- #36
pranj5
- 386
- 5
I just forgot to add the word adiabatic.
So, what do you think will happen to the amount of liquid water in the container if we compress the original contents of the container with a piston to the equilibrium vapor pressure of water at 23.6 C?pranj5 said:I just forgot to add the word adiabatic.
Well, compressing it mechanically with a piston is the same as compressing it using the superheated steam (as you yourself pointed out), provided the original contents is kept separate from the injectate using a massless, frictionless, insulated piston to separate them.pranj5 said:If you want to mean that if by mechanical means, the pressure has been increased from 20C saturation level to 23.6C saturation level; then the answer is very much evident. Kindly read all the posts (especially posts by you) to any third person and ask him/her the same question and let's see the answer.
I haven't said that. I just want to consider this for the sake of simplicity. And can you tell me how the amount of water can be a factor here. I mean if the amount of water is sufficiently high and more than the amount of steam, then amount of water will increase and will decrease if the case is reverse.Chestermiller said:You said in a previous thread that, for the adiabatic reversible compression of a steam/water mixture, the change in entropy of the mixture should be zero.
Yes, as long as the initial wetness is greater than about 50%.pranj5 said:I haven't said that. I just want to consider this for the sake of simplicity. And can you tell me how the amount of water can be a factor here. I mean if the amount of water is sufficiently high and more than the amount of steam, then amount of water will increase and will decrease if the case is reverse.
One simple explanation is that, if case of lesser amount of water, additional heat generated by the inefficiency of the process will evaporate it. That can certainly happen in reality. But, at least we both are agreed now on one point that if the amount of water is sufficient, then the steam will remain saturated during the process of compression. Even if the compression is adiabatic. Right?
Yes. Also, even if it's not more, it will still stay saturated if you limit the amount of compression.pranj5 said:Do you mean that if the amount of water is more than the amount of steam, then the steam will remain saturated during the compression process? I hope this is what you want to mean by initial wetness, right?
It depends of the fraction of liquid water. To find that out, it is easiest to use the temperature-entropy diagram or the enthalpy-pressure diagram.pranj5 said:In that case, what should be the limit of compression ratio?
There are a lot of factors involved. Can you provide a specific initial state?pranj5 said:Can you guess some limit?
I'll check the Mech_Engineer's T-S diagram, and get back with you.pranj5 said:Lets start with our old initial states i.e. saturated steam at 20C and 2.536 kPa.
You move up a constant entropy line until you hit the 100% dry envelope. You determine the temperature at that point. Then you determine the corresponding saturation vapor pressure, and take the ratio. For a temperature higher than that, the compressed gas would be superheated (i.e., beyond your desired limit).pranj5 said:How the compression limit can be determined by the T-S diagram?
The amount of liquid water increases with pressure if there isn't enough liquid water around to start with. Mech_Engineer showed this (i.e., if it's pretty wet to start with). Otherwise, the mixture will become drier as you compress. So the amount of water increasing or decreasing depends on the initial wetness. Check out the T-S diagram.pranj5 said:If the amount of water increases with pressure, then how can we hit the 100% dry envelope?
That's contrary to what you have said in post 42.Chestermiller said:The amount of liquid water increases with pressure if there isn't enough liquid water around to start with.
I'm going to try to say this as clearly as I can.pranj5 said:That's contrary to what you have said in post 42.
Superheated steam and water together refers to a state where water and steam are both present in a system, with the steam being at a higher temperature than its boiling point at a given pressure.
The main difference between superheated steam and regular steam is the temperature. Regular steam is at its boiling point, while superheated steam is at a higher temperature, making it more energy-rich and useful for various industrial processes.
Superheated steam and water together have properties that are a combination of both water and steam. It has a high temperature and pressure, low density, and high energy content, making it useful for power generation and heat transfer.
Superheated steam and water together are produced by heating water to its boiling point and then further heating it in a separate vessel. This process is known as superheating and is used in power plants and other industrial processes.
Superheated steam and water together have various applications, including power generation, heating and cooling systems, and industrial processes such as sterilization, drying, and cleaning. It is also used in steam turbines to produce mechanical work.