Is all temperature the same regardless of smoker used ?

[Norcoredneck]

Hey Spicewine owners, What happens when you are at a controlled temp exhaust wide open, then cut exhaust back to 1/3 open?
Also why do cookers have varying hot/cold spots, given centered efficient fire?

 

[Captain Dave]

Water will boil in a vacuum of 29.92 in. or greater. And 90* in the sun is hotter than 90* in the shade. At least it feels that way to my meat.

 

[CajunSmoker]

Now I don't know how this translates to cookers but In my job I run thermal vacuum chambers. We control temp on the inside through shrouds . There is no actual air movement in the chamber (vacuum) only radiation. In the units we use to transition the shrouds air density makes a huge difference in how fast something transitions. The TCU's (temperature control units) use rod type heaters and inject LN2 (liquid nitrogen) to cool. All this circulates in a closed loop. If I set a temp that a PID controls the temp I can speed this transition rate by changing pressure. Higher pressure on hotter temps lower pressure on lower temps works best.

Damn deep discussion for my first cup of coffee:icon_blush:

My UDS's definitly cook faster than any other cooker I've ever used. I just assumed it was due to no water pan and convection from the air intake being at the bottom and pulling the air (and heat and smoke) across the meat to exhaust from the top.

 

[Sledneck]

I only cook on WSM's. WHen I went out to kansas this past spring to cook the GAB i used ANdy' s FEC & big pellets hog cooker. I cooked at the same exact temp on the FEC as I do my WSM;s.wrapped the meats at the same times I didnt change a thing. tHe meats all cooked and finsihed at the same times 225 is 225

 

[Yakfishingfool]

I nominate Phil to experiment for our benefit..

He's got the Spicebox, FEC, BGE, WSM, Klose and Bandera readily available in his yard.

:biggrin:

Instead of meat, with all it's variables, reduce the independent variables and try to heat a homogenous material...I vote for bricks of tofu. All same sized, weight, density, etc. Let's see what heats fastest!

 

[SirPorkaLot]

A WSM, ECB, etc..with a water pan above the heat source will act as a heat sink, and will maintain the heat around 212, So what hits your meat is a superheated steam, instead of a dry heat.

The converse of this is having moisture in the meat - IE: foiling, which basically traps the juices in the meat, plus self bastes the meat with condensation.
This in effect cooks the meat from the inside, which cooks it faster, but has a down side (to some) of changing the texture of the meat.


An offset will cook the slowest, as it is indirect dry heat. No moisture (unless you foil), no direct heat (few hot spots).
A WSM type will fall in the middle
A UDS, along with foiled and injected meat will cook the quickest (more of a direct heat, lots of moisture retention)


IMHO

 

[timzcardz]

Is all temperature the same regardless of smoker used ?

Yes, all temperature is the same regardless of the smoker used.


However, thermodynamic effects of smokers vary.

 

[RubMeTender]

Temperature is the same obviously, but cooking environments change so much. A rolled steel trailer smoker is going to cook much different than a Weber for example. It'll hold in humidity better as well.
Doesn't everyone just use a slow cooker to make their ribs and butts with a healthy dose of liquid smoke? ;-)

 

[SmokeInDaEye]

would the La Caja China have more pressure in the cooking chamber, aren't they kind of sealed?

Yes, it's basically a big convection oven with high heat on top and the pig or whatever in a somewhat airtight box below.

Yep, when I throw pumpkins and corn in with the meat the temp rises slower and a lot more steam comes out, definitely takes longer.

OT, but you smoke pumpkins? Are they good??? May have to try that if you have instructions.

 

[Bigdog]

Yes, all temperature is the same regardless of the smoker used.


However, thermodynamic effects of smokers vary.

Ding, Ding, Ding. Correct answer. :eusa_clap:eusa_clap:eusa_clap

Science teacher here: Many variables are at work. So while 225 is 225, its effects can vary. Great thread Milt. :icon_cool

 

[Mo-Dave]

Hey Spicewine owners, What happens when you are at a controlled temp exhaust wide open, then cut exhaust back to 1/3 open?
Also why do cookers have varying hot/cold spots, given centered efficient fire?

