the same for high temperatures as the curve given in the report) the emissivity should have been .402. The error being 46 % !!!
For me this is an indication that something must have been wrong. Possibly the temperature due to the emissivity error the dear professors are said to have been made or that the body temperatures in table 6 of the report was wrongfully reported in degree K instead of degree C and thus 273.15 has to be extracted from those values.
The curious thing is that both type of corrections leads to temperatures which are close.
If we assume that the values in the second column of table 6 where wrong (But assuming all other temperature where reported correctly) , the real temperature would have been 987 degree C. Now if we for this temperature calculate back the emissivity we arrive at a value of .472 and the value according to the Nasa curve is also .472
This is a strong indication that indeed the real temperature must have been 987 degree C.

Note that these lower temperatures makes the use of Kantal A1 possible as the heating wire used in the Lugano device.

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LDM. You have to be very careful when making theoretical arguments: I recommend you TC's paper - he was very careful. And we know this now because his work has been very well tested and validated by others.

I don't trust your speculation here against Paradigmnoia's experimental evidence. P has been studying this problem (experiment and theory) for a long time.

As an example of how tricky this stuff is you get the theory wrong about fins and cooling (and P is right). Here is the problem:

As a consequence of using the correct fin area when calculating radiated power for the Lugano device you have to calculate with an area of 0.0237 square meters instead of the 0.0125 meters.

One mistake. You suppose that the ridges double the surface area. They are 45 degree ridges, and therefore on a flat surface would multiply area by sqrt(2), not double. Big difference.

If we assume a view factor of the fins of .9 the effective area with fins is 0.9 x 0.0263 = 0.0237 square meter.

Your assumption about view factor is wrong. If you'd read TC's paper you would see he calculated this from first principles (p4) and referenced a web source [11] to get the same answer. The view factor in this case is 0.293 (where VF=0 corresponds to a flat surface). Your estimate of 0.9 is way out - even if you are defining VF as 1-VF, so that 1 would be a flat surface, you are still way out.

Finally you ignore emissivity when considering the affect of View Factor on total radiation. This matters. For a black body (e=1) the surface geometry makes no difference to radiation. Thus a ridged black body radiates the same as a flat one. For lower emissivity the affect of a non-zero VF (or, since you I think are using a non-standard 1-VF definition, a VF' < 1) is the same as an increase in emissivity. The ridges do increase the power dissipated at high temperatures a small amount, because total emissivity is low, but do this much less at lower temperatures where the alumina is nearer to a black body. See TC's paper. At 800C the effect of the ridges on radiation is small. At 1400C it would be significantly larger (maybe 20%).

Briton archeology (Graham is Master of the Mint, as Sir Isaac Newton)

Certainly the ridges do improve cooling some, but not as dramatically as one might tend to think. The main cooling improvement would be to convection cooling, but convection cooling is a small part of the heat budget once the object begins to visibly glow.

As for radiation cooling, the 45 degree ridges have a large component of captured and re-emitted heat from the adjacent ridges (View factor effects). This slightly increases emissivity.

Viewed normal to the length of the main tube, as the IR camera should be, the ridge profiles are not visible. The hotter valleys and cooler tips temperatures are averaged within the Optris measurement boxes, and they are not directly visible in the images provided, even though there may be as much as 75 C differences between the immediately adjacent peaks and valleys.

Testing using the Lugano results lead me to using 2.3 cm diameter for the Main Tube, instead of 2.0 cm, as a quick fudge to dealing with the ridges that was consistent with posted Lugano figures when using their methods.

I have tested many scenarios where temperatures K might have slipped in instead of degrees C, and vice-versa, and none of them seem at all likely.

Quote from maryyugo

I "uncovered" Sniffex's extremely dangerous and lethal fraud in 2006.

The US military actually uncovered it in 2005. They even wrote a report about it... Late to the party as usual Yugo?

http://s3.amazonaws.com/propub…ssets/docs/NavyReport.pdf

Quote from maryyugo

My report was requested by the FBI including original video and was used by the SEC to put Sniffex out of business.

Are you saying you bought an actual Sniffex device, tested it, and made a video of that?

Quote from maryyugo

How's Rossi working for you these days, Zeus? Still love Defkalion perhaps?

What on earth are you talking about? You're obsessed with both of those to the point where you imagine everyone must support them. Find a quote of mine that offers blind support to either, or STFU.

zeuss - attempting to harrass Mary does not advance your argument, and does not make you look good. And it is OT

Off-topic in the Playground thread?