Steaming. Temperature. Concept. Questions.

[kayb]

22 minutes ago, rotuts said:

@kayb  

 

read them all

 

w

 

Chips and Dps ?

 

something

 

you will not regret it

 

start w True Grit

I have. I don't remember what the snack du jour was.

[JoNorvelleWalker]

Hang on, I still disagree with all of you.  OK, except for @kayb.

 

Superheated steam is a dry gas, not wet.

https://en.wikipedia.org/wiki/Superheated_steam

 

Remember that first time you steam baked a chicken thigh in your CSO?  I thought so.  Industrially steam is used to dry things.  You can't have a relative humidity of 100% above the boiling point of water.  I am still looking for the relevant equations, however I found this article helpful...

 

https://www.macinstruments.com/blog/whats-wrong-with-relative-humidity-above-100-celsius/

 

"Below 100°C it is possible to achieve 100% relative humidity at any temperature. Above 100°C (in the super heat area) the maximum possible relative humidity plunges rapidly as the temperature increases. Pure steam (100°C dew point) will register only 20% on the relative humidity scale at 150°C. At 175°C the maximum possible RH is only 10%. At 200°C, maximum RH is only 5.9% and at 370°C, maximum RH is a mere .48%."

 

 

 

[rotuts]

"""  relative """

 

?

 

Actual ?

[JoNorvelleWalker]

48 minutes ago, rotuts said:

"""  relative """

 

?

 

Actual ?

 

Relative.

 

[gfweb]

hmmm.

 

 

 

Edited December 19, 2020 by gfweb (log)

[kostbill]

That changes things a bit.

[gfweb]

so what does Modernist Cuisine say?

[JoNorvelleWalker]

1 hour ago, gfweb said:

so what does Modernist Cuisine say?

 

Well, Scott Heimendinger, anova's chief marketing officer, formerly worked for Modernist Cuisine.  All he says is:

 

"As you get hotter than 212°F / 100°C, the maximum theoretically possible relative humidity plunges from 100% to very small numbers, really fast."

 

[gfweb]

37 minutes ago, JoNorvelleWalker said:

 

Well, Scott Heimendinger, anova's chief marketing officer, formerly worked for Modernist Cuisine.  All he says is:

 

"As you get hotter than 212°F / 100°C, the maximum theoretically possible relative humidity plunges from 100% to very small numbers, really fast."

 

So whats the application here? Thoroughly confused.  How does this explain my thermometer reading 240 f in a steamy oven?

[JoNorvelleWalker]

2 minutes ago, gfweb said:

So whats the application here? Thoroughly confused.  How does this explain my thermometer reading 240 f in a steamy oven?

 

Why are you surprised your thermometer would read 240F in a steamy oven?  Your oven produces superheated steam.

 

As to low relative humidity, I may slowly be coming to an understanding.  Relative humidity is the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water.  I'm pretty sure that in an open system in my kitchen (say, inside my APO) the partial pressure of water vapor is never going to exceed atmospheric pressure.  But look what happens to the vapor pressure of water above the boiling point...

 

https://en.wikipedia.org/wiki/File:Vapor_Pressure_of_Water.png

 

[rotuts]

the issue is '' relative "

 

steam cooking works 

 

as it is supposed to.

 

very expensive professional combi's

 

allow you to set the humidity at what ever temp you are cooking at.

 

actual humidity ?  relative humidity ?

 

terms might not matter in actuality.

 

can you have 100 % humidity at 350 f 

 

a common cooking temp ?

 

don't know.     but I don't see why not

 

w a steam generator that adds steam

 

to a closed space   

 

closed is important as

 

leaking steam at that temp is very dangerous 

 

and might be difficult to maintain in a '' kitchen setting '

 

 

[JoNorvelleWalker]

23 minutes ago, rotuts said:

the issue is '' relative "

 

steam cooking works 

 

as it is supposed to.

 

very expensive professional combi's

 

allow you to set the humidity at what ever temp you are cooking at.

 

actual humidity ?  relative humidity ?

 

terms might not matter in actuality.

 

can you have 100 % humidity at 350 f 

 

a common cooking temp ?

 

don't know.     but I don't see why not

 

w a steam generator that adds steam

 

to a closed space   

 

closed is important as

 

leaking steam at that temp is very dangerous 

 

and might be difficult to maintain in a '' kitchen setting '

 

 

 

With all respect I disagree,  My Fisslers are closed cooking spaces.  The APO is not a pressure cooker.  The APO cooks at near atmospheric pressure.

 

Please source the statement that very expensive professional combi's allow you to set the humidity at whatever temp you are cooking at.  I have a bridge perpetual motion machine I'd like to sell.  I read through a Rational combi oven manual and learned how to set the IP address but not how to set the relative humidity above 100C.

