How much heat is needed to evaporate water at 2 bar?

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SUMMARY

The discussion focuses on calculating the heat required to completely evaporate water in a vessel at 2 bar pressure. The key parameters include the final enthalpy, h(g), at 2 bar, and the initial enthalpy, which is contingent on the temperature of the water. The enthalpy values of water at 100°C, saturated steam, and the enthalpy of vaporization are critical for this calculation. The pressure dynamics within the vessel, particularly whether a pressure relief valve is present, also influence the calculations.

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Homework Statement



A vessel of 1m^3 volume is half filled with water. The pressure inside the vessel is 2bar.
Steam tables are given

Homework Equations



How much heat is needed to completely evaporate the water?


The Attempt at a Solution



I can find the final enthalpy by finding h(g) at 2 bar. But how do you find the initial enthalpy?
 
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Does the vessel have a pressure relief valeve that maintains the pressure at 2 bar? If not, the pressure is going to increase linearly with the volume of water boiled off. This part is easy to calculate. As for your steam tables, I'm not sure exactly what you are looking at (different steam tables have different sets of data and use different forms of presentation). There are 3 relevant enthalpies: the enthalpy of water at 100C, the enthalpy of saturated steam, and the enthalpy of vaporization (the difference between the previous 2 numbers).

Have you written down the question completely, and exactly as it was given to you? If not, please post the question EXACTLY as it was given to you. What is the temperature of the water in the vessel?
 
Last edited:
I quoted this question from a thermodynamics past paper. This is all that is given.
It is a short answer question ie. given only couple of lines to answer.
 

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