When Does Water Completely Vaporize in a Constant Volume Process?

In summary, the conversation discusses finding the temperature at which 5 kg of saturated liquid-vapor water in a fixed volume container is completely vaporized. The solution for a) can be found using tables and the temperature is determined to be 140.7 ºC. For b), the speaker initially struggles to understand the process, but eventually realizes that the specific volume is constant and the temperature changes due to the pressure not being constant. The resulting temperature-specific volume diagram should be a straight line from the starting red dot to the final blue dot.
  • #1
Cozy_Powell
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0

Homework Statement


5 kg of a mixture of saturated liquid-vapor water is in a container of fixed volume 2,5 m3. Initially the temperature is 75 ºC and then the water is heated.
a) Find the temperature at which the water is completely vaporized.
b) Draw the temperature-specific volume diagram.

The Attempt at a Solution


a) Is easily solved from the tables and I've found a temperature of 140,7 ºC.

b) Here I am completely at a loss... From what I can understand from the problem, initially the process begins somewhere inside the "dome shaped" region.
The specific volume is constant and equals 0,5 m3/kg, which lies between Vf and Vg for 75ºC. I put a red dot where I think the process begins... is it right?
But now... how can we get to the final state? I think the final state is a saturated vapor state... is it right?
Because specific volume is constant, I put a blue dot where I think the final state is... but how can the temperature change inside the dome shaped region??

Many thanks!
 

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  • #2
oh... I think I got it! Temperature changes because pressure is not constant... So the diagram should be a straight line from red to blue dot. Is this okay?
 

FAQ: When Does Water Completely Vaporize in a Constant Volume Process?

1. What is a T-v diagram at constant volume?

A T-v diagram at constant volume is a graph that represents the relationship between temperature and specific volume of a substance at a constant volume. This means that the volume of the substance remains constant while the temperature changes.

2. How is a T-v diagram at constant volume different from other thermodynamic diagrams?

A T-v diagram at constant volume is different from other thermodynamic diagrams, such as P-v and H-s diagrams, because it only shows the relationship between temperature and specific volume at a constant volume, while other diagrams show the relationship between different thermodynamic properties at varying conditions.

3. What is the significance of a T-v diagram at constant volume in thermodynamics?

A T-v diagram at constant volume is significant in thermodynamics because it helps in visualizing and understanding the behavior of a substance at a constant volume. It also allows for the calculation of important thermodynamic properties, such as specific heat and internal energy.

4. How is a T-v diagram at constant volume used in practical applications?

A T-v diagram at constant volume is commonly used in the design and analysis of heat engines, refrigeration systems, and other thermodynamic processes. It helps in determining the efficiency of these systems and in making design decisions based on the behavior of the substance at a constant volume.

5. What factors can affect the shape of a T-v diagram at constant volume?

The shape of a T-v diagram at constant volume can be affected by factors such as the type of substance, its phase (solid, liquid, or gas), and the temperature range being considered. Other factors, such as pressure and composition, may also influence the shape of the diagram for certain substances.

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