GEK Wiki / Glow Plug Test
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Glow Plug Test

Page history last edited by Daniel Chisholm 10 years, 5 months ago

Glow Plug Test

Date: 2/24/08

 

Online Discussion of Heating Element Start Up: http://listserv.repp.org/pipermail/gasification_listserv.repp.org/2009-February/013180.html

 

Description:

A set of diesel glow plugs were purchased and tested to explore their potential to start the GEK with minimal hassle.

 

Plugs where choosen to be commonly available (Bosch 0250202254/ Ford F2TZ-12A342-A): a "factory replacement for 1988 to 1994 Ford and IH (Navistar) Trucks and Vans" (ebay)

 

Individual power consumption is roughly 50 W (when glowing red in open air).

Plugs can not handle direct connection to a 12V car battery, they will overheat. Recommended circuit pending.

 

Shown below is video from ignition of a wood pellet in open air (behaviour in packed material is less impressive).

Images from ignition of a wood pellet in open air. Ignition was near instantanous (0.25 sec after contact).

Video of ignition (download [mp4, 384k])

 

Video of ignition of charcoal with air flow and glow plug (download [mp4, 824k])

 

Charcoal was at air equilibrium moisture content. Torch used to minimize CO emission. Full ignition not shown in video. Ignition of wood pellets was also tested with the same arrangement.

 

Discussion:

The open air ignition of the wood pellet is promising. As a packed bed with air flow, char appears to ignite faster via the glow plug than a bed of wood pellets (not shown).

 

The glow plug was integrated into a "wand". The obvious dangers associated with an exposed element advocate for a stationary perminent itegration into the GEK. One potential design is to mount the plug/tube assembly coaxially centered with the cowling. For a fixed mount the optimal vertical position that will avoid overheating of the element will need to be determined. The assembly could also be mounted to provide manual vertical adjustment and fixing with a set screw if a suitable permenant vertical position is not found.

 

A circuit may need to be developed to maintain a constant temperature of the element (e.g. fully stopping current after combustion is started and [potentially over-]heating the element).

Comments (3)

Andrew Schofield said

at 6:49 pm on Feb 26, 2009

In the 1980 model year Oldsmobile 5.7-L diesel (Cutlasss), There was a controller which operated from senced water-jacket temperature. Output was: a timed pulse of two seconds duration on, two seconds off , pilot-operated a heavy solonoid switch very similar to the ubiquitous Ford starter switch. This pulsed cycling of the glowplugs ensured their correct operating temperature, until the engine reached operating temperature.

Being a solid-state black box, that used to be off the shelf, these would be ideal for gasifier light off duty.

I had a duiscussion last winter with a gentleman in the Netherlands whom strongly recommended using a retractable glowplug arrangement, to prevent damage to the element when the gasifier is operating. I would have the plug enter the hearth, near a nozzle to complete the fire-triangle for lightoff.

Either timed, or from a senced-temperature set-point, the assembly would be retracted radially to a safe-location.

Andrew Schofield
GL-RFS

Dutch John said

at 12:43 am on Feb 27, 2009

"Gentleman in the Netherlands".... Just call me DJ!

Hey Andy!

Yes, I am using a glow plug for ignition of the hearth. After playing and experimenting a lot, because it is hard to ignite something in the open air with a glow plug. But not in a blasted charcoal environment. Just 10 seconds power on the plug, wait another 10 seconds untill pale blue smoke comes from the stack. Then pull the glow stick and plug the sonde tube.

The difficulty is the position of the sonde tube. It should enter the oxidation zone somewhere between nozzles and restriction, because that is the spot you want to ignite. Higher is not possible because there is no draft and less or no char. And igniting the reduction zone will take too much time to have the heat creeping up. I have two preheating mantles, so made the sonde tube in the bridge between the mantles. Some air leaking between tube and outer cowling mixes with preheated air.
For the GEK it will be challenging to add a sonde tube. Perhaps a sloped tube from above directed to the hearth, but not to long to avoid obstruction of wood. The pointed glowplug will find its way through the chips.

When pushing in the glow stick, there is almost no resistance of char. As if the oxidation zone is empty.

For a next setup I want to introduce a solenoid that pushes in the glow stick and pulls it way back after ignition. And a solenoid valve for the chimney. Start the whole thing from the drivers seat.

Regards,
DJ

Rib said

at 2:24 pm on Mar 5, 2009

Hi from Ireland been lurking for awhile.
Just to add to the glow plug theme. Most modern diesel glow plugs (indirect injected anyway) are 3v continious with 12v applied for 3-4 seconds to achive rapid heating to operating temp. then controller drops voltage to 3v to mantain at operating temp. this prevents Misfires while engine is still cold and prevents excess white smoke. system turns off after engine reaches set temp.
Another posssibility that could be used for initial ignition is to Use a a hot air Paint stripper to provide te inital heating to heat the wood to is flash point. this is what is used in most wood pellet burners.I have seen in Larger burners a modified Bosch paint stripper. while smaller burners like PELLEX /Iwabo/ use the own small heater cartridge.

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