Tea kettle question.

[Gawdzilla Sama]

The issue is the time I spend in the kitchen waiting for the kettle to whistle.

Less water, less wait.

That was the point of this thread, to get confirmation of that.

[JacksSmirkingRevenge]

The pressure is a important component. The amount of heat require to boil water under pressure is less than that when not under pressure. And the pressure will act on just one surface of the cylinder of water. So although volume is not relavant the shape of the kettle may be?

...Doesn't sound right, to me.
Water boils more readily at lower pressure, surely (tea isn't as nice at higher altitudes)? And water under pressure boils at higher temperature, doesn't it (pressure cookers)?
Also, I don't understand what you mean by pressure acting on only one surface.

[Gawdzilla Sama]

The pressure is a important component. The amount of heat require to boil water under pressure is less than that when not under pressure. And the pressure will act on just one surface of the cylinder of water. So although volume is not relavant the shape of the kettle may be?

...Doesn't sound right, to me.
Water boils more readily at lower pressure, surely (tea isn't as nice at higher altitudes)? And water under pressure boils at higher temperature, doesn't it (pressure cookers)?
Also, I don't understand what you mean by pressure acting on only one surface.

I worked with boilers that produced 750 psi steam at 900F. The water was under that pressure continuously throughout the pressure vessel. And it started off at atmospheric, steam was the only means of increasing the pressure.

[JacksSmirkingRevenge]

The pressure is a important component. The amount of heat require to boil water under pressure is less than that when not under pressure. And the pressure will act on just one surface of the cylinder of water. So although volume is not relavant the shape of the kettle may be?

...Doesn't sound right, to me.
Water boils more readily at lower pressure, surely (tea isn't as nice at higher altitudes)? And water under pressure boils at higher temperature, doesn't it (pressure cookers)?
Also, I don't understand what you mean by pressure acting on only one surface.

I worked with boilers that produced 750 psi steam at 900F. The water was under that pressure continuously throughout the pressure vessel. And it started off at atmospheric, steam was the only means of increasing the pressure.

Now, I bet that made a nice cup of tea.

[Gawdzilla Sama]

The pressure is a important component. The amount of heat require to boil water under pressure is less than that when not under pressure. And the pressure will act on just one surface of the cylinder of water. So although volume is not relavant the shape of the kettle may be?

...Doesn't sound right, to me.
Water boils more readily at lower pressure, surely (tea isn't as nice at higher altitudes)? And water under pressure boils at higher temperature, doesn't it (pressure cookers)?
Also, I don't understand what you mean by pressure acting on only one surface.

I worked with boilers that produced 750 psi steam at 900F. The water was under that pressure continuously throughout the pressure vessel. And it started off at atmospheric, steam was the only means of increasing the pressure.

Now, I bet that made a nice cup of tea.

It would set a teabag on fire. Literally. When we looked for leaks, we would wave a "corn broom" around the suspected area until it caught fire.

[JacksSmirkingRevenge]

Strange thought, isn't it ...water setting stuff alight? Even if it is at getting on for temperatures twice the flash point of paper.

[Gawdzilla Sama]

Strange thought, isn't it ...water setting stuff alight? Even if it is at getting on for temperatures twice the flash point of paper.

It was superheated steam at that point, not water. Basically a very hot gas. We used it to run 70,000 hp. turbines.

[Warren Dew]

To restate: Will 500 ml of hot water boil faster than 750 mi of hot water if all else is equal. If you add equal amounts of energy to both you get a higher total quantity of energy in the 750, yes?

You will get a lower specific energy - that is, a lower energy per ml of water.

[FBM]

The pressure is a important component. The amount of heat require to boil water under pressure is less than that when not under pressure. And the pressure will act on just one surface of the cylinder of water. So although volume is not relavant the shape of the kettle may be?

...Doesn't sound right, to me.
Water boils more readily at lower pressure, surely (tea isn't as nice at higher altitudes)? And water under pressure boils at higher temperature, doesn't it (pressure cookers)?
Also, I don't understand what you mean by pressure acting on only one surface.

Right. Lower pressure, lower boiling point. Water boils in a vacuum, even without heat applied.

[apophenia]

If you performed the experiment on the surface of the sun, both would reach boiling faster than you could measure. The devil is in the details.

[Hermit]

Speaking of detail, the sun is entirely gaseous. In terms of resting a kettle on, it has no surface to speak of.

[apophenia]

Speaking of detail, the sun is entirely gaseous. In terms of resting a kettle on, it has no surface to speak of.

Well if you want to be technical, nothing has a surface in the sense you speak of.

[Feck]

Yes of course it will .

[Svartalf]

Speaking of detail, the sun is entirely gaseous. In terms of resting a kettle on, it has no surface to speak of.

which doesn't matter, as the kettle would have vaporized into its component atoms long before approaching close to any arbitrarily designated "surface point"

[Gawdzilla Sama]

Define "surface".