By Roy Martin, 31 Jan, 2012
It appears that the conclusions of this experiment are incorrect, that it has not proved that the higher temperature reached in a container at a constant higher pressure, relative to an identical container at a lower constant pressure, is in fact simply due to the higher pressure. Such a result would be contrary to the Gas Laws, which have been successfully applied by physicists and engineers for a very long time. After musing on the details of this experimental set-up for some days I have come to the conclusion that the humble hot water bottle is the culprit.
To recapitulate relevant set-up details:-
There are two identical containers, each of 1.0 litre volume.
Container 1 is vented to atmosphere. We can accept that pressure will be quite constant at 1.00atm..
Container 2 is connected to and can vent into a hot water bottle (HWB). The initial volume of the HWB is unknown, but is of the same order as the container 2, and the actual volume does not affect this analysis.
Container 2 and the HWB are pressurised to close to 1.1 atm., using 25 kg mass contacting the HWB over an area of 250cm^2. Konrad’s estimate of pressure was confirmed. This set-up is intended to maintain a constant pressure in container 2. The actual pressure in container 2 and the HWB were not measured during the experiments.
We do not know the shape of the contact area, but for simplicity and later reference, the 250cm^2 contact area is assumed to be a rectangle 17.9cm long by 14.0cm wide.
After being exposed to a heat source of equal intensity and for the same time:-
The temperature of the air in container 1 increased from 25C to 50C => 298K to 323K
The temperature of the air in container 2 increased from 25C to 52C => 298K to 325K
The volume expansion of a gas is calculated from: V1=V0(1+at)
Where V1 is the volume at the higher temperature, V0 is the volume at the lower temperature, a is a characteristic constant, 0.003672 and t is the temperature rise.
For container 1, V1=1(1+(0.003672*25) => 1.0918 litres. The 0.0918 l. or 92cm^3 was vented to the atmosphere.
For container 2, V1=1(1+(0.003672*27) => 1.0991 litres. The 0.0991 l. or 99cm^3 was vented into the HWB. For the moment we will ignore the fact that the air vented into the HWB is heated, and will cause a small rise in the temperature of the air in the HWB.
The addition of 99 cm^3 to the HWB will raise the top surface by about 99/250=0.396cm. This will be shared equally by the upper and lower halves. We will come back to the effect of this shortly.
If we assume that the gas laws are fully applicable here, the only way that the temperature rise in container 2 can be higher than in the heated container 1 is for the pressure to have also increased. The applicable gas equation is (P0*V0)/T0=(P1*V1)/T1.
V0=V1, so P0/T0=P1/T1, then P1=(T1/T0)*P0.
Using pressures in atmospheres: P1=(325/298)*1.1=1.1997, say 1.2atm..
Could the pressure have increased by 0.1atm. during the experiment?
The only way the pressure could increase would be for the area of the HWB in contact with the weight to decrease. The mass of the pressurising weight does not change, thus P0*A0=P1*A1.
Then: A1=A0(P0/P1), which gives, with A0=250cm^2 from above: A1=250(1.1/1.2)=229.2cm^2.
An area of contact 17.23cm*13.3cm=229.2cm^2. This is just 3.5mm less on all sides than the initial dimensions from above of 17.9cm by 14.0cm.
The pressure in container 2 could therefore have increased as required to satisfy the gas laws because as the HWB inflated, the 2mm increase in height would cause the surface around the periphery of the contact area to roll away from contact. The loss of 3.5 mm of contact all round is of just the amount that might be expected.
I conclude from this analysis that omitting to measure the actual pressure in container 2 and the HWB during the experiment has resulted in a false conclusion being drawn. The existence of a temperature effect based on pressure was not proved. I venture to suggest that if the experiment is duplicated with truly constant pressure, the results will confirm the analysis above, and demonstrate that the long standing gas laws are still valid.
It is for Konrad to decide how to do that, but at the level of pressure in the experiment, he needs a way of measuring pressure that is sensitive to around 0.005atm. or less. That converts to 0.07psi, 0.5kPa, 2.0 inches or 52mm of water.
