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It seems, for example a volume of water is heated to boiling point, then part of the water is vaporized, while the remainder need much more heat to vapor, which means that part doesn't receive latent heat yet.

Is there any way to make the whole volume of water to receive latent heat before part of it is vaporized?

Adding pressure will rise boiling point, and it seems the problem still remains, as part of water will be vaporized while the other part has not received latent heat yet.

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  • $\begingroup$ what do you mean, "receive" latent heat ? latent heat is freed at vaporization. $\endgroup$ – Fabrice NEYRET Apr 7 '16 at 16:45
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I am not sure if I could understand your meaning. I think you ask about a situation that the water phase changes from liquid to the gas without passing across two phase region. If the pressure is greater than the critical pressure, then there is no distinct phase-change (boiling) process. You can see this as below figure from “THERMODYNAMICS An Engineering Approach, Fifth Edition, by YUNUS A. CENGEL and MICHAEL A. BOLES”.

enter image description here

But if you ask about a situation that whole of the liquid water change to the gas at a moment, I think it depends on our definition about time. If we define the time as a continuous quantity, then it is impossible that you can change some liquid water to the gas at a moment. But if we define the time as a discrete quantity (like quantum mechanics about energy), then maybe it is possible that you can change some liquid water to the gas at a moment by using of a very very high rate of heat energy.

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This can happen when water is heated under pressure. If the pressure is sufficient to keep the water liquid at a temperature well above its usual boiling point, and then the pressure is abruptly removed, the water will "flash" into steam all at once, causing what's known as a boiling liquid expanding vapor explosion.

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if the water is heated quickly enough, you can temporarily avoid the process by which boiling ordinarily gets started in a body of hot water and therefore superheat it. the superheat enthalpy then furnishes the heat of vaporization necessary to boil the water and the result is referred to as a superheat vapor explosion. it can be quite violent because in this case the vaporization rate is not set by the heat transfer rate from the heat source to the water; the superheated volume of water basically explodes into vapor all at once. This effect can easily occur at ambient pressure. In fact, superheat vapor explosions in water-based ink furnish the propulsive power which ejects droplets of ink from the nozzles of a thermal inkjet printhead.

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