how to keep water from freezing

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Challenger Red
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how to keep water from freezing

Postby Challenger Red » Thu Oct 07, 2010 11:44 pm UTC

ok, so heres the problem:

I'm building an H2 generator for my truck to improve its gas mileage. that parts fine, and should be done by next friday. the issue is that i live in the upper midwest and its heading into winter. im worried about the water in the generator freezing while im not driving. I'm under the impression that adding antifreeze would mess with the electrolysis, and i dont know of any other way to keep it from freezing short of removing it from the vehicle. do you guys have any ideas?

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Re: how to keep water from freezing

Postby minno » Fri Oct 08, 2010 12:38 am UTC

Electric or chemical heater.
Adding solute.
Applying large pressure.

That's what I can think of off the top of my head. I'd suggest the heater, because you're already producing energy. You'd just get slightly lower gas mileage. Also, you can try insulating the tank to keep heating costs to a minimum.
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Re: how to keep water from freezing

Postby Charlie! » Fri Oct 08, 2010 3:07 am UTC

Antifreeze wouldn't be too bad. As long as it's glycol or alcohol, and not rock salt :P It might slow down the electrolysis a tiny bit, but... well, heck, you can try it yourself. I doubt it will be a big difference.
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Re: how to keep water from freezing

Postby Sockmonkey » Fri Oct 08, 2010 5:09 am UTC

You could just make sure your tire pressure is good. Most people forget to check and being low causes a bit of drag. Also, in winter the cold makes the air in your tires contract making it worse. Oh, and the hydrogen thing won't help. Laws of thermodynamics yanno?

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Re: how to keep water from freezing

Postby Izawwlgood » Fri Oct 08, 2010 5:20 am UTC

Sock, I think he's talking about the fear that his hydrogen source, being water, will freeze in the winter.

Can you run heating coils into the tank itself, and run it a couple of minutes prior to starting the car up? I'm thinking something akin to an aquarium heater.
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Re: how to keep water from freezing

Postby Sockmonkey » Fri Oct 08, 2010 5:25 am UTC

Yes I know what he's talking about. I'm bringing up an alternative means of increasing efficiency that's easier to do and that actually works. Seriously, who buys into that hydrogen bit anymore?

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Re: how to keep water from freezing

Postby ++$_ » Fri Oct 08, 2010 7:05 am UTC

How do you know what he plans to power the generator with? Maybe he's going to install regenerative braking. Maybe he's got a wind turbine on his roof.

It's much easier to make hydrogen at home than it is to make hydrocarbon fuel or ethanol, so if you want to provide a chemical fuel for your car (and make it at home as part of an awesome science project) hydrogen is the way to go.

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Re: how to keep water from freezing

Postby Tass » Fri Oct 08, 2010 7:22 am UTC

++$_ wrote:How do you know what he plans to power the generator with? Maybe he's going to install regenerative braking. Maybe he's got a wind turbine on his roof.


In which case making hydrogen would still be stupid.

If he has a stationary source of abundant renewable energy for some reason, and is not connected to the distribution net so he could sell it, then making hydrogen to power his car makes sense (although getting an electric car would be easier and cheaper). But if that is the case he could just have the water for the electrolysis indoor.

I agree with sock, the guy has obviously fallen for a well known hoax, and you guys are just giving small advice on a technical detail. The truck will actually run better with the water frozen solid since he will lose less energy on the electrolysis.

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Re: how to keep water from freezing

Postby ++$_ » Fri Oct 08, 2010 7:51 am UTC

Yes, if you are trying to power a hydrogen generator with the car engine, it will make the engine less efficient. That's obvious, and I kind of assume that people who visit these fora would have thought of that. Maybe that was a stupid assumption to make.

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Re: how to keep water from freezing

Postby tussock » Fri Oct 08, 2010 8:58 am UTC

Strictly speaking, generating H2 could provide more power overall, with a few rare conditions.

Adding H2 to the mix makes each combustion cycle run somewhat hotter, potentially producing a more complete burn of the hydrocarbons. Of course, you have to have a motor that's burning fairly dirty with an overabundant supply of oxygen, which is pretty damned uncommon, and really just needs timing adjustments.