At first the temp will rise and then settle down to hopefully the temp I am looking for.

I would venture a guess as to metal mass, spacial volume of said cooker and structural placement of things like shelves, side rails and deflector plates plus exhaust location.

In my Lg Spice the center plate/water pan force heat up two sides and the back. The two exhausts are located at the back and to the sides, drawing the heat in that general direction. I have been kicking around the idea of adding elbows and longer nipples running toward the front and turned toward the center. Hopefully alowing the heat to rise more efficiently around the entire box before being expelled. Don't get me wrong it cooks just fine but I have to believe it is hotter around the sides and even more so toward the back causing my front to be a bit cooler thus maybe giving me false reading on my gauges. My guru helps I am sure to move the air around the box a bit but I still cant help think there is wasted heat going up the exhaust. Thats me thinking out loud. :wink:
Dave

 

[Mo-Dave]

Instead of meat, with all it's variables, reduce the independent variables and try to heat a homogenous material...I vote for bricks of tofu. All same sized, weight, density, etc. Let's see what heats fastest!

Thats a good Idea Olly.:idea:
Dave

 

[Lake Dogs]

Love the thread, and we learned this lesson the HARD way in a comp. Even my
two different stick burning offset cookers cook very differently at 250. My ribs,
previously dialed in to a 5 minute range, varied and were done literally an hour
quicker in the newer one. In this case, I'm fairly certain it's AIR FLOW difference.
MUCH better air flow in the newer/larger one.

For us, it's like the difference in a regular oven vs. a convection oven. Not
exactly, but close....

 

[smoke it if ya got it]

Nope...my UDS (sans deflector shield) cooks quicker than my WSM (with water in the pan) at the same temp...trust me on this...really! :lol:

I agree my UDS cooks faster at the same temps than my ECB and my Char Broil offset, and while the water will be a heat sink that's only until it reaches boiling point.

 

[jdub]

I think there is a LOT of difference with respect to airflow. I say it with the experience of my oven. After years of having a standard oven I got a super cool guy Wolf convection oven. Changed EVERYTHING. Times, how things brown, how pies bake, breads, meats, everything.
Quick moving HOT air is a big change.

 

[Mark]

I had to learn ths $hit as a mechanical engineer and again in Navy dive school. I think its mainly pressure but it's not simple.

PV = nRT

But this equations is for an ideal gas, which neglects various intermolecular effects This law has the following important consequences:

If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas.

If the temperature and volume remain constant, then the pressure of the gas changes is directly proportional to the number of molecules of gas present.

If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume.

If the temperature changes and the number of gas molecules are kept constant, then either pressure or volume (or both) will change in direct proportion to the temperature.

The inside of a smoker is far from an ideal gas since we have smoke a complex mix of gasses as well as air and water vapor. Therefore, Dalton's law of partial pressures applies as well as Henry's law.

• Dalton's law states that the pressure of a mixture of gases is the sum of the partial pressures of the individual components.
  
• Henry's law states that at a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

Are we clear now?

 

[Mark]

PS:

jdub's also right since smokers are not a closed chamber

 

[Mark]

PSS: And this brings us to the subject of high temperature psychrometrics.
A psychrometric chart provides a convenient graphical methodology for determining the thermodynamic properties of air and moisture mixtures. The various lines include dry-bulb and wet-bulb temperatures, relative humidity, humidity ratio, specific volume, dewpoint temperature, and enthalpy.

Additional references
UNDERSTANDING THE PSYCHROMETRIC CHART
http://www.techtrol.com/psyc.htm

The Mollier Diagram and the Psychrometric Chart
http://www.natmus.dk/cons/tp/mollier/moll1.htm

 

[Mark]

And a note to Pat:

Your "thermal geek" suggestion to research emissivity may have some relevance in outer space but not much in a smoker.

 

[Lake Dogs]

And, there's Boudreaux's Law:

If'n Dalton and Henry (see above) or Thibodeaux have gas, you best be a goin'
to da otha room...