Another approach to the set-up, rather than use the HWB, might be to vent container 2 into a large container of 20 or more litres volume. A beer keg that can be safely pressurised up to a much higher level is one suggestion. The small volume of air or gas vented into that volume should have a negligible effect on the pressure, but any small increase detected on a sensitive pressure gauge could be bled off to bring the final pressure back to the starting pressure.
My money would then be on finding no difference in the temperature rise between the two test containers, regardless of the gas used.
Tallbloke's Talkshop 
And the Scientific Laws formulated over the centuries triumph again.
Why is it that the only things not subject to these inviolate laws are climate models. The similarity to celebrity models who consider societal laws don’t apply to them is perhaps appropriate, the climate models are the “celebrities” and the CAGW crowd follow their every whim.
Looks like a very plausible explanation.
So now we have the GHE and the ATE both trying to explain the difference between their resp blackbody temperatures of 255K and 154K with the actual 288K and neither theory seems overly convincing at the moment. Both effects may exist, but are imo not capable of explaining all of the the said differences.
Perhaps give my simple Ocean Temperature Effect a serious look?
(deep oceans are ~275K, in thermal balance with the hot core, and also in radiative balance with the sun, so neither loosing nor gaining heat on average, just shedding incoming solar heat back to space through the atmosphere)
If I’m wrong, fine. But at least explain why.
Ben Wouters
The increase in pressure due to heating simply doesn’t matter. Yes it follows the gas law.
That temporary heating effect due to the increase in pressure as the vessel warms is soon dissipated to the environment and we are then left with two containers, one permanently warmer than the other because the denser atmosphere in that container simply stores more energy from the same light source.
The denser atmosphere represents a larger sink for energy and it will maintain its energy level so long as the light source delivering that energy remains shining.
By Roy Martin, 31 Jan, 2012
Perhaps you don’t realise that the water bottle was added due to critisism of his original experiment by warmists on the WUWT thread?
Even more telling was when he used Air and pure CO2.
What do think the result was?
I’d suggested in Konrad’s thread that a proper automated pressure release should be used to maintain a constant pressure rather than a venting chamber. As far as I understand the experiment, the hot water bottle was added to regulate the pressure inside the bottle and for no other reason; it isn’t necessary to have a venting chamber if you’re going to have a sensitive pressure gauge and a means to maintain constant pressure so I don’t see why it’s even being talked about.
“After being exposed to a heat source of equal intensity and for the same time…”
This would be a very straightforward application of the IGL. This isn’t the point, however. What we’re interested in is what happens after the apparatus reaches thermal equilibrium, i.e. energy in = energy out. It’s likely that the amount of time it would take to reach that equilibrium would be different for the two bottles since the amount of gas is different.
“The applicable gas equation is (P0*V0)/T0=(P1*V1)/T1…”
This is an equation of state and assumes you are talking about a fixed quantity of gas. So, if at state “0”, you have values P0, V0, and T0, then change one of those properties to state “1” (e.g. by increasing T), the IGL predicts what the values of the other two properties will be. In the experiment, there are TWO fixed quantities of gas, both at their own initial state “0” at the beginning of the experiment and at their own state “1” at the end. You can’t say that because V(bottle 1) = V(bottle 2), there is some sort of direct relation between the two bottles. More accurately, you are confusing whatever relationship there might be.
It’s very confusing to me to try to visualize what N&Z are talking about. Pretty much every experiment to prove or demonstrate the IGL consists of varying P,V, or T by some amount, then taking measurments, which is very easy to follow. N&Z are discussing a dynamic system where energy is constantly entering and leaving the system and predicting where those values will settle in when equilibrium is reached.
Still, a good discussion and it’s helpful to me to follow others’ lines of reasoning.
@Roy Martin; If you are such a competent scientist, then do your own experiment and report. Every “improvement” you suggest would actually add greatly to the complexity, cost and number of areas of argument. Such as your calculations of the changes of contact surface of the water bottle to the plywood pad to show pressure changes in PET cell #2. I for one don’t buy your argument. pg
@PG: easy now, Roy is an old friend of the talkshop. I think Konrad’s reply about the amount time given for relaxation after compression will be key here. And the experiment will have to be better specified before the others at WUWT will accept it anyway.
