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Post by Andrew on Feb 25, 2012 13:18:36 GMT
1. If you consider the following arrangement and imagine the left hand cylinder is hot and covered in highly polished reflective silver You will observe it has very little ability to radiate heat because of the low emissivity of a polished lightly coloured reflective surface like silver. You will note the extremely small air gap and you will expect a higher conductance on the right side of the block to that present in the large thickness of air on the left side You will then expect these results 2. On the other hand if the surfaces were matt black and the gap was much larger of around 5-10cm then you would expect the results to be reversed. 3. If the expected results were not achieved you could then heat both blocks and expect to see it very similarly warmer in the middle of both faces than on their very similarly warm but cooler outer faces. 4. If temperatures were even but the expected results were not found for experiment 3 you could cool the environment of all the lines of sight of the blocks and objects in that environment and repeat the experiment and do so within reasonable limits of being able to cool the environment. Eg the experiment is done in a cool store. 5. If you got results from 4, you could then heat the hot block to a temperature of 150 and the warm block to a temperature of 130 and expect to get higher temperatures on the inside faces as in 4
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Post by magellan on Feb 25, 2012 14:03:50 GMT
It's becoming apparent not only are there more cups, there is no pea.
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Post by Andrew on Feb 25, 2012 14:27:43 GMT
It's becoming apparent not only are there more cups, there is no pea. You began by refusing to learn what you were supposed to be building Apparently the description was too long for you. The experiment always involved 3 temperatures. And all you can do when it is pointed out you never built what you were supposed to build, is that goal posts are changing or you know better, and it is best to stick to the original proposal. That can only be described as weird behaviour The beginning idea here was to somehow build Spencers vacuum test in a zero degree environment with one heated block using home techniques. You do have a vacuum chamber. But I do not think you know what you are supposed to be building unless you build what he suggested where he has three temperatures of 160 150 and Zero - temperatures like that anyway. If you cannot understand what you are doing you cannot modify the experiment in a meaningful manner The 0.25mm gap was bizarre. Blindingly reflective surfaces does not help And why chose 10mm gap when gaps below 12mm are known to have poor conductivity and probably 10cm is far better? Do you want to test for backradiation?
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Post by trbixler on Feb 25, 2012 14:47:16 GMT
You are paying him for his efforts? A physics lab experiment typically starts with a specification for the experiment and an expectation of results. Did you provide such a specification? I was surprised that magellan spent as much effort as he has on this experiment. No specification then a non paying client complaining is beyond belief. Did you read the link www.engineeringtoolbox.com/radiation-heat-transfer-d_431.htmlFill in the equations and write up your expectations. Run the experiment (log the results enough times to see the consistency) the analyze the results. Be a professional. My physics lab professor Dr. Geer would be shocked. siris-archives.si.edu/ipac20/ipac.jsp?uri=full=3100001~!140167!0 It's becoming apparent not only are there more cups, there is no pea. You began by refusing to learn what you were supposed to be building
Apparently the description was too long for you.
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Post by Andrew on Feb 25, 2012 15:52:17 GMT
You are paying him for his efforts? A physics lab experiment typically starts with a specification for the experiment and an expectation of results. Did you provide such a specification? I was surprised that magellan spent as much effort as he has on this experiment. No specification then a non paying client complaining is beyond belief. Did you read the link www.engineeringtoolbox.com/radiation-heat-transfer-d_431.htmlFill in the equations and write up your expectations. Run the experiment (log the results enough times to see the consistency) the analyze the results. Be a professional. My physics lab professor Dr. Geer would be shocked. siris-archives.si.edu/ipac20/ipac.jsp?uri=full=3100001~!140167!0 You began by refusing to learn what you were supposed to be building
Apparently the description was too long for you. Interestingly that links provides Net Radiation Loss Rate If an hot object is radiating energy to its cooler surroundings the net radiation heat loss rate can be expressed as q = å ó (Th4 - Tc4) Ac (3) According to Magellan there is no such thing as a net loss rate between a hot object and a cooler object. His argument is that warmer objects, that are near the hot object, but warmer than the colder surroundings will suck heat out quicker from the hotter object, than the colder surroundings
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Post by trbixler on Feb 25, 2012 16:10:42 GMT
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Post by Andrew on Feb 25, 2012 16:14:33 GMT
How about you help me prove that physics is right? Talk will not help. Currently the matt black 400 oC heat resistant paint on my latest experiment is drying.........
