Hi, as part of my senior project, I am using an injector pop tester to check spray pattern of diesel/ biodiesel and veggie heated to different temps... The only place that I have seen mention of anything similar is craig reese's thesis (neoteric/ plantdrive) Has anyone else out there done this type of testing ?

I haven't seen any mention on the board here of something like this, but what I am most interested in is somehow being able to measure the exact temp right before the injectors.

This is important in my case because fuel flow is slow through the (hand pumped) tester, and even though I am able to controll the temp precisley at the fluid container, it travels quite a distance before going to the injector...

therefore, I don't think that just insulating things and pumping fuel through for awhile would help much...

The metal line going from the tester to the injector is about 5" long, and the best idea that I can come up with so far is some type of water bath heater for this section of line... but this would be difficult...

Any other ideas/ suggestions? (they would be very greatly appreciated)

This will be using vw 1.6 injectors (aprox 2500 psi), and therefore teeing in any type of heating element or sender to the metal line going to the injector would be scary..

Any ideas for precise monitoring in my situation could also be applied to heating or monitoring temps on the metal lines going from the ip to injectors on almost any engine.

I'll try to post pictures and of course the results of this study asap...

Thank You!

Greg

For heating a single short injector pipe I'd recommend Dana's electric line heater, or Fat John may also offer some option.

For monitoring the temperature, spot-welding thermocouples in appropriate locations would be my first choice. I'd control the heat with a temp control unit that uses the thermocouple for sensing and the heater for heating. Alternatively, use a variable power supply to the heater and take what temperature you get.

Don't reuse the injector pipe on an engine if it's had thermocouples spot welded to it - they create stress risers that will eventually lead to the pipe breaking a few thousand miles down the road. If you want to spot weld thermocouples to a running engine, keep track of the hours on the pipes, and change them when the testing is done. The fuel jet from a cracked pipe is invisible, but can easily penetrate skin.

For very precise monitoring that is for testing purposes only (not meant to last thousands of miles) then I would use a digital temperature sensor such as a Dallas DS1820. This part measures -55°C to +125°C in 0.5°C increments. Use a thermally conductive adhesive paste to mate them together and then insulate the sensor and line so radiation of heat does not reduce the measured temperature.

Using a metal thermocouple would work, but the large mass will act as a heat sink and reduce the observed temperature. A small DS1820 will not.

I've thought of doing this and if I were I'd heat the whole setup that way you know the temp is accurate. We use hose clamps or fiberglass heat tape to hold T/C's in place at work and this seems to work fine. Some heat cable, some control and away you go! Make sure to post results here with pictures please!

The only problem I see with this test is that the injector will not be as hot as it would be in the head on a running vehicle which may have an effect on the heating of the oil, thus the spray pattern.

We do sell a single cylinder hearter... the cost is $18.. and we also do bench testing with a heated line... The combustability is dramaticallly improved when the VO is hot.. even when passing trough a cold injector..

Patent-pending ---

I have been doing some testing along these lines, I am using small standard steel tubing clamps with solid state sensors attached, they just clamp over the lines wherever you want to measure temp. You have to supply a small dc voltage to the sensors to power them, 5 volts works, the output is a dc voltage directly related to the temp, this voltage can be read using a cheap digital volt meter ($3-8.oo from harbor freight). You can then calculate the temperature using the measured voltage from the sensor.

The clamp is the style that completely surrounds the steel line and has a wing with a hole in it for mounting ( dosen't need to actually be mounted to anything, just clamp them around the fuel or injector line), I solder a 1/2 inch length of brass hobby tubing to the outside of the clamp, the tiny 1/2-pea sized sensor and the small 3 wires connected to it are then completely submerged and sealed in epoxy inside the brass tube.

Eventually these sensors will feed a small LED dash display that will indicate one of 4 selectable sensor temperatures directly in either F. or C. temps.

This is a link to a 1 page pdf of the clamps,I am using the ones at the upper left hand of page.

This link is to a list of solid state sensors that can be used, lm34 output in F, lm35 output in C., dosen't matter much, still have to calculate the temp from the measured output voltage, higher precision costs more, click the blue part number for more info and specs.

Both these links go to Digikey.com electronic parts on-line catalog, same parts are available many places.

How about this idea:

Use a standard lab constant temperature water bath and a small submersible aquarium pump. Pump the water through an outer hose and run the metal fuel line through a hose within the outer hose (HIH setup). If you monitor the temp of the fuel in the container and the constant temperature water bath, you can be fairly confident that the fuel reaching the injector will be the temperature you desire.

The injectors will act as a heat sink, although its worth considering fattys point that even with cold injectors heating the fuel makes a difference.
Girl Mark was threatening to do some testing a while back and I think she was going to heat the injectors with a blow lamp before testing.
Getting an idea of the working temperature of an injector would be usefull (but difficult?).
Need to consider all this to get usefull results...

The mass of metal that is the injector and its nozzle will take quite some heat, I guess one of Fatty's heaters could be wound round the body, as well as the line and sufficient time allowed for the heat to transfer to the nozzle before testing was carried out, with a thermistor in thermal contact with the nozzle itself.....