Not so fast folks.
We have a pressure vessel in the form of a gravity well: central mass causing gravity, gas envelope clinging to the outside. This has a static pressure profile set by gravity. I seem to recall the equation was complicated.
The situation is made more complex by a lapse rate modifying the gas density/pressure. Different maths laws are fighting each other.
In the context of an experiment where a greater atmospheric mass is being artificially created, what is the accurate law for pressure control?
Old friend or not tallbloke, Roy’s criticism is misplaced. This was an interesting very informal experiment, that’s all. Konrad never claimed it was peer-reviewed science and obviously a properly-designed formal experiment, with replicability, would be needed to validate or refute the preliminary findings. One would have to be very naive to accept the results of Konrad’s experiment at face value. I don’t believe that was ever his intention. IMO any reader of average education is discerning enough to recognize the difference between an informal experiment and replicable science. To wit, the above criticism is pointless. Talk about shooting oneself in the foot!
Krazy glue the contact edges of the HW bottle to the surface?
Roy,
Your analysis of the deformation geometry of the hot water bottle may in part be valid. However this is not the only variation that I have tried. Earlier I used fixed volumes, then a fish tank pump connected to the high pressure bottle. The tubing was run through ice water and a pin hole bleed was made near the bottle connection. All tests so far have resulted in a similar pressure differential.
I have bellows foot pumps I could use, but a poster on a previous thread suggested a water column. When I get time I may be able to construct one. I have already acquired two halogen down lights as constant light sources, and time permitting will make further improvements.
Above all, I think it would be good to have others physical test the N&Z hypothesis independently.
Chris M: I don’t give a monkeys what other people might regard as foot shootings. Let the chips fall where they may. I think the failure to have already replicated the experiment under more stringent conditions is speaking volumes about the regard the AGW riddled scientific establishment has for computer games; and its disregard for empirical scientific discovery.
Konrad: Thanks for responding, and I realise your unpaid volunteer time is limited. You’d think the millions being spent on AGW confirmation might spare a bit to test other hypotheses and empirical studies such as yours.
Unless they are bullshitting?
Tallbloke, believe it or not we are fully in agreement! The wasted billions are an absolute disgrace, and as FOIA said a tragedy for the less fortunate on this Earth. btw kudos are due to Konrad for his practical nous in designing and building his experiment. Most people in Western societies are sorely lacking in such skills.
Chris M: No worries, science will overcome.
The moving finger writes and having writ moves on
Nor all your piety nor wit shall call it back
To cancel half a line
Nor all your tears wash out a word of it.
The writing is on the wall for AGW.
Thanks TB and all who have commented so far. I have just come on deck in the SH and have a busy day ahead. I will pick up on as many points as I have time to during the day.
Konrad:
Pleased to see you here for the discussion.
I see only one key point at issue in your experiments. It is that by not actually measuring the pressure in container 2 you cannot be sure you are actually controlling that most important variable.
At the present low pressure level in the set-up a simple U tube water manometer is practical, one end connected to the pressure container and the other open to atmosphere. 0.1atm pressure will create a differential in the heights of the water in the arms of 1,033mm, one down and one up equal distances. A quick and dirty, but quite accurate set-up would be a length of clear PVC plastic half inch hose taped to a length of board with the arms either side of a scale. The pressure reading from this can be very accurate, because it is easy to read each arm to within +/-1mm.
Assuming you retain the HWB and weights as a convenient way of setting the initial pressure, and that the pressure would tend to rise as predicted, it can be regulated quite simply by reducing the weight on the HWB to compensate.
I am a little confused about what this experiment is attempting to show and the criticism. If I have two identical containers, with identical gas and pressure, and I release some of the pressure from one of the containers, that container will cool. I think that is what Konrad’s experiment does (venting the first bottle as he heats and pressurizes both bottles), so the above criticism is wrong, kind of.
