KeroZen
Chronic vapaholic
I think @OF was talking more about the thread topic than your cube @Hippie Dickie. Your design is quite different and closer to say the Vapolution 2.
Arizer portable heater tech discussion
- Thread starter stickstones
- Start date
OF
Well-Known Member
Exactly so, thanks for sorting that out, KZ. I was talking about Arizer heaters.
I don't know about either of those, but suspect they're like ESV (where the source is hotter than the load)? Has to be since heat only goes from hot to cold (in net movement) and we need to move heat (in calories) to evaporate THC in and still maintain heat (in degrees) at the magic temperature. Replacing the heat in the load lost to making vapor is the key to keeping the production rate up. Ascent showed this in spades. Adding 'glass flowers' to the load as heat reservoirs allowed for much longer hits over waiting for replacement heat to 'trickle in' through the glazed ceramic walls. It took longer for the load temperature to drop, without them as a reservoir that could be called on in a timely manner it was possible to hit really hard and have it drop from 400F to 300F......
OF
Last edited:
KeroZen
Chronic vapaholic
I hope I won't say incorrect things, correct me if I am @Hippie Dickie, but his design is:
- a rather large gauge nichrome heater in the form of a coil
- heater driven by custom PID controller (from a PIC MCU if I remember correctly, but it's irrelevant)
- temperature sensor for feedback located in the middle of the heater
- inside the coil there is a glass test tube (so open only on top)
- load is inside a second glass tube (the vial, also a test tube but with holes at the bottom)
- said tube is inserted into the larger tube, with the load close to the bottom side
- you draw from the small tube, so air has to travel from the top, between the two glass tubes, then into the vial holes and through the load, then through the vial and to your mouth
- a rather large gauge nichrome heater in the form of a coil
- heater driven by custom PID controller (from a PIC MCU if I remember correctly, but it's irrelevant)
- temperature sensor for feedback located in the middle of the heater
- inside the coil there is a glass test tube (so open only on top)
- load is inside a second glass tube (the vial, also a test tube but with holes at the bottom)
- said tube is inserted into the larger tube, with the load close to the bottom side
- you draw from the small tube, so air has to travel from the top, between the two glass tubes, then into the vial holes and through the load, then through the vial and to your mouth
Andreaerdna
If God is the answer, then the question is wrong
From wiki
Thermal conduction is the transfer of heat (internal energy) by microscopic collisions of particles and movement of electrons within a body...Conduction: transfer of heat via direct contact
So the answer should be NOT, as you probably already know. the only way to transfer heat from a body to another body without contact is radiation and/or convection
Even when you smash some flowers against a flat surface the real contact area between hot metal and flowers and flowers/flowers (accountable for conduction) is very small (microscopic scale) hence also in PAx style vapes IR heat transfert should be considered as the main way to heat the load IMO
But on FC conduction seems to have another definition that includes radiation
OF
Well-Known Member
This might be the source of some/much of the confusion. Conduction is an 'atomic level' thing. The materials don't have to be solids. They can also be liquids and gasses? The same rules apply (of course). When I put the tea kettle on the stove in the morning, the hot metal pot on the stove heats the water by conduction, right?
Same happens in say Solo. Heat is conducted through the insulation around the heater, through metal to the cup, to the glass stem (either directly or by heating the gas (air) which in turns transfers heat to the glass) and to the load from there. It is evenly distributed through the load, again via gas intermediary as needed. Some of course comes to the load through the bottom of the cup, even though there's no direct contact with the herb, by heating the air in contact with the metal. Just like cooking a turkey in the oven, where the air inside is heated by the element which in turn heats the walls, door and the bird. All by conduction.
As was pointed out to all us students many years ago, there really is no such thing as convection. It's simply a subset of conduction involving the transportation of the heat by moving a 'working fluid'. Radiation is something entirely different since it involves photons. And is not a practical way to convey heat in most vapes since it needs a HUGE difference in temperature to be practical (remember, with IR heat goes 'both ways' so the source has to transfer heat to the load much faster than the other way about).
There are a few exceptions, like the ones that use 'hot' halogen lamps or Bender which uses an incandescent ceramic heater. Not practical otherwise, unless we have a very large temperature to work with we can't move enough calories to make useful vapor.
