Austin, Heres a pic ot my glow plug WVO heater
 

Does anyone on the forum know how to reduce the voltage to the glow plug so it does not get as hot?

Thanks,
Matt

If you lower the voltage enough it will be equally less-hot, every 1.2 volts or so you take away, it will be about 10% cooler. I suppose the voltage decrease can be done with a large pentiometer, or a large heavy duty resistor etc.....

I don't know how to do that, I'm sure it would be easy, but trying to heat a glow plug to regulate temperature seems a disaster waiting to happen. There will be such point concentration of heat, you are likely to vaporize fuel in the line, and risk possible ignition.

This is assuming you are using that for an inline heater. Even if you could tone that down to a moderate temperature, and control it exactly, and put it in a tank recirc loop, rather than on the way to the engine, the lack of surface area to the glow plug for heat transfer would take forever to heat to temp.

As I said earlier, I don't know your intention with that, but to me it seems a bit dangerous. Please be careful with electricity, fuel and heat outside the combustion chamber. If this is something you have past experience operating successfully, pardon my ignorance, I'm just trying to give you some feedback.

John

If you get a snap disk style of thermoswitch from an appliance repair house and install it on the return line you can have the glowplug heater cycle to maintain consistent heat. Snap disk switches are available in different trigger temperatures and you simply use one to drive a relay to power the heater. Snap disks are used in water heaters and the like. This is one of Dana Linscotts ideas. It is not dangerous to use a glowplug heater provided its properly controlled. RT

Its an excellent idea that is not quite properly executed. Glow plugs are designed to produce an insane amount of white-hot heat on a very small little spot, an alternative would be to construct something along the lines of a "heatsink" that the glowplug could insert into, which fuel flowed through with a lot of surface area and turbulance, so it heats up well and without a concentrated hotspot like that.

Computer watercooling heatsink blocks come into mind.....except modified so they get real hot with a glowplug, I don't think it'd be all that hard.

I agree your current setup will probably vaporize/coke up the fuel along the way unless you increase the surface area or drastically lower the voltage (at which point it'd probably be useless anyways)

To not burn the glow plug out you have one of two options:

#1: use a thermoswitch of some kind

#2 Use some resistance wire. Resistance wire is what's between each glow plug in a series system. Like this

Your design is very similar to others I've seen on the infopop veg. oil forum and the reports from it seem to be pretty good, you probably won't see any problems if you get it regulated somehow.

Mac2,

Thanks, thats the kind of info I needed!!! :D

Matt
 

1. The glowplug will last indefinetly without burning out as long as there is a flow of liquid going through it... which there will be.
2. There are 12v glow plugs for Fords that will not get any hotter than 150degrees F. So you don't have to reduce the voltage...

3: Matt, What are the parts called that you used to build this thang? I am ready to put one together tomorrow....
AA

What is a "heatsink" design? What is used to build this with a glowplug as the heating element?

1..3/8 Steel T fitting

2.. 3/8 brass barbed fittings

1.. Brass fitting that fits the T & Glow plug

Austin, Call me if you need more help. Oh yeah, Can you find out what the part# is for the low heat glow plug is?

You would attain one of the "waterblocks" pictured below, then attach a heating element and/or glowplug to it by way such as milling out a little hole in it, making threads for the gp, then "sealing" it into the block so it has good thermal conductivity. I'd think this would work pretty good due to the large heating surface area for the flowing oil/fuel......

Well now we are talking. i have built many custom watercooling setups for my pc and the best way to heat your fuel would be with a peltier (TEC) and a waterblock. one side of the peltier needs a heatsink(to cool it) and the other side gets extremely hot. i use a 220W peltier with my pc, and it will have a equally cold side. most are made to run at 12v, and are easily attached and made into a fuel heating module.

the H is the hot side, the other gets cold, and in case of the processor it cools it so it runs faster. you would just need a simple heatsink on one side of the peltier and the other side has what pawoSD has pictured, your run the fuel through that, and all is well. i think i will build one with my extra parts i have and show you guys.

in the pics below is my peltier from my pc, it removes heat, but all i have to do is turn it around and it would add heat to my chip. in this case we need heat added to the fuel.

I think the waterblock idea is a bit overkill (no to say they don't work, they do and well) its just not necessary . The WVO will be flowing past the trip rather fast so damage to fuel is extraordinarily unlikely (vaporization won't be a factor) and heat will get transferred to the pipe which will then be conducted into the oil. The pipe design is cheap and easy and works well enough that there is no real reason to lathe out a block design.

Glow plug heater didn't work for me
 

I was trying to heat wvo for use in my 1.6L N/A Rabbit and I used a Bosch gp from the Rabbit and a tee fitting. Even at idle, that Rabbit pushed enough fuel through the fitting to completely cool the glow plug. As soon as I'd stop the motor, the gp would heat way up. Start the motor again, and it cooled right off to damn near nothing. I was hoping for about 150F, but wound up with a little more than ambient.