For the most part, for home-built stuff, you should just add a very small amount of water to the air coming into the engine, which is a slight pressure increase for no added energy thanks to the state change, acts to cool the block a little which helps the air feed, and can keep incoming air cooler which is always good. Particularly useful in a dry (i.e. frozen) climate. Potential corrosion issues abound, but such is life. You'd probably have to drain the system overnight in a cold climate too.

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Re: how to keep water from freezing

Postby Challenger Red » Fri Oct 08, 2010 3:22 pm UTC

well, perhaps i have fallen for a hoax. but i dont think so. to me, this dosent seem to violate the laws of thermodymaics. when a car starts, it pulls energy off of the battery to fire the engine. once the engine is going, the battery recharges to its maximum level, but the engine/alternator continues to produce enough energy to charge the battery and run the engine (at least, this is what appears to happen, i know very little about how engines really work). the h2 generator would be powered off of the surplus energy generated after the battery has been recharged. it seems to me that this would work, but like i said, i dont know much about cars.

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Re: how to keep water from freezing

Postby jaap » Fri Oct 08, 2010 4:27 pm UTC

Challenger Red wrote:when a car starts, it pulls energy off of the battery to fire the engine. once the engine is going, the battery recharges to its maximum level, but the engine/alternator continues to produce enough energy to charge the battery and run the engine (at least, this is what appears to happen, i know very little about how engines really work).


There seems to be a misconception in there. While an engine clearly produces enough energy from its fuel to do its job and on top of that to top up the battery, that doesn't mean that once the battery is fully charged the engine is continually producing surplus energy that is going to waste.
When the battery is charging, the alternator is more difficult to turn and this places a load on the engine. When the battery is full, the alternator is easy to turn, and the engine is under a lighter load, and so uses up less fuel. You can actually hear this in some cars that the engine, running stationary, changes in pitch when you switch the air-conditioner on or off.
So when the battery is full the engine is not producing surplus energy that it isn't using, it is simply producing less energy. What is does have is more spare capacity for you to use when you press the gas pedal.
If you hook up an H2 generator, you are once again putting an extra load on the engine. Sure, it can handle it, but this does put an extra load on it that it didn't have before, and so cost energy/fuel to run (and most likely much more than the H2 later produces).
Last edited by jaap on Fri Oct 08, 2010 4:33 pm UTC, edited 1 time in total.

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Re: how to keep water from freezing

Postby Korrente » Fri Oct 08, 2010 4:30 pm UTC

But the engine is theoretically going to have to work harder (burn more fuel) to provide the extra energy to run the H2 generator, is what they're saying. Hydrogen has a lower energy density than gasoline, so you're probably not making a large enough volume of hydrogen to offset the amount of gasoline you're burning. /ninja'd

The only situation I could see this being useful is during idling, when your engine is running for no reason, maybe the hydrogen offsets it a little? But I doubt it. I wouldn't think all the H2 in the small tank of water you'll have would come anywhere close to equaling the energy it would take to separate it, unless you had a Very efficient method. But then you're just having to get energy/chemicals for it from somewhere else, etc. etc.

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Re: how to keep water from freezing

Postby Charlie! » Fri Oct 08, 2010 4:35 pm UTC

I seem to recall we had a thread on this before... someone with good google-fu and less laziness could probably find it, but the upshot was that adding hydrogen or hydrogen/oxygen does increase efficiency, but not by a lot more than it takes to split it in the first place. There are other things you could do that would be better at increasing your fuel efficiency. But if you want to to it just to do it, hey, go for it.
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Re: how to keep water from freezing

Postby Jplus » Fri Oct 08, 2010 4:41 pm UTC

Disregarding the question whether it is actually useful to do it:

To prevent the water from freezing (or actually, to melt it as fast as possible when you go driving), I think you should combine several strategies for optimal efficiency. First of all, you should realize that the hydrolysis generates some heat, so if you insulate the water tank very well (which you should do), that will allmost certainly keep it from freezing while driving. Adding an organic antifreeze like glycol will help alot as well (I suspect ethanol will help less), and it shouldn't hinder the hydrolysis much (if you keep the concentration low). Finally, if it is technically feasible, it would be beautifully efficient to let your engine coolant exchange heat with the water tank.