I think the original experiment is the correct one, if I remember correctly. The first sealed bottle at one atmosphere, and the other sealed bottle at a higher pressure.
My problem with that experiment (or what is brilliant about it ; ) ) is that I don’t think it is measuring what everyone seems to think it is measuring (pressure vs temp). I think it is measuring conduction vs radiation heating too. If you have two different masses and equal energy going to each mass the larger mass has to warm less than the smaller mass.
I am guessing that in Konrad’s experiment the black cutouts are conducting heat more efficiently to the denser (higher pressure) gas and that is why despite the greater mass the higher pressure gas warms up more. The radiation absorption is probably the same in both containers. Or in other words, the non GHG’s are absorbing/retaining more of the energy in the system.
” If you have two different masses and equal energy going to each mass the larger mass has to warm less than the smaller mass.”
Why? Would it not warm more slowly, but not necessarily less. More mass equals a large heat capacity and more residence time of energy within the medium. Is it not possible that each molecue would reach an equilibrium from the source, but more molecues per volume would manifest greater T?
Roy,
as I see it it should be possible to use a water column itself to regulate the pressure. If a small diameter tube was run down inside a 2m water column it would take approximately 0.2 bar to expel air from the open end of the tube. This could be used to simply regulate the test bottle to 0.2 bar. If pressure in the bottle rose above this, bubbles would escape from the tube in the water column returning the test bottle pressure to 0.2 bar. The system would need to be primed so that the relief tube was just about to expel bubbles before the test was run.
However ideally I would want a method of regulating higher pressures. The PETG bottles can take over 5 bar. Tests at higher pressures would provide more robust results.
David – “Why? Would it not warm more slowly, but not necessarily less. More mass equals a large heat capacity and more residence time of energy within the medium. Is it not possible that each molecue would reach an equilibrium from the source, but more molecues per volume would manifest greater T?”
First, temperature is independent of the number of molecules per volume. Temperature is the average kinetic energy of the molecules. Heat content on the other hand is dependent on the number and the mass of the molecules. A bucket of ice water has a lot more “heat” than the deuterium atoms in the Tokamak fusion reactor, that are heated up to several hundred million degrees C. In fact if we were to take the atoms from the reactor and put them into the bucket of ice water I doubt it would register on a thermometer. Temperature is simply a way to ‘infer’ how much energy is in something, given its mass.
There is a lot more energy in a given volume of moist tropical air than there is in dry arctic air at the same temperature. Averaging the two temperatures is almost meaningless, but the warmers like to do it because it magnifies any warming effect. That is the reason that they like anomalies but hate actual temperatures.
The reality is that most of the natural variation and temperature fluctuations that we measure and read about is fiction. The amount of energy that the earths absorbs and emits on a daily, yearly and decade long basis is extremely stable. What we are measuring with thermometers is rounding errors in the energy budget.
Suggestion: for someone who is taking baby steps these concepts do not always make sense. The experiment by Konrad and the suggestions made by Roy have a lot of merit. However, what would be really helpful would be to have someone film the experiment and then upload it to Youtube. In that way, we can see what is happening and then maybe understand it a little bit better.
As far as I am concerned, Roy’s suggestions are quite valid and I believe that this is the way that scientists or whatever should work together.
To me, personally, this is why I have problems with the AGW crowd – their science is settle b.s. is not conducive for real scientific research. It is doing more harm than good.
P G Sharrow said,
January 31, 2012 at 5:09 pm
@Roy Martin; If you are such a competent scientist, then do your own experiment and report. Every “improvement” you suggest would actually add greatly to the complexity, cost and number of areas of argument.
Just for the record, I am an engineer. I am not, and have never claimed to be a scientist, but I did spend a lot of time during my career either working in and around laboratories and test facilities, or having them do work for me. More than enough experience to know how an experiment should be set up and conducted, and what to expect from it.
Re: measuring pressure in this experiment, see my comment to Konrad Feb.1 at 12:05 am. Simply measuring and then regulating pressure will eliminate the only issue I have with Konrad’s experiment and eliminate one area of argument, not add any.
