12V small induction heater... possible, feasible?

Discussion in 'General Electronics Chat' started by CPUNeck, Sep 8, 2009.

  1. CPUNeck

    Thread Starter New Member

    Sep 8, 2009
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    Ok, I'm re-engineering my Waste Vegetable Oil (WVO) powered diesel pickup, and trying to move away from using conventional resistance heat, coolant heat, and exhaust heat. Is inductance heating a feasibly economical solution? My heat requirement is no where near what these things are capable of, 180-200 degrees Fahrenheit max, for sections of 1/4" pipe. I'm a noob here, and while I've done lots of things, designing electronics isn't one of them. Before I dive in and learn more than I'll ever use more than once, I'd like ya'lls opinion on if I'm wasting my time on this. Thanks for the read, sorry for the length.

    -C
     
  2. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Hi.
    Try a typical 120VAC conventional resitive element powered with 12V; or a variac; or a dimmer, to warm your fluid to needs.
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Why? (fill characters)

    Ken
     
  4. CPUNeck

    Thread Starter New Member

    Sep 8, 2009
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    Well, turns out Vegetable oil is an AMAZING cleaning agent ;), it also destroys copper, eats zinc (read anything galvanized), delaminates single part epoxies (POR-15), strips paint, and on and on! I'm afraid to submerge anything in the tank (HDPE) with current as this could introduce galvanic activity, melt the plastic, and if it isn't hot enough to melt the plastic, it'll take to long to heat the oil.

    On a 33 Gal tank, the oil presents a significant amount of thermal mass, and in the past a lot of my intoduced heat has been absorbed by it. I'm intreged by the rapid heating I could attain in a small, contained area. I could also form a coil around the exterior of part strategic locations on the fuel line, to maintain the temperature in cold weather.

    Oh and can't forget the "cool" factor:D, I'm kinda like that. So, would I need a cooling circuit even for such low temperatures. How about this, could I use an audio amplifier for the driving unit fed by a tone generator tuned to the coil I build to heat the metal? Thought of that going to work this morning. If it's crazy complicated, I'll punt and go a different way, but a change will have to happen one way or the other because what was in place was to complicated, and grossly inefficient. Thanks for the replies.
     
  5. eblc1388

    Senior Member

    Nov 28, 2008
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    Have you ever try to find out exactly how induction heating works?

    It is done via induced eddy current circulating inside a conducting medium and the current creates heat due to ohmic effect.

    Now, how would you induce eddy current in oil, which is a very good insulator?
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    You could just wrap a decent amount of turns of wire (to make a coil) around the metal fuel line, then put an AC current into the wire.

    But I agree it would be easier and more reliable just to epoxy a heap of 1watt resistors around the metal fuel line (for a few inches) and run some DC current into the resistors. The wrap some insulation around that. Warming oil is not rocket science! ;)
     
  7. CPUNeck

    Thread Starter New Member

    Sep 8, 2009
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    Thanks guys for the suggestions, I know it seems hard to get your arms around.... so

    Would the AC output of a standard audio amp be sufficient? Being that this system is on a vehicle, AC voltage is not easy to come by;).

    The two most important places I'll need heat are right at the pickup in the tank, because this is on the suction side of the fuel pump, and if the oil is congealed, it will cause my pump to cavitate and that's bad. Second place is the filter element, as standard motor oil filters, it doesn't function as designed until the fluid flows at the expected viscosity. I've tried to heat the filter with an element "formed" around it, and the AMP requirement was crazy! Not to mention, it was trying to cook, not warm.:rolleyes:
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    See the second part of my post, I really believe you are better off with a resistive heater. ALL the heat is at the output and it must be more efficient than an induction setup provided you insulate it well. An induction heater needs a controller that is lossy (wastes heat) and will quite likely be unreliable and fail.

    If you use resistors as the heating elements you can dial in EXACTLY how many amps it will draw and how hot it will get. Resistors have a resistance value that will remain the same (current will be the same) both hot and cold provided it runs under boiling point as example. So heaters built from resistors don't make the big current inrush when cold, and last practically forever compared to other types of heater elements .
     
  9. CPUNeck

    Thread Starter New Member

    Sep 8, 2009
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    Well I suppose I discounted a "resistor" type heater. I need to understand better how to build that. Would I just figure the total resistance needed, maybe divide that by a quantity (say 4 or 6), than wire them in series to some 14 gauge wire?

    If it could be that simple, perhaps I could embed the resistors in an epoxy casement surrounding the parts that need pinpoint heat. I certainly could make this work if I understand it... just was not aware that a resistor getting hot, wasn't literally melting down. Thanks
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    How many watts do you think it requires? It won't take a lot of power to heat your 1/4" metal fuel line for a few inches. Then it depends how much oil will be flowing through and how many degrees the oil needs to be heated.

    I would start at about 20 watts, just as a guess. Unless you know the wattage of commercial electric heaters used for this?
     
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