To qualify as convection, we need to 'convey' the heat by moving the 'working fluid' (which can actually be liquid, solid or gas) from one location where it's produced to another where it's delivered. In your car engine heat is absorbed (by conduction) from the block and the water pump then moves it to the radiator where it's transferred to the air (again by conduction?). Ironically, heating rocks 'in the campfire (largely by radiation, fire is real hot) an putting them in a cold sleeping bag to warm it up is also convection? The Latin root of convection is 'together carry'. Heat energy is carried to a new place in convection heating.
So this has got me thinking perhaps part of the problem is folks aren't considering conduction heating of the air molecules by conduction from the hotter surfaces which then heat cooler gas or solid atoms they contact in their travels.....again by conduction? Atom by atom. Phase (liquid, solid or gas) not withstanding. Conduction because heat energy is transferred atom to atom by being 'atomically close', but never actually touching.......
Regards to all.
OF
okay, here is the fundamental fact: when herb is heated to a sufficiently high temperature, the thc is released as a vapor or aerosol - which i consider to be more-or-less equivalent, relative to the humidity of the gas.
so @OF, what you are describing is two types of conduction:
direct conduction, where the herb is in direct contact with the heater surface - like a PAX
indirect conduction, where the ambient air is drawn past the heater surface, and drags against it, and is heated to 400°F, and delivered to the herb. This would be the EVO or Glass Symphony, and Bud Toaster - i don't know about the Arizer design.
From the point of view of the heater, it is all conduction (plus some radiation) ... from the point of view of the herb, it is convection (or indirect conduction - i can accept that terminology), since the heated air is cooling as it delivers its heat to the herb (versus the heater which never cools - with a good PID and enough amps).
Also,
i find the temperature difference to be about 50°F, which is the difference i measure between the heater surface and the middle of the herb.
i'm confused by what you are saying about the car radiator - clearly, the coolant is removes heat by conduction, so when it moves into the radiator, the radiator is convection-ing the heat to the ambient, or is this also conduction. Or is that black box radiation, or both?
from my experience, i prefer the indirect conduction design - with a bit of radiant heat thrown in. Although, once the herb is toasted a bit, broken up and stirred, it is entirely direct conduction at that point. i feel like a lot more lipids than THC are being released at this point.
so @OF, what you are describing is two types of conduction:
direct conduction, where the herb is in direct contact with the heater surface - like a PAX
indirect conduction, where the ambient air is drawn past the heater surface, and drags against it, and is heated to 400°F, and delivered to the herb. This would be the EVO or Glass Symphony, and Bud Toaster - i don't know about the Arizer design.
From the point of view of the heater, it is all conduction (plus some radiation) ... from the point of view of the herb, it is convection (or indirect conduction - i can accept that terminology), since the heated air is cooling as it delivers its heat to the herb (versus the heater which never cools - with a good PID and enough amps).
Also,
i find the temperature difference to be about 50°F, which is the difference i measure between the heater surface and the middle of the herb.
i'm confused by what you are saying about the car radiator - clearly, the coolant is removes heat by conduction, so when it moves into the radiator, the radiator is convection-ing the heat to the ambient, or is this also conduction. Or is that black box radiation, or both?
from my experience, i prefer the indirect conduction design - with a bit of radiant heat thrown in. Although, once the herb is toasted a bit, broken up and stirred, it is entirely direct conduction at that point. i feel like a lot more lipids than THC are being released at this point.
OF
Well-Known Member
I think that's a good characterization. With two refinements. First off, it's reversible, that is THC vapor is also condensing when at equilibrium. Secondly it's not a 'suddenly at XX degrees the THC converts anymore than a rain puddle (if you can still recall them.....) happens in an instant. Laundry on the line dries (water evaporates) at a rate set by many factors.
But yeah, that's the idea, heat it up and good stuff comes out.
I don't think that's what I'm saying, at least it's not what I intended? There is only one kind of conduction. But it's happening at an atomic level. To the nearest cooler atoms, even if they're a different material of phase. The ease of this flow (call it 'thermal resistance'?) is a function of a lot of things with solids conducting better than liquids or gasses typically due to better 'atom to atom' contact. But they don't touch, ever, it's electron fields that make up the outsides of all atoms (and molecules for that matter) repelling each other against other forces pulling them together. Some otherwise good candidates for easy/rapid thermal conduction don't work very well. Like ceramics. A fun link occurs with electrical conduction, materials that conduct electricity well (like metals) tend to conduct heat well. Insulators, like glass, ceramics, wood etc 'heat more slowly'.