How are you going to examine the performance?...Specialised photography is usually used during nozzle development....The human eye wouldnt really be accurate enough at the tiny droplet sizes found with nozzles, although you should see a difference between a cold and hot nozzle!

Info on my recent pop tester work here.
Pictures and videos of the popping here.

quote:

The combustability is dramaticallly improved when the VO is hot.. even when passing trough a cold injector..

I should have also mentioned that a hot injector doesn't always provide hot VO.. At very low flow rates / idle / yes the VO does come out hot but... combutability is still improved by heating the injector line.. heating the injector has even more benefit when you increase the flow rate..

quote:

How are you going to examine the performance?...Specialised photography is usually used during nozzle development....The human eye wouldnt really be accurate enough at the tiny droplet sizes found with nozzles, although you should see a difference between a cold and hot nozzle!

I outfitted a heated combustor to simulate compression temperature at the end of the injector.. when the VO is cold it doesn't combust... If you hold a torch in the spray it will ignite and you can ctually see large droplets burning... combustion is not complete.. as the line heats up it burns more completely.. eventually with no smoke.. and with fairly violent combustion..

Your pyromania is showing John... did you forget to take your medication again?

Ha ha.. very funny.. everyone knows I never take my meds...

quote:

Originally posted by Tim c cook:
Patent-pending ---

I have been doing some testing along these lines, I am using small standard steel tubing clamps with solid state sensors attached, they just clamp over the lines wherever you want to measure temp. You have to supply a small dc voltage to the sensors to power them, 5 volts works, the output is a dc voltage directly related to the temp, this voltage can be read using a cheap digital volt meter ($3-8.oo from harbor freight). You can then calculate the temperature using the measured voltage from the sensor.

The clamp is the style that completely surrounds the steel line and has a wing with a hole in it for mounting ( dosen't need to actually be mounted to anything, just clamp them around the fuel or injector line), I solder a 1/2 inch length of brass hobby tubing to the outside of the clamp, the tiny 1/2-pea sized sensor and the small 3 wires connected to it are then completely submerged and sealed in epoxy inside the brass tube.

Eventually these sensors will feed a small LED dash display that will indicate one of 4 selectable sensor temperatures directly in either F. or C. temps.

This is a link to a 1 page pdf of the clamps,I am using the ones at the upper left hand of page.

This link is to a list of solid state sensors that can be used, lm34 output in F, lm35 output in C., dosen't matter much, still have to calculate the temp from the measured output voltage, higher precision costs more, click the blue part number for more info and specs.

Both these links go to Digikey.com electronic parts on-line catalog, same parts are available many places.

Not a bad idea. I would take a few steps to help get an accurate reading, namely wrapping the clamp and measuring device in an insulative wrap so heat is not radiated while traveling to the sensor. Also make sure you pick a thermally conductive epoxy. Many epoxys aren't very good thermal conductors. You can get special thermally conductive epoxys, although they are not dirt cheap and have to be purchased through a specialty supply company.

quote:

Originally posted by asnowquall:
Info on my recent pop tester work here.
Pictures and videos of the popping here.

WOW, very impressive! That must be some high frame rate video :-) Keep up the good work!

quote:

Originally posted by rackley:
Also make sure you pick a thermally conductive epoxy. Many epoxys aren't very good thermal conductors. You can get special thermally conductive epoxys, although they are not dirt cheap and have to be purchased through a specialty supply company.

IMO you can use gasket silicon as epoxy. I think it's a good thermal conductor.

What data can you cite to back up this assertion that gasket silicone is a good thermal conductor?

Take a look at this link and look at "Silicone Rubber" - as you can see, it conducts heat slightly better than an absolute vacuum. Which isn't much, BTW.

http://books.google.com/books?vid=ISBN0412084317&id=qUv...bSCuINiA0cAlE4meGY8M

Also note this citation of GE's silicone rubber RTV:
http://books.google.com/books?vid=ISBN0815512953&id=qPM...s3icf32Dv3vDZVDbwjcc

You'll see that the thermal conductivity ratings are extremely low and one of it's applications is actually listed as a thermal insulator.

Most of the metal-filled epoxies are pretty good thhermal conductors. Almost any adhesive in a very thin layer offers little insulation, but why not choose something better if you've got a choice?

Just started testing the sensors, using good old JB weld epoxy for now. Will test several types of epoxy but really don't expect it to make any practical differance as there is such a small amount used.

These sensors are not expected to follow instantaneous changes in temp, just soak up and average of whatever heat the steel fuel line has to offer. They have a tiny mass and are mounted within 3/32 of an inch of the fuel line and heat conduction is through steel and brass in intimate contact with 1/2 inch length of the fuel line ( clamp is 1/2 inch wide). The actual semiconductor sensor has, at most, only a few thousanths of epoxy between it and the brass outer shield. They will be insulated with a bit of foam or silicone tape eventually.

They will also be used to sense and control the cab-adjustable fuel line temperature using PWM heat controllers to match fuel and injector line heat to whatever blend I am burning at the time. This same closed-loop control will also automatically control of electric line heaters to compinsate for cooling caused due to engine RPM flow rate demand of fuel through the line.