Your mileage may vary.

Chris Boyer
San Diego, CA

:confused: :confused:
HUh!!!!!!!!!!!!!!!

How does this relate to reducing the voltage to my Glow Plug heater :confused: Thats the orginal Q I had asked :rolleyes: I guess its hard to stay on the same page somtimes ;)

The Glow plug heater IS a proven WVO heater. YOU must use the right amperage glow plug though. The Mercedes Glow plug heats to about 1100/1200degs!! Theres no way the WVO is going cool a red hot glow plug tip down around 100degs or so.

well MAttSD300, your question was going south. many posters said it is not the best design and there might be something else you can do. pawoSD made a suggestion about a better way, and that idea is what i was trying to improve upon.

with comments like that you might as well just answer your own questions...

You wanna reduce the voltage to a glow plug?
Wire a 2nd glow plug in series with it. Now you have 1/2 the voltage and 1/4 the wattage in each plug, they should last forever and convert half as much electricity into heat as a single plug.

Thats what I would suggest as well. Twice the surface area of two GPs would make for a much better heater.
You would have to electrically insulate the pipe fitting from ground. Two insulated tees plumbed together, connect +12volts to one gp terminal ground wire to the other gp terminal. Added bonus is the current requirement drops too.

That sounds like a plan....
As discussed...run 2 of these orignial t fittings together, with 1 mercedes gp in each unit. If each heats to about 1,200 degrees, with the reduction in voltage each would now heat to 600...or 300 degrees...(Dan says 1/4 the wattage...would be 300 degrees each.) AND with 2 in unison the fuel is being heated longer , and would get to the temp you're looking for ......

ANy comments?

Mitch & WhiskyDan,

Thanks so much!... Thats a great idea!:D

I'd make a controller circuit using a large MOSFET and a variable duty-cycle pulse controller, to get the right temperature. The temperature can be measured indirectly by the resistance of the heater, which can be determined by the voltage across a low-value high-wattage resistor in series with the ground. More voltage (during the on cycle) means more current, lower resistance, and thus lower temperature.

Translation please for the rest of us...

I understand him......:D







But then I have a background in electronics...








Its basicly building a self regulating heater...........

I was thinking the same thing. Your not necessarily limited to MB glow plugs. Look around till you find one that suits your needs.

Danny

Partial translation: A MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) is a type of transistor which takes no input control current (that's a fudge - there is capacitance at the junction) and, if run in so-called saturation mode, has extremely high or extremely low conductivity, which means that in reality, it takes almost no power from the circuit even if switching a high current (which you will have). "Normal" transistors are called bipolar, and they always have a voltage drop on the controlled current, thus they always take power from the circuit. Taking power isn't the problem; the problem is getting rid of the heat generated to avoid destroying the transistor. With a 1 volt drop and a 15 amp current, you need a 15 watt transistor. That's a lot of heat. While it can be achieved, I'd just go with a MOSFET.

Duty-cycle is the ratio of on-time to total-time for a square-wave signal. A duty cycle of 1 (100%) means always on, 0 means always off. In between gives you variable power, even though it's always either full or none at any given instant. Varying the duty cycle can give you variable power, as needed.

As for measuring the temperature, this is how it's done in a MAF sensor. Controlling the duty cycle from this is really not very complex, although the circuit design is complicated by the fact that you can only reference the temperature when the MOSFET is conducting.

You are overthinking this one. All glowplugs, not just MB plugs, get really hot like 1100-1200*F hot. A glowplug is designed to heat the air in a prechamber and provide a localized hot spot for the fuel to ignite on. When you use them to heat WVO or any other liquid they stay MUCH cooler if there is significant flow past the element. This should be obvious as you are now asking the glowplug to heat a much more than it was designed to and also using a far better conductor of heat than air, WVO. Chrisboyer has already pointed out that a single glowplug heater was not enough for a VW Rabbit diesel. Glowplug "heaters" installed in WVO systems are generally used to boost the WVO temp after it has already gone through the coolant heat exchangers right before the WVO enters the IP. They also work well installed in a fuel filter head to keep the filter from plugging. They are not enough to heat the WVO significantly on their own. On domestic pickup truck diesels that have been converted to a two tank WVO system is isn't uncommon to see 3 or 4 glowplugs used at full power to heat WVO. Another way to regulate the WVO temp is to install a temp gauge in the fuel line right before the IP. If the WVO temp gets to high, turn the heater off. RT

Porcocane!
 

:eek: Note to self: Never buy a used diesel from a WVO'er.:eek:

LOL :P

But think of all the interesting engineering that may be onboard the vehicle! :D :D ;)