Hot water / cold steam interaction

AI Thread Summary
The discussion revolves around the interaction between hot water in a large volume (V1) and cold steam in a smaller volume (V2) when a valve connecting them is opened. It raises a question about the thermodynamic behavior of the system, particularly regarding heat transfer and phase changes. The initial assumption is that heat cannot transfer from the cold steam to the hot water, yet the expected outcome is that liquid water would flash into V2, increasing its pressure and temperature. As V2's temperature rises, it could eventually exceed the temperature of the water in V1, allowing for heat diffusion. The inquiry seeks guidance on how to approach this problem using thermodynamic principles and calculations.
bamse207
Messages
1
Reaction score
0
Hello,

I came to consider the following problem, and cannot seem to find the right way to tackle it.
It is not homework, merely a question I'd like to address out of personal curiosity:

Consider two volumes V1 and V2, each assumed adiabatic, and linked with a valve.
V1 is considered infinite (or at least very big compared to V2), V2 being finite and small compared to V1.
V1 is initially filled with, say, water, in liquid state at high pressure (T1, P1). T1 being below the saturation temperature at P1.
V2 is initially filled with steam at lower pressure and temperature (T2 < T1, P2 << P1)
At t=0, the valve is opened, what happens then?
According to the second principle, heat cannot be transferred from the cold steam to the hot water.
However it seems obvious to me that the end state would be liquid, at ~P1 and some other temperature.

Qualitatively, I'm expecting the liquid would flash through the valve from V1 to V2, which would gradually increase P2, until it equals P1. During that process, somehow, the steam in V2 would condense, increasing T2 upto a point where T2 > T1, from which heat can diffuse. Does this sound correct?

Any tips on the right approach to solving this? I've been through a couple of thermodynamics books, and couldn't find any mention of such a situation. Any pointers or keywords to look for to help me find an answer to such a case would be highly appreciated!

thanks!
Laurent
PS: this is my first post here, I hope I've found the right place for it...
 
Physics news on Phys.org
I think that you have to give values to V1 and V2 then calculate the total mass and energy in V1 and V2 then combine them and see what temperature water you're left with.
 
The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
Thread 'Beam on an inclined plane'
Hello! I have a question regarding a beam on an inclined plane. I was considering a beam resting on two supports attached to an inclined plane. I was almost sure that the lower support must be more loaded. My imagination about this problem is shown in the picture below. Here is how I wrote the condition of equilibrium forces: $$ \begin{cases} F_{g\parallel}=F_{t1}+F_{t2}, \\ F_{g\perp}=F_{r1}+F_{r2} \end{cases}. $$ On the other hand...
Back
Top