I must say that I find it a very cute idea and also very cool to patch your car like that. Even if we'd be sure that your car would become less efficient, I'd support the project. :P
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Re: how to keep water from freezing

Postby savanik » Fri Oct 08, 2010 7:21 pm UTC

Hrm. My thought on this was 'this is a neat way to bypass the "hybrid motor required" part of an electric vehicle by using electric for hydrolysis while the machine is at rest', which seemed like a pretty neat idea to me: You park the car, plug it in, and hydrolysis happens, storing the electrical energy as H2. Then when you drive off, it mixes in the H2 into your intake gradually, so your octane doesn't blow the rods out the top of your engine. No new engine required, running on electrical power - nifty!

Trying to do it off of the alternator will just cause more drag due to increased load on the electrical system, and you'll have frictional losses in the alternator, losses in the electrolysis process, and losses in the heat of combustion, so I'm 99% sure it'd be a net loss on mpg done that way.

But plugged into the wall should be effective, if you were in an area where electrical energy is cheaper than gasoline.

As far as keeping the water from freezing - running electrolysis with chemically pure water is surprisingly difficult. It's non-conductive. In a typical electrolysis setup, you have mixed some kind of ionizing substance, often dilute sulfuric acid, into the water to make it conductive, and if you didn't know this already I strongly recommend you learn more about the process you're using. Electrolysis produces both hydrogen and oxygen gas, and stored in an improper environment these gases WILL produce a powerful detonation.

Antifreezes are typically composed of polar compounds, which will not affect the conductivity of the water. Depending on what you've mixed into the water to make it conductive, these chemicals may react and toxic gases may be emitted which would make your vehicle difficult to operate.

It is an interesting idea. However, I would investigate the chemistry of the substances you're trying to use very carefully, and keep in mind that any impurity in water (such as whatever you're using to make it conductive) will alter the freezing point to some degree.
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Re: how to keep water from freezing

Postby Coffee » Fri Oct 08, 2010 8:43 pm UTC

There's people here with a better grasp of the chemistry involved than I, so I will defer to them. Here's where I'm confused though; how could one ever hope to get more energy out of recombining two elements than it took to split them in the first place, especially considering that energy is always lost to entropy in the process? If you're splitting H2O into H2 and O2, and then recombining them into H2O, even assuming 100% efficency how could you expect to get more energy in the outcome?
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Re: how to keep water from freezing

Postby Jplus » Fri Oct 08, 2010 9:10 pm UTC

Coffee wrote:There's people here with a better grasp of the chemistry involved than I, so I will defer to them. Here's where I'm confused though; how could one ever hope to get more energy out of recombining two elements than it took to split them in the first place, especially considering that energy is always lost to entropy in the process? If you're splitting H2O into H2 and O2, and then recombining them into H2O, even assuming 100% efficency how could you expect to get more energy in the outcome?

Nobody should expect that to be possible, because your intuition is right that it isn't.

If I understood the discussion well, nobody was assuming that energy could be generated in such a way.
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Re: how to keep water from freezing

Postby Challenger Red » Fri Oct 08, 2010 9:47 pm UTC

hm..I didnt know that the alternator stops producing excess energy after the battery is charged. however, i think that the load put on by my h2 generator (Im using KOH to make it more conductive) will result in a small boost to mpg. and seeing as my truck gets between 8 and 15 mpg, anything would help. thanks for the input, ideas on efficiency are always welcome.

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Re: how to keep water from freezing

Postby Technical Ben » Fri Oct 08, 2010 10:22 pm UTC

Coffee wrote:There's people here with a better grasp of the chemistry involved than I, so I will defer to them. Here's where I'm confused though; how could one ever hope to get more energy out of recombining two elements than it took to split them in the first place, especially considering that energy is always lost to entropy in the process? If you're splitting H2O into H2 and O2, and then recombining them into H2O, even assuming 100% efficency how could you expect to get more energy in the outcome?


Yep. Now try and convince all the "put electrolysis in your car" people. :|
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Re: how to keep water from freezing

Postby Technical Ben » Fri Oct 08, 2010 10:24 pm UTC

Challenger Red wrote:hm..I didnt know that the alternator stops producing excess energy after the battery is charged. however, i think that the load put on by my h2 generator (Im using KOH to make it more conductive) will result in a small boost to mpg. and seeing as my truck gets between 8 and 15 mpg, anything would help. thanks for the input, ideas on efficiency are always welcome.