 

 

[Duvel]

1 hour ago, JoNorvelleWalker said:

Please source the statement that very expensive professional combi's allow you to set the humidity at whatever temp you are cooking at.

I think there is a small misunderstanding here. Yes, a professional combi will allow you to set the temperature & steam% independently, but not in any combination. 
 

The volume of steam generated per time unit depends on the power of the evaporator, and while these machines certainly have impressive specs, they have limitations. Besides, there are very limited applications to „cook“ at say 200 oC and 100% humidity.
 

Please do have a look this, taken from a manual for the machine that @rotuts posted upthread ...

 

 

Temperatur is - well - temperature and  Feuchte means humidity. You can see that the limitation will be around 130 oC at 100% humidity, which in a preheated closed* system is well achievable ...
 

*Edited for clarity: a closed (self-)pressurised system, as the vapor pressure of the steam (water) will exceed ambient pressure.

Edited December 20, 2020 by Duvel (log)

[rotuts]

@Duvel

 

Kiss Kiss !  kudos coming your way !

 

have a dortmunder beer

 

https://www.hopculture.com/definition-dortmunder-beer/

 

on me ,

 

with some meat !

 

https://en.wikipedia.org/wiki/Mett

 

350 F is a common cooking them , 176 C

 

how much humidity you might want to use at those baking temps is beyond me

 

but , if you wanted 100 % , you simply would have to build-in a more powerful steam generator.

 

Mett, w Kudos ,  for @Duvel    : On the way.

[Duvel]

1 minute ago, rotuts said:

Kiss Kiss !

Finally a useful application for 8 long years of studying thermodynamics 🤗

[rotuts]

Took thermodynamics for only one semester.

 

it was a complicated course , and required understanding partial differential equations.

 

I found the Second Law especially impressive .

[kostbill]

Speaking of the second law, here is a great one: 

 

 

So, more questions: if the humidity cannot get above some percentage at certain dry bulb temperatures, then how come the anove supports the setting of humidity to every level from 0 to 100% at higher than 100C?

[rotuts]

@kostbill 

 

"   humidity cannot get above some percentage "

 

it can get to 100 % at any DBT

 

if you go to the troubler and expense to build your Combi

 

or experimental set up

 

properly.

 

it seems that Rational has chosen to build

 

an system , already relatively expensive for me

 

that can give you 50 % humidity @ 230 C.

 

for practical cooking purposes , I shave no idea what

 

you gain @ 230 C  ( 446 F )  w 50 % humidity

 

careful opening that door !  and that's why these machines need

 

impressive hoods and venting.

 

massive amount of energy released when you open that door !

[Duvel]

37 minutes ago, kostbill said:

if the humidity cannot get above some percentage at certain dry bulb temperatures, then how come the anove supports the setting of humidity to every level from 0 to 100% at higher than 100C?

I think this might be another misunderstanding on terminology. The manual talk not about the setting of the absolute humidity, it talks about steam injection. 
 

Under 100 oC the setting seems indeed to be interpreted as a humidity selection (as this corresponds to the SV mode, where the humidity is monitored via WBS), above 100 oC it is just the channel usage (hot air / circulation vs. steam inlet), as in the absense of a pressurized cell a humidity selection above the partial pressure of water at the selected temperature would not work.

 

[gfweb]

3 hours ago, rotuts said:

Took thermodynamics for only one semester.

 

it was a complicated course , and required understanding partial differential equations.

 

I found the Second Law especially impressive .

I avoided thermodynamics and differential equations (and P-chem for that matter) like the plague.

 

I can tell you a lot about glaciers and the size of sparrow's beaks though.

[JoNorvelleWalker]

5 hours ago, gfweb said:

I avoided thermodynamics and differential equations (and P-chem for that matter) like the plague.

 

I can tell you a lot about glaciers and the size of sparrow's beaks though.

 

I suffered only one semester, but my once four year old has/had an autograph from Donald Swann.

 

[gfweb]

31 minutes ago, JoNorvelleWalker said:

 

I suffered only one semester, but my once four year old has/had an autograph from Donald Swann.

 

He doesn't google, unless the composer had in interest in physics.

[JoNorvelleWalker]

29 minutes ago, gfweb said:

He doesn't google, unless the composer had in interest in physics.

 

https://forums.egullet.org/topic/143487-steaming-temperature-concept-questions/?do=findComment&comment=2278072

 

[Duvel]

29 minutes ago, gfweb said:

He doesn't google, unless the composer had in interest in physics.

 

The link is entropy, my friend ...

 

Decomposing composers