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Discussion Starter · #1 ·
I've recently learned about these flameless propane heaters and it seems like people use them inside tents for camping even while sleeping overnight. It has a low setting of 1500btu and a high setting of 3000btu and it seems like this should probably be safe since I've worked out mathematically that 1500btu combustion should make CO2 at the same rate as about two people breathing.

Supposedly a 1lb cylinder should last about 10hrs on low which will be substantially less than the 0.4g per hour rate of gasoline the heater will run at. Gonna mount is as pictured.

Gonna also run this with both a CO and CO2 detector for extra safety
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Assuming you're serious, a few questions come to mind. 1) A similar unit on Amazon from Martin says in capital letters for OUTDOOR use only. I'd want to know why. I don't know how this flameless technology works. 2) Besides CO and CO2, burning any hydrocarbon in air produces other pollutants that are harmful, like NOx. Even gas cooktops in our kitchens generate enough pollutants after a few minutes to exceed health standards. That's why gas cooktops are now being talked about as something we should move away from. What are the by-products of these propane heaters? 3) What are the advantages of burning propane this way vs. gasoline in the ICE built into your car? Seems like Hyundai engineers have done a pretty good job of efficiently using the ICE only when needed, and when they do, it captures as much energy as possible to charge the battery while warming up, then harvesting any waste heat to heat the cabin. It also turns the ICE off as much as possible, so it maintains the cabin temp. without burning gas continuously. As long we already have gasoline and an ICE onboard, it uses them efficiently. Your calculations don't include the added benefit of the battery charging. Plus, we get to use the back seat, and there's no question of inhaling pollutants.
 

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Discussion Starter · #4 · (Edited)
I bet the outdoor labeling is liability to be honest. There are plenty of people that use these inside tents and using the catalytic reaction the heat is reduced compared to an open flame and the production of nox is from high temperature combustion on a flame. Of course there is a danger with oxygen depletion in a very enclosed space but the space would have to be very enclosed indeed for the low heat ratings

I'd put the counterpoint that a combustion open flame 3000btu unit from mr heater is actually labeled for indoor use and this is half of that with lower temperature heat and a cleaner reaction

The empirical efficiency improvement is hard to dispute too. You combust inside the car so all the heat is made inside the car. That's 100%. So basically it'll burn the quarter gallon of propane in 10 hours as opposed to 40mins to burn a quart of gasoline in the case of the car engine. Energy density of gasoline is higher than propane as well.

Even some math showing the co2 rate is low

The heater on low is 1500BTU/hr which is 1.055KJ x 1500 = 1585.2kJ / hour

The combustion reaction of propane is:

C3H8 + 5O2 -> 3CO2 + 4H20 -2220kJ / mol

which means in an hour 1.58/2.2 \* 3 = 2.1 mols of CO2 are created

CO2's molecular weight is 44g/mol which means every hour 94g CO2 is created.

A human being breathes out about 1kg of CO2 per day, which translates to 41grams per hour.

So the heater on low produces a little more than 2 humans breathing worth of carbon dioxide.





Assuming you're serious, a few questions come to mind. 1) A similar unit on Amazon from Martin says in capital letters for OUTDOOR use only. I'd want to know why. I don't know how this flameless technology works. 2) Besides CO and CO2, burning any hydrocarbon in air produces other pollutants that are harmful, like NOx. Even gas cooktops in our kitchens generate enough pollutants after a few minutes to exceed health standards. That's why gas cooktops are now being talked about as something we should move away from. What are the by-products of these propane heaters? 3) What are the advantages of burning propane this way vs. gasoline in the ICE built into your car? Seems like Hyundai engineers have done a pretty good job of efficiently using the ICE only when needed, and when they do, it captures as much energy as possible to charge the battery while warming up, then harvesting any waste heat to heat the cabin. It also turns the ICE off as much as possible, so it maintains the cabin temp. without burning gas continuously. As long we already have gasoline and an ICE onboard, it uses them efficiently. Your calculations don't include the added benefit of the battery charging. Plus, we get to use the back seat, and there's no question of inhaling pollutants.
 

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Discussion Starter · #5 ·
Also we can calculate the contribution to charging the engine as well

If the car is burning 0.4 gallons of hour for heat this means it is using 13.5KW, of which you are charging the car maybe at 3KW at the high idle. The rest of it is heat but it also has the thermal mass of the engine as well as exchange with the outside cold air which are sources of loss, so that the heat that makes it into the cabin is a fraction of that.
 

