Double Boiler

[KingGheedora]

Has anyone ever measured to see if this is actually the case?

A double boiler is often used to melt chocolate for example. You fill a pot with water, and then put chocolate in a smaller pot. You heat the pot with water to a boil, and then partially immerse the pot with chocolate in the boiling water. Since water will boil when it reaches 100 degrees at 1 atm, the chocolate will not exceed 100 degrees.

Seems like the chocolate would fluctuate at a temp very close to 100, sometimes going over, sometimes under. What's the reality?

 

[FleshLight]

The temp of the chocolate and water will fluctuate until they reach equilibrium at 100C, assuming that the external heat is at a constant 100C.

 

[KingGheedora]

What do you mean the external heat? Let's say it's a stove, the flame from the stove is the external heat? I think that flame is a lot higher than 100C. What if the flame temp is higher than 100C and constant?

 

[EagleKeeper]

Chocolate temp will get to 100C until there is not more water. At that point the extra heat will be heating the air and start being transfered to the chocolate bringing it above 100C

 

[Howard]

Unless there's agitation, I don't believe there would be a "fluctuation" in chocolate temperature.

 

[Sukhoi]

Originally posted by: EagleKeeper
Chocolate temp will get to 100C until there is not more water. At that point the extra heat will be heating the air and start being transfered to the chocolate bringing it above 100C

If the air doesn't cool below 100C by the time it reaches the surface of the smaller pot.

 

[Zenmervolt]

What's all this 100C stuff? We're in the US. It's 212F.

ZV

 

[soydios]

The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

 

[KingGheedora]

Originally posted by: soydios
The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

Can that water vapor exceed 100C? A lot of the water vapor will come in contact with the bottom of the pan with chocolate.

 

[91TTZ]

Originally posted by: FleshLight
The temp of the chocolate and water will fluctuate until they reach equilibrium at 100C, assuming that the external heat is at a constant 100C.

Nope.

 

[mugs]

The temperature of boiling water is 100C. The water is heating the chocolate. What else is going to heat the chocolate above 100C?

 

[Howard]

Originally posted by: KingGheedora

Originally posted by: soydios
The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

Can that water vapor exceed 100C? A lot of the water vapor will come in contact with the bottom of the pan with chocolate.

No. The water will turn into vapor at 100C, transfer some of its heat energy to the bottom of the top bowl, condense, and turn into vapor again. All the external heat is moderated by the liquid water. Now, if the walls of the boiler (pot) were heated, the vapor could go over 100C.

 

[Toastedlightly]

Originally posted by: Howard

Originally posted by: KingGheedora

Originally posted by: soydios
The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

Can that water vapor exceed 100C? A lot of the water vapor will come in contact with the bottom of the pan with chocolate.

No. The water will turn into vapor at 100C, transfer some of its heat energy to the bottom of the top bowl, condense, and turn into vapor again. All the external heat is moderated by the liquid water. Now, if the walls of the boiler (pot) were heated, the vapor could go over 100C.

Also, if pressure built up, the bP increases (IIRC)

 

[BigJ]

Originally posted by: Toastedlightly

Originally posted by: Howard

Originally posted by: KingGheedora

Originally posted by: soydios
The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

Can that water vapor exceed 100C? A lot of the water vapor will come in contact with the bottom of the pan with chocolate.

No. The water will turn into vapor at 100C, transfer some of its heat energy to the bottom of the top bowl, condense, and turn into vapor again. All the external heat is moderated by the liquid water. Now, if the walls of the boiler (pot) were heated, the vapor could go over 100C.

Also, if pressure built up, the bP increases (IIRC)

And sweet jesus, what if someone put salt in the water!

 

[Toastedlightly]

Originally posted by: BigJ

Originally posted by: Toastedlightly

Originally posted by: Howard

Originally posted by: KingGheedora

Originally posted by: soydios
The temperature of the water in a boiling pot at 1 atmosphere of pressure will *never* exceed 100 degrees Celsius. If any water molecules traveling at speeds found at temperatures higher than 100 degrees Celsius would turn into water vapor.

Can that water vapor exceed 100C? A lot of the water vapor will come in contact with the bottom of the pan with chocolate.

No. The water will turn into vapor at 100C, transfer some of its heat energy to the bottom of the top bowl, condense, and turn into vapor again. All the external heat is moderated by the liquid water. Now, if the walls of the boiler (pot) were heated, the vapor could go over 100C.

Also, if pressure built up, the bP increases (IIRC)

And sweet jesus, what if someone put salt in the water!

OH THE HUMANITY!