Thermodynamics of evaporative cooling, and humidity.

[TehPurplePills]

Howdy.
The topic is brisket, electric smoker.

humid pit, or dry pit? and does that change if using a crutch? how does a butcher paper crutch change the dynamic vs a foil one?



I was formerly convinced into smoking without a water pan. The idea being: the stall is caused by evaporative cooling. You don't want to add moisture to the surface, because that is moisture that evaporates from the briskets surface, cooling it, increasing the cook time, the time its drying out.

I've done about 12 packers, half w and without water pans, about half crutched or not. & I came to the preference of uncrutched, unpanned. Not sure if that's due to the science, or my experience and skill, or bias, NVM dumb luck.

theoretically, in 100% water saturated air in a pit, the brisket cant sweat.
but also,
if the air isn't 100% saturated, and you're adding moisture to the meat's surface, that's giving it moisture to sweat, increasing cook time, particularly stall, right?

So is my scientific mind correct in thinking that the best conditions for a brisket to be in must be either a super high humidity method, where the air is 100% saturated, where there can be no more evaporative cooling,
OR
a dry method where the air doesn't deposit any moisture onto the meat, and therefore doesn't aid it in cooling itself off?
But anything in between is fraught with issues?
if true then does something in-between make sense? like butchers paper vs naked or foiled meat?
and can we achieve 100% humidity? has anybody ever used a hygrometer in a pit?
or are we running a water pan and getting a dry 20% humidity anyways? Maybe a hygrometer is MORE important than the thermometer.

This isn't about steam regulating temp, purportedly the water pans biggest reason for existence, that's not an issue for electric.


P.S. its a 14lb really stout (more square than rectangle vs ur average brisket) packer, plan to inject w totole brand chicken soup base mix, msg, I+G + water for 18-24ish hrs, possibly try garlic and butter, sit wet in a marinade bag, and rub 2 hrs before smoking with mustard, and my mix, which is heavy fresh fine black pepper, same injection minus the water, paprika, korean chili flake, light garlic powder, light salt, light coconut sugar. Going to try to have it done 4-6ish hrs early and sit till ready, incase it takes longer. planning on a 225f first 3-6 hrs, then 250-275f till done, but that depends on if i crutch or not and with butcher paper or foil, and if i use waterpan or not.
Cherry and mesquite chips and an A-MAZE-N running w Traeger pitmaster blend pellets, going to throw on a half butt too, but pork is criminally easy compared to brisket and doesn't have me concerned at all.

 

[912smoker]

Whew that's tough. But for starters, what brand of electric smoker are you using and where are you located?

Keith

 

[Up_In_Smoke]

What do people in Phoenix do?
That's about as dry as it's going to get.

What do people in Boston do?
Pretty humid there.

 

[chopsaw]

My goodness ,,,,,

 

[912smoker]

I'm in S GA and ran a water plan in the MES one time. All of the rub actually slid off of the meats and into the pan. Then I found SMF and the advise here and always ran the pan dry or filled with sand for a heat sinc.
I have been wrapping with BP but am going back to either full foil or the boat method to save all of the valuable liquid gold drippings.

Keith

 

[dsk]

In a 100% humid environment, the meat will still sweat due to proteins contracting and expelling moisture, but since it cannot evaporate, the moisture would simply drip off. No stall, at least due to evaporative cooling. I think part of the stall is due to the heat being absorbed to convert the collagens to gelatin, and this portion would be unaffected.

 

[pineywoods]

^^^^Bingo the stall is caused by the fat and collagen breaking down. No two pieces of meat will cook in exactly the same amount of time because no two pieces have the exact same fat and collagen content.
As for the water pan from everything I've read it adds very little if any moisture inside the smoker. The water pan is more for a heat sync than anything. People add all kinds of liquids to the water pan but most have said they couldn't taste any difference in the taste of the meat.
I used to have aa GOSM propane smoker and mostly used the water pan filled with water. When I didn't have liquid in the pan and had sand in it the only difference I could tell was the sand didn't help with temp recovery after opening the door as well. I did try adding different liquids to the water pan but never noticed any of whatever it was taste in the smoked product.