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Discussion Starter · #6 ·
What on Earth are you trying to achieve with this? Your post isn’t delayed from April Fools day is it?
Efficiency. Put it another way, there is 6.3KWh of energy in that bottle of propane. That's more than 2/3rd the total energy of the PHEV battery itself. All of the bottle will turn into cabin heat with this and it will last about 10hrs per bottle
 

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You may be correct about the heater producing little more CO2 than two people, but when the car is moving, the air inside the car is constantly being replaced by the ventilation system as the car moves through the air.

HafuDutch and I have our locations clearly stated in our details so others responding to any questions we post have a rough idea of the climatic conditions we encounter. If you live in the snow belt, there are Canadian members who discuss the heating in their garages, some have electric engine block warmers, but this is a new one on me.

Your petrol is so cheap (here it’s currently £7/UK gallon) that this level of over thinking to avoid a few Cents of petrol being burnt isn’t needed.

Keep the seats for their intended purpose, have your main dealer service the car to schedule and just sit back and enjoy the ride!
 

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Discussion Starter · #8 ·
You may be correct about the heater producing little more CO2 than two people, but when the car is moving, the air inside the car is constantly being replaced by the ventilation system as the car moves through the air.

HafuDutch and I have our locations clearly stated in our details so others responding to any questions we post have a rough idea of the climatic conditions we encounter. If you live in the snow belt, there are Canadian members who discuss the heating in their garages, some have electric engine block warmers, but this is a new one on me.

Your petrol is so cheap (here it’s currently £7/UK gallon) that this level of over thinking to avoid a few Cents of petrol being burnt isn’t needed.

Keep the seats for their intended purpose, have your main dealer service the car to schedule and just sit back and enjoy the ride!
You're probably right about this being over optimization to the extreme :). For a bit of background I live in Boston so it definitely gets cold here though our gasoline is indeed cheap, like $3.20 a gallon (though ours are smaller right?). I think this was a fun experiment to do and see if the back of the envelope calculations about co2 emissions actually play out. Also a lot of my trips in the winter are within 30 miles but I need to drive maybe 3-5miles in gas mode at 25mpg to get the coolant heat up enough hence the motivation for this. Definitely more of a purity and curiousity issue than a financial one I agree. I'm an engineer who likes to tinker so this was probably the motivation. Plus I thought those catalytic heaters were really neat.

I did a more detailed analysis in this Twitter thread

 

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catalytic heaters like this put out a lot of water vapour as well, your car would get very humid and water would condense on any cold areas.
Which, for visibility and safety, would require you to run the window defroster, which would kick on the car's ICE. While the idea has a seed of a theoretical solution to burning a little less fossil fuel, the practical downsides, as well as several unknowns and higher risks seem to outweigh this initial benefit.
 
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Discussion Starter · #13 ·
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Which, for visibility and safety, would require you to run the window defroster, which would kick on the car's ICE. While the idea has a seed of a theoretical solution to burning a little less fossil fuel, the practical downsides, as well as several unknowns and higher risks seem to outweigh this initial benefit.
Ice doesn't kick in if temp is set to low. But clears the window pretty well with low fan. Also airflow is enough to make the air quality indoor like
 

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Discussion Starter · #14 ·
This gas burner inside a car is a big fire hazard, not just CO poisoning hazard. :rolleyes:
Using it in a moving car is entering into Darwin Awards Contest.
CO poisoning happens with oxygen depletion so co2 concentration is a good proxy for this. This has been measured (check screencap and Twitter thread) and co2 concentration remains at nominally indoor levels. 1500btu isn't very strong heat and doesn't eat up much oxygen. Check the math in the post

The need to restrain it is why there are four bungees as well. But the metal guard surface isn't as hot as you'd think when things are on low
 

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Discussion Starter · #15 · (Edited)
catalytic heaters like this put out a lot of water vapour as well, your car would get very humid and water would condense on any cold areas.
To quantify the amount of h20 vapor, the amount is basically like two extra people breathing. Once again 1500 btu also determines the rate of water formation. Confirmed from testing

Catalytic heaters put out no more water vapour than any other kind of combustion heaters.

Y'all need to put this in perspective. This heater is putting out 440watts here. This is like one of those tiny desk space heaters worth of heat. Sure it uses combustion but the fuel consumption rate, co2 rate and h20 rate are going to be measured in 10s of grams an hour.
 
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