Arizer portable heater tech discussion

[invertedisdead]

Wrt "hybrid" heating, as shown in the mighty video, I wonder what temperature the conduction oven gets to. If the conduction element preheats below vaporization temperature, but above ambient air temp thus reducing ∆T needed to be achieved by the convection, does that still constitute conduction heating? I agree it changes the function of the vaporizer, but is it technically "hybrid" or is the convection still the heat transfer which vaporizes the load?

It's absolutely a hybrid, with the cooling unit removed and the device at temp you will see conduction vapor instantly forming without drawing air through the device.

I'd call this convection?

Yes the legacy volcano is pure convection, (I own one of those too) you need to look at the later units: Plenty, Mighty, Crafty, or the Volcano Hybrid specifically for hybrid functionality. The Volcano Hybrid was released last year so it is most recent.

 

[Stu]

I don't really see a conduction path to the load (past minor heating from the screen?) I'd call this convection?

That's one of the differences between the original Volcano (all convection) and the Volcano Hybrid that I referenced. Here's a vid:

 

[nms]

My guess is that the heat transferred by conduction heats the bottom and outer layers of the herb first, as it heat soaks through the rest of the chamber. When you take a draw, that hot vapor is displaced, passing over the thermistor in the center. While this seems like convection, since hot fluid is seeming to change the temperature within the load, in order to qualify as convection vaporization that hot air needs to contribute to the vaporization of the load. Meaning that the temperature change needs to be significant enough to heat the herb to reach vaporization temperatures.

I think this design contributes to the good flavor the Solo is known for. Since the center/top of the herb takes a long time to heat soak you get many hits which taste great and produce vapor, the vapor being produced from the edges of the load, and the flavor being preserved in the middle. Then once the oven finally heat soaks the middle gets vaporized and the last few hits lose that flavor.

I think a lot of people mistake the fact that the flavor is preserved so well to mean that the oven has convection heating at play. Once we divorce ourselves from the notion that convection is naturally better (which I disagree with vehemently, and I imagine OF does as well) this discussion becomes a lot easier, since saying the Solo is conduction is no longer perceived as pejorative.

Sort of a side note, but this topic (vaporizer heat transfer, not arizers specifically) was topic for my heat transfer final project. I discussed how convection is perceived to be superior, and how people often project this onto their beloved vaporizer of choice - and how manufacturers sometimes adapt to this by advertising their vaporizers accordingly. My professor remarked how it's not exactly a lie to call all vaporizers convection, so long as they don't specify that they mean convection cooling and not heating in many cases

Again, we're not discussing if conduction is better or people's opinions. This discussions runs to that quite fast. We are discussing if convection does happen in the Solo. I don't really care about the experience, I am discussing the definition, there is a thread on the solo 2 where people can happily discuss their opinions.

First if you assume the bottom of the herb is heaten, we're now including a substancial effect from radiant heat, or from convection from the bottom oven wall to the bottom of the weed, which is in contact with air alone. Which one do you mean?

Convection means that the air transfers energy into the herb instead of taking it where we'd classify it as cooling convection. If it transfers energy into the herb it by definition contributes to vaporization, correct?

If it was the displacement of air, how do you explain, and this question keeps popping and being avoided:
- There is a continuous increase of temperature for the whole duration of the draw, and given the volume that fits the oven(let's say it's 2cm by 1.8cm so around 2kmm3), how could as soon as this air leaves the oven not decrease temperature as COLDER air enters the oven?

Then the other simple question that needs to be answered, is:
- Can the heater heat the air around it to a temperature close to it's own if you're not sucking(the discs alone will average to 280º, can't they put this energy into the air that's in contact with them)? Can it do so while you're sucking air?

I don't care if it uses convection or conduction, it's the same to me, what I now do care about is having a satisfying response, meaning a scientific one. Unfortunately my ignorance does not allow me to do an estimation of the second question, so I was hoping someone would pop in and do this.

Notice that the air is forced to go through the heater in a very thin film, so there is contact area!

AIR 2: https://cdn.shopify.com/s/files/1/0...g-element-1024x256_2048x2048.jpg?v=1580852642

SOLO 2: https://cdn.shopify.com/s/files/1/0...uit-front-1024x384_2048x2048.jpg?v=1580862290

Solo:

 

[hinglemccringleberry]

I've got the answers...and you guys weren't even close.....

Convection: That white stuff they sprinkle on cookies.

Conduction: What happens when the maestro waves a baton.

Radiation: Holding a cell phone to your ear.

I'll take my warning point and go home now........

