L912 Injector

[RMusselman]

Jeremy,

Hello. I am a newly registered forum visitor.

In reviewing the capability of the L912 injector, you mentioned the model number description of the injector and the need for 900 watts of heating. Is this to maintain a steady state high temperature on the injector body and plunger as to prevent heat loss form the injection water through these parts? So the operating power for each injector would be 900 watts + solenoid power?

Obviously solenoid power would be intermittent and at a frequency required based on the crankshaft pick-up (engine speed & timing).

On your 2-D layout you mention a S08 injector, is this a new development?

As for flow capacity, since you are injecting water, you take advantage of the expansion factor of the water-to-steam transition after the fluid reaches the cylinder. If this injector was to be used for a fluid which is already steam, I assume the valve/orifice size would need increased to accommodate the capacity required? Obviously the higher the steam pressure, the higher steam density (lb mass/cu.ft.) would require lesser valve size.

In your current valve design, do you have a sense of ultimate life of the unit in hours and the potential to renew (repair) it once the plunger/orifice seats are worn? Approximately 25,000 hours continuous use may be a reasonable target I have prior to any necessary repairs.

I am investigating a concept and the use of this injector may have application.

Best regards,

Randy Musselman

[JeremyH]

Hi Randy,

Yes, the model L912 injector does use 900watts electric heat, actually there are 6 150watt cartridge heaters silver soldered to the nozzle tube.

“Is this to maintain a steady state high temperature on the injector body and plunger as to prevent heat loss form the injection water through these parts?”

Initially that was the objective, however the electric heating elements became very useful for bench testing and rating-in the seal. Using the electric heating, it is possible to mount the injector in a vise, then fill it with water then seal it, plug in the heaters and watch pressures develop inside the injector to about 3000psi, and of course discharge flash steam from the injector. This makes it possible to test the injector without any sort of boiler. Since 900watts is a significant energy sink, when attempting to run an engine, its preferred to use a heat transfer fluid (oil) circulated around the nozzle tube instead, not unlike a water jacket. It makes more sense to utilize the primary heating source (external combustion chamber) directly, instead of converting heat to electricity then back again. I prefer to have the solenoid, as the only electrical load. Here is a picture of the mosfet array (solidstate switching array) that drives the solenoid part of the injector to actuate it



The S08 injector is a miniaturized version of the L912 injector. The two are nearly identical, except the S08 has a smaller discharge orifice. This reduces the power the injector will consume when actuated. (this is related to the spring force to keep the valve closed and valve float)         

“If this injector was to be used for a fluid which is already steam, I assume the valve/orifice size would need increased to accommodate the capacity required? Obviously the higher the steam pressure, the higher steam density (lb mass/cu.ft.) would require lesser valve size.”

That’s correct, the L912 was designed to do just that. Its orifice is about .190inch  The supply pressure had to be quite high such as 3000psi.

Although I can not give an effective lifetime range with the injector, I do feel its quite durable. If the injector is manufactured properly and has good alignment, it simply comes down to the materials of the seat and pintle and planned nozzle geometry. I highly recommend a work hardening stainless steel, such as 316L for both parts. The endurance tests that were performed, occurred under parameters such as, running a 4 cycle engine using the injector as the DI valve to 3000 rpm, for sustained periods, in total, most likely this added up to about 4 hours continuous operation for the testing I did at the time. The injector was then disassembled and the pintle (control rod) and valve seat were inspected, there was no deformation and the seal held up extraordinarily well. The valve guide is made of 954 bearing bronze, it also held up well (there was no wear). The injector can be operated comfortably with working fluid operating temperatures to 550°f

There’s been quite a bit of email correspondence that I’ve had with folks over the years. This forum is my attempt to share some of that, since I’m reluctant to publish email conversations. I’m hoping that as more questions are asked, the reader will be able to access that info and it will benefit those interested in the technology.

Just for the heck of it heres a picture of the combustion chamber



Best

Jeremy

[JeremyH]

Is anyone aware of a sanctioning body, that certifies heat engine thermal efficiency?

We all know that co-gen applications, add's thermal efficiency to heating efficiency, to come up with combined cycle efficiency's upto 60% eff, I realize boiler-eff is a seperate number aswell.

I was thinking that UL Laboratories could verify "thermal efficiency" of a given heat engine... However in my research I have found they do not actually do this type of testing.

Any suggestions for a third party, that could give certified "thermal eff #'s" of the proposed heat engine's that are using external combustion? There's a bunch of new steam engine's being developed at this time, but seems to be no authority on deterning how [only-engine] thermal efficiency rates on these new group's of engine's, what complicates things further, is that a "Desuperheating 4cycle Flash Steam engine" is not a rankine cycle...

Jeremy