 

[rjob]

Long read on humidity by Dr. Blonder

its not easy being humid

 

[Fraser]

At bbq temperatures, water is by definition superheated; ie above vaporization temperature (except within the boundary layer) and therefore the term ‘humidity’ has little meaning.
Water, whether on the surface of a water pan or brisket vaporizes by absorbing enormous amounts of energy within the boundary layer until superheated to pit temperature. The vaporization energy (energy absorbed when 100C water transforms to 100C vapor) is roughly 5 times the energy to heat ice to boiling!
The water exuded from a brisket is a function of the muscle fibers cooking and the resultant evaporative cooling are inevitable (unless non-bbq pressures are applied!).
Hope this helps!

 

[TehPurplePills]

Whew that's tough. But for starters, what brand of electric smoker are you using and where are you located?

Keith

Indiana, and masterbuilt. real basic of the basics analog model. the heating element/controls it came with was giving me trouble, i replaces it, generic amazon parts, itl hea tup now, importantly it will keep it hovering right around where i set it, very low fluctuation, mabye 3 degree max either way every time ive checked, and thats always been without water regulating heat. (my favorite smoke is whole chicken wings, joints broken, skin intact, and you need a dry heat for the skin to crisp, although finishing them in the air fryer is a valid option.)

 

[TehPurplePills]

In a 100% humid environment, the meat will still sweat due to proteins contracting and expelling moisture, but since it cannot evaporate, the moisture would simply drip off. No stall, at least due to evaporative cooling. I think part of the stall is due to the heat being absorbed to convert the collagens to gelatin, and this portion would be unaffected.

yes, thank you. I really dug into the science mabye 8 yrs ago, and you just reminded me, I believe the theory at the time, and the one I believed, did mantain that that conversion between collogen to gelatin was a huge heat sink. so mabye that is just a fact of the stall, a large part of the stall, that cant be fixed by humidity.

 

[TehPurplePills]

^^^^Bingo the stall is caused by the fat and collagen breaking down. No two pieces of meat will cook in exactly the same amount of time because no two pieces have the exact same fat and collagen content.
As for the water pan from everything I've read it adds very little if any moisture inside the smoker. The water pan is more for a heat sync than anything. People add all kinds of liquids to the water pan but most have said they couldn't taste any difference in the taste of the meat.
I used to have aa GOSM propane smoker and mostly used the water pan filled with water. When I didn't have liquid in the pan and had sand in it the only difference I could tell was the sand didn't help with temp recovery after opening the door as well. I did try adding different liquids to the water pan but never noticed any of whatever it was taste in the smoked product.

The thing with propane molecules though, C3H8, is those 8 hydrogen atoms turn into 8 H20 molecules (as combustion is just rapid oxygenation) as it burns. so the propane is itself, its own water pan of sorts. I have NO IDEA how much moisture that adds to the equation though.
But also it being a combustion smoker, it requires airflow, to maintain combustion. As opposed to electric, which just has a small exhaust hole, and doesn't "NEED" combustion air or airflow, so that will affect ability of a pit to retain humidity too.

Apple juice is a very common alternative to water, when ive used it, its also been in the crutch, so i have no idea what, if anything, it did. I suppose not much. (when you do both, it definitly has an effect tho)
and ive had a friends smoked meat that was very appley, too sweet.
I think the thing is, a 2liter of apple juice is about $1.50, so "why not" when you're spending a day on a $45-100+ cut of choice meat? also im an adult, i dont want to drink apple juice, so the bottle is a one use item...

