will it take off?
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patrick_g
Elite Member
SPYDY, I have some experience with environmental chambers and have a rather low confidence in any that haven't been thoroughly checked out. Also the aerodynamics are disturbed by the test samples.
I suggest you instrument two samples just as before but use hot water in both and note the uniformity or lack thereof in freezing times. Repeat the experiment with cold in both locations and observe the difference in the time to freeze. If the water samples of the same starting temp vary as much or more as the difference in time noted for different temp samples then the "noise" is bigger than the effect you are trying to observe and the results are not valid. The results are invalidated by any significant variatioin in freezing times of samples starting at the same temp. This is sort of a confidence builder. If yoiur setuyp can't freeze two equal samples at darned near the same time then the experimental setup (environmental chamber) is suspect.
Pat
I suggest you instrument two samples just as before but use hot water in both and note the uniformity or lack thereof in freezing times. Repeat the experiment with cold in both locations and observe the difference in the time to freeze. If the water samples of the same starting temp vary as much or more as the difference in time noted for different temp samples then the "noise" is bigger than the effect you are trying to observe and the results are not valid. The results are invalidated by any significant variatioin in freezing times of samples starting at the same temp. This is sort of a confidence builder. If yoiur setuyp can't freeze two equal samples at darned near the same time then the experimental setup (environmental chamber) is suspect.
Pat
SPYDERLK
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Pat. Good point, but unlikely to make enuff difference to swing the other way - - particularly the part about sample disturbing flow considering respective volumes. I did plan to check this tho. My central placement of the 0.06 cuft sample in the 8cuft chamber was the 1st effort to avoid this effect.patrick_g said:
Larry
patrick_g
Elite Member
Larry, No prob, Dude, I think there is more here than our original thoughts covered. This is the fun part. Whenever experiment doesn't conform to theory or preconceived notion, finding out why is so very much more interesting. I'm reminded of a physics prof I had who was squirting little blasts of air with a large eye dropper kind of thing (smaller than a turkey baster) into a vent on the side of an enclosure of a He-Ne LASER and causing it to change emission modes. He could step it through a couple variations and then left alone it would step back down through the changes and return to its original condition. He had a gaggle of obeservers offering esoteric explanations, mostly specious, some incomprehensible, a few quite scholarly, and mine. This was a big attraction at that end of the physics bld and was becoming sort of a contest or competition among various profs and grad students. I remnded tham of my simple explanation and was ignored, again. I challenged all present to prove me wrong and offered to buy the first to do so a rootbeer float. I required noting if I was right. The little blasts of air differentially cooled the laser tube and warped it microscopically altering the geometry of the resonant cavity and in effect slightly changing the allignment of the mirrors. Q.E.D.
I have no ready reference to data on the freezing of water saturated with atmospheric gasses vs de-aired water (like the hot would be.) I don't know if that effect is appreciable in this context or such a minor effect as to be unmeasurable with your setup do to its being a low order phenomenon. It was just a casual observation I made when considering the differences between the samples other than their temp.
You can buy heavy water on the open market and it isn't all that expensive. If you really want to mess with someones mind, compare the freezing rate of heavy water to regular water in equal volumes (staying away from weights) starting at the same temp in both samples.
Pat
I have no ready reference to data on the freezing of water saturated with atmospheric gasses vs de-aired water (like the hot would be.) I don't know if that effect is appreciable in this context or such a minor effect as to be unmeasurable with your setup do to its being a low order phenomenon. It was just a casual observation I made when considering the differences between the samples other than their temp.
You can buy heavy water on the open market and it isn't all that expensive. If you really want to mess with someones mind, compare the freezing rate of heavy water to regular water in equal volumes (staying away from weights) starting at the same temp in both samples.
Pat
Egon
Epic Contributor
Last night Egon was having trouble getting to sleep and started thinking/dreaming about freezing water. Please note any Thinking on Egon's part can be dangerous!
Any way he started considering the facts about a hot sample and a cold sample being placed in the same cooling unit and time till both were solid ice.
To Egon it would seem at initiation Brownian movement would be much greater in the hot sample and allow more molecules to depart than would happen with the cold sample. Returning molecules may also be less on the hot sample as compared to the cold one.
Then the heat transfer seemed to come to mind. Is there not some law stating nature tries to maintain things at the lowest energy content possible. This would mean some heat is transferred to the cold sample.
Also means my old truck may eventually rust to oblivion.
Next; isn't there some point when a lot of energy is required to effect a change of state in a substance. This should indicate that the cold sample will wait till the hot sample is at the same temperature.
Now two samples at the same temperature but the cold one having more volume thus contains more energy should take longer to divulge it's energy than the original hot sample.
Thus the results obtained are skewed by placing both samples in the same chamber.
Only way to do it is to keep the samples separated! ehh or???
Any way he started considering the facts about a hot sample and a cold sample being placed in the same cooling unit and time till both were solid ice.
To Egon it would seem at initiation Brownian movement would be much greater in the hot sample and allow more molecules to depart than would happen with the cold sample. Returning molecules may also be less on the hot sample as compared to the cold one.
Then the heat transfer seemed to come to mind. Is there not some law stating nature tries to maintain things at the lowest energy content possible. This would mean some heat is transferred to the cold sample.
Also means my old truck may eventually rust to oblivion.
Next; isn't there some point when a lot of energy is required to effect a change of state in a substance. This should indicate that the cold sample will wait till the hot sample is at the same temperature.
Now two samples at the same temperature but the cold one having more volume thus contains more energy should take longer to divulge it's energy than the original hot sample.
Thus the results obtained are skewed by placing both samples in the same chamber.