No, anything will not help. Even the weight of the extra parts and water needs to be taken into account for your fuel efficiency.
I would have thought, if hydrogen was even a good catalyst, we would be using it already. What about NOZ? It's used in some cars (or is it just the movies ;) ).
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Re: how to keep water from freezing

Postby ++$_ » Fri Oct 08, 2010 10:30 pm UTC

Technical Ben wrote:What about NOZ? It's used in some cars (or is it just the movies ;) ).
Nitrous oxide is used in cars as an oxidizer. It's 33% oxygen, so you get a higher oxygen saturation than you do using air. The decomposition of N2O at high temperatures is also exothermic, but that's not the main effect.

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Re: how to keep water from freezing

Postby Sockmonkey » Fri Oct 08, 2010 11:17 pm UTC

Try checking if you have a lot of junk cluttering up your truck. Guys being how we are, we tend to have at least 50 pounds of tools and other crap rattling around in there.
Clean your air filter regularly.
When a traffic light a quarter mile off turns red just take your foot off the gas and coast to it. Burning half a tank racing to it isn't gonna turn it green any faster.
In winter covering your hood with an insulated blanket when it's parked for a bit and/or parking in a garage or enclosure as much as possible will waste less fuel getting the engine warmed back up when you start it again.

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Re: how to keep water from freezing

Postby Technical Ben » Fri Oct 08, 2010 11:20 pm UTC

I kind of gathered some of that, but never looked into it myself. I've got a turbo (and effectively and inter-cooler I think) on my diesel engine. It compresses the air, and cools it down. So more fits in, so it's got more oxygen, and a higher pressure for the pistons*. Even the likes of a turbo does not provide "free" energy. The car suffers from turbo lag, as it needs to put energy into the turbo to get it up to speed. However, it does then get a benefit afterwords.


*I'm happy to be corrected, as said, I've not read up about it much.


[edit]
Oh, and it's often down to the car you have. I know needs differ, but my Opel/Vectra Estate (really old thing) should give around 45mpg. No idea what it is now, as it's not going to be as good as when it was new. :oops:
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Re: how to keep water from freezing

Postby Carnildo » Sun Oct 10, 2010 12:19 am UTC

savanik wrote:Antifreezes are typically composed of polar compounds, which will not affect the conductivity of the water. Depending on what you've mixed into the water to make it conductive, these chemicals may react and toxic gases may be emitted which would make your vehicle difficult to operate.

This is worth repeating. Salt, for example, is an obvious choice, but it tends to be counterproductive. Yes, you'll get hydrogen at one electrode, but at the other, the chlorine will react in place of the oxygen, giving you a stream of chlorine gas to deal with.

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Re: how to keep water from freezing

Postby dedalus » Sun Oct 10, 2010 11:46 am UTC

Putting it out there, given that combustion engines are pretty inefficient, couldn't you use something off of a cooling system to provide a heat source to some sort of thermally driven engine, and *that* way get electricity? It wouldn't help a huge amount, but if you can recover 10% of the wasted heat you'd be getting a lot more fuel efficiency, definitely more then enough to make up for the weight.
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Re: how to keep water from freezing

Postby Tass » Sun Oct 10, 2010 12:05 pm UTC

dedalus wrote:Putting it out there, given that combustion engines are pretty inefficient, couldn't you use something off of a cooling system to provide a heat source to some sort of thermally driven engine, and *that* way get electricity? It wouldn't help a huge amount, but if you can recover 10% of the wasted heat you'd be getting a lot more fuel efficiency, definitely more then enough to make up for the weight.


Better to just use the power directly rather than making electricity, but yes, you can make more efficient engines using stirling engines, it is, however, not worth the extra weight and investment, if it was car factories would be making them.

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Re: how to keep water from freezing

Postby Jplus » Sun Oct 10, 2010 12:22 pm UTC

Didn't dedalus mean this: feed the heat from the combustion engine into a stirling engine, generate electricity with the stirling engine, make hydrogen by hydrolysis, feed hydrogen into combustion engine? I think that could work great, as long as you keep the stirling engine light (maybe if you hook it up to a bicycle dynamo) and don't bring too much water. And less energy will be wasted on cooling the combustion engine.
You can actually also add the oxygen from the hydrolysis to further improve pressure and combustion. And at the same time use heat from the engine to warm your water, since it generates lots of heat anyway.
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Re: how to keep water from freezing

Postby Tass » Sun Oct 10, 2010 1:17 pm UTC

Jplus wrote:Didn't dedalus mean this: feed the heat from the combustion engine into a stirling engine, generate electricity with the stirling engine, make hydrogen by hydrolysis, feed hydrogen into combustion engine? I think that could work great, as long as you keep the stirling engine light (maybe if you hook it up to a bicycle dynamo) and don't bring too much water.


