induction heating diesel injection lines

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I have to wonder what your car insurance company would say if your truck caught fire because you were heating your fuel lines.

Why not biodiesel? It's quite easy to make.

Is your fuel pump located in the fuel tank? If so, you've got a problem.

Michael

uhh...I think an actual steel tube should be used for the test. A tube cross section has more magnetic reluctance than a rod with same diameter. iow..you may need to apply more power to get a tube as hot. (I think I got that right..My magnetics is rusty..)

I'd try:

*Aim to make the steel permeability frequency = to the series resonant frequency.

• Perhaps use turns for say 50% power from winding loss. Might as well do element heating + induction heating at the same time. Glass cloth insulated nichrome litz wire. Arrff! Arrrf! :P (If the induction heating flops..you're all set for element heating!)

Consider a parallel resonant circuit that uses the winding capacitance for resonance at the permeability cutoff frequency.

Nice artsy project...lots of math involved. It'll probably take me a week of scribbling on paper. I'm not even sure what I wrote above is correct.

D from BC myrealaddress(at)comic(dot)com British Columbia Canada

s

I now have a driver circuit made solely of discretes that powers a tank circuit with the heating coil and a high quality capacitor (the cap doesn't get hot, even carrying over six amps at 90 kHz). The scope shows a very clean sinewave at the coil, and the screwdriver gets too hot to touch in a matter of seconds. Well, at 75 watts what would you expect. I can fix that by increasing the turns count I think.

Your heat energy is due to copper resistance and steel core resistance. I^2Rsteel where I is due to core eddy currents. I^2Rcopper where I is the inductor current.

You can add turns for more magnetic flux (if inductor current is made the same and core perm. ur stays constant) but you increase copper heat. Decide how much copper heat to have.

This project is a math/physics project. It's also a cooking project.. Not too much salt..not too much pepper..just a dash of parsley. And I'm not a magnetics expert. Maybe there's a magnetics simulator program out there?? Dunno..

Maybe this will work as a design approach..

1)Select an ac coil current.. 2)Take rms of above and run dc current through wire spread all over the place. (Don't cause a fire.) 3) Start winding. 4) Stop winding when your coil temperature is at risk of lamination breakdown. Or whatever toasty level. Next, AC testing: 5) Find Bsat and -Bsat 6) Find the time it takes to go from -Bsat to +Bsat.. That will determine your operating frequency. (I think it begins to be hard on the driver to compensate with more current to get back up to Bsat at higher frequencies.

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Sheesh, didn't you read my last post? I have a prototype that kicks @$ $, all I have to do is get away from the bench now so I can work with the actual injection line (will have to do this under the hood, unfortunately) and adjust the number of turns to get optimum power level. Or I could need to do some other tweaking, like change the capacitance in the tank circuit. No big deal. Copper resistance accounts for negligible loss. No detectable warmth in the wire. I also calculated the skin depth, effective cross section, yada yada yada. Nada.

Work remains, I have to build a feedback loop with a thermistor to regulate the temperature. Just a comparator with hysteresis, turn the shebang off when it's nice and toasty, then turn it on again a few degrees lower. I ordered teflon-insulated wire for the coils, some nice mosfets...

I stopped reading after the word 'screwdriver' :P

I suspect heating up an injection tube with heat bleeding endlessly along the metal and the heat capacity of the oil will take more energy than raising the temperature of a screwdriver. And...a tube has a lower cross section[1] than a rod, so I think it's going to take even more changing flux to get a tube hot. (You should be using an oil filled tube for experiments, not a screwdriver.)

So.that's why I suspect you might bump into a copper heat problem if it's required to 'beef up' the coil and drive harder for higher flux density at the max.frequency. That's why I think some posters suggested element heating instead. There's an efficiency cutoff on the EM to heat energy conversion on a tube section.

Here's a poor example: It takes my 800W microwave oven about 2 minutes to raise 230mL of water 75C. (Note vegetable oil and water have roughly the same heat capacity.)

All depends really on how much heat you need and how fast.

Notes: [1] Perhaps fix by putting a thick steel (or other lossy) collar on the injection tube.

D from BC myrealaddress(at)comic(dot)com British Columbia Canada

one end is connected to the cylinder head the other has cold fuel coming into it, once the head heats up not much heat will be lost that direction, and the incoming cold fuel will make good use of any heat leaking out that end.

more of a problem is that the screwdriver was probably made from a completely different type of steel to the pipe. different magnetic properties and different conductivity.

vegetable oil has about half the heat capacity of water. (as do most other types of oil)

yeah, flow rate and heat requirements figures would be useful.

Yeah ..I guess that was stretching it too much..

Specific heat of Vegetable oil 1.67KJ/KgK Water = 4.19KJ/KgK