Pots With Heat Exchangers

[David Thomas]

I actually checked online images before drawing that and they were running 3:1 for right-handed:

Don’t try to be more pedantic than me (smile).

[DAN-Y]

I was stationed in Orleans, France back in 65-67 and saw that statue of Napoleon and remarked at that time he was left handed. (I’m right handed)

A link to a study of lefties:  https://pubs.aeaweb.org/doi/pdfplus/10.1257/jep.28.4.193

By Ben Wright9:58AM GMT 02 Dec 2014
Leonardo Da Vinci, Michaelangelo, Albert Einstein, Napoleon Bonaparte, Winston Churchill, Henry Ford and Pelé.

 

 

It would be hard to argue that these people did not reach the absolute peak of their chosen fields of endeavour. But, according to new study, they did so against the odds; they were (or are) all left handed.

The research runs contrary to popular perceptions that lefties are disproportionately more talented than their right-handed peers. The author of the new study says that this mistaken belief is based on unrepresentative anecdotal evidence such as the fact that four of the last seven US presidents – including Barack Obama – have been left-handed.

https://www.telegraph.co.uk/finance/jobs/11267184/Are-you-left-handed-Bad-luck.html

[MJ H]

Wouldn’t a left-handed person be more likely to stick their right hand in their coat? At least, I’m right handed and my left hand is usually the hand in my pocket because I’m using the right hand.

[Jerry Adams]

if he’s left handed, maybe he’d put his right hand in his jacket?

[DAN-Y]

I used both hands when lifting and placing the canister on the scale :-) No hands in pockets ;)

On 2 separate mornings the stars and planets aligned and my scale registered 2 grams of fuel used to boil 500ml/2 cups of water. No BS.

Here is what my score sheet looks like the day of my first testing. Note the 1st set of figures. The burner was removed from the canister and then weighed. The burner was left on the canister for the remaing tests.

The humidity was high that day. I did wipe condensation off the canister at least 2 times before weighing.

The burn pattern, distance from flame tips to bottom of pot is unique with this etekcity burner. The skirt used is directing all heat upward and held in close proximity to sides of pot.

I’ll see if I can do a quick video of the flame pattern sometime today.

2 grams boiled 2 cups…….hard for me to comprehend how and why that could happen. I’ll go back to playing with alcohol stoves and let the canister stoves for Roger to play with. :-)

 

[Roger Caffin]

I have no idea!

Cheers

[DAN-Y]

Roger, what is the fastest that water is able to absorb heet and bring it to a boil?

 

[Roger Caffin]

what is the fastest that water is able to absorb heet and bring it to a boil?
There is no limit … IN THEORY. But that assumes you can get the energy into the water. We can’t do that directly unless we use a microwave oven.

In the case of heating water in a pot with a flame, the limiting factor is probably getting energy from the hot gas or flame into the wall of the pot. This has real limits, as the heat transfer through the bulk of the hot gas to the thin film of gas in contact with the wall of the pot is definitely limited. The flow of energy from the wall of the pot is much easier or faster.

So when you blast a big flame at a basic pot base, the hot gas in contact with the pot wall transfers its energy, but the hot gas millimetres away does not. Instead most of that hot gas goes up the sides of the pot with its energy intact and is wasted.

A Heat Exchanger pot disrupts the gas flow, breaking it into many smaller streams between the fins, with much more of the hot gas in contact with metal. That is why HX pots are more efficient: far greater surface area for energy transfer.

<removes mortar board …>

Cheers

[DAN-Y]

Thanks Roger, good explanation. An induction heater might be able to get a quick boil.

Here is what the flame pattern looks like out of the Etekcity burner that got the 2 gram boil using the Inferno HX Pot. Can simmer down nicely. So far there is no discoloration on the bottom of the pot from the flames of the burner.

[Roger Caffin]

An induction cooktop does not heat the water; it heats the bottom of the steel (ferrous) pot. (It won’t work with simple aluminium, copper or glass pots. Some forms of SS won’t work either.)

That certainly can be faster than a flame or a trad resistive hot plate. Induction cooktops have a neat safety factor too: when you take the pot off the stove, the induction heater essentially turns off.

Cheers

[DAN-Y]

Came across this video yesterday:

[Roger Caffin]

I ordered 3 of the $13 ebay pots. When they arrive I’ll send you [DT] one and one for Roger.

