Thermal Mass with a Weber Kettle, a PartyA, and a Slow'N'Sear

[radshop]

Nice - thanks

[holehogg]

Dont mean to hi-jack this post but dont know where to post photo's otherwise radshop without cladding and with cladding.



The smoker is still a work in progress and therefore haven't clad in SS sheeting as planned yet. I'm about 90% happy with the results, still figuring out a few tweaks needed.

[radshop]

Makes sense holehogg - I get the idea, but would love to see a pic or 2 if available.

[holehogg]

Just on that point even when I cladded with timber boards with no insulation just an air gap between the SS container and the wood cladding also made a difference, I trust this makes some sense to the discussion.

[holehogg]

radshop I agree with you and am by no means an expert but I think before adding internal mass, insulating the vessel should be the first consideration. I noticed a huge difference when insulating my vertical with aerolite material. jfmorris

[radshop]

When trying to smoke a brisket on a PK Grill, I put a heavy cast iron griddle between the coals and meat as both a baffle and thermal mass. It's 1 unscientific data point, but I found it to work against me more than for me.

I spent some time thinking about it - I'm by no means an expert, but I think physics and chemistry of energy transfer are basically the same now as when I studied them in the dark ages. Adding internal thermal mass without improving insulation means you still have the same amount of heat loss out of the system that has to be replaced by adding energy to the system. Depending on how you use the thermal mass (where it is placed, etc.) it might have some benefits when it comes to diffusion of temperature, consistency of temperature, etc. But ultimately by adding mass you are increasing the amount of fuel you need to heat the mass, and then you have to continue to burn fuel to maintain the temperature based not on the internal thermal mass but on the heat loss from the system.

One man's amateur thoughts - what did I get wrong?

[gmascolo51]

I certainly do not have the answer but couple thoughts pop into mind:

1. If this is freight rail aren't we talking close to if not we'll more than 100 lbs/ft?

2. Would you be pre-heating the rail as it seems like it would take an enormous amount of energy to heat something with that mass?

3. Would you not benefit from insulating the unit in addition to adding something with mass wether it be iron or some sort of ceramic material?

just curiosity on my end as the concept is interesting.

[jfmorris]

Your thoughts match up with mine Buck. If you want heat retention get a big 1/4" thick offset or a kamado. That said, the original poster's idea is worth an experiment. I see the mess (greasy chunk of metal in the bottom of the grill) as making it not worth it for me, even if it does stabilize the cook. I'll just use a water pan for a thermal mass, and throw it away after the cook.

[Buck Flicks]

I don't see the overall benefit. If you don't have insulation like a kamado, what's the point? Yes, you're saving some heat on the back end of the cook, but you're also taking it longer to get up to the proper heat. If you're using a kettle and an SnS, your temps are pretty stable already. Add a fan, and it's not going to waver at all unless you open the lid or run out of fuel.

Maybe I'm missing something?

[EdF]

That matches my intuitive understanding and experience!

[jfmorris]

Jon Solberg sorry to bum you out! I hang out with engineers of the electrical/mechanical/software variety much more than I do the ones who drive trains. I'll let you keep imagining them in those striped hats!

[jfmorris]

For heat retention, while the overall thermal mass is important, and a big chunk of metal has that going for it, you probably also have to consider the thermal conductivity. Case in point - cast iron is less conductive than aluminum, and takes longer to heat up, and longer to cool down. Steel is somewhere in the middle between those 2 metals. I would think fire bricks or other ceramics would be even less conductive than cast iron, meaning they take longer to heat up, but retain the heat longer as well.

[Jon Solberg]

jfmorris bummer I would like to think you train pilots stuck with this tradition.

That said it takes a lot of skill to operate a massive train. Much respect to the engineers of the world that move the goods we need! Thank you to engineers and truck drivers everywhere!

DWCowles

[jfmorris]

Haha, I don’t know, maybe on reruns of Petticoat Junction?

[jfmorris]

You misunderstand me. I am saying that a kamado grill HAS thermal mass, as does a large offset made from 1/4” steel, unlike a thin walled grill.