- #31
voko
- 6,053
- 391
I am not sure what problem you are trying solve now. Doing one at a time could be helpful.
Non-flow process with steam (Constant Pressure)
- Thread starter freshbox
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Homework Help Overview
The discussion revolves around two questions involving steam processes in closed systems. The first question concerns wet steam at a pressure of 5 bar and a dryness fraction of 0.2, which is heated at constant pressure until a specified volume is reached. The second question involves superheated steam at 10 bar cooling at constant pressure. Participants are exploring the implications of heating wet steam and the conditions under which it may remain wet versus becoming dry or superheated.
Discussion Character
- Exploratory, Conceptual clarification, Assumption checking
Approaches and Questions Raised
- Participants discuss the conditions under which wet steam can remain wet after heating and question how to determine the state of steam when not explicitly stated in the problem. They explore the relationship between temperature, pressure, and steam state, including the implications of constant pressure heating.
Discussion Status
The discussion is active, with participants providing insights into the behavior of steam under various conditions. Some guidance has been offered regarding the relationship between steam state and temperature, but there is no explicit consensus on how to approach the problems or determine the steam state without additional information.
Contextual Notes
Participants note the lack of explicit hints in the problems regarding the steam state and express confusion about the implications of heating wet steam at constant pressure. There is also mention of the need for steam tables to determine specific properties, which may not be readily available to all participants.
- #32
freshbox
- 290
- 0
I am trying to solve:
In a closed system, 0.05.kg of dry saturated steam is heated at a constant pressure of 8 bar until the volume is occupied is 0.018m3
(A)Calculate the change in internal energy, the work energy transferred and the heat energy transferred during the process.
You told me to use perfect gas law to solve it, but i thought this question is about non-flow process with steam?
To solve using perfect gas law from the formula sheet:U2-U1=mcv(T2-T1), Cv is not given at all, how do I solve?
In a closed system, 0.05.kg of dry saturated steam is heated at a constant pressure of 8 bar until the volume is occupied is 0.018m3
(A)Calculate the change in internal energy, the work energy transferred and the heat energy transferred during the process.
You told me to use perfect gas law to solve it, but i thought this question is about non-flow process with steam?
To solve using perfect gas law from the formula sheet:U2-U1=mcv(T2-T1), Cv is not given at all, how do I solve?
- #33
voko
- 6,053
- 391
Do you have tables for superheated steam?
- #34
- #35
voko
- 6,053
- 391
What is "superheated steam" in your book?
- #36
freshbox
- 290
- 0
The specific properties of a superheated steam are normally tabulated in separate tables for selected values of pressure and temperature. For steam in the superheated region, temperature and pressure are independent properties. When the temperature and pressure are given for superheated steam then the state is defined and all the properties can be found.
- #37
voko
- 6,053
- 391
Yes, that is fine, but how does one MAKE superheated steam?
- #38
freshbox
- 290
- 0
From 1 of my book example, it says ts2>ts (stage 2 temp > stage 1) to be superheated.
So for this question, stage 1 at 8 bar=170.4°C. I am only given Stage 2 volume which is 0.018m3. How can I use it to help me find the temperature?
So for this question, stage 1 at 8 bar=170.4°C. I am only given Stage 2 volume which is 0.018m3. How can I use it to help me find the temperature?
- #39
voko
- 6,053
- 391
You heat the steam at constant pressure, so you know that as well.
- #40
freshbox
- 290
- 0
is the stage 2 temperature 359.39°C?
- #41
freshbox
- 290
- 0
Should be correct, i got the final answer.. Hmm this type of question are harder than those guiding you to find "the dryness fraction of the steam after cooling"
Any tips for tackling this type of question? Sometimes I get confused+exam pressure then everything goes down hill..
Any tips for tackling this type of question? Sometimes I get confused+exam pressure then everything goes down hill..
- #42
voko
- 6,053
- 391
You seem to be a little unsure about what all those things really mean. Wet steam, dry steam, saturated steam, superheated steam, and how one changes into another. Review that. Make sure you can explain every step you made solving these problems.
- #43
freshbox
- 290
- 0
Thanks voko, thank you for your time and help.
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