 

[TehPurplePills]

At bbq temperatures, water is by definition superheated; ie above vaporization temperature (except within the boundary layer) and therefore the term ‘humidity’ has little meaning.
Water, whether on the surface of a water pan or brisket vaporizes by absorbing enormous amounts of energy within the boundary layer until superheated to pit temperature. The vaporization energy (energy absorbed when 100C water transforms to 100C vapor) is roughly 5 times the energy to heat ice to boiling!
The water exuded from a brisket is a function of the muscle fibers cooking and the resultant evaporative cooling are inevitable (unless non-bbq pressures are applied!).
Hope this helps!

but im saying: can you make the pit 100% humidity, to prevent the brisket the ability of evaporative cooling? or, by not adding moisture to the pan, can you keep the moisture level so low in the pit, you dont add any significant moisture for the brisket to use for evaporative cooling?

 

[Up_In_Smoke]

So are we saying that ambient humidity has no effect on the internal cooking?

 

[Fraser]

So are we saying that ambient humidity has no effect on the internal cooking?

At BBQ temperatures (225F or higher) water is entirely gaseous and obeys the Ideal Gas law; there is no water vapor, only water weight per volume of gas.
Yes, ambient conditions (eg humidity) affect combustion, combustion products and the amount of fuel used.
In an open system the meat is below the vapor temperature and the forced convective air is above it, therefore evaporative cooling takes place.
Adding a water pan simply slows the cook (which arguably might be a good thing). Think about it: water in liquid state at normal pressure must be no greater than 212F; the pit is running 225F or more. It takes an enormous quantity of energy to a) state change to gas, and b) raise the gas from 212F to 225F. That energy comes from the bbq fuel, leaving less energy toward the cook. Which again, possibly be a good thing.
Even if you submerged the meat in another fluid such as water, yes evaporative cooling would be eliminated but the meat will still exude its water during the cook. You could inhibit the evaporative cooling by tightly wrapping in foil, but even then it still occurs.
All I’m saying is: cooking is a function of energy (temperature and pressure). Flavor, on the other hand……

ps - For lots of good info on the Stall, evaporative cooling, etc please see Prof Blonder’s studies. For ex: https://genuineideas.com/ArticlesIndex/stallbbq.html

 

[Up_In_Smoke]

Fraser,

Thank you very much!!
And I love how Prof. Blonder makes things easy for us mentally challenged old guys to understand.

 

[pineywoods]

So are we saying that ambient humidity has no effect on the internal cooking?

Humidity does have an affect in cooking. From what I have read I think people believe they are getting a lot more humidity inside the smoker that what they actually are

 

[WallyP]

What about the rate at which the smoke travels over the meat? Does greater air flow cause more evaporation resulting in a drier brisket?

I usually close my firebox damper butterfly down by 2/3. It keeps a lower temp but it also creates a strong draw of smoke over the meat. My last briskets were heavily smoked, but somewhat dry.

I’m thinking of opening the firebox door entirely. Thus flooding the box with air, creating smoke that lingers over the meat, rather than a strong draw of smoke over it. Sure, my sticks might burn faster, but not necessarily hotter.

Thoughts?

 

[kelbro]

What about the rate at which the smoke travels over the meat? Does greater air flow cause more evaporation resulting in a drier brisket?

I usually close my firebox damper butterfly down by 2/3. It keeps a lower temp but it also creates a strong draw of smoke over the meat. My last briskets were heavily smoked, but somewhat dry.

I’m thinking of opening the firebox door entirely. Thus flooding the box with air, creating smoke that lingers over the meat, rather than a strong draw of smoke over it. Sure, my sticks might burn faster, but not necessarily hotter.

Thoughts?

Slightly opening the firebox door is how I do it now. Much better flavor. Tender, moist meats. Yes, it uses more fuel. Yes, you will have more and larger temp swings but the duration of those swings is not long and the briskets and butts do not care.

 

[Fraser]

What about the rate at which the smoke travels over the meat? Does greater air flow cause more evaporation resulting in a drier brisket?

In a word, yes. Bernoulli states that faster moving air = lower pressure = lower boiling point, more evaporation. Probably not hugely significant but nevertheless.