Electric WAI

[RedDevil]

Originally Posted by XYZ

Immersion heaters are meant to be immersed - in liquid ...

I think he meant that. Anyway 1500 W would heat the air way too much, and I cannot pull that from the battery.

I know the eWAI would be less effective than block heating, but it is a 'no strings attached' solution; it would work anywhere.
While it does put additional load on the system it uses way less energy than a block heater would, because it only has to run for a few minutes before the engine parts are warm enough to heat the intake air by themselves.

[XYZ]

Originally Posted by RedDevil

I think he meant that. Anyway 1500 W would heat the air way too much, and I cannot pull that from the battery.

I know the eWAI would be less effective than block heating, but it is a 'no strings attached' solution; it would work anywhere.
While it does put additional load on the system it uses way less energy than a block heater would, because it only has to run for a few minutes before the engine parts are warm enough to heat the intake air by themselves.

I like your idea, but executing it will be a challenge. The reason I'm not a fan of block heaters is that they only can be used where electric power is available to plug into. This is fine for when starting out from home, but the block heater can't be utilized in other places when the engine is again cold.

[Frank Lee]

Anyway 1500 W would heat the air way too much, and I cannot pull that from the battery.

Hair dryers are more powerful than that, and even at that power I am still having difficulty with the concept having enough juice to work.

There's your test right there. Cold start, 1500w hair dryer in the intake, what happens? Or stick two 75w light bulbs in there. That is the power you are talking about.

[RedDevil]

Originally Posted by Frank Lee

Hair dryers are more powerful than that, and even at that power I am still having difficulty with the concept having enough juice to work.

There's your test right there. Cold start, 1500w hair dryer in the intake, what happens? Or stick two 75w light bulbs in there. That is the power you are talking about.

Don't need to test that; I know what will happen. Within a minute the plastic airbox will melt. The engine might misbehave or stall befiore that. 1500 Watt is way too much.

I'll break down the math for you.
This morning my engine was running at 1300 RPM when cold (9 degrees Celsius). At sea level.
The displacement is 1339 CC and the engine load, equal to intake manifold pressure when the EGR valve is shut, was just 28%. Not very cold so not an ideal example, but real and verified data.

How much air did it use per second?
1300 RPM means 650 intake strokes/minute or 10.8333333 per second.
Times the displacement (1339 CC) is 14,505.833333 cc per second or 14.50583333 liter.
But that is just at 0.28 atmospheric, so 14.505833333 times .28 is 4.061633333 liters of air per second at atmospheric pressure.
It used just 4 liters of air per second.

How much does that weigh?
First we need to know how much that amount of air weighs by factoring in the density. Wikipedia says the density of air at sea level at 10 degrees Celsius is 1.2466 kg per cubic meter, or gram per liter. We use 4.06163333 liter per second so that's 5.063232113333 gram per second.

By how much can we raise the temperature of that using 1500 Watt?
Need to apply the heat capacity of air which is about 1.01 kiloJoule per kilogram per Kelvin change (Kelvin uses the same scalar unit as Celsius).
It takes 1.01 Joule per second to heat up 1 gram of air by 1 degree Celsius (or Kelvin, or 1.8 Fahrenheit).
Joule per second is Watt.
We need 1.01 times 5.06323113333 makes about 5.114 Watt to raise the air temperature by one degree.
When we apply 1500 Watt we'll raise the temperature by 293.32 degrees Celsius.
As we started at 9 Celsius we end up just beyond 300 Celsius.

That's the whole point.
It takes an enormous amount of energy to heat up an engine block with oil and coolant and all the other stuff.
But it takes just 150 Watt to heat a few grams of air per second to summer spec.
The purpose of heating the air is NOT to heat the engine directly, but to make the combustion process run leaner and therefore hotter, cleaner, more efficient.

The nice thing about making it electric is that I can switch it on and off to study its effect. I will.

[Frank Lee]

There will be tremendous heat losses from the air charge to the intake tract, valves, head, pistons, and cylinders; I don't think 150w will do it.

[Cobb]

I like the light bulb idea. Back in the 1900 shortly after electricity was invented my folks had an electric water pump. To keep it from freezing they had it in a small dog house like with a light bulb. I think it was 75-100 watts and was enough heat inside the dog house to keep it from freezing up on the cold night.

5 watts huh? A brake or turn signal bulb is 5 watts I beleve. How about putting a few of them in your filter box? Maybe the photons will help to boost your fuel economy?

[Frank Lee]

Yeah, run an intake scoop past the headlight.

[t vago]

Originally Posted by Frank Lee

There will be tremendous heat losses from the air charge to the intake tract, valves, head, pistons, and cylinders; I don't think 150w will do it.

One could make much the same argument for using engine coolant for heating intake air - with the added proviso that the intake air being sucked in is also sucking the heat out of the coolant that the engine would need to warm up to operating temperature, thereby lengthening engine warmup times.

[NachtRitter]

heh... The intake on my TDI actually does go "around" the back side of the driver's side headlight... Always thought that was a bit odd and it makes changing the bulb a PIA, but maybe they were on to something... ?

[rmay635703]

Originally Posted by RedDevil

Don't need to test that; I know what will happen. Within a minute the plastic airbox will melt. The engine might misbehave or stall befiore that. 1500 Watt is way too much.

The nice thing about making it electric is that I can switch it on and off to study its effect. I will.

No you really don't know what will happen, I have run this experiment with a hair dryer but I allowed the dryer to heat the intake for about a half hour, then the diesel could start. Nothing melted (or even got warm per seh)

Anyway...

I am all for experimentation but 150 watts on a running engine is NOT enough

A hair dryer "typically" can put out about 20FT3 per minute and generally raises the temperature of that 20FT3/minute of air by 60 degrees. The purpose of a dryer is to heat a very small amount of air to a high temperature and eject that very small amount of air at a high speed. So you really don't get much more than 4ltrs/sec (9.8ltrs/sec on a cheap dryer) High end models peak around 41CUFT/minute (but who has a 1900watt outlet)

This means if it is -10F (as it has been around here lately) you would in theory get your 20FT3/min = 9.8ltr/sec up to about 50 F or get which is all fine and dandy and also rather meaningless because its just as easy to cool the air as it is to warm it. The element also wicks a LOT of heat into the housing and other areas, hence why a dryer is not super efficient (compared to theory)

You would need your heating element inside the engine (like a glow plug) to even heat the air inside the engine significantly because the temperature drop after touching lots of plastic and steel and of coarse the fuel evaporation would bring you down basically to where you start.

So that 100 degree temperature raise a dryer would give you at 4ltr/sec would likely turn into a 20 degree increase once it gets to the block (if you are lucky) The solution would be to insulate the intake but then once the air hits the liquid fuel and the metal in the block and intake the temperature will drop like a rock.

To be honest, I WOULD LOVE to see gasoline motors with glow plugs, then we could run hydrous ethanol year round. An added bonus might be better fuel economy on startup because of the timing affects from having a glow plug in there. (it would need to be hot but not too hot and would be VERY interesting to see)

If you have a strong head design and room to put in some $9.99 glow plugs do me a favor and mill/drill your head so you can fit in 3 of them, I would love to see that because it REALLY would have a very real affect on combustion

You would probably need to retune your motor though as it would affect the flamefront beyond your normal ECU trims.

Ah well but I digress.