Why go: Waste heat -> stirling -> mechanical power -> generator -> electricity -> hydrolysis -> hydrogen -> combustion engine -> additional mechanical power

When you can just go: waste heat -> stirling -> additional mechanical power

Thing is that Stirlings are not economical on vehicles. They have way to low power to weight ratio. I any engine there will be a tradeoff between power density and efficiency. We could actually also make the combustion engine bigger and slower and that way have it release the waste heat at a lower temperature, then we could achieve a higher efficiency, but the lower power density is not worth it.

Jplus wrote:And less energy will be wasted on cooling the combustion engine.


No. The Stirling wont help the engine cool. Heat flows down its gradient (from hot to cold). We need cooling water to keep it flowing fast enough, because the engine is small and powerful. The stirling engine stems the flow of heat to extract work from it, like damming a river.

Bigger gradients means faster flow and therefore higher power density, however bigger gradients also means more entropy generated and a lower efficiency, that is why we get the before-mentioned trade-off.

Insulate the engine so you can divert every last drop of heat through the stirling, then you can extract more work from the fuel, but you will have to run the engine much slower to avoid overheating (if the river is dammed you get a flood if more water flows into it than the turbines can handle), or make the whole thing ridiculously huge to process the heat quickly enough.

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Re: how to keep water from freezing

Postby Jplus » Sun Oct 10, 2010 2:26 pm UTC

Of course you make valid points, but let me elaborate a bit more.

The reason to go Waste heat -> stirling -> mechanical power -> generator -> electricity -> hydrolysis -> hydrogen -> combustion engine -> additional mechanical power

while we could go Waste heat -> stirling -> additional mechanical power

is that, as you say, stirling engines have a very low power to weight ratio. If we restrict ourselves to a small stirling engine (which would be wise), then most of the additional mechanical power from the stirling engine is likely to be lost in elastic deformations if we just deliver it directly to the drive shaft. In fact, the drive shaft is more likely to turn the stirling engine. If, on the other hand, we use the low power of the small stirling engine to generate a little bit of extra fuel, then we we can slightly reduce the amount of gas in the combustion fuel mixture. So instead of attempting to add power with the stirling engine, we use the waste heat to let the engine generate the same power with the same amount of fuel, but with the fuel containing a lower fraction of gas.
(Thus, the efficiency of the engine has maybe not really improved, but it may still drive with an improved gas mileage).

Also, I think the use of a stirling engine doesn't necessarily have to stem the cooling water flow. There is no need to mechanically decelerate the cooling water flow. True, elongating its cycle path will add some resistance, but you can compensate for that by using slightly wider tubes in the elongated section.
I think the following cooling water cycle would be nice: engine -> hot side of stirling engine -> water tank -> air cooler -> cold side of stirling engine -> engine.
(Yes, this will heat up the cooling water a little bit before it re-enters the engine. That's no big deal, because the small stirling engine is only transfering very small amounts of heat.)

Besides, even if stemming of the cooling water flow turns out to be a real problem, you can decide to just connect the warm side of the stirling engine directly with the engine through a piece of conducting material. Same story for the water tank.
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Re: how to keep water from freezing

Postby Charlie! » Sun Oct 10, 2010 5:09 pm UTC

Carnildo wrote:
savanik wrote:Antifreezes are typically composed of polar compounds, which will not affect the conductivity of the water. Depending on what you've mixed into the water to make it conductive, these chemicals may react and toxic gases may be emitted which would make your vehicle difficult to operate.

This is worth repeating. Salt, for example, is an obvious choice, but it tends to be counterproductive. Yes, you'll get hydrogen at one electrode, but at the other, the chlorine will react in place of the oxygen, giving you a stream of chlorine gas to deal with.