Don't forget induction: the stimulation of uterine contractions during late pregnancy.

 

[Tranquility]

I hate to wade in without understanding all that's been going on, but, when I pull out the stem from the Solo II completely, hold it up to the air and inhale then get vapor on exhale, what is that?

Convection or conduction?

 

[Farid]

Fst if you assume the bottom of the herb is heaten, we're now including a substancial effect from radiant heat, or from convection from the bottom oven wall to the bottom of the weed, which is in contact with air alone. Which one do you mean?

It depends how it's packed. I was assuming it was packed fully with the bottom of the bud making contact with the plate. But even if you keep a gap between the herb and the oven what I said still would apply from the sides of the glass, which would be heated before the center.

Convection means that the air transfers energy into the herb instead of taking it where we'd classify it as cooling convection. If it transfers energy into the herb it by definition contributes to vaporization, correct?

When we are talking about convection vaporization, we are not just talking about convection, but convection of heat within the temperature range to vaporize. Otherwise taking a vaporizer from a cold to a warm environment would be enough to constitute convective heating due to the ambient air temperature change.

If it was the displacement of air, how do you explain, and this question keeps popping and being avoided:
- There is a continuous increase of temperature for the whole duration of the draw, and given the volume that fits the oven(let's say it's 2cm by 1.8cm so around 2kmm3), how could as soon as this air leaves the oven not decrease temperature as COLDER air enters the oven?

I'm not saying that air around the oven is not preheated, I am saying it is not preheated to vaporization temperatures. The air being preheated, and the airflow controlled is what allows the heater to keep up with long draws.

-Can the heater heat the air around it to a temperature close to it's own if you're not sucking(the discs alone will average to 280º, can't they put this energy into the air that's in contact with them)? Can it do so while you're sucking air?

Yes, the boundary air will be heated. But the bulk flow will not reach to vaporization temperatures during normal use.

 

[nms]

Check all the disassembly and you notice that indeed the air is forced around the heater.

No when you let the herb touch the bottom of the oven, it often burns it.

If it is not preheated to vaporization temperatures, and for the last time, how does the temperature increase when COLDER air comes into the oven?

PS: "But the bulk flow will not reach to vaporization temperatures during normal use." - WHERE, again WHERE is the backing science for this claim?

 

[Farid]

Some air is indeed forced around the heater. But this mixes with air that has not had contact creating a preheated bulk that is below vaporization temperatures (for bud).

As for how the heater maintains temperature, one guess I have is that the heater is programmed to increase output when a the temperature sensor detects a drop? I'm not familiar enough with the programming side of these things to know if that makes sense. I'm not claiming I have all the answers to explain those results. But from looking at the heater design of the vaporizer alone I have a hard time seeing how vaporization temps could be achieved through convection

 

[nms]

So we're back to considering the heater temperature on pull triggering a overshoot of temperature(because the heater before pull was already maintaining the temperature which is measured on disc 2). Center oven temperature never drops on pull, it increases.

But then, how can it be so responsive via conduction when the travel path for the conduction to the center of the oven where the measure is taken is:

Bottom ceramic disc: Heater element
Top ceramic disc: Regulating thermocouple
Metallic oven wall(loosing heat to the chassis)
Glass(loosing heat to wherever else)
Herb
CENTER OF OVEN

Not saying this is not viable, but can it have the responsivity we see the experiments if the explanation is the heater overshooting temperature on temperature drop from draw?

 

[OF]

That's one of the differences between the original Volcano (all convection) and the Volcano Hybrid that I referenced. Here's a vid:

Thanks, seems similar to the smaller vape adverts posted before? As I now understand it, the system was modified to add conduction heating to what was a straight up convection vape?

It will take some more thought, but off hand I think it's still a convection vape with an attempt to keep the load temperature from dropping as much by conduction, that is no vapor is actually made by conduction in normal use? I still see only one heater and only one controller, so I don't yet understand the claim to the contrary earlier on.

Again, we're not discussing if conduction is better or people's opinions. This discussions runs to that quite fast. We are discussing if convection does happen in the Solo.

I don't care if it uses convection or conduction, it's the same to me, what I now do care about is having a satisfying response, meaning a scientific one. Unfortunately my ignorance does not allow me to do an estimation of the second question, so I was hoping someone would pop in and do this.

I agree. We're burdened in trying to be objective since we 'know' convection is superior automatically? After all we all 'read it on the internet'..... FWIW I'm of the school that 'heat is heat' but it is also true I think that Solo gives generally better than average taste because it's easier to keep clean being glass in key parts.

