 Poster: A snowHead
|
|
stoatsbrother, there was a woman on North West tonight who had one as part of her massive Christmas display, she'd imported it.
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
There's an incredible amount of bad science being spoken here 
So to debunk a few of the comments made
1. Water is incompressible, you can only pressurise it, its volume doesn't get smaller.
2. The energy need to pressurise water is because of no.1 very low so by de-pressurising there is bug**r all coolong effect.
3. The cooling effect from compressed comes about because in compressing it in the first place it got hot, that heat of compression was removed by the compressors charge cooler of the compressor. When you release the pressure the temperature drops by the amount it rose in the first place (you get the energy you pumped in the first place). OK this is very simplified I know and ignores efficiencies and a lot of other stuff.
4. Spraying water only into the air, the water cools itself by evaporation, anything you can do to increase the evaporation rate increases the amount of cooling
You can increase the cooling effect by :
i) reducing the water droplet size which gives more surface for evaporation,
ii) increase the droplet speed, in reality there will practical limitations of air drag
iii) reduce atmospheric humidity, unfortunately pretty much out of your control
iv) add a fan which will produce turbulent fast moving air.
|
|
|
|
|
|
Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
|
rich, Have you actually read this thread before telling us off?
Apart from the helpful link Phil Jordan posted, which explains everything very clearly, others have already emphasised that it is air compression which is more important in conventional air-water guns, and yes - it does play a part in cooling the water as the air expands. See Richmonds post above, and Phil Jordans link etc etc. Haven't you ever made CO2 snow?
However the water pressure is also important, but as far as I can tell, mainly for ensuring sufficient flow per minute through the small nozzles, and - I suspect in water-only guns - to propel the atomised water a sufficient distance. Incidentally it seems that fan-gun makers go to some effort to ensure air flow is not overly turbulent.
I don't pretend to be an expert in anything but I think your rant was unjustified.
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
There was a videoclip on BBC News 24 earlier today (Sat), which showed some dude, apparently in the Arctic Circle, throwing a tankard full of bogstandard drinking water up into the air from ground level.
The water almost instantly 'vaporized' into snow-, hail- or ice-crystals, or however they might be defined. There was a 'cloud' of 'snow' long before the mixture had reached the ground.
So, the conclusion is that, yes, it is seemingly possible to make snow by spraying untreated water into the air.
However, it looks to me like the temp would need to be somewhere in the region of -20c to -60c.
There was no clarification of the air temp during the BBC report, but the bloke throwing water up in the air was part of a husky-sled race that had been canceled due to excessively cold temps. It would surely have to be extremely cold to postpone an Arctic dogsled competition.
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
| Whitegold wrote: |
The water almost instantly 'vaporized' into snow-, hail- or ice-crystals, or however they might be defined. |
Kind of worrying if you were to get caught short in those conditions isn't it? 
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
stoatsbrother, reread what I posted ande agree it was a bit over the top, my apologies to all concerned. Must have got up on the wrong side of the bed 
|
|
|
|
|
|
|
|
rich, No worries - Happy Christmas and may it snow where ever you want it to... 
|
|
|
|
|
|
|
|
|
|
|
You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
|
Phil Jordan, it would create interesting yellow snow 
|
|
|
|
|
|
|
|
|
Yellow snow would have a lower freezing point so be harder to make from scratch.
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
It's always going to be hard to produce artificial snow outside in the UK due to our relativly high humidity compared to the air over the alps.
However if you are going to stand any chance the best method will be to get the mist of water as fine as possible and as high into the air as possible to give the droplets as long as possible to cool, you could also try feeding the water through a long hose laid outside before spraying to reduce its starting temperature as much as possible
|
|
|
|
|
|
And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
|
|
However don't let it freeze in the pipe!!
|
|
|
|
|
|
|
|
|
|
|
You know it makes sense.
|
Well folks,
So far it ain't been cold enough for this to work despite a week of high pressure.
Good to see enthusiasm though
|
|
|
|
|
|
|
|
FAQ
