02-01-2007 19:16

Stuart

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

so whats the risk of fire/explosion if one of the hydrogen tanks gets damaged

02-01-2007 19:33

lukevanoort

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

I imagine if a leak was formed it would be very, very high. Hydrogen burns very easily and with a very faint flame. Hopefully the tank is durable enough that a puncture is unlikely.

02-01-2007 19:37

Conor Ryan

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

I was waiting for someone to ask that question, it's no joke, hydrogen is best described as a Invisible Explosive. When we recieved out kit for the project at school, we weren't there to sign it, so when they saw this:
They freaked out.

We take every precaution neccessary (actually it's a rule of the game I think) when assembling the fuel cell (such as working on it in a lab environment). Right now, hydrogen isn't even allowed into venues of the competition (see original email blast). Phase 3 of the Green Machine Competition (released yesterday) is titled, "Design a Fuel Cell "Green Machine" Game and Hydrogen Safe Game Floor. They elaborate on it with one of the design parameters being, There is no such thing as a completely safe game, even games like Tag, have people that get hurt, so it's a touchy subject. I'd imagine an almost battle bots like venue with walls and everything.

02-01-2007 19:49

Arkorobotics

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Looks awesome! It would be nice if fuel cells were allowed in FIRST.

How much did that cost?

02-01-2007 20:02

MikeDubreuil

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

If you'd like you can buy a kit.

02-01-2007 21:24

ThomasP

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Buying a kit isn't nearly as fun as building one with stuff around a chemistry lab. We had a group project in AP Chemistry my senior year where we had to build something that produced electrical energy out of stuff we could find in the lab. My friend and I built a hydrogen fuel cell, it actually worked decent... after the first time we ran it we considered setting it up again to run something but never got the time to :-/.

02-01-2007 21:57

Stuart

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

ok my next question is how much current can you suck out of one of those things?

and what happens if you suck too much?

03-01-2007 08:10

Peter Matteson

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Keeping a hydrogen leak from causing a fire is actually fairly simple, use proper ventilation to keep the maximum credible leak below the lower flamability limit of hydrogen. The basic way to figure this out should be clearly described in ANSI FC1 (Formerly ANSI Z21.83).
Pete

03-01-2007 08:30

chris31

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Im seeing them for $140. That seems low, am I missing something?

03-01-2007 08:35

Chuck Glick

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

What your seeing is for the 1 cell kit, the 10 cell they have retails at $399.99.

03-01-2007 09:10

ngreen

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Cool.

I think $140 sounds reasonable. I am on the Chemical Engineering Car team and the fuel cell car kits were prevalent at competition a couple of years ago. Since then they've made them illegal because they can be ran nearly unmodified, and make the competition unfair to those with completely team built cars. A few team still run fuel cell, but they manufacture them themselves (including the proton exchange membrane). The team that won nationals this year, Puerto Rico Mayaguez, built a fuel cell for their car.

To be dangerous, the hydrogen would need to be at proper concentration between the LFL and UFL, and require an ignition source. With proper precautions this shouldn't be a problem. I haven't seen problems with hydrogen at our competition, however, the green machine competition uses larger tanks and more hydrogen than the chemEcar.

On another safety note: Last year at nationals a car exploded during its run. It was using a chemical reaction to generate pressure and using PVC as a pressure containing device. Bad idea. Luckily, this year major rule changes required proper pressure containing devices, gauges, check valves, and proof your car won't blow up when you put it on the line.

edit: $140 is reasonable, albeit high, for the car type kits (experiment kits). For the fuel cells they are using it would be higher.

03-01-2007 09:24

Conor Ryan

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Well the amount of current you get, is very much dependant on the flow of the fuel (hydrogen) through the unit. We have the capability in the kit to have a forced hydrogen flow, or more of an ambient flow. So there is no definitive answer I can get you right now, but once we run a test I'll post the results from the multimeter. In the mean time, you can look at some of the information on the TekStak page, they say 1.5amps, but we'll be testing a system 4 times the size they talk about, as well as a hybrid battery/fuel cell system.

How big is that stack? In the kit we recieved 2 10-Cell TekStak kits, they are $399 retail each.

03-01-2007 17:36

John Gutmann

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

I am a little confused, I don't see a PEM in the stack, and from looking at the picture of the plates, I don't see how the gasses flow through.

*I am new to fuel cells...I am only used to seeing PEM fuel cells

-john

03-01-2007 18:19

chris31

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Oh. OK. I didnt think just one would be enough to power much.

03-01-2007 18:29

Fuzzy

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

The MEA (the proton exchange membranes) are very thin, and there's one (and two surrounding PTFE gaskets) between each bipolar plate. The reason you can't see them in this picture is simply because of the angle at which it was taken at.

This fuel cell system is "open breathing," as the oxygen just enters from the outside into the spaces inbetween the plates. We got computer fans to increase air flow to the cell.

The hydrogen enters through the tube seen in the picture.

Nice close-ups by the way

03-01-2007 18:36

Conor Ryan

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Yeah it's a pretty lose fitting system, and not the most efficiently way you would think but it's cost effective and produces a good bit of electricity. Fans included in the kit not only make it more efficiently by cooling it, help it produce more electricity. Because of the design, the first time you run it your supposed to run it essentially on no load to help it flow better.

With a 1 cell stack, it would be pretty hard to get 1 volt, let alone 1 amp out of it, unless it was really big.

03-01-2007 18:46

John Gutmann

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Well i know it enters through the tube, but what I meant is how does it flow from plate to plate?

Connor can you get a picture up of the PEM? Do you know what brand PEM they use? I know Nafion is basically the best out there right now.

04-01-2007 08:09

Peter Matteson

Re: pic: Green Machine Competition - 10 Cell Fuel Cell Stack

Sorry for the repeat.