And 'knowing' it's automatically better than just a plain old conduction vape we're set up to accept that a 'hybrid' is also superior when told that by someone looking to make sales?

I hate to wade in without understanding all that's been going on, but, when I pull out the stem from the Solo II completely, hold it up to the air and inhale then get vapor on exhale, what is that?

Convection or conduction?

If it was cold to start with (not still hot from conduction) that would be convection. Are you saying that under those conditions you get the same vapor production levels as when in the oven? I sure don't...... My experience is the production is modest at best, to me demonstrating the load is hotter with conduction in charge.

I'm not sure we can fully model the system with what we know. We'd need information on heat losses and such and how much energy is used making vapor. I tried to find this information (typically called 'molar heat of vaporization') for THC with no success. This factor is why heating a pan of water on the stove shows the water getting hotter until it evaporates (boils) then the temperature staying the same as all further heat added goes to making steam, not the water hotter. To a certain extent that means that the hot air in a convection vape is cooled to about 390F making vapor and exits at that temperature. The 'heat lost' made the vapor.

Thanks to all.

OF

 

[Farid]

So we're back to considering the heater temperature on pull triggering a overshoot of temperature(because the heater before pull was already maintaining the temperature which is measured on disc 2). Center oven temperature never drops on pull, it increases.

But then, how can it be so responsive via conduction when the travel path for the conduction to the center of the oven where the measure is taken is:

Not saying this is not viable, but can it have the responsivity we see the experiments if the explanation is the heater overshooting temperature on temperature drop from draw?

Since the system is preheated at this point, conductive heating to return to vaporization temps is pretty responsive.

 

[nms]

As much as I can't say that's not a possibility without doing the math, you can't say convection is not a possibility without doing the math. They both seem perfectly viable to me as justifications for the experiments at hand.

When comparing to other conduction devices, it's obvious because they don't pre-heat the air, and that's for sure happening here. That's not something we can argue because even with all conduction it'd result in a temperature loss in the oven. Now whether this air is heated above oven temperature or not is another question. If the air coming in was far apart from oven temperature, no amount of conduction could compensate it.

The theory of the heater overshooting temperature also feels off, because we see no such thing in any of the graphs, the heater heats pretty steady and evenly, and maintains it's temperature throughout the session. It doesn't increase the temperature by such an ammount that it'd transfer THAT MUCH energy to the whole system for such a fast increase of temperature in the very center(such increase is not even seen during initial heat up). The very center is pretty insulated from conduction from my point of view. But again it's possible. Whatever the case as soon as the second disc reaches the desired temperature, the heater would turn off and the desired temperature in the second disc would result in the most stable scenario in the equivalent temperature mid oven as seen in the graphs, I don't see how this justifies the increase yet.

My current belief is that air is indeed being heaten above oven temperature, to near heater assembly temperature, and this results in the steady increase in temperature seen from draw start to draw end, with the open chamber(glass sink) sucking the heat through conduction again right after. It seems to me that the way the heater chamber is built, forces the air to flow around the heater, increasing the contact area of air while preventing it from escaping upwards right away. As air passes in the center of the oven, experiment sensor temperature increases. Draw restriction is made to ensure the air moves slowly enough around the heaters to reach the desired temperature. If you suck too fast trying to overpower the draw restriction, it stops producing vapor because the air cannot be heated anymore and instead of convection(or if no convection existed/exists conduction stabilization) we start seeing convection cooling happening. Hybrid tech from S&B allows for mostly unrestricted air flow because it has two heaters(hybrid fills a bag ultra fast, dual heater and huge surface area allows for air to heat really fast).

Further conclusions on this need the aforementioned math to justify them.

A point of relevance otherwise is that on idle the heater temperature is maintained steady, I have no reason to assume that drawing air would somehow increase it like that. Heater turns on, the first thing to reach temp is the second disc and as soon as it does heater turns off and cycles to maintain the temperature at that. How do you explain this overshooting in the other end of the system?

 

[Farid]

As much as I can't say that's not a possibility without doing the math, you can't say convection is not a possibility without doing the math. They both seem perfectly viable to me as justifications for the experiments at hand.

When comparing to other conduction devices, it's obvious because they don't pre-heat the air, and that's for sure happening here. That's not something we can argue because even with all conduction it'd result in a temperature loss in the oven. Now whether this air is heated above oven temperature or not is another question. If the air coming in was far apart from oven temperature, no amount of conduction could compensate it.