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Post by trbixler on Feb 25, 2012 17:36:14 GMT
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Post by numerouno on Feb 25, 2012 17:58:56 GMT
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Post by Andrew on Feb 25, 2012 18:08:22 GMT
Icefisher only allows his own thought experiments,
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Post by magellan on Feb 25, 2012 20:42:07 GMT
You are paying him for his efforts? A physics lab experiment typically starts with a specification for the experiment and an expectation of results. Did you provide such a specification? I was surprised that magellan spent as much effort as he has on this experiment. No specification then a non paying client complaining is beyond belief. Did you read the link www.engineeringtoolbox.com/radiation-heat-transfer-d_431.htmlFill in the equations and write up your expectations. Run the experiment (log the results enough times to see the consistency) the analyze the results. Be a professional. My physics lab professor Dr. Geer would be shocked. siris-archives.si.edu/ipac20/ipac.jsp?uri=full=3100001~!140167!0 Interestingly that links provides Net Radiation Loss Rate If an hot object is radiating energy to its cooler surroundings the net radiation heat loss rate can be expressed as q = å ó (Th4 - Tc4) Ac (3) According to Magellan there is no such thing as a net loss rate between a hot object and a cooler object. His argument is that warmer objects, that are near the hot object, but warmer than the colder surroundings will suck heat out quicker from the hotter object, than the colder surroundings His argument is that warmer objects, that are near the hot object, but warmer than the colder surroundings will suck heat out quicker from the hotter object, than the colder surroundings It's not nice putting words on other people's mouths; you have completely massacred the King's English with that mess. We all know however what your claims are, which seem to be changing by the minute. No doubt they will again after looking at these results I'm thinking you should go back to arguing with Numerouno about ice breakers. Today I used your recommended distance of 12mm between the discs to ameliorate the effects of air conduction between the discs. How stupid of me not to think of that. Thanks for the heads up, it will come in handy the next time I build a window. Somehow it doesn't seem to be relevant for this type of test however. This time the test was a bit more controlled. The T2 disc was soaked at 200 degF for 2 hours before removing. The bead probes were then inserted to assure both ends of the disc were the same before placing next to the T1 (back radiating) disc. T= 173.0 and 173.5 respectively. I'd say that's pretty consistent. Unfortunately I did the test the wrong way again by not having the faces painted black. That will not happen because these parts are used as an inspection reference. However, they can be black oxided which does not add material and is uniform on all surfaces. If painted, the thickness should be inspected otherwise it could bias the results, but I'm sure you thought of that. They also should have the same surface finish. Nonetheless, below are the results from this back radiation test based on YOUR claim. Times are approximate. Nothing was moved during the test. The room circulation fan was turned off as was the AC/heater unit. Initial conditions: Ambient temperature- 70.1 F Test specimen T2- 173/173.5 F just prior to putting into position as recommended by Iceskater to be ~12mm T1B was relabeled T2C. After ~20 minutes: After ~40 minutes: After ~1 hour 5 minutes T1A (center probe cold part) temperature did rise as expected even at 12mm distance: 72.7F peak vs 70.1 initial (ambient) Maybe with the parts black the results will change. Maybe doing it over and over again will give different results. Thus far I've yet to see a slowing rate of cooling, or any indication of it. Tell you what Iceskater, just to anticipate the rules changing again, I will take measurements at equal distances from the center instead of at the gap. This will mean modifying the part more, but it won't affect its original function. Keep searching, the holy grail is out there somewhere.
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Post by trbixler on Feb 25, 2012 20:51:38 GMT
magellan did you leave enough room for the demon to work? Labor laws and such need to be considered.
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Post by magellan on Feb 25, 2012 21:06:53 GMT
magellan did you leave enough room for the demon to work? Labor laws and such need to be considered. I did notice it felt colder than usual at work today, mainly when I brought the hot part in; saw some dead flies on the window sill too. I think I'll reheat some chicken in my Easy Backradiation R (no power needed) oven and skip this thread for a while.
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Post by Andrew on Feb 25, 2012 22:35:19 GMT
My wife and I were active in the Sauna and produced the following: Distance between concrete blocks painted matt black with 400 oC heat resistant paint is 16cm Blocks are 7.5cmX27cmX12cm Sauna is 14C Blocks were heated for 1.5 hours to 150C and moved to Sauna. One was then wrapped in aluminium foil and a jacket and left for about 15minutes Blocks were then set up as shown with hot block on the right. After about 40 minutes we began recording the results and messing around with Excel. The results were as expected img824.imageshack.us/img824/1084/dataeb.jpg [/img] Tomorrow i will heat just one block and will expect the other to warm up and give me good results. Please note: I tried this arrangement yesterday without the matt black and the grey blocks gave me barely visible expected results. I am holding the radiation thermometer on two pieces of string so my body is out of the way of line of sight between the various surfaces. As you can see pointing the thermometer at the middle of each face where the temperature is highest for each side gives consistant results
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Post by icefisher on Feb 25, 2012 23:13:36 GMT
My wife and I were active in the Sauna and produced the following: Distance between concrete blocks painted matt black with 400 oC heat resistant paint is 16cm Blocks are 7.5cmX27cmX12cm Sauna is 14C Blocks were heated for 1.5 hours to 150C and moved to Sauna. One was then wrapped in aluminium foil and a jacket and left for about 15minutes Blocks were then set up as shown with hot block on the right. After about 40 minutes we began recording the results and messing around with Excel. The results were as expected img824.imageshack.us/img824/1084/dataeb.jpg [/img] Tomorrow i will heat just one block and will expect the other to warm up and give me good results. Please note: I tried this arrangement yesterday without the matt black and the grey blocks gave me barely visible expected results. I am holding the radiation thermometer on two pieces of string so my body is out of the way of line of sight between the various surfaces. As you can see pointing the thermometer at the middle of each face where the temperature is highest for each side gives consistant results [/quote] You need to do at a minimum what Magellan is doing, providing information on equipment positioning of the measuring device, photos showing the read outs, etc. We can't tell what errors you are making without all the details. We don't know if you met your demand for 3 thermometers simultaneously that you demanded from Magellan or any of that information.
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