Strange Question

lsayre wrote:In order to extract latent heat the water must be heated to above 212 degrees. The OP is asking how to turn 180 degree water into 212+ degree water.

I think what he is trying to do is boil sap by using hot water or steam rather than an open flame. Im don't know the # but water will get to somewhere north of 220 deg f at 30 psi before it boils. Im not sure the temp you could achieve with steam .... I believe he is thinkng of a way to eliminate scorching the syrup that happens with a open flame. maybe

That's what's neat about steam. It takes only 162 BTU's to raise one pound of well water (50 degrees) to boiling point (at normal atmospheric pressure). Then another 970 BTUs to vaporize that pound of water to steam. When that pound of steam condenses back to water, it gives up that 970 BTUs. As compared to a normal water differential of a boiler, that one pound of water only gives up 20 BTUs.

Its "cool" how that works in reverse too. As Mac was saying, compressing Freon into a liquid requires it to give up heat, which is why the coils on a fridge are hot. Then, it's allowed to return to a gas by lowering its pressure which requires it to absorb heat, making the fridge cold.

As for compressibility of water? One of the "rules" for matter in a liquid state is that it has a definite volume. You guys goin all physics on me lol.. I'm rambling again haha..

I didn't realize this effect was the result of phase changes....makes sense...I like the idea of a stoker under an evaporator....a flame shield was sued it would scorch too much. sounds like I would need to increase the pressure of the water too much to in order transfer enough heat (i.e. increasing the boiling point by increasing the water pressure. I don;t want to do anything too dangerous either!

lsayre wrote:Water is hardly compressible. At ~2.5 miles down (4,000 meters) the density of ocean water (its measure of weight per unit of volume) is merely a scant 1.8% higher than it is at the surface. It is generally classified as incompressible.

I got into a debate with an engineer once on that subject. We ended up calling it a draw because he didn't like my way of looking at it.

He said water cannot be compressed, I said water can be compressed significantly just not in its liquid form, that is water vapor can be compressed into liquid water.

Sure I agree with you. Just like propane. It exists as a gas at normal atmospheric pressure. Then it can be pumped into a bottle and once the pressure reaches a point where it boils at that temperature, it will begin to condense into a liquid.

Water boils at 98 degrees at 63000 feet. It's the Armstrong altitude. Boiling point and condensation points are all relative to pressure.

I believe the OP was asking if 180 degree liquid water at outside conditions generally indicative of sea level type atmospheric pressures could be compressed to thereby (and not by any other means) achieve 212 plus degrees. I've merely been trying hard to stay on topic.