Other conduction devices do indeed preheat the air (tubes in a vapman, channels in a Dynavap tip). Whether the air is preheated to vaporization temperatures is precisely what we're discussing. Otherwise it would contribute to convective cooling not heating.

Your theory of the heater overshooting temperature also feels off, because we see no such thing in any of the graphs, the heater heats pretty steady and evenly, and maintains it's temperature throughout the session. It doesn't increase the temperature by such an ammount that it'd transfer THAT MUCH energy to the whole system for such a fast increase of temperature in the very center. The very center is pretty insulated from conduction from my point of view. But again it's possible.

If the heater overshoots it's output during a draw at the same time as you are taking a draw, the cool (not preheated air) moving over the heater would cool it back, making it seem to be steady. The jump in temp seen in the middle of the oven can likely be attributed to the displacement of heated air, which was heated by conduction from the walls of the glass.

My current belief is that air is indeed being heaten above oven temperature, to near heater assembly temperature, and this results in the steady increase in temperature seen from draw start to draw end. It seems to me that the way the heater chamber is built, forces the air to flow around the heater, increasing the contact area of air while preventing it from escaping upwards right away. As air passes in the center of the oven, sensor temperature increases.

I think a large point of disagreement stems from our understanding of the potential for the heater to heat the air. In my mind, the heater surface area is too small, and the volume of air around the heater too large to possibly heat the air.

I agree a FEA analysis is the only way to get a definitive answer. Based on my experience, my gut says convection does not transfer heat within the range to vaporize cannabis in the arizer solo.

A point of relevance otherwise is that on idle the heater temperature is maintained steady, I have no reason to assume that drawing air would somehow increase it like that. Heater turns on, the first thing to reach temp is the second disc and as soon as it does heater turns off and cycles to maintain the temperature at that. How do you explain this overshooting in the other end of the system?

Drawing air would trigger the heater to increase output while simultaneously the heater would be cooled by the incoming cool air, which would then be preheated to temperatures close to the oven temp, so as to maintain the temperature of the load. The measured increase of temp in the load comes from the displacement of air, which has already been heated through the walls of the glass.

 

[nms]

So the walls of the glass can create convection heating, but the walls of the much hot heater can't? Hmmmm.

Anyway, all in all we've gone over the subject as much as we can without going into mathematics. I'll try to find some time to understand the subject and see if I can come up with an accurate representation of the system, hopefully with the assistance of someone with expertise on the subject. If someone that works on this area could chime in, perfect.

 

[Farid]

No, the walls heat the weed through conduction. That vapor produced through conduction is displaced, creating the temp increase measured in the herb's center. But that is not causing convection valorization of the weed, since that vapor will never be hotter than the wall which heated it.

If you want to mathematically analyze the system without using FEA software you're going to have a hard time. You can use approximations, but first you'll need to calculate the volume of air that surrounds the heating element. But then you also need a way to visualize the streamlines and airflow patterns, which is almost impossible without software.

Maybe the way to go about this is to assume an airflow that is even more condusive to convection (so assume the air travels through a smaller/simpler internal airspace than it really does - say parallel plates). I am willing to bet that even with these assumptions that favor convective transfer compared to the real system it will still show the air temperature to be below the oven temperature at the point where it reaches the bud.

 

[nms]

What FEA software would provide a reasonable solution to this problem?

 

[Farid]

Solidworks Simulation is very good. Haven't used others though

Here's how a quick video that shows it in action.

 

[invertedisdead]

Don’t you have to know all the math already for that type of computation to be accurate?

 

[Andreaerdna]

Drawing air would trigger the heater to increase output while simultaneously the heater would be cooled by the incoming cool air, which would then be preheated to temperatures close to the oven temp, so as to maintain the temperature of the load. The measured increase of temp in the load comes from the displacement of air, which has already been heated through the walls of the glass.

so, it is guacamole.

covective heat transfert coming not only from the heater directly but also from glass walls heated by the same heater through conduction and radiation, does not change the end results, convective heat transfert.