True, but a standard glycerol antifreeze shouldn't give you anything more dangerous than a short aldehyde, if that. And then you burn it anyhow!

Coffee wrote:There's people here with a better grasp of the chemistry involved than I, so I will defer to them. Here's where I'm confused though; how could one ever hope to get more energy out of recombining two elements than it took to split them in the first place, especially considering that energy is always lost to entropy in the process? If you're splitting H2O into H2 and O2, and then recombining them into H2O, even assuming 100% efficency how could you expect to get more energy in the outcome?
By making the combustion properties better, increasing efficiency. Basically. You can't assume 100% efficiency - this only works for imperfect systems :P
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Re: how to keep water from freezing

Postby Coffee » Sun Oct 10, 2010 7:37 pm UTC

My point is that you'd never get any more energy out of it than you put in to it. There's a reason water is used to put out fires. Oxygen has a pretty strong grip on those electrons and doesn't want to let go of them.
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Re: how to keep water from freezing

Postby Tass » Mon Oct 11, 2010 6:17 am UTC

Jplus wrote:Also, I think the use of a stirling engine doesn't necessarily have to stem the cooling water flow.


I wasn't talking about stemming the water flow, but the heat flow. The water was an analogy. Sure you can circumvent this, but only through either have it produce a negligible power, or being obscenely big.

The point is that the power density is to low.

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Re: how to keep water from freezing

Postby dedalus » Mon Oct 11, 2010 11:36 am UTC

Tass wrote:
Jplus wrote:Also, I think the use of a stirling engine doesn't necessarily have to stem the cooling water flow.


I wasn't talking about stemming the water flow, but the heat flow. The water was an analogy. Sure you can circumvent this, but only through either have it produce a negligible power, or being obscenely big.

The point is that the power density is to low.

Any chance of getting some calculations on this? Combustion engines are fairly inefficient (wikipedia is saying average 18%), and most of the excess is given off as heat. Assuming heat is output at 120 Celsius, Carnot efficiency is 0.25. Even running at 50% of this, and only collecting 50% of engine output, you're talking about another 5% of total efficiency, which is about a quarter of what we already have - surely this more then compensates for the extra weight...
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Re: how to keep water from freezing

Postby Velifer » Mon Oct 11, 2010 3:38 pm UTC

Challenger Red wrote:seeing as my truck gets between 8 and 15 mpg, anything would help. thanks for the input, ideas on efficiency are always welcome.

Sell it, buy a Geo Metro.
...and a 500 gallon fuel tank for your yard. Buy gas when it's cheap (not before holiday weekends). Drive with fuel efficiency in mind (but not like a douchebag hypermiler). Seal up all the gaps in the body so it's smooth and aerodynamic, remove the antenna, etc. Trim off all extra weight: throw out the passenger seat (If you're a grown man in the Midwest driving one of those, you're not married.)

Putting money into dubious hacks to make a pickup more efficient is false economy. So is spending stupid amounts on a new hybrid--calculate the TCO and what you save in gas was burnt at the dealership before you were over the curb.

Putting money into an electrolysis rig to fuel the Turret Mounted Flame Thrower of Science(TM) however...
Run the water lines along the exhaust manifolds, let the engine warm them up before switching on the pump.
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Re: how to keep water from freezing

Postby Technical Ben » Mon Oct 11, 2010 4:50 pm UTC

I'd probably avoid the death trap micro cars. But that does not mean you cannot get an efficient saloon or estate.
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Re: how to keep water from freezing

Postby frezik » Mon Oct 11, 2010 5:01 pm UTC

Carnildo wrote:
savanik wrote:Antifreezes are typically composed of polar compounds, which will not affect the conductivity of the water. Depending on what you've mixed into the water to make it conductive, these chemicals may react and toxic gases may be emitted which would make your vehicle difficult to operate.

This is worth repeating. Salt, for example, is an obvious choice, but it tends to be counterproductive. Yes, you'll get hydrogen at one electrode, but at the other, the chlorine will react in place of the oxygen, giving you a stream of chlorine gas to deal with.


