Thermodynamics - Find final pressure

AI Thread Summary
The discussion revolves around calculating the final pressure of steam undergoing a constant volume process, starting from an initial pressure of 0.1 MPa and temperature of 350°C, and ending at 300°C. A participant initially attempted to use linear interpolation but arrived at an incorrect final pressure of 28.3 kPa, while the correct answer is 93.4 kPa. It was pointed out that steam tables should be utilized for accurate calculations, specifically focusing on the specific volume, which remains constant in this scenario. The conversation emphasizes the importance of referencing steam tables to find the correct specific volume and corresponding pressures at the final temperature. Accurate use of thermodynamic properties is essential for solving such problems effectively.
Ribz
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Homework Statement



An amount of steam undergoes a constant volume process from an initial state for which the pressure and temperature are 0.1MPa and 350°C respectively. The final temperature is 300°C. Using linear interpolation estimate the final pressure.

Homework Equations



Use Thermodynamics and Transport Properties of Fluids

The Attempt at a Solution



I used linear interpolation for the pressure at 100°C, which was 1.01325 bar. Got my answer which was 28.3 kPa. The answer stated is 93.4 kPa
 
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Ribz said:

Homework Statement



An amount of steam undergoes a constant volume process from an initial state for which the pressure and temperature are 0.1MPa and 350°C respectively. The final temperature is 300°C. Using linear interpolation estimate the final pressure.

Homework Equations



Use Thermodynamics and Transport Properties of Fluids

The Attempt at a Solution



I used linear interpolation for the pressure at 100°C, which was 1.01325 bar. Got my answer which was 28.3 kPa. The answer stated is 93.4 kPa
Hi Ribz. Welcome to Physics Forums!

Let me guess. You are supposed to be using steam tables to solve this, correct?

What is being held constant in this system:
(a) specific enthalpy?
(b) specific volume?
(c) specific internal energy?
(d) specific entropy?

Chet
 
Specific volume is constant
 
Ribz said:
Specific volume is constant
Good. So, from your steam tables, what is the specific volume of the steam initially? Now look in your steam tables for 300C, and find a condition as close as you can get to this specific volume. What is the specific volume at that point, and at the two adjacent pressures in the table? What are the pressures and volumes that go with the three points in your table?

Chet
 

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