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DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 10:52 am
by seudo_411
So I have this idea of making a glow plug. to vapourise fuel.

This is what I plan to do:

Using a 1/4" male to male coupler, Nichrome wire and a ceramic clay or epoxy.

I am going to make a halo out of the nichrome wire about the size of a penny. bring the two ends through the coupler. and screw that into a 1/4" T, the idea is that fuel is suplied from one end, (remote of course) and vapourized by the wire, it then flows out the T into the burner cup. and well burns. need to draw it up first but its coming alright.

Now what I need help with is the wire. I have ordered it and its 8ohm per meter. I have no idea what this means, how much voltage or current is needed.

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 11:20 am
by DarenN
the resistance of the wire is 8ohms for every meter. it follows that 50cm will have a resistance of 4ohms. i've seen foam cutting equipment that uses Nichrome for the cutting element and the power supply is always low voltage Direct Current. what i would try is a model train set DC transformer of the type that has a voltage control reostat. start out at zero volts and slowly increase the voltage until you reach the desired temp. then a multi-meter can be used to see exacly what voltage was attained. from there you can build a battery pack that carries the voltage you want.

Daren......

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 11:33 am
by DarenN
Seudo;
i emailed a freind that knows more about this stuff than i do. i'll post what he has to say after he replies.

Daren........

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 2:24 pm
by seudo_411
Thanks DarreN, The one part that has me stumped, is how much voltage do you need,I'm sure there are some calculations I can do. For instance If resistance across a 1000mm length is 8ohm, and across 125mm it is 1 ohm OK got that bit down. I think I'll start with a fixed voltage and then adjust the wire length.

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 8:05 pm
by DaddyMnM
It is not so much the voltage you apply but the power. This depends on your power source and is a combination of the voltage supplied and the load or resistance.

There are several formulas that apply in this case. Here are a few:

V = I X R
P = V X I

V is voltages in volts
I is current in Amps
R is resistance in Ohms
P is power in watts

A standard AA cell battery outputs approximately 1.5Volts. Alkaline AA cells can provide about 1700 mAh (milli amp hours) of charge (milli means 1/1000). This means it can output 1700 1/1000th's of an amp for an hour before it is dead.

Say you have a 10 ohm load on an Alkaline AA battery.

1.5Volts/10 ohms = 150 milliAmps so connecting 10 ohms on an Alkaline AA battery will draw 150mA. If left on the battery, the battery would last 1700mAh/150mA = 11.33 hours.

1.5Volts X 0.15Amps = 0.225 Watts consumed as heat

Now you will have to experiment to determine if 0.225 watts is enough heat to suit your purpose. But the basic electrical formulas should apply. I don't know if a single AA battery has enough energy to vaporize alcohol. That will be something you will need to determine.

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 8:36 pm
by DarenN

Re: DIY glow plug- Help needed

Posted: Wed Mar 25, 2009 10:34 pm
by zelph
I made some electronic firestarter with nichrome wire. I also used rocket motor igniters as ignitors for magnesium powder and shavings. The photo shows 4 wires sticking out of the ziplock bag of magnesium. I used a 9v battery as the power sourch. I was using 9v everything at the time of the survival kit making era :D See the mega LED DIY flashlight and also see the commercial cap for the 9v bat.

Image

Re: DIY glow plug- Help needed

Posted: Thu Mar 26, 2009 7:12 am
by seudo_411
Image

Just a little table i drew up, It shows loads from 1to 10ohms and voltages from a single AA rechargeable and two in series. hence, 1.2 v and 2.4 volts. The approximate length of wire per load is also show.

I'll know what the different wattages look like once i get the wire. Because the wire could get quite long, I was going to take some ceramic clay and make a disc to fit inside the tin i'll be using, and cut a spiral groove.

Re: DIY glow plug- Help needed

Posted: Thu Mar 26, 2009 9:37 am
by zelph
I'll know what the different wattages look like once i get the wire. Because the wire could get quite long, I was going to take some ceramic clay and make a disc to fit inside the tin i'll be using, and cut a spiral groove.
Adding a ceramic disc is more mass to be heated, more drain on the battery, longer vaporization time. Things to be considered.

Re: DIY glow plug- Help needed

Posted: Thu Mar 26, 2009 10:31 am
by seudo_411
Thanks Zelph I had not considered that. But I have been chatting to the supplier for a few more parts, basic stuff battery holders on of switch, and a twisty knobby thing to control the power.

I know myself, I have to do this in stages or I'll get side tracked. Once I have the heating element, figured out, I will look at how i can integrate it. Currently I have two options in mind. Making a circular coil and integrating it into a pressurized photon style stove. Or making a similar container that houses the fuel and heating element topped with a jet. gonna try 0.6mm. and adding a burner head. so it looks a like a canister stove.