all vapes are hybrids as all them transfer heat through multiples ways as any hot source transfer heat toward colder ones by radiation, always
the distance heater-load and the on demand function of the heater reduce the amount of radiation (Tynimight on demand or session modes shows it). The first volcano is, by this mean, an hybrid too but radiation is so little it doesn,t show to our senses, in normal use
but what if you leave the chamber on it a whole night without pump (i should try), at max temp? anyway, radiation heat transfer is there by definition

arizer did a very good job calibrating their simple heater into their design IMO and this is what makes solo so popular and long lasting

besides dabbing, conduction which is a very popular term in vape world, is a misused one as conduction needs continuity in material to be effective and hemp is an heat insulator because it is full of empty spaces breaking down conductive heat transfert from hot tiles to your house and from a hot oven into your dried + grinded flowers

unless you pack your flowers so tight on the oven surface that your load becomes almost a solid puck glued on the bowl (a press puck?) conduction heat tranfert in flowers vapes is very marginal at best

reasoning by absurd: if conduction was the main way heat flows to the load, solo stem should pump vapor like a boiling tea kettle very quick, without the need to inhale.
the difference between the rate of vapor you get by inhaling and the rate that excapes in between hits is the different contribution from convection and (radiation + conduction)

still, an accurate calculation would be very cool

 

[DrJynx86]

reasoning by absurd: if conduction was the main way heat flows to the load, solo stem should pump vapor like a boiling tea kettle very quick, without the need to inhale.
the difference between the rate of vapor you get by inhaling and the rate that excapes in between hits is the different contribution from convection and (radiation + conduction)

still, an accurate calculation would be very cool

Agreed on the absurd, lol.

Why would you assume cannabinoids will vaporize on the oven without pulling, when to decarb your weed you place it in the real oven covered with aluminum sheet, bake to the same temperatures, and there is no "magic tea kettle vapor clouds" nor the cannabinoids are lost, as you use them later to cook/cannabutter.

 

[nms]

Don’t you have to know all the math already for that type of computation to be accurate?

Generally the software handles most of it. Like photoshop you don't have to know the math behind the effects, masks or whatever else computer vision algorythms are used. I assume this as all different softwares are the same, you model the details, materials and set the initial conditions. I may be wrong though.

For the purpose of the discussion we're not considering the interactions inside the oven, as for sure the air in there will transfer heat between things inside it. We're considering the effects of the incoming air, if any and trying to figure out if this air coming from the heater actually transfers energy to the herb(or removes it), which I believe it does as it seems the most reasonable explanation for the results provided by the experiment.

I find it quite far fetched to believe that the heater could overshoot the temperature in a way seen in no other circumstances. It would turn off when reaching the stable temperature, which results in a oven center temperature measured during idle and not above it, and even if it somehow kept it on longer and let it hit above the defined temperature in the second disc where it is measured, I find that conduction would never be responsive enough to create the effect it does in the oven center, particularly when taking into account that in no other heating phase does it have a curve growing at such inclination.

 

[Andreaerdna]

for decarbing i read you need lower temps (115C) for longer period of time (40 minutes)?
if you put your oven @210 C you should see vapor, but at a slower rate than if you where able to move 210*C hot air into the load (convection)

there is another factor: the depression induced by hit which also helps lowering phase changing temperature but it is even harder to measure

 

[OF]

No, the walls heat the weed through conduction. That vapor produced through conduction is displaced, creating the temp increase measured in the herb's center. But that is not causing convection valorization of the weed, since that vapor will never be hotter than the wall which heated it.

I agree with "vapor will never be hotter than the wall which heated it". Nothing (air, the stem, vape body, or vapor) can be hotter than the hottest part of the heating system.

But, if "creating the temp increase measured in the herb's center" refers to the long discussion earlier in the thread involving thermocouples, I still maintain that measurement is not real, a result of instrumentation error from not understanding how T/Cs work (the leads sink heat out locally). I suggested that thinner leads on the T/C would yield less drop (which was confirmed), and zero cross section leads would show no drop at all). This makes sense when you consider where the heat in the load could have gone?

OF

 

[nms]

OF relative measurements remain valid when taken with the same equipment correct? Whether the temperatures are absolute or not doesn't change anything, or does it? And why would it? And I believe nothing will loose more heat than the glass making the heat loss through leads irrelevant.

EDIT

there is another factor: the depression induced by hit which also helps lowering phase changing temperature but it is even harder to measure

The effects of drawing are present in both hypothesis we're considering whether they favor conduction or convection. If colder air was coming in and wasn't somehow compensated it would lower the temperature, but we don't see that, so either hotter air is coming(my current opinion) in or it's somehow being compensated by conduction(their current opinion). Past posts have been discussing this matter extensively.

 

[Farid]

Don’t you have to know all the math already for that type of computation to be accurate?

You have to know how to setup various parameters, but the math itself is done by the computer. With the tools available it's not nearly as difficult as attempting the calculations by hand would be. Even a heat transfer professor would have a very hard time getting accurate results by calculation alone. FEA allows many variables to be combined together to create accurate models, whereas calculations by hand so often involve assumptions and simplifications.