Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
 
 


Closed Thread
 
Thread Tools Display Modes
 
Old 09-30-2018, 12:44 AM   #41
Platinum Member
 
Join Date: Feb 2018
Location: Colorado
Posts: 106
Default

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.
Mfturner is offline  
Old 09-30-2018, 02:09 AM   #42
Platinum Member
 
Join Date: Sep 2014
Location: Missouri
Posts: 113
Default

Quote:
Originally Posted by MobileCabin View Post
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.
__________________
2003 Roadtrek 190 Popular
Gryphon is offline  
Old 09-30-2018, 02:15 AM   #43
Platinum Member
 
Boxster1971's Avatar
 
Join Date: Mar 2012
Location: Maryland
Posts: 1,197
Default

Quote:
Originally Posted by Mfturner View Post
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.
__________________
2024 Airstream Interstate 19
Boxster1971 is offline  
Old 09-30-2018, 02:32 AM   #44
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 5,424
Default

Quote:
Originally Posted by Gryphon View Post
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.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline  
Old 09-30-2018, 04:36 AM   #45
Platinum Member
 
Boxster1971's Avatar
 
Join Date: Mar 2012
Location: Maryland
Posts: 1,197
Default

Quote:
Originally Posted by avanti View Post
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?
__________________
2024 Airstream Interstate 19
Boxster1971 is offline  
Old 09-30-2018, 08:02 AM   #46
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 3,271
Default Calculation

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.

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.
GeorgeRa is offline  
Old 09-30-2018, 03:00 PM   #47
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 12,387
Default

Quote:
Originally Posted by GeorgeRa View Post
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.
booster is offline  
Old 09-30-2018, 03:33 PM   #48
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 5,424
Default

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 View Post
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.
Well, if this is to be believed

http://www.irv2.com/forums/attachmen...2&d=1370080130

Generator Fuel Efficiency Table - iRV2 Forums

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.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline  
Old 09-30-2018, 03:51 PM   #49
Platinum Member
 
Join Date: Feb 2018
Location: Colorado
Posts: 106
Default

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.
Mfturner is offline  
Old 09-30-2018, 04:29 PM   #50
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 5,424
Default

Quote:
Originally Posted by Mfturner View Post
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.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline  
Old 09-30-2018, 04:43 PM   #51
Platinum Member
 
Join Date: Aug 2010
Location: Minnesota
Posts: 12,387
Default

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.
booster is offline  
Old 09-30-2018, 05:36 PM   #52
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 8,828
Default

Little typo there - it would be carbon dioxide

Was the 6 adults in van comparison for CO2 output or heat or both?

I agree, condensation inside the van could be a real issue.
markopolo is offline  
Old 09-30-2018, 07:19 PM   #53
Platinum Member
 
Join Date: Feb 2018
Location: Colorado
Posts: 106
Default

My first attempt at a link so my apologies if I mess it up, but the emissions discussion was between 2:45 and 3:20 or so in this video

https://youtu.be/naQk7RrWUdI

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.
Mfturner is offline  
Old 09-30-2018, 10:39 PM   #54
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 3,271
Default

Quote:
Originally Posted by avanti View Post
Ah, finally a topic amenable to reality-based discussion.
(You are entitled to your own opinion, but not your own chemistry )


Well, if this is to be believed

http://www.irv2.com/forums/attachmen...2&d=1370080130

Generator Fuel Efficiency Table - iRV2 Forums

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 doesn’t 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.
GeorgeRa is offline  
Old 09-30-2018, 11:22 PM   #55
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 5,424
Default

Quote:
Originally Posted by GeorgeRa View Post
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.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline  
Old 10-01-2018, 01:54 AM   #56
Platinum Member
 
Boxster1971's Avatar
 
Join Date: Mar 2012
Location: Maryland
Posts: 1,197
Default

Quote:
Originally Posted by avanti View Post
... 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.
__________________
2024 Airstream Interstate 19
Boxster1971 is offline  
Old 10-01-2018, 01:02 PM   #57
Platinum Member
 
markopolo's Avatar
 
Join Date: Oct 2006
Location: New Brunswick, Canada
Posts: 8,828
Default

There's another post on Airforums that mentions a $15,000 price tag. The post is from approx 10 months ago: The fuel cell experiment - Page 3 - Airstream Forums

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 ..........
markopolo is offline  
Old 10-01-2018, 03:39 PM   #58
Platinum Member
 
Join Date: Oct 2014
Location: League City, TX
Posts: 1,172
Default

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.
InterBlog is offline  
Old 10-01-2018, 04:24 PM   #59
Platinum Member
 
GeorgeRa's Avatar
 
Join Date: Feb 2016
Location: Portland, Oregon
Posts: 3,271
Default $299 generator.

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.
Attached Images
File Type: png 3.png (337.3 KB, 15 views)
GeorgeRa is offline  
Old 10-01-2018, 07:55 PM   #60
Site Team
 
avanti's Avatar
 
Join Date: Jul 2013
Posts: 5,424
Default

Quote:
Originally Posted by InterBlog View Post
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.
I kind of tried to do that in message #14 above:

http://www.classbforum.com/forums/f2...html#post81601

We'll see what the actual price is. As far as I'm concerned price and warranty are the only potential deal killers.
__________________
Now: 2022 Fully-custom buildout (Ford Transit EcoBoost AWD)
Formerly: 2005 Airstream Interstate (Sprinter 2500 T1N)
2014 Great West Vans Legend SE (Sprinter 3500 NCV3 I4)
avanti is offline  
Closed Thread


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 07:42 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.