I've seen a couple of videos so I don't recall which one mentioned it, but it sounded like Roadtrek plans to initially put this in the cabin under the rear sofa on at least one floorplan.
A side comment on this fuel cell. Looking at their info, they say under design operation the Imperium uses a little over .3lb/hr of LPG. Has anyone found out how much water and CO2 is generated? Is there enough to plumb in a seltzer dispenser at the sink?
It depends on what the fuel cell is doing. Just burning 0.3 pounds of propane, by my calculation, yields just under 1 cup of water. That seems to be a best case scenario, where all of the hydrogen atoms from the propane end up in water molecules. If the fuel cell is doing something else with some of that hydrogen so it doesn't all end up in water, then you'd get even less, but I don't know anything about the chemistry going on in a fuel cell so I couldn't say.
I've seen a couple of videos so I don't recall which one mentioned it, but it sounded like Roadtrek plans to initially put this in the cabin under the rear sofa on at least one floorplan.
Yes - see photo in post #17. In the video from first post the Hymer rep said the Watt fuel cell would first be offered in the E-Trek models.
This is definitely an interesting product and if fully integrated with batteries and solar as described in the first video this could certainly be a game changer. It appears to provide the same power as a good set of solar panels when the sun isn't shining.
If the fuel cell is doing something else with some of that hydrogen so it doesn't all end up in water, then you'd get even less, but I don't know anything about the chemistry going on in a fuel cell so I couldn't say.
Nope, propane is c3h8. Oxygen is o2. The only outputs are h2o and co2.
One molecule of propane + five molecules of oxygen give you c3h8o10, from which you can build four molecules of water and three molecules of co2. Nothing left over but energy.
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Nope, propane is c3h8. Oxygen is o2. The only outputs are h2o and co2.
One molecule of propane + five molecules of oxygen give you c3h8o10, from which you can build four molecules of water and three molecules of co2. Nothing left over but energy.
OK - but then I wonder what happens to the Nitrogen in the air used to get the Oxygen?
From previous post stating 0.3 lbs./hr. Here it is - 0.3 lbs. of LPG will generate 0.90 lbs. of CO2 and 0.49 lbs. of H20, that is a lot and would need to be vented outside. (C3H8 + 5O2 = 3 CO2 + 4 H20)
Consumption of 0.3 lbs. of LPG per hour will generate 1.76 kWh at 100% efficiency which would equal to 147 A at 12V. If indeed it is 40A as quoted earlier this fuel cell would be running at less than 30% efficiency, similar to ICE generator.
Nitrogen reaction with oxygen requires temperatures above 1,500 degree C, much higher than the catalytic decomposition of propane, so nitrogen should stay intact as N2.
Time will tell, but throttling this propane decomposition and hydrogen to electrical energy reactions can be very difficult.
Time will tell, but throttling this propane decomposition and hydrogen to electrical energy reactions can be very difficult.
If the units need to be using full, or near full, input all the time, that would necessitate also having full, or near full, output all the time to keep the efficiency decent.
If they can't have the output throttled down (preferably automatically) to handle varying loads, and especially charging lead acid batteries, that could be a big issue for use in RVs.
Ah, finally a topic amenable to reality-based discussion.
(You are entitled to your own opinion, but not your own chemistry )
Quote:
Originally Posted by GeorgeRa
I did some back of the envelope calculation:
From previous post stating 0.3 lbs./hr. Here it is - 0.3 lbs. of LPG will generate 0.90 lbs. of CO2 and 0.49 lbs. of H20, that is a lot and would need to be vented outside. (C3H8 + 5O2 = 3 CO2 + 4 H20)
Consumption of 0.3 lbs. of LPG per hour will generate 1.76 kWh at 100% efficiency which would equal to 147 A at 12V. If indeed it is 40A as quoted earlier this fuel cell would be running at less than 30% efficiency, similar to ICE generator.
efficiency of real-world propane gensets is more like 20% at 100% load. At 50%, it is closer to 15%.
I wonder if the Watt device has any provisions for capturing waste heat for cabin heating. That trick can significantly improve the efficiency numbers for fuel cells.