Gasses conduct poorly, but better under pressure..... The atoms are closer at higher pressures, at zero atoms (vacuum) the whole process grinds to a halt for lack of 'contact'? Likewise, cold metals conduct better than when hot (atoms closer together) for whatever use past possible insight that might be.
Sorry, I don't know any of those vapes but thing the arguments would be similar as with Solo/Air/ArGo I'm thinking? There air is drawn in through ports in the cup into the load. The cup is at 400F, give or take. The idea is at least some of the air going in gets heated, perhaps to that very 400F. But that's only a tiny fraction of the air really. And recent updates have made the holes bigger and undercut the openings (making the potential heating path shorter), both of which changes would seem to lessen this effect yet nobody notices?
The average air temperature is surely less that 400F, right? Only a tiny fraction might be that hot.
Contrast that with ESV, where the air goes past a heroic heater wire which is 'glowing hot'. There the temperature of the load reaches 400F 'in due time' heated by airflow alone (the heater is in another part of the vape).
For convection to work the average air temperature needs to be hotter than the load, not colder. And by a fair bit if we expect to have enough heat (in calories, not degrees) to make vapor (which calls for a constant input of heat or the 'latent heat of vaporization' of evaporation will quickly eat up the calories (or BTUs if you will) and the load will cool off again. A dynamic thing. Heat in, vapor out. Like keeping the tea kettle boiling.
50F? Interesting, I'd always meant to ask...... So that temperature difference is because there's resistance to the heat flow. When designing heat sinks for electronics gear this is a 'degrees C per Watt' number. That is a value of 4 means one Watt causes the device to be four degrees hotter than the HS. If we run 15 Watts we have 60C to deal with and potential issues on standard 70C parts.
There's an 'Ohm's law' for this part of Thermodynamics, just like Hydraulics and Electricity. A temperature difference is evidence of heat flow, same as a difference in pressures describes liquid flow in plumbing or voltage 'drops' (differences) accurately indicate the current (flow of electrons) causing it. It all fits together in the end......
Sorry, I guess I wasn't being clear enough with the car cooling system. It's an example of a convection deal. Hot water is heated (by conduction again) and then pumped to a new location to be cooled bringing net heat with it. Making the radiator hot. Making that black helps with radiation transfer (never big) but it too depends on a difference, that is as the water temperature and air temperature become closer (on a hot day, say) that effect gets smaller and smaller. But it looks good that way...... This is also why we use a fan these days to force more (cooler) air through, bigger difference, more heat transfer. That costs energy, of course, which we just burn more gasoline to make up, which i why we no longer turn fans 'full time' off the engines? Anyway, your car has a genuine convection system. The block heats the cooler water which is then 'conveyed' to another system where the hotter water heats the cooler air. Temperature drops at every step as the heat flows (the magnitude and polarity controlled by the rate and direction). This means, of course that the block is hotter than the air through the radiator. It cannot be the same temperature as long as there's heat flow going on.
Sorry for all the confusion, I'm sure I've made a hash of most of this good stuff, but it's an honest attempt at least.
Regards to all with the poor fortune to have read this far......both of you.
OF
okay, replace "hot water" with "ambient air" and "radiator" with "herb" and that sounds like a convection vaporizer ... which is what the EVO, GS and Bud Toaster are doing.
Thank-you for your patience in explaining this topic ... it is fun to work through the science/engineering of vaporizers - mainly a terminology clarification.
OF
Well-Known Member
Yup, fun stuff if you've a mind for such.
I agree, I think, with what you propose. It should be 'heated air' though, right? Ambient isn't going to heat anything now much colder than the room. Again, I don't know the vapes but if a working fluid carries net heat into the load IMO that makes it convection.
Such is not the case in the subject vapes (Solo et al) I believe, the incoming air averages less than 400F (I suspect by a lot) and therefore doesn't contribute heating, but rather is an example of convection cooling.......
OF
stickstones
Vapor concierge
OF
Well-Known Member
I understand we still disagree about what those graphs show but I still believe it's an instrumentation error as I said. I don't follow why it would make 'a shitty vaporizer', isn't that (leaking in cold air) what PVHES does? Vapes like QQ (and a bunch of similar concentrate vapes) do exactly that and seem to work quite well doing so.