I've heard about this problem before in using NaCl in electrolysis setups, but I'm not sure it's true. If you're getting elemental chlorine off that reaction, then you should also be getting elemental sodium, which should be even more exciting than chlorine when it meets such a wet environment. If the NaCl is actually part of the reaction, then it must be in very trace quantities or else the whole apparatus would blow up.

dedalus wrote:Putting it out there, given that combustion engines are pretty inefficient, couldn't you use something off of a cooling system to provide a heat source to some sort of thermally driven engine, and *that* way get electricity? It wouldn't help a huge amount, but if you can recover 10% of the wasted heat you'd be getting a lot more fuel efficiency, definitely more then enough to make up for the weight.


Yes, see Six-stroke Engine for one way to implement this. As Tass noted, it's not worth the extra weight in cars, but it could be worth it in large trucks, ships, or standing engines.

Velifer wrote:...and a 500 gallon fuel tank for your yard. Buy gas when it's cheap (not before holiday weekends).


Pendentic note: if you're going to do that, be sure the tank is treated with fuel stabilizer. Unless you're the type that can go through 500 gallons in two weeks or less. Gas ages when left to itself. Alternatively, you could add a bottle of octane boost when you fill up with older gas, but these may or may not be legal for road use in your area.

On the larger issue of HHO devices--there are a few places where you'll see some possible and usually very modest improvements:

1) Engines with lots of carbon buildup, causing floating valves. The water created at the end of the reaction will "steam-clean" the exhaust valves. However, you could just as easily do this with some fuel additives made for this job, or by reving your engine to redline at least once a week. Further, once the carbon is gone, the HHO device is just dead weight until the carbon builds up again.
2) Carbureted engines. There will inevitably be conditions where the carburetor is running too rich. This won't apply to almost any car built within the last 25 years.
3) Badly tuned fuel injected engines. Need to fix the real problem, not install HHO.
4) Increased flame front speed. This is mainly for working around a fundamental design flaw in Wankel engines. Nearly all the people who are qualified to experiment with this work for Mazda (which they're doing with the upcoming 16X rotary). Even there, the aim is for stored hydrogen, not creating it on the fly as HHO does. It could help performance in piston engines, but the effect would be much like Superchargers--sapping away efficiency in order to get higher overall power.
5) Extra octane boost. The engine will need some kind of modification to take advantage of it, such as running a higher compression ratio or using higher supercharger boost. Still better to use stored hydrogen rather than on-the-fly, for the same "sapping efficiency" reasons as #4. Easier still to use water/ethanol injection to get the same effect, which is fairly well known in racing circles and is a lot less cumbersome.
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Re: how to keep water from freezing

Postby Tass » Mon Oct 11, 2010 5:49 pm UTC

frezik wrote:I've heard about this problem before in using NaCl in electrolysis setups, but I'm not sure it's true. If you're getting elemental chlorine off that reaction, then you should also be getting elemental sodium


No. No reason for that. The thing easiest reduced/oxidized is what will become reduced/oxidized. Chlorine is easier to oxidize than oxygen, but hydrogen is easier to reduce than sodium.

As you note, the sodium would react it the moist environment, but it will not happen violently. As soon as a minuscule amount of elemental sodium was produced it would react with the water and release hydrogen instead, it would never build up enough for an explosion - really it will never build up at all, hydrogen comes of the katode.

The result is a sodium hydroxide solution. Of course as soon as the chloride concentration drops too low, oxygen will be produced.

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Re: how to keep water from freezing

Postby Coffee » Mon Oct 11, 2010 8:26 pm UTC

Technical Ben wrote:I'd probably avoid the death trap micro cars. But that does not mean you cannot get an efficient saloon or estate.

Ya know, small cars wouldn't be deathtraps except for all the yank tanks on the roads.
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Re: how to keep water from freezing

Postby frezik » Mon Oct 11, 2010 8:46 pm UTC

Coffee wrote:
Technical Ben wrote:I'd probably avoid the death trap micro cars. But that does not mean you cannot get an efficient saloon or estate.

Ya know, small cars wouldn't be deathtraps except for all the yank tanks on the roads.


There's a whole argument from Game Theory on that one. Gist is that it's in the collective interest to have everyone on the smallest car possible, but it's in my own interest to have the largest size/weight advantage over anything else.

That said, micro cars, like the Peel P50, are probably less safe than getting thrown from a scooter/motorcycle (assuming you wear a helmet). You will almost certainly get crushed inside a Peel, while the chances of walking away when getting thrown are a lot better than most people think.
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