@Konrad; your loaded waterbottle is the most elegant solution but I doubt that it will stand more then 1/3 bar. While I have used water columns of one kind or another to regulate vacuum and pressures, to do more then 1/10 bar is difficult. I would suggest going back to the gravity loaded device. This time use a hydraulic cylinder type unit gravity/mass loaded, and a pressure regulator as well as a gauge.
The pressure regulator is not needed as the gravity loaded cylinder will maintain the desired pressure because it has to. Pounds per square inch or grams per square centimeter. What ever the gauge reads. Gravity is not likely to change over the length of time that you will run the experiment. 😎 Have fun. pg
Konrad said: February 1, 2012 at 3:26 am
Roy,
as I see it it should be possible to use a water column itself to regulate the pressure.
Konrad:
Your idea is theoretically sound and should work as an automatic pressure relief regulator. Again, inexpensive PVC tubing with a diameter large enough to avoid surface tension effects would be easy to set up. If you stay with 0.1atm as the test pressure, requiring only ~1m water head, you can keep the HWB + 25kg weight and pump up to pressure as before, until bubbles start to escape. An advantage of repeating with 0.1atm is that you will have a direct comparison with the previous tests.
During the test the height the 25kg load was initially raised to should not change, because the pressure inside the HWB will be constant. Incidentally, it will be neat watching the water column lifting that much weight as the rig is pressurised.
Over at WUWT, on January 23, 6:13 am, Joel Shore, (a wizard of great CAGW wisdom and voluminous broadcasts at WUWT), made some deprecating remarks concerning Konrad’s experiments, including in part:
I enquired here: http://wattsupwiththat.com/2012/01/22/unified-theory-of-climate-reply-to-comments/#comment-876755 if he would elaborate on this, but as of a moment ago, he still remains atypically silent.
@Roy; I have never had expensive lab tools and people to do my bidding.I have to find solutions on the simple and cheap. Often many bells and whistles are unneeded. So using the K.I.S.S. method is of great importance. Konrad has taken it upon himself to test the concept under conditions that anyone can reproduce, even school kids. This is great! real science, no wonderful algebraic physics formula to confuse the untrained. After the science is proved then the physics can be added to apply it to other conditions. Real science will explain that gravity load on the #2 PET pressure system will maintain and regulate that cell pressure and volume reasonably well because it has to. pg
Roy and Konrad: Excellent, this is what I hoped would come out of publishing this critique; a discussion on how to improve the set-up to eliminate uncontrolled variables. I think both of you have the right ideas: to improve the existing set-up and repeat the experiment; and also to test a system under a series of much higher pressures to generate a curve of results.
It looks to me like the water column with the ‘pressure relief tube’ idea is an elegant solution, and not too expensive or time consuming, while being nicely sensitive. Better than fancy and expensive control valves in several ways. You can easily measure the set-up to calculate exact pressure, and using clear tubing, you can film the experiment for post analysis and verification. Under blue skies when the Sun is near zenith, the incoming energy can be closely estimated too.
For the high pressure rig, an adjustable pressure relief valve of some kind is required. For the reservoir, a big old
acetylene[see comment from PG below] oxy-welding bottle might do the job. Plenty of old empty ones around in workshops where increasingly tight regulation higher costs and cheap MIG welders discouraged owners from getting them refilled.Acetylene bottles have some kind of solid matrix in them, this would give plenty of thermal inertia.Plus they come with nice pressure gauges and high pressure hoses ready fitted.The surface pressure of Venus is around 90 atmospheres. We won’t get that high, but it’s something to aim for. According to Ned Nikolov, Venus absorbs 31% less solar radiation than Earth because of the high albedo it has. yet the surface temperature is more than twice that of Earth: Hot enough to melt quite a few metals!
Roy Martin @ February 1, 6:23 am
Well me, a mechanical engineer, I think of myself as an applied scientist, as do geologists et al, as distinct from academics. A big difference between us applied scientists and the academics is that we need to be far more confident in our assumptions if we do not want kill people or cause infrastructure dramas.