Did you try the 'insert the stem part way' experiment I suggested? It sure seems to say 'conduction with no convection (heat soak with no draw) makes good vapor' and 'convection with no conduction (draw only) does not' to me. Gets me to wonder what if you reversed the flow (blow in the stem and look for vapor) with Solo. Real convection vapes, like say VGs, obviously won't make vapor, but I bet Solo does? Mind, I haven't tried it.......
Regards to all.
OF
well, it is heated water in the car because it is a closed system, but it is ambient air for the vaporizer - which gets heated by the heater to become heated air, which air then conveys the heat to the herb. a slower draw is more effective to allow the ambient air to reach heater temperature.
the graphs make sense to me, because it is measuring the temp in the middle of the herb, and the heat rises there when the hot air in drawn into the herb to release the vapor. between inhales, the temp in the middle of the herb drops back down to the radiant heat difference - about 50F, depending on the geometry. i've seen the same behavior - plus there is an air layer between the heater surface and the herb, which acts as an insulator, so the herb cools a bit.
i use an air gap to isolate the heater structure from the wood cube - very effect to keep the cube cool on the outside surfaces.
It's not instrument error. I have used this equipment on many vaporizers and it is very consistent in the graphs/temp slopes that it produces. I posted the difference between conduction/hybid temp slopes earlier in the thread. I also have temp slopes for full convection devices if you'd like to see them, but it's not really relevant for this thread. Please stop blaming our equipment as it's nothing but a red herring.
Also, you can't really compare pure convection vapes with hybrids. Of course hybrids have a smaller temp delta before/between hits relative to the temp during the draw vs. pure convection models. The chamber in hybrids being pre-heated ffs (it's not a big secret) whereas pure convection vapes have no heat applied to the load before/between hits. I don't consider a vape to by a hybrid unless the temp increases during a hit showing that some convection is at work. Arizer models fit this definition so it's appropriate to label it as such.
Temps don't lie.
OF
Well-Known Member
And you are not alone in that. My 'take' is that the temperature drop is because of heat flow (again), in this case up the leads. When I did this same sort of test years back I also tried the same test with smaller gauge wire and got a smaller drop. I've said as much and encouraged others to make that test. AFAIK this hasn't happened? Why otherwise would the load cool off? Where did the heat go to between hits?
Attempts to actually read the temperature rise of the air alone (which would most likely end the debate if it could be shown to be 400F?) fail since the heat transfer from the air is so minor compared to the ability of the heat to migrate up the leads. The air is just not that hot I believe or that heated air alone would make vapor when you pull the stem up out of the cup on ArGo?
Again, I'd like to point to the idea that small as this heating effect is on the OG Solo porting, making the ports bigger and shorter reduces that effect? To supply useful heat energy to a 400F load the heated air has to be hotter than that since it has a specific heat of about one calorie per gram per degree C (about what water is) and air weighs very little. IIRC a 'whole lung full' is under a gram?
Heat that air up a lot hotter going in (as VG and others do) and it's a different ball game.
I've never seen your vape, it could well be different from Solo/Air/ArGo. And I've no idea what "the radiant heat difference" is as I don't see IR losses?
I still think 'hybrid vapes' are largely a marketing idea for those reasons. Heating the air limits the cooling of the load (which makes more vapor instead), but doesn't directly make vapor. Conduction does the work.
OF
I have tested several different gauge t/c's. The current one I'm using has leads of just 0.13mm. The entire 3 foot lead weighs a measly .67g. That's 0.002g per centimeter if I did my math correctly. I haven't measured it, but I've never found the leads to get warm/hot during testing, so I don't think there is anywhere near enough thermal mass to account for the kinds of temperature fluctuations that we are talking about here.
Again, red herring.
It cooled off because the draw ended, so the convection stops, thus decreasing the temp at the load. The heat went into your lungs if you were doing it right.
I think I addressed the other portions of the above post in my post above yours as I believe you might not have read it when you posted a few minutes after mine.
Edit: If the leads were really drawing that much heat from the load so as to make the graph drop in the dramatic fashion that we see post hit, then the same "anomaly" would appear when testing pure conduction vapes as well with the same equipment; and it most certainly does not happen with those.
