Thursday, February 7, 2008

Overnight Misting Results

The night before last we tried an experiment to see what results we'd get from setting the mister on top of the car overnight. We were thinking the ice would travel down the sides and fill out the tank after a few nights but we are now debating the aesthetics.

Since the car is primer black and steel, heat conducts itself differently by day and night.

9 comments:

Anonymous said...

You are doing it all wrong, if you had a tech student helping you it would be frozen by now...

The Frozen Car Project said...

We are happy to have help & would love to hear your suggestions. We are working with a tremendous volume of water. Too much water at one time will never freeze completely with the current temperatures. Working in accordance with nature we are subject to fluctuating temperatures. Based on that information, what would you recommend?

Anonymous said...

You got a bit of a late start, tech students had begun construction starting on the 14th of January. Also, misting on top of the car may build up too much ice on the car and not let much of it fill the empty space of the tank. With the car being on a slant it is freezing unevenly. I would try getting a few inches of water on top of what you have frozen over your base and freeze in layers that way. I think that is the only way to do it. Running water over it continuously is not the way to do it.

I love the idea (and the car) and really would like it to succeed.

The Frozen Car Project said...

We now realize the implications of letting the hose run over the car. But from the experiment we found that using this method during the night cools the water significantly (water from spigot hits frigid steel) before it falls into the tank & when it lands on the ice it freezes more quickly. That allows us to build ice faster, instead of flooding the tank with water. (Two inches of standing water takes 2-5 days to freeze at sub zero degrees...the water coming out of the hose is appx. 36 degrees... cooling it off at night allows it to freeze faster.)It does sound like it would work-just adding a few inches at a time-that was our initial plan actually, but we have faced the fact that we most keep the water moving, mist spraying it over time, much like one would construct an ice hockey rink. We were in contact with Scott McGinness, the city manager today. He was able to bring us some harvested ice that wasn't used in a project at the carnival. We also got a frontloader of snow and packed it underneath the car to form a "core." We have soaked it and are waiting for this underbelly to freeze. Tomorrow some help will come to lift the harvested ice into the tank. We will then proceed with misting the chunks of ice until they fuse together. Again, a tremendous amount of work, but we hope to gain a great deal of depth, along with cooling the water when it hits the frozen ice chunks. Can you think of/ foresee anything we should be aware of before we proceed? Wanna come help us? :)

phil said...

Mary this is your brother in law phil. My brothers would like to know what is in the water up there.
We all just assumed it was a car that was frozen--did not realize the story behind it. I think you guys could sell ice water to an eskimo. In any event looks exciting and good luck. Make you save some ice and when you come through Virginia we can make a batch of Margarita's

JWilly said...

I assume the aesthetic effect you're after is a big clear ice cube. That amounts to what the ice plant people call "carving block". What you're doing is developing a casting process for carving block...which of course already is well-settled technology.

To make carving block, you need de-gassed water, frozen from liquid, with minimized exposure to the air during which air gases could re-dissolve into the liquid. It helps to have the water supercooled a degree or two, and hold the mold below freezing. The water has to flow smoothly onto the freezing surface. No spraying, no splashing, no streams through the air.

You can partly de-gas water by getting it near freezing while exposing it to the air and vibrating it to knock bubbles free from boundary surfaces as they form. Gas solubility decreases as temperature decreases.

Or, you can thoroughly de-gas water using vacuum exposure plus vribration, just as you might de-gas any other low-viscosity dense liquid that contained dissolved or mechanically entrained gases.

Misting, non-degassed-water ice chips and snow all will bring entrained or absorbed air to your ice cube. Air-water mix leads to macrostructure and opacity. It also leads to weak ice, if that's relevant.

You might be able to supercool your fill water by flowing it slowly through a boiled-out car radiator, via some jury-rigged plumbing into and out of the cooling-system ports. The goal of the boiling-out would be to avoid trace contamination dissolving into your water stream, both because it would interfere with clarity and colorlessness, and because it might lower the freezing point.

In such a supercooling kludge, the radiator coils would be cooled by bathing them in a water-ice-salt bath (cheap and effective, but takes a lot of maintenance), or a circulating bath of ethylene glycol/water mix or cheap vodka that's pumped out of, and back to, a reservoir in an old chest freezer. Slightly supercooled degassed water is an excellent way to cast carving block.

The evaporative cooling you're getting from the misting process, unfortunately, is very counterproductive in regard to your need for degassed water and no entrained air.

I got my BSME from Tech a few decades ago. Hope you're having fun. Don't forget to study.

The Frozen Car Project said...

Hi jwilly:

The process you are describing would be the ideal method! We appreciate your insight & expertise ... we'd love to try this but have a few factors that constrain us. We worked with students at UMich's ME Department a year ago & they provided us a design document which called for some of these procedures. We were concerned with the toxicity of glycol and also did not have the means to build a $36,000 cooling system. We did carefully consider these methods but given the above we decided to work with nature without intervention. Although now that we have trucks delivering snow & ice, we are seeing that it is almost impossible to work without the "system." It is also difficult to critique a system when one depends on it. This is part of the dilemma with the project and also a talking point with the public. The ideas you have, however, seem to work in tandem with the project, especially the use of a car radiator. Excellent & we appreciate your comments. At this point we haven't gone over the wheels of the car ... Come on down with that radiator & cheap vodka- !

JWilly said...

"...$36,000 cooling system..."

Heh. Must have been a suggestion from someone that's planning to get hired by a big rich outfit.

You can find cheap radiators in auto junkyards everywhere. Practical hose fitting adapters into and out of the radiator could be done with $10 worth of fittings and silicone caulk. Borrow a mortar mixing tub somewhere, requisition some rock salt, immerse your plumbed radiator in the tub, submerge it in a regularly changed salt/ice bath, and hook up your trickle-fill hose (no spray!) to run through your $50 supercooling heat exchanger. Of course, that $50 doesn't get you degassing, but an ordinary tap water ice cube grade of Chevy-Nova visibility might be good enough art. Of course, you have the added human cost of periodically visiting the site to replace the ice/salt bath.

Or, in a part of the world where well-used but still running appliances are available, get a chest freezer for ~ $40, pick up a couple of cheap centrifugal sump pumps, do a little more garden hose plumbing with fittings/sealant/clamps, and you've got active-refrigeration supercooling of your trickle fill within a budget of ~ $250.

Or $36,000 the really fancy way, which I suppose might include vacuum ultrasonic degassing, imported water from the Himalayas or somesuch.

If you wanted to use the active-refrigeration approach but were put off by ethylene glycol as the circulating refrigerant, and had other uses for cheap vodka, you could use propylene glycol antifreeze, or isopropyl alcohol, or water with salt in it. Practically every engineering student at Tech, even the ones who suggest $36,000 approaches to art projects, should know enough chemistry to be able to come up with a way to lower the freezing point of water by a few degrees.

The Frozen Car Project said...

Hi jwilly-

We are very intrigued by your solution ... Today we are going to see if it will be possible to work this way.

Do you think it's possible using this method to freeze an area that is 4' high x 9' wide x 19' long?
We have only a few weeks left to work, and if this solution would fly we are willing to try it.

If it's easier to email is we're at frozencar@gmail.com ...

Thank you!