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Might they be planning to use this only with lithium batteries so that throttling is less of an issue? Or maybe they think they can pwm it for faux throttling? My old RV's instant hot water heater tried to do this, with probably ten or twenty seconds of scalding hot water interspersed with similar amounts of freezing cold water lol. At least it seemed that way.
I'd love to see a Roadtrek install, they acted like they didn't need to vent it, with comments that its output is similar to six adults, which would recover all of the lost heat so long as it isn't summer, but that sounds like a lot of water. Six people sleeping in a closed van overnight would probably leave lots of condensation.
Might they be planning to use this only with lithium batteries so that throttling is less of an issue? Or maybe they think they can pwm it for faux throttling?
I don't think PWM solves the problem. If the extra energy continues to be generated, it has to go somewhere.
It is easy enough to dump excess energy into some resistive sink. One just doesn't want to waste the propane. You could always do it to keep your water hot, I guess.
But, we don't even know if this is an issue. It is quite possible that they have a technique to throttle consumption.
Quote:
I'd love to see a Roadtrek install, they acted like they didn't need to vent it, with comments that its output is similar to six adults, which would recover all of the lost heat so long as it isn't summer, but that sounds like a lot of water. Six people sleeping in a closed van overnight would probably leave lots of condensation.
I'd be at least as worried about the CO2 as the water. I find it hard to believe that one would want to vent such a system into the cabin. I could be wrong, though.
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Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
I just don't see venting into the cabin as being remotely acceptable to us. Water, carbon dioxide are both bad for the van and the occupants. Add to it the previously mentioned, possible, need to run it on cabin air do to low temp issues, and you would also have an oxygen depletion issue if you vent back inside.
I think we all have heard all the moisture running down the walls, be sure to leave a window open, warnings about the catalytic propane heaters, and that is basically what you would have.
Where the Watt sales/marketing guy says "about the same as six human beings"
Early in this video the Watt guy says the charge controller can handle lead acid or lithium, and latte in the video is where they allude to offsetting costs by possibly reducing battery, but they are very squirrelly at the point.
efficiency of real-world propane gensets is more like 20% at 100% load. At 50%, it is closer to 15%.
I wonder if the Watt device has any provisions for capturing waste heat for cabin heating. That trick can significantly improve the efficiency numbers for fuel cells.
Yes, 30% was just a wishful thinking from my recent reading of free piston generators. So, if it is 15% efficiency it still doesnt have flexibility of ICE generator.
Regarding chemistry, it is only one as far as I know. Please correct it if I made any mistakes, I just used molecular weight ratios, simple math.
Regarding chemistry, it is only one as far as I know. Please correct it if I made any mistakes, I just used molecular weight ratios, simple math.
I worded my little joke poorly. Your chemistry appears spot on. I was just reveling in our having stumbled upon a topic that is actually amenable to proof.
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... It is quite possible that they have a technique to throttle consumption....
Yes they do in the first post video at 5:05 the American rep from Watt says they can throttle the output down. He used the example of a 200 -300 watt load if that was all a that was needed.
It kind of makes the EFOY look like a bargain -> https://www.efoy.com/ <- and the 2800W Champion Dual Fuel generator look like pocket change ..........
I'd like to see some propane consumption scenarios calculated out. I could do this, if I didn't have to go to work today. In the videos they are jabbering about numbers but the information is not presented methodically.
A couple of years back on Air Forums, we tackled the question of how to carry extra propane safely in a Class B (here). Based on the scenario of a conventional Onan combustion generator, we didn't come up with any retrofit suggestions that were both safe and promising. Perhaps for certain SOBs, this would be an easier task. But there's a finite number of ways to add propane in the limited space of a Class B, given how much else is hanging under the chassis. And there's also a finite number of tanks available in the market of the proper specs for that type of operation.
This one is a very interesting 700W generator, LPG powered, of someone would make one like it but water cooled, quiet with a starter for twice as much I would get it. I am not financial guru but it seems to me that $299 is less than $15,000 by large margin, in fact you could get 50 Ryobi generators.
Based on the spec it consumes 1/3 lbs. of LPG per hour at 175W.
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