Last edited:
OF
Well-Known Member
Again, I think the problem is the conduction of heat through the load at idle is slow, causing local drops? Heat drops will be a function of the relative conductivity of the various parts of the path, same as in hydraulics and electricity. If it's not conducted heat, what keeps the curve when you stop the hit from continuing down? No convection then.
Did you get the same readings with thick and thin leads? I did not 'back when'.
What measurement do you get on the air temperature incoming through the vents with no load? I got very low readings........
TIA
OF
i agree with what @Stu said about the leads not being a heat sink - i don't have any leads to sink the heat, and anyway the PID is maintaining the proper 400°F temp the whole time, as it is designed to do. the measured heat drop in the load is due to not drawing heat into the load, and the load is not in contact with the heater, so it returns to the radiant heat temp.
edit: oh, you mean the leads of the thermocouple probe in the load ... no, it ain't that - not enough heat sink to drop 50°F in a second or two.
edit: oh, you mean the leads of the thermocouple probe in the load ... no, it ain't that - not enough heat sink to drop 50°F in a second or two.
Last edited:
Well, this inspired me to do another test using the original (thicker) t/c and my newfangled thin kapton t/c simultaneously.
Here is the setup
Here's the chart of an empty load at temp 7 with one draw.
I was surprised by the temp delta between the probes. The t/c closer to the glass wall (albeit by a fairly small margin) read a much higher temp throughout the test. They both showed a temp increase during the draw (as is tradition), but the difference between them was striking. I would guess that this wouldn't be the case if the stem had been full and maybe I'll test a full load later (since I already have it setup) to see the difference.
In any case, thanks @OF for the suggestion. Intriguing stuff!
OF
Well-Known Member
Here's the chart of an empty load at temp 7 with one draw.
In any case, thanks @OF for the suggestion. Intriguing stuff!
Thanks for running that test. It's along the lines I saw, which is why I decided it was an instrumentation issue (and have been so stubborn about it). This is not always the case. If you get solid contact rather than have a bunch of 'soft' stuff like herb between the T/C and source it doesn't matter of course. This is most of the time? FWIW the signal doesn't really happen at the junction like most guys think (how could it, they're welded together.....) but rather up the leads as the temperature drop gets distributed. One metal behaves a bit differently and the signal happens as a very small current caused by a very small voltage difference typically.
Because of this 'signal happens where the temperature changes' thing you can buy lower grades of T/C cable for say the run from controller to the big furnace it controls. Then use the expensive stuff for the short run into the furnace. Often the outside run is thick while the run in thin and higher grade (better control of the exact alloy used).
The tracking as you point out is a confirmation of what's going on as well. Notice the 'step' is smaller with the smaller wire (since the effect is less?). There is an argument that you can compensate even in such tough to read situations as we have by plotting a series of diameter wires. Say .025, .010, and .003 inches? From those curves you extrapolate what you'd expect with wires of zero cross section (ideal of course). I've worked on experiments like that, but am not sure it has a use for us.
And you're exactly right, of course, it's fun stuff indeed. I used to work for an Engineer who advised, "never argue with the electrons, they know what they're doing". Words to live by......science has to all fit together or gravity wouldn't work and we'd all fall off.
Thanks again for doing and posting the experiment.
Now I guess we'll have to find a new topic to beat senseless? How about the need for precision in temperature control? I've felt for a while now that the steps in Solo I were plenty fine although perhaps not cool enough for some? 9F and 5C per, right? I'm not sure about the precision on Solo II being all that useful. IIRC I decided Solo I 'drifted up and down' by about a full step anyway between heater on and off (known as hysteresis for those keen on crosswords, or looking for extra credit on the final.....). This is sometimes called 'the deadband', a range of temperatures where the heat is either on or off.....depending on what happened before.
Regards to all.
OF
@Stu - too many variables in your setup to be able to interpret what is going on in that graph ... do you have two of each type of thermocouple? suggested additional tests: both probes in the same location; swap the probe locations; both probes smashed against the wall; both probes in the middle of the load, radially located - which has to be done twice to swap the positions.
maybe use a bit of cotton to hold the probes reliably. or a bit of wood.
based on thermodynamic graphs of airflow past a surface, there is drag, so there will be more heat against the wall than in the center.
although if the leads are a heat sink, the temp of the wall probe should drop much more than it does in the graph - and continue to drop.
i have a bunch of N-type thermocouples - bare junction, 0.010" wire - i could send you a couple. it should cover the heat range of interest. and maybe some 28ga polyimide tubing to insulate the leads, if you don't have any.