Do you discard recognition of being a scientist in embarrassment of what some of them do?
And yes, I’ve done and observed quite a lot of test and development thingies before my retirement, young fella.
@tallbloke says:
February 1, 2012 at 7:34 am “For the reservoir, a big old acetylene bottle might do the job.”
I would recommend against that Idea. Acetylene bottles are filled with diatomacious earth saturated with acetone. Not a good thing to play with. pg
PG: Fair enough, I bow to your greater experience. Konrad, use the empty oxy bottle instead.
Bob FJ: Joel is going to see his favourite century-old physics overturned – by some three-century-old physics. 🙂
Ghengis: The system under test is energetically dynamic, not static. Because of the throughput of solar radiation, the higher air density matters.
Thinking about it some more, for high pressure tests, the additional pressure generated by the solar energy in the PET bottle will be negligible, and relaxation times short. So we can simply use a ready pressurized oxygen cylinder connected directly, with a pressure gauge inline, and a bleed screw to fine tune the pressure once the system is near equilibrium.
Oxy welding cylinders come charged to 2200psi. Where to get a stronger clear plastic test bottle? Hmmm. The hotter it gets, the easier the plastic will deform. Crash helmet and ear plugs required I think. 🙂
AHA! Data! http://waterrocket.uh-lab.de/lr010101_bursttest.htm
looks like PET bottles will go to 9.5 bar with a metal ring round the mouthpiece.
So, for a cheap rig, a footpump should be sufficient. A mate of mine has a beauty which came with a pump-up air rifle.
Bob Fernley-Jones said:
February 1, 2012 at 7:46 am
“Well me, a mechanical engineer, I think of myself as an applied scientist, as do geologists et al, as distinct from academics.”
OK, I would be happy enough to accept a hat for being an applied scientist. Certainly much of what I was involved with used fundamentally the same investigative methods and rigorous controls used by academics in fields recognised as science.
The majority of scientists have my every respect and admiration for what they achieve. The climate science community are so highly visible that it seems a great shame some of the work in the area can be criticised for not meeting appropriate standards. That just makes it harder for the rest of us to get a grip on where the really solid bits are.
Be careful Guys, you are making a bomb. A PET bottle is full of liquid and a little pressurized gas. A gas cylinder is full of many cubic feet of gas. A failure can be explosive. I would recommend that 2 bar is a high enough pressure to work with for solid results. pg
tallbloke says:
February 1, 2012 at 7:34 am “oxy-welding bottle might do the job” and later “a footpump should be sufficient. A mate of mine has a beauty which came with a pump-up air rifle.”
Those Air Rifles often come with Divers Air bottles, complete with pressure gauges and high pressure hoses, Scout Groups use them a lot.
Think I might have a solution. Beware bags, get all stretchy when you hump a load onto them.
In this case the polymer is under load and is a non-linear spring, even though the intent is lifting against gravity.
A solution is consider the bag is a protective membrane separating fluids and immerse the bag as deep as you can in water, adding an even hydrostatic pressure provided the bag is kept in a sufficiently relaxed state. The obvious problem is static head. It’s possible to use a closed outer container and a long plastic pipe to whatever height can be managed.
(looks out at tree, notices long tape measure, binoculars, laser level, ladder, ink, etc.
Got plenty of tubing then you could also put a bladder in the outer container and use that to adjust the pressure. There we are, pneumatic remote control.)
Done string and paper, now for the sealing wax.
Tallbloke – “Ghengis: The system under test is energetically dynamic, not static. Because of the throughput of solar radiation, the higher air density matters.”
I agree, the higher density matters. Where I disagree is in what everyone is thinking is actually being tested.
I think the higher pressure/density improves the contact area between the insert and the air, increasing the thermal conduction to the air. That is what accounts for the higher temperature in the higher pressure bottle (that and the fact that the gas in the lower pressure bottle is being released), despite its increased mass (which should slow the temperature increase by comparison).
I would like to see the experiment run without the insert and again with the insert flat against the bottom of the bottle.
What makes this ‘simple’ experiment more difficult than it appears is the number of variables that are coming into play here.
