Shiny Doom Forum

Trool · Good Karma Joined: 12 Sep 2003 Posts: 1486

This is just kinda creepy....

http://www.nytimes.com/2004/11/11/technology/circuits/11hugs.html?ex=1100754000&en=95f5402149274588&ei=5040"ner=MOREOVER
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rklee · Posted: Fri Nov 12, 2004 3:43 pm Post subject:

.... it gets worse... we have an engineering design project... I'm finishing up my product design for a solar and brake heat regeneration powered refrigeration unit for trailers (they use a ton of fuel a year on diesel generators for this purpose).
Here are some of the other ideas:
Air pressure -> electricity portable generators... because they claim in construction sites, it's easier to transport compressed air than it is to transport electrical or chemical energy.... yea... that makes so much sense. Stray bar falls and punctures hose or tank... and kablooy. not to mention inefficiencies.
Aluminum automatic plant watering pot. you stick your pot into this pot that has a pump and a huge water reservoir that pumps water into your plant on a customized schedule (with nice LCD screen!!!).
Roomba type mopping system. (carries water with it...)
These were just some of the better (sarcastic) ideas senior mech e's came up with.....
BTW we're sponsored by ALCOA that's why all our designs are (or are supposed to) make use of aluminum in a good way.... pretty much none of the 3 mentioned above does anything good with aluminum... the air pressure to electricity one is just stupid, the plant waterer could be plastic and the roomba mopper... well that's just stupid too and uses no aluminum.
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Mogri · Posted: Sat Nov 13, 2004 1:57 pm Post subject:

Well, huge I-beam falling on anything* will make a big mess; and unless it's a combustable gas, I'd think there would be less chance of combustable explosions, less permits, less inspections than any other chemical-based source. Granted I doubt that makes up for the loss of efficiency, but the safety is probably a selling point, although a small one.

(* with some exceptions)
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rklee · Posted: Sat Nov 13, 2004 4:27 pm Post subject:

A shovel, small rock, welding spark, falling bolt,... etc can cause a compressed air tank to explode possibly shooting pieces of metal at people. Or could puncture an airhose causing it to fly around like crazy.
A electrical cord plugged into an outlet... sure... a sharp shovel could cut it and cause a quick spark but that won't cause any damage... there are circuit breakers... and electricity would most likely NOT flow through people... or equipment.
An electrical generator is also not easy to damage.

Let me do a quick 20 min analysis
Lets see... a small suitcase sized electrical generator can do about 20 kW on one gallon of fuel per hour (continuous) Assuming approximately 40% efficiency of diesel -> electricity. For one day's work (10 hrs) that's about 200 kW of power and 10 gallons of fuel. Space usage approx 15 gallons.
"KBB constructed the world's first CAES salt dome storage cavern project at Huntorf, Germany, where two 10-million cubic foot caverns support a 2-hour, 290 MW power plant."
290 MW for 2 hrs... that's about 580MW power. So about 2900X our suitcased electrical generator.
20 million cubit foot / 2900= 6896cubic feet (assuming power proportional to volume)
This is not including the generator.... (which would be far less efficient than the big air compressor power plants shown above which is about 20%... small generator probably can't get over 10%).
6896cubic feet = 51593gallons

So for a day's work you need 15 gallons versus 51,593 gallons...
Lets see how much the a large dumptruck can hold...
Quick search shows max a truck holds is 1,800 gallons (of water... I don't think they make air tanks that big.... too dangerous)
so we need about 29large dump trucks worth of compressed air per each 10 hr day of work.
29 dump drunks versus something that can be carried by one or two men.

Completely absurd... if they even spent 20 min to look at this... they'd figure out that it's not a good idea unless they can come up with another reason why air is better....
Oh yea... this does not take into account that the compressed air needs to come from somewhere eh?? well generally that comes from a huge air compressor sitting somewhere... Electric and diesel air compressors run probably around the 30% range in efficiency also. And airtanks of that size... well that's insanely expensive. Also airhoses are more expensive than electrical wireing.
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"My Heart Is In the Work" - Andrew Carnegie