this doesn't seem right ... Wikipedia says the voltage is at the junction, not up the leads - the weld just makes the contact gas tight, but the wires are not alloyed together. usually copper is used to connect the junction wires to the control board for a long run.
maybe use a bit of cotton to hold the probes reliably. or a bit of wood.
based on thermodynamic graphs of airflow past a surface, there is drag, so there will be more heat against the wall than in the center.
although if the leads are a heat sink, the temp of the wall probe should drop much more than it does in the graph - and continue to drop.
i have a bunch of N-type thermocouples - bare junction, 0.010" wire - i could send you a couple. it should cover the heat range of interest. and maybe some 28ga polyimide tubing to insulate the leads, if you don't have any.
this doesn't seem right ... Wikipedia says the voltage is at the junction, not up the leads - the weld just makes the contact gas tight, but the wires are not alloyed together. usually copper is used to connect the junction wires to the control board for a long run.
I will try to run some of these tests later. Manipulating the exact location of the probes can be a bit challenging with my ET, but with the help of polyimide tape I should be able to manage something.
Can you elaborate on this? I'm not sure I understand at what point the temp should be dropping more. FWIW there wasn't really a "wall probe", just one that was slightly closer to the wall than the other.
Do you think the 0.010" (0.25mm) bare wire would provide better results than the polyimide sheathed 0.13mm wire that I'm already using? I'm certainly open to testing out whatever I can, so I'd be grateful to you for any help you can offer.
I do know that both the K-type thermocouples that I used in the above test have different temp ranges that they specialize in so I wonder how that might affect the overall result.
You're right, so many variables make it tough to interpret exactly what's actually going on. Further testing can only lead to better understanding. The only thing that I know for certain is that the temp always rises during the draw - no matter the test scenario. This would not be happening if cool(er) air were entering the chamber during the hit as has been speculated.
OF
Well-Known Member
I agree it doesn't seem right, but it is. It's a very common misconception for sure, I was caught up in it until set straight. I'm sure if we voted on it that would be gospel. I don't think it's the first mistake on Wiki, weren't they the 'reference source' for Google claiming 'Nazi doctrine formed the base for the Republican Party in California' a bit back? I read it on the internet, it must be right........
The big dog in T/Cs is Omega. They used to publish 'the bible' on the topic, a hardcover catalog about 8 inches thick, slick paper, seriously expensive to product but with a killer reference section so that Purchasing Agents would give them to Engineers who would in turn select an Omega product from the front part. I'd often get several new ones in a single year. Very expensive, but effective? It was later split into 8 or more sections, smaller books but took up more shelf space. Most of us clung to our old books (where we could find answers in the reference section.....). Now, of course, it's a web page and no longer seems to carry the useful reference sections.......a sales effort, go figure.
All is not lost, however. We can still go back to the science behind it all. It's linked to thermal conduction actually and depends on temperature differences across the conductors. Check out references like this one, please:
https://www.explainthatstuff.com/howthermocoupleswork.html
It all depends on 'the Seebeck effect', check out the section so titled a few paragraphs down? There are really to junctions to consider, the obvious hot one and a cold one typically simulated 'on the meter end'. If you're really serious about it, you have the cold junction in an ice bath. A small step back is 'isothermal blocks' where the wires remain insulated electrically but thermally connected together again. After that copper for both is fine. Anyway, notice the discussion says the voltage develops end to end on any metal bar? If two bars are the same material and connected together at one end they develop exactly the same potential and again have zero difference at the cold ends? From a different perspective, in real T/Cs one is simply a reference automatically subtracted from the other.
Another description is here:
https://us.flukecal.com/how-does-thermocouple-work
Often hearing it in different terms helps?
Consider if it really happened at the weld you could immediately weld say SS wires on and save a bunch of bucks. One of the very best pairs is Platinum and Platinum doped with 13% Rhodium. Stuff sells by the inch, even in tiny diameters.
But it's really all about comparing the temperature change induced voltage between two wires. That happens only where the temperature is changing......which means flow of temperature is happening?