Only way to do it is to keep the samples separated! ehh
or??? patrick_g
Elite Member
Egon, I agree that the effects you mentioin exist but I don't agree that they are the reason for the results reported.
I'm still waiting for the delta T (in seconds) between the freezing times of two samples starting at the same temp. This sort of calibrates and proves the experimental setup capable of measuring the experiment of interest. If you get too much variation betwen equal temp samples then the experimental setup is flawed or there are things going on not accounted for or both.
Now to reduce the problem a bit... The data reported said that the originally hot sample caught up with the cold sample and passed it in loosing heat. This is supposed to support the contention that a warmer sample freezes first.
I claim that at the instant the originally warmer sample passed the originally cooler sample (in a negative direction thermometer wise) that it then became the cooler sample and the originally cooler sample is now the warmer sample. So the NOW warmer sample does not freeze first, does it!!!
There is something beyond simple calorimetry going on here and I am not claiming that it has to be experimental error. It could be all or in part but we just don't know yet.
What if you fill a large insulated coffee carafe with tap water and then fill one side of the tray from the carafe. Put the tray in the chamber for a few minutes and then remove it and fill the other side from the carafe and return the tray to the chamber. One sample is warmer than the other but both have similar disolved gas content.
If the experiment were repeated succsessively with a smaller and smaller temp differential between samples you would expect the freeze times to converge. Why should there be an inflection point above which the hot will cool down, catch the cool and pass it but below which they act the same.
I say again, this is interesting. The calorimetry is really just a yardstick against which the real mystery is able to be observed. Everyone who has a modicum of physical intuition knows that given a "fair" start the cold should freeze first. WHY it doesn't, not THAT it doesn't, is the interesting part that should be the focus of the investigation.
If masses of the samples are equal (not volumes) and the disolved air is equal from sample to sample then the results would be even more interesting. It might be interesting to start with triple distilled water that is heated to boiling and placed into two full containers and kept from contact with air. cool one container and reheat the other in a microwave to get a large delta temp and then put the respective samples in the tray and into the chamber and see what happens.
Triple distilled water is available by the quart or gallon real cheaply at most grocery stores.
CAUTION: Be careful using a microwave to heat a full container. The lid must allow pressure to escape. Any contaminate introduced into water heated beyond the boiling point but without boiling can cause a rapid boiling effect, steam explosion.
Pat
I'm still waiting for the delta T (in seconds) between the freezing times of two samples starting at the same temp. This sort of calibrates and proves the experimental setup capable of measuring the experiment of interest. If you get too much variation betwen equal temp samples then the experimental setup is flawed or there are things going on not accounted for or both.
Now to reduce the problem a bit... The data reported said that the originally hot sample caught up with the cold sample and passed it in loosing heat. This is supposed to support the contention that a warmer sample freezes first.
I claim that at the instant the originally warmer sample passed the originally cooler sample (in a negative direction thermometer wise) that it then became the cooler sample and the originally cooler sample is now the warmer sample. So the NOW warmer sample does not freeze first, does it!!!
There is something beyond simple calorimetry going on here and I am not claiming that it has to be experimental error. It could be all or in part but we just don't know yet.
What if you fill a large insulated coffee carafe with tap water and then fill one side of the tray from the carafe. Put the tray in the chamber for a few minutes and then remove it and fill the other side from the carafe and return the tray to the chamber. One sample is warmer than the other but both have similar disolved gas content.
If the experiment were repeated succsessively with a smaller and smaller temp differential between samples you would expect the freeze times to converge. Why should there be an inflection point above which the hot will cool down, catch the cool and pass it but below which they act the same.
I say again, this is interesting. The calorimetry is really just a yardstick against which the real mystery is able to be observed. Everyone who has a modicum of physical intuition knows that given a "fair" start the cold should freeze first. WHY it doesn't, not THAT it doesn't, is the interesting part that should be the focus of the investigation.
If masses of the samples are equal (not volumes) and the disolved air is equal from sample to sample then the results would be even more interesting. It might be interesting to start with triple distilled water that is heated to boiling and placed into two full containers and kept from contact with air. cool one container and reheat the other in a microwave to get a large delta temp and then put the respective samples in the tray and into the chamber and see what happens.
Triple distilled water is available by the quart or gallon real cheaply at most grocery stores.
CAUTION: Be careful using a microwave to heat a full container. The lid must allow pressure to escape. Any contaminate introduced into water heated beyond the boiling point but without boiling can cause a rapid boiling effect, steam explosion.
Pat
Egon
Epic Contributor
Pat, you mean sorta like heating Baked beans in the microwave with no cover over the container??
patrick_g
Elite Member
Egon said:Pat, you mean sorta like heating Baked beans in the microwave with no cover over the container??
Well... So what is wrong with that?
1. My microwave has a power setting so you don't have to BLAST everything at full power.
2. One of our microwaves has a probe so you can set the controls to heat the food to the set temp and shut off.
3. And besides I like the texture of "PUFFED BEANS!"
Oh, I think refried beans are more treacherous! Uh.. as regards being explosive... I mean in the microwave!
Patrick
SPYDERLK
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On all the microwaves I have owned the full power is employed on a shorter duty cycle in order to "turn it down". If the oven is not too powerful this works well, but somewhere around 1200W these become unsuitable for heating sludgy fluids. The hi energy imparted per unit time causes them to crisp and crust at the edges. Every ON cycle instantly sounds like rice crispys on drugs. Presumably, some hi power ovens are more elegantly controled.
Larry
Larry
Egon
Epic Contributor
If the microwave has all the adjustments [ ours does ] you gotta remember how to set them which can become a problem for some of us. Therefore Blast away.