Does anyone know where I could pick up some (cheap is the operative word here) solar collector vacuum tubes? Because if what is being claimed here is accurate, instead of using vacuum tubes they should be filling the tubes with high pressure gas. The results should be easy to test.
Genghis,
I think that is about insulation.
We are dealing with a flux, which doesn’t behave in the way most things do in our experience.
Their objective is maximum energy transfer but the source has an infinite source resistance. This is not a usual situation. If they are right they are slamming this into as near absorb only as they can, surrounded by (I assume) a hard vacuum to stop convection and conduction. Heat takeoff up the inside.
This seems correct.
Tchannon – “If they are right they are slamming this into as near absorb only as they can, surrounded by (I assume) a hard vacuum to stop convection and conduction. Heat takeoff up the inside.”
That is correct, but if the above experiment is correct they should be surrounding the black copper rod in the center of the tube with high pressure gas to heat the rod (temperature probe) up even more, conduction and convection be damned.
The experiment above isn’t really measuring the effects of pressure on temperature it is measuring the effects of pressure induced conduction on temperature. I think it is a very important experiment, that is central to the whole AGW debate, convection vs radiation.
This is why the N&Z calculations that show the surface 100K lower than the AGW numbers is huge! The atmosphere is primarily heated via evaporation, conduction, and convection, Not Radiation. Radiation is only a small proportion, not the 80%+ that they are claiming now.
I think Genghis has a point. Anyone who has worked with flames and flames licking the walls or product stream knows the importance of convection. A badly position burner pipe can burn holes through furnace walls. Flame temperatures depend on the fuel mixture chemistry, the burner design, the entrainment of oxygen and combustion products and to a small extent heat transfered by radiation to the surrounds. Oxygen enrichment increases flame temperature because there is less heat held by nitrogen from air. Insulated surrounds ie no radiation absorption, does not increase flame temperatures beyond the theoretical calculated for no heat loss. The concept of back radiation is nonsense. One can not create heat out of nothing. Insulated combustion chambers have sometimes been used to get better mixing of fuel and combustion gases but good burner design is usually a better and less costly option.
Just a further point. Heat conduction only occurs in solids and is very similar to electrical conduction. Conduction heat moves from atom to atom in the direction of temperature difference. Convection occurs in fluids (gases & liquids) and between surfaces and fluids. It involves molecules that move and have an heat capacity. These molecules will not radiate to their immediate surrounds if the temperature is the same.
Genghis says:
February 1, 2012 at 5:18 pm
“…The atmosphere is primarily heated via evaporation, conduction, and convection, Not Radiation. Radiation is only a small proportion, not the 80%+ that they are claiming now.”
I think you are nearly right, Genghis. Gas laws and thermodynamic processes rule in the troposphere, while radiation physics dominate in the stratosphere and above regarding the energy held in the oceans and atmosphere. On land a mixture of both processes are important as shown by our rampant biosphere – radiation to fuel photosynthesis and thermodynamics to provide the water necessary for growth.
I posted a comment on the original thread, broadly in line with what Genghis has said on this one: The experiment, as described, does not adequately control for conduction and convection within the vessel.
This subject has received some recent blog attention elsewhere, such as the attempted reproduction of the “Wood’s Experiment” by Vaughan Pratt. DeWitt Payne [who usually gives a good account of himself] has also commented on the difficulties of these experimental considerations at the “Science of Doom” website. I think he also reports some of his own experimental results [that is real experimental, not modelled]. The relevant posts might require a bit of searching though.
“MyDogsGotNoNose” also posts regularly, and compellingly, at JoNova and Bishops Hill websites. I think his comments about the IR-responsive role of the container walls also need to be taken seriously. I’m still digesting what he says about density of states and IR-thermalization, but I find myself increasingly persuaded.
I don’t want to sound too negative, but it’s a good first line to this article. [Yes, I know that sounds arrogant, but you can always identify an experimentalist-at-heart: They have more experience of being wrong, are less afraid to admit it, and are better scientists as a result]
I have here, in Gedankenland, a tethered helium balloon, silvered and such so that conductive and radiative influences on it are minimized. Inside is a teensy wireless thermometer, which uses a microwatt-millisecond burst every 3 seconds to report internal temperature.