If it's any comfort to you it took me a long time to get my arms around this, even with very sharp guys insisting it didn't understand what I was sure I'd learned correctly. Then again, these same guys insisted that current went from minus to plus, not plus to minus like I was taught......even brought an old text book in to 'prove' it at one point. They were right (again) of course, Science was on their side, electrons do go minus to plus we now all agree (or vacuum tubes would have negative plate supplies......) but those old dead guys that come up with the idea of current couldn't see or measure electrons to they took a guess? 50% chance of being right with "Conventional Current" so they were of course wrong. The last texts I taught from (Grob and Malvino) came in two versions, Conventional Current and Electron Flow. The formulas are all the same, just the arrows on the diagrams are backwards..... FWIW Electron Flow is a lot easier to teach semiconductor theory from since it's based on the physics of crystals. This is why transistor leads are called Emitter (emits electrons to the device), Base (the forward biased junction it emits them to) and Collector (the reverse biased junction that collects the electrons liberated by the B/E current).
I didn't even know that there was an Electron Flow version of either text when I was taught from them I guess, that came later. Common texts, BTW. While at sea I came across both of them on Engineer's book shelves, in English, German and French no less? Small world.
So while "signal goes left to right" on schematics as I was taught, "current goes top to bottom" depends on what you all current? It doesn't really matter, of course, as long as you keep to the same rules.
Sorry to ramble, but you didn't have to read it you know. The short of it is I don't agree, I 'know' that the signal develops along the leads in step with temperature drops (and therefore heat flows). Even more sure than I am we're looking at instrument issues not evidence of convection heating.......
Seebeck says so. It's his fault.
Regards to all.
OF
Edit: While I was prattling on, Stu responded and agreed to run more tests, good on 'im.
Further testing can only lead to better understanding. The only thing that I know for certain is that the temp always rises during the draw - no matter the test scenario. This would not be happening if cool(er) air were entering the chamber during the hit as has been speculated.
Agreed, experimenting can be very good. I'd quibble that the temperature INDICATION goes up please continue to keep an open mind on that? Thanks.
You can probably get some useful data by adding a copper wire twisted around the same T/C, increasing the heat flow?
Remember, please, the T/C really works on heat flow, the device has to remove some heat from what it's hooked to to get a signal. It's not a static thing like it seems at first glance. Again, blame Seebeck it wasn't my idea.....
Air flow changes the heat flow by increasing the thermal conduction through the load, the heat 'measured' was already there I believe. Easy to prove me wrong, measure the input air through the vents with no conduction contributions. Measure anything close to 400F and I'll need a new theory. I maintain a small fraction of the flow in contact metal and gets heated to a fraction of that heat. It is then 'averaged in' with the vast majority of molecules who made no such contact and are therefore still at room temperature. 'cuz that's how I understand that kinda stuff.
Regards to all, and thanks for your kind attention.
OF
Last edited:
stickstones
Vapor concierge
nice @Stu !
fwiw, I don't do any more tests on empty bowls...readings were all over the map and hard to reproduce. Location in the bowl also makes a big difference, I think. I heard one tester report measuring with herb in the bowl and getting readings a hundred degrees apart simply by twisting the wire (I could see this if the twist moves the probe from an area of flow into one with little flow.) I now use abv or cbd flowers if I'm testing when I don't want to get fucked up!
fwiw, I don't do any more tests on empty bowls...readings were all over the map and hard to reproduce. Location in the bowl also makes a big difference, I think. I heard one tester report measuring with herb in the bowl and getting readings a hundred degrees apart simply by twisting the wire (I could see this if the twist moves the probe from an area of flow into one with little flow.) I now use abv or cbd flowers if I'm testing when I don't want to get fucked up!
maybe i am lost in this discussion but i thought @OF said that the thermocouple leads are acting as a heat sink and that is why the temperature drops 40°C after the hit stops - rather than this being an example of convection heating to the load. i am suggesting that if this is the case, the temperature should continue to drop, not reach a stable point as it does (because, theoretically, the ends of the leads are outside the heated space). if such tiny leads could sink that much head, why are CPU coolers such big blocks of aluminum, for instance?
i would like to see the probe mashed against the wall - each different one, in the same spot, together and individually ... different spots on the wall may have different temps.
can your thermocouple reader handle the n-type as well as k-type? the ones i have don't have a plug or anything - just bare thermocouple wire (6"). the 30awg wire provides faster response - don't know how much faster or if that is significant.
I think I can manage this. I'll report back.
The thermometer I have won't work with those, unfortunately. It needs the plug that the K-type uses. Thanks for the offer anyway.