Pot has arrived. Minimalist, but with reasonable-looking heat exchanger on the bottom. Markings on the inside go to 1 L, such that rim capacity would be about 1.2 L. That is workable for two.

Someone in a Post Office (which one? had really thumped the side of the box/pot such that the rim was dented inwards by about 10 mm. Talk about rough! Not to worry: a little persuasion got the rim close enough to original. The main pot wall and the HX are fine.

No handles: what did they weigh?
No lid: none came with it?
Just checking for all the details.

I will have to resurrect my stove test system. That normally uses an external inverted canister on a very flexible hose (NOT suitable for field use!) which will let me monitor the weight of the canister in real time, along with the temperature of the water. That may take a little while as the electronics have been ‘repurposed’ for another job, and I have had to replace the original data logger as it was totally dependent on the original Mostek parallel port chip (which was a strange beast!). Not a problem, just time.

I can then test this HX pot against a fairly similar diameter Al pot with a plain bottom, with the stove running at a fixed level of flame. Any variations will be seen in the logging of the canister weight of course. I suppose I could also put my Ti pot in the trial.

I am not sure about the three rivets holding the steel handle bracket in place: are they steel or aluminium? I think the latter. I may try to remove the steel bracket to see what it weighs. That would mean putting some sort of replacement rivets in the holes. Can do: soft aluminium and a lathe.

Cheers

[DAN-Y]

Roger, handles weigh 34gr Your pot lifter weighs 27gr

Lid 61gr

Stuff sack 29 gr

[Roger Caffin]

@Dan: Thanks.
Photo is not the same as the pot: the HX engineering is different. No matter of course, just FYI.

Cheers

[DAN-Y]

That photo was the one provided by David 2 pages back. This is one from his link but the bottom of mine is different, has swirl slots for more air flow. Will provide photo when time allowed.

[Louis T]

I’ve been frustrated with my the time to boil toaks/windmaster combo while out on the trail on my last few trips. Sometimes waiting for water to boil can be forever!

Well today I modified my jetfoil TI pot to accept a windmaster soto triflex, and did a quick boil time test:

Room temperature, 250mL of water from the tap, boil tests operated by ~30 seconds. Tried to keep the output similar for both. Inside kitchen (no airflow):

Time to boil:

JetboilTI + windmaster soto: 2:10 minutes

Toaks 900ml wide pot + windmaster soto : 1:50 minutes

Baffled, I tried again with 500mL:

JetboilTI + windmaster soto: 3:35 minutes

Toaks 900ml wide pot + windmaster soto : 4:05 minutes

 

Might try to repeat tests tomorrow; anyone have an idea why once the volume of water goes up, the time difference increases?

PS: jetfoil pot significantly louder!

[Roger Caffin]

I did the maths. The difference is not that great, and may be entirely due to ‘experimental error’.
You need to do 10+ runs of each sort to get decent results, OR to use real-time data logging (ie a reading every second).

Cheers

[DAN-Y]

In the interest of stove/pot science I modified my pot which is one of three I purchased for testing. One I sent to Roger in Oz and David in AK. I’ll ship

I removed the heat exchange fins from the pot and will send it to Rogger so he can test it against his pot to determin efficiency between the 2. It will be shipped tomorrow, probably take 2 weeks to get there, weather here in the states is winter.

Removed the fins:

 

[Roger Caffin]

Just to tantalise everyone:

Only the red (water temp) and blue (mass of gas used) plots are relevant here.

Cheers

[Jon Fong / Flat Cat Gear]

So,  about 7 grams of gas to heat up how much water?

[Jerry Adams]

used almost an extra gram of fuel after the water reached boiling temp : )

[Roger Caffin]

I KNEW the vultures would descend!

OK, 7 g for 500 mL, at medium power. At slightly lower power you can do better. We figure on 10 g for morning coffee (2×350 mL) for the 2 of us.
Yes, I let the stove run on a bit once boiling was reached. There were reasons.

I will see whether Ryan will publish the report on the whole test series later on when it is complete.

Cheers

[James Marco]

Looking forward to it!

[Jerry Adams]

just screwing with you : )

[DAN-Y]

Testing the HX pots against titanium pots of approximate size will be of no value. Only the comparison between the two same pots with and without fins will be of worth.

[Author]

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