OT: Water Pipe Insulation

You guys are not on the same train. Carefully worded statements of different effects create useless arguments. And it's turning nasty.

I'd agree that water at 35F won't freeze. And that blowing 35 degree air on a pipe won't make it freeze. But there's evidence that you can start with water at 35F and an ambient air temperature above freezing... insulate the water from the air and enhance radiation into clear night sky and make it freeze. You don't want wind. It's a solar funnel cooker run backwards into clear night sky.

So you can continue the gunfight between a bunch of blind men shooting in different directions... Or pick something common to discuss.

I wanted to experiment with the solar cooker idea, but it's often so cloudy here that it wouldn't be much use. Anybody made one work?

PV=nRT

Phase diagrams:

...Jim Thompson

Evaporative cooling. Remember I said, in a previous post "pipe/vessel" versus "free standing water".

(I have studied (and experimented) extensively with evaporative coolers preceding the condenser of air-conditioning systems. If you have the space to set it up, evaporative cooling can do marvelous things.) ...Jim Thompson

Wind chill does not work if there is no evaporation. Blowing 5 mph air at 35F across a steel or plastic pipe, is not going to create any cooling below 35F. In order to produce wind chill, the pipe has to be wet, where the surface water evaporates and therefore becomes cooler. Last time I checked, steel and plastic do not evaporate. Even 100 mph air at 35F across a steel or plastic pipe will produce nothing lower than a 35F pipe temperature. As long as there's no evaporation, the temperature will go no lower than 35F, and wind chill has no effect.

If the humidity is high enough, and the temperature drops below the dew point, there will be condensation on steel pipes. That will produce some wind chill cooling, but I don't think enough to freeze the water in the pipe.

If there was such a thing as wind chill cooling without evaporation, I could cool a dry heat sink with a fan, and end up with a heat sink temperature that's lower than the intake air temperature. Too bad that doesn't work, or I could make millions on the idea.

The reason that you (not your pipes) feel colder when the wind is blowing is the heat loss from the evaporation of sweat from the skin.

PVC pipe and Copper pipe, which one is more vulnerable to freezing weather? My house is all copper pipe on the water supply line, which survives freezing temperatures better than PVC pipe.

Newsgroups are so damn frustrating... don't bother to read/snip/swing/miss/head off in another direction... Another shot into nowhere. If you want to discuss evaporative cooling, we could do that. But that's not what I suggested. The funnel cooker fridge has zero to do with evaporation. It's all about radiation...like it says in the paragraph I wrote above. Newsgroups are so damn frustrating...

There are several forms of ice which are solid at room temperature. They require *very* high pressures by our standards. Based on the phase diagram at Wikipedia, water at room temperature won't solidify until you reach about 10 kilobars (10,000 atmospheres, 300,000 PSI) of pressure - at that point the water will solidify into ice VI. At higher pressures it will phase-change into ice VII (21 kbar), ice XI (620 kbar), and finally ice XI (around 4 Mbar).

At 3000 psi (100 bar) it looks as if the freezing/melting temperature is only a degree or two below 0C.

An array of black PVC (further painted matte black) in a glass covered 'hot box' following the sun, piped into the line feeding your hot water tank saves a lot as well. You can also use such an array to heat your pool water, in climes and at times where that is desired.

for heat loss from pipes,

nding air is not significant.

Well, duh, note that "trace heating," which is the industrial term for heat tapes and cables, are rated in Watts (per unit length) and, last time I ch ecked, Watts is a measure of heat energy *rate*. This is why all the engine ering calculators for systematically sizing the trace heaters take wind exp osure into account, and this is wind exposure of insulated and uninsulated pipes and tanks. Seems like you're the main "stump" around here.

or heat loss from pipes,

ding air is not significant.

The walk-in uses convection for cooling, the fan is there to circulate the air drawn through the evaporator and blow it throughout the volume. Is your fan in front of or in back of the evaporator?

heat tapes and cables, are rated in Watts (per unit length) and,

last time I checked, Watts is a measure of heat energy *rate*.

This is why all the engineering calculators for systematically

sizing the trace heaters take wind exposure into account,

and this is wind exposure of insulated and uninsulated pipes

and tanks. Seems like you're the main "stump" around here.

Apples Oranges. The thread started to address phase change...freezing...or prevention thereof. Energy input equals energy output. If that equilibrium happens at a temperature prior to the phase change temperature, you don't get no phase change...no matter how loud you yell at it...or how hard you blow.

ts for heat loss from pipes,

rounding air is not significant.

Seems that topic and the other thread about the mentally insane walking the streets strike a chord with you... wonder why.

ts for heat loss from pipes,

rounding air is not significant.

Are we still talking about pipe freeze? Because wind speed accelerates the cooling. We're still talking about a steady state equilibrium of ambient te mperature of the air, which is to be avoided to prevent freezing. Phase cha nge is not a consideration here. In this case rate of energy input maintain s a delta-T somewhat above 32oF for worst case ambient and wind .

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There's only 9 oz water in his exposed pipe, the coldest is at midpoint, an d he only has 1.5 ft to what are in effect infinite heat sources of well ab ove freezing water on the house and underground side. You figure it out.

In the case of a pipe, heat is flowing out of the building and out of the ground. It's not like a vehicle sitting on rubber tires in the wind.

Best regards, Spehro Pefhany

Bye Jack

Capt. Kirk responds... "These are not the tomes you are looking for..."