Thermodynamics: Unsteady Flow (Charging) Process

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Discussion Overview

The discussion revolves around the thermodynamic analysis of an unsteady flow (charging) process, specifically focusing on determining properties at different states of a fluid, including temperature and internal energy. Participants are seeking assistance with calculations and interpretations related to the states of a saturated mixture and superheated vapor.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about how to proceed with the problem due to missing information regarding initial and final states.
  • Another participant suggests using interpolation to find the internal energy at state 2, proposing a value of u_2 = 3047.35 kJ/kg.
  • A participant questions the interpretation of the mass of the saturated mixture, suggesting an assumption about the quality of the mixture to calculate the mass of vapor.
  • There is a proposal that at state 2, the fluid is a superheated vapor based on the temperature being higher than the saturated temperature.
  • One participant offers to share reference slides via private message to assist with the discussion.

Areas of Agreement / Disagreement

Participants have differing views on how to approach the problem, particularly regarding the assumptions about the quality of the mixture and the state of the fluid at point two. No consensus has been reached on the correct method or values to use.

Contextual Notes

Participants have noted limitations in the information provided, including missing values for initial and final states, which affects their ability to determine temperatures and other properties accurately.

Who May Find This Useful

This discussion may be useful for students or professionals interested in thermodynamics, particularly those dealing with unsteady flow processes and the analysis of phase changes in fluids.

afpskierx
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Please see the attached photo.

I am not sure how to proceed. I do not know Mi or M2, nor do I have enough information to determine the temperature at point two (when the valve is closed). Any help getting me going along will be much appreciated. :)
 

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Hi afpskierx,

Have you find the [itex]u_2[/itex] by doing interpolation? I got the answer for [itex]u_2[/itex] = 3047.35 kJ/kg

At state 1, I don't quite understand with the question which stated that that mass of saturated mixture of water is 12kg.

So, I assume the quality, x = mass of vapour / total mass. You will get 7.2kg for your mass of vapour.

At state 2 (which is the [itex]P_2[/itex] = 400kPa and [itex]T_2[/itex] = 450 C) I assume it SUPERHEATED VAPOUR seems the [itex]T_2[/itex] larger than saturated temperature.

I just can help for what I wrote above. Otherwise, I'll try come out for the full solution later.
 
What did you use to look up u2? The only thing we know about it is that its quality is one (it is a saturated vapor).
 
can you PM me your e-mail address? I'll send to you slides for your reference. Thanks :)
 

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