new to rf - need help!

[Matt_barnett]

Hey there

I'm a final year Industrial Design student studying at Brunel University London. Part of my course involves carrying out a major design project, researching, designing and creating prototypes of a product of our choice.

I'm looking into creating large amounts of 'frost' to be used in conjunction with my project.

My initial plan, is to spray a fine mist of water onto a large plate attached to a cooling unit (at around -10³C), so that this mist is converted into ice, and can then be removed as a fine 'ice dust' or frost.

I want this to be quite a compact unit, with a plate (and therefore cooling unit) no larger than 0.4m³.

If this makes sense, I need to convert roughly 0.06kg's of water to ice per cycle, which should take around 18Kj of energy (and I want to do this quickly, at least once every 10seconds, hence I'm using a very fine mist of water).

Can you suggest any of your equipment I could use in order to do this (in an insulated chamber obviously), or what type of equipment I need to be looking at?

Thanks for any help you can impart.

Yours sincerely Matthew Barnett

[Peter_1]

Welcome.
Nice project.
If I should live closer to you, I could help you, making a cold plate. I think you will have to evaporate much lower then -10°C, propably -20°C or even lower.
We have a lot of experience with the construction of these cold plates.

[Matt_barnett]

HI Peter
You suggest cold plates, is this anything to do with heat exchange plates?
Can you suggest somewhere I could find more information on cold plates and how to make them?

Thanks for the help

Welcome.
Nice project.
If I should live closer to you, I could help you, making a cold plate. I think you will have to evaporate much lower then -10°C, propably -20°C or even lower.
We have a lot of experience with the construction of these cold plates.

[Josip]

Hi, Matt_barnett

HI Peter
You suggest cold plates, is this anything to do with heat exchange plates?
Can you suggest somewhere I could find more information on cold plates and how to make them?

Thanks for the help

Yes, they are heat exchange plates, similar to that one in the fridge

Please check this:

http://www.jackstonefroster.com/contact.html
http://www.dsi-as.com/default.aspx?m=2&i=81
http://www.vilter.net/menu.html

Best regards, Josip

[US Iceman]

Hi Matt,

Perhaps you can use a snow generation device with compressed air and water?

Try this for a quick review of possibilities...
http://science.howstuffworks.com/snow-maker3.htm

[Peter_1]

This gives you already an idea

http://www.refrigeration-engineer.co...ght=cold+plate

I posted already many other pictures. You need +/- 250/300 W/m² (850 BTU/h/10.7 ft²) (evaporating at -10 °C/14°F)

[Matt_barnett]

HI iceman

Already looked into snow generation, visited acer snowmec, the people who invented indoor snowmaking, and making snow in a confined space is a no go, hence i'm trying to find a way around this problem!
Thanks anyways, any other ideas would be great!
[quote=US Iceman;51721]Hi Matt,

Perhaps you can use a snow generation device with compressed air and water?

[Tycho]

To form "frost" or snow like crystals on a plate, you need a room with high air humidity and lots and lots and lots and lots of time.

if you spray water onto a plate, it will just freeze to the plate and not form crystals.

if you leave the plate froozen in a room/container with high humidity for some hours, it will form a thick layer of snow crystals.

When we test plate freezers during commisioning of a plant, we sometimes leave them on for maybe 6-7 hours at -35-40 C and they always form a 5-10 cm layer of "snow dust"

if you spray a mist on them, it will freeze solid.
-------------------------

if you watch this video http://www.youtube.com/watch?v=nnW4sTpjVKQ

Not very good quality, but you get the gist of it.

Make a chamber you can keep at as low temperature as possible and blow steam through that chamber and you have instant snow.

My take on it would be tubes bent into a circle, like this
"0" at the bottom of the 0 you place an evaporator and a fan circulating the air, at the top, you split the 0 and blow steam or very fine hot water particles through the cold air and then onto a frozen plate.

that way the frozen water particles would stick to the cold plate.

to remove the "ice dust" shut off the steam / hot water mist and hotgas defrost the plate to make it let go, But this would most likely produce a ice slush falling to the ground.

if you want "snow" shut off the steam / hot water and them use a fan to blow the ice crystalls off the plate.


Roughly like this:

[Peter_1]

http://www.snowathome.com/internal_mix_page2.htm

[Gozzy]

Vortex tube with a high pressure nozel and a mist of water will atomize. Due to the expansion water it will vaporise. Almost like the dessert bag effect. you can also make a brine to allow the water to atomize at 10 degrees celcius.

[Matt_barnett]

Thanks for the help guys, really appriecate it!

Another avenue i'm looking down, is using conventional snow machines (indoor small compact ones) inside a refigerated housing, with a vortex inside to keep the snow particles spinning untill they become dense enough to fall out the bottom. The major problem with this would be keeping the cold air inside this contained housing. Any idea's how I could achieve this, or at least make it more economical?