I let the tether out till the thermometer reports 5°C. I then rapidly reel it in down to 2 meters height and immediately record the reading.
What will it be? Higher? Lower? Unchanged? Explain, and show your work.
Boyles law tells us Pressure and Volume are related. So as the balloon is winched down, the surrounding air pressure increases and the balloon shrinks. As the He in the balloon equalises with the higher near surface temperature (due to the lapse rate) and the compression of the gas heats it, it expands again.
Result, the temperature is higher pretty much immediately it is winched down.
Not so TB: First we have to assume that Brian H. meant that he allowed the balloon to stay at altitude long enough for both pressure and temperature of the He to stabilize at the same temperature and pressure as the surrounding air. If the He in the balloon is rapidly compressed by pulling is down to ground level where pressure and temperature are both higher, work will be done on the He by the sudden increase in pressure causing it to compress and increase in temperature. It is not an isothermal change obeying Boyles law, but because of the rapid change and the silvered surface reducing radiate heat loss, it will follow the adiabatic form PV^n=a constant, so the He will not only be compressed but heated as well, by the work done on it. At that stage the pressure in the balloon will be higher than when it first left the ground, due to the higher temperature of the He, so it will also be slightly larger. If the balloon is then left to return to ground level temperature, it will eventually return to it’s original pressure and hence size.
Perfect balloon, gas, nothing happens, although the work of moving the balloon will produce losses coming out as heat.
No, we mustn’t “assume that Brian H. meant that he allowed the balloon to stay at altitude long enough for both pressure and temperature of the He to stabilize at the same temperature and pressure as the surrounding air.” The balloon’s thermometer and I know nothing and care nothing about the surrounding air. When it transmits 5°C, down comes the balloon.
The hidden kicker here is: why would the internal temp go down? Internal pressure may or may not be equalized to the outside air, depending on whether this is a rubber inflatable or a sonde-type loose fabric balloon (and even then fabric weight requires higher balloon pressure than ambient — otherwise it won’t inflate and rise in the first place.)
About the original experiment: as one black surface begins to heat more than the other, it will radiate away more, too. In IR, those black strips are bright white.
OT, sorta: in UV, black/dark skin is shiny bright (in whatever colour UV looks like for those who can see it), whereas paleskins are dark/black. The former reflect UV, the latter absorb it.
tch;
I’m doing the work, winding the reel. So I get warmer, and so does the reel. The balloon and contents?
Just a quick update to the experiment for those interested –
I have eventually managed to find a few hours to build a water column to regulate the pressure in the test bottle more accurately. I have used 2.5m of 50mm PVC pipe with an end cap to make the column. 5mm diameter fish tank tube is dropped into the column with a weight to keep the open end at the base of the column. The bottle is then pumped up until bubbles are released from the tube in the water column. Before exposure to the sun both bottles are stabilised at the same temperature. Unfortunately rain stopped play on my first test day, however initial results observed before the rain were as before. A 3 degree temperature differential was observed within 5 minutes of exposure to sunlight. My next step will be to set up two identical 12v halogen lights so I can test indoors.
Konrad,
I greatley look forward to your latest experimental developments, and I hope N&Z take note.
I haven’t been following this thread recently, but someone up there talked about balloons. I don’t see the relevance to this discussion. It’s a bit like Ira’s naive analogy of using pressure vessels. They would simply respond to there environment, whereas the topic is the total unrestrained atmosphere. There might be some complications due to various tidal effects and also centrifugal force, notably at the equator though?
Konrad: Well done! Now, be sure to find a way to monitor the bubbles out of the tube end with a video camera so we can exclude doubt about pressure stabilisation. Keep up the good work. You are nearly there!
[…] Konrad Hartmann performed an experiment using pet bottles in direct sunlight. There was some constructive criticism of his experiment, and he made some design improvements which we are awaiting results from. Konrad […]