Printable View
Hello
this will be my first attempt to use injectors in a phase change system, today only pics of the main parts i will use (they are very high q- if someone wants i can send him 2048x1536 res pics, 1.3mb each)
Ok, first: the vital parts: evaporator base and injector
How will the injector be place on the base, it will be lifted a few mm so the freon flowing out of it spreads on a wider area
The injectors connection is a banjo joint, ill simply drill a hole through the screws top and braze a very thick cap tube to it
btw. its a startup injector from a ford escort rs turbo
And my favorite pic (the best pic a took in the history of my digi cam, finnaly learned how to use it)
Tomorrow ill post pics of the rest if the evap and probably tomorrow, the day after ill test it with my lil danfoss sc10b.. shuld own my cap tube configuration ;]
Oh and one more thing ^^
Me and the guys from Poland work on projects with injectors quite hard, were more advanced on it than with cap tubs etc. and probably soon there will be a small flood of refrigeration systems from poland using injectors ^^
Some pics of my friends work, Radek_Marko:
http://www.antyksklep.com.pl/FC/wtrysk/IMG_5664.jpg
http://www.antyksklep.com.pl/FC/wtrysk/IMG_5665.jpg
The software were writing to controll injectors:
http://www.antyksklep.com.pl/FC/wtrysk/program.jpg
This a alpha 0.001 software, the more advanced will read temps from multiple sensors and adjust to the conditions based on scripts we will write, were planning with Radek to use cfg files and a "console" (quake 3 style :P) to load certain cfg filed (like: thermal paste burn in, low temp reading, 100W load, 150W load etc)
Very cool berkut (no pun intended)!
I like the idea if the practicality works out...you'll definitely be able to utilize the interface you guys are working up. Best of luck.
Looking forward to hearing more.
..... yes this injector system is interesting.
I am really following this with utmost interest. I also need another way of injecting refrigerant than a captube (and I need throttling over a short distance for a reason I won't explain yet), but I am investigating the road of converting a TEV into a heat-motor operated EEV and such. Also, the Alco EX2 pulse-width valve with orifice X might be useful, though it's recommended cycle time (6 seconds) is too long for our small evaporators.
Would a system like this (if it were capable of detecting cpu load with the software) be able to be adapted to allow a system to be charged for optimum temps @ load conditions?
what I mean is, what it allow you to charge the system for full load conditions and then reduce the flow when under little / no load so you didnt slug the compressor.
Im not quite sure how it would behave tho. Would it behave like an overcharged system (when under little to no load) or, would it behave like a system with a too-restrictive captube. or both?
Obviously either way idle temps are going to suffer somewhat, since there will be too much refrigerant in the system for the load, but would that adversely affect the system in a negative way? (cause increase in highside pressure?)
Oh, just to add, I actually work for a ford dealership and I just checked the price of these injectors new.
Not good news. We're talking just under £130 + vat.
Something I have been wondering, some of you may or may not know, but nitrous systems use a similar design. They have a solenoid valve which allows the NOS to run through to a small injector. 1 benifit of this system I can see is that they are significantly cheaper than these injectors.
If I remember correctly, they are about £40 - £50 for the solenoid and the injector itself can be anything you want. As simple as using a small carburettor jet screwed into the end of the line from the solenoid.
Im not sure however, if these solenoids can respond quick enough for them to be a viable option as opposed to an injector, but its worth a thought.
What you basically want to control is the superheat. Thus, you measure the temperature of the refrigerant directly after the injector (or evaporator pressure), and the temperature of the evap outlet. You want this a few degrees higher since that indicates just no liquid returning from the evaporator.Quote:
Originally posted by Devilman
Would a system like this (if it were capable of detecting cpu load with the software) be able to be adapted to allow a system to be charged for optimum temps @ load conditions?
If you do this correctly, the system will always adjust itself perfectly for the condition.
TEV's work on the same principle, but TEV's are in fact a proportional controller. An electronic expansion device with a suitable PID controller can deliver faster reactions to load changes and better superheat control, leading to lower evaporator temperatures in our case. Even more important, they can work independant of the refrigerant.
Hmm, perhaps I interpreted berkut's idea incorrectly, but I had asumed from the picture that the injector itself would be used directly in the evap, rather than having a small piece of pipe from it, to the evap.
If that is the case, it would be impossible to messure the temp (or pressure) of the refrigerant after the injector, since the injector is mounted directly in the evap and spraying the refrigerant into it.
Also on another note, I would question the ability of these injectors to handle the pressure involved. Bare in mind that these injectors were designed for fuel systems, which at most, usually only have about 3bar pressure. It could be quite possible that once the system is charged and under pressure it will blow the "guts" out of the injector, straight into the evap :eek:
No, you did not misinterpret his idea. I have no idea on what principle berkut bases his control system. What I mentioned is how a simple EEV controller could (and does) work.Quote:
Originally posted by Devilman
Hmm, perhaps I interpreted berkut's idea incorrectly, but I had asumed from the picture that the injector itself would be used directly in the evap, rather than having a small piece of pipe from it, to the evap.
I am not too worried about the injector blowing, but more about the ability of the coil to lift the plunger (correct english?) with much pressure behind it. Also lubrication of the injector, coil heat dumped into the evap and resistance to extreme cold worries me. These are the reasons why I am awaiting Berkuts results first before jumping on the injector bandwagon.Quote:
Also on another note, I would question the ability of these injectors to handle the pressure involved.
That is indeed a very valid concern. these type of injectors were never designed to operate at the pressures we would be putting them under. they may not open correctly, they may not open at all. It may blow the "plunger" of the injector straight out of the injector body.Quote:
Originally posted by DaBit
I am not too worried about the injector blowing, but more about the ability of the coil to lift the plunger (correct english?) with much pressure behind it. Also lubrication of the injector, coil heat dumped into the evap and resistance to extreme cold worries me. These are the reasons why I am awaiting Berkuts results first before jumping on the injector bandwagon.
No, at most it just won't open. Those injectors are built for a harsh environment, so they won't blow due to extra pressure.
The opening problem can be solved by applying extra current, btw. But then you are pushing the limits of the coil.
Personally I would prefer a piezoelectric injector instead of a magnetic one. These are much quicker and more accurate (4 pre-injections and 1 main-injection per cycle on some modern engines. At 6000rpm this means 50 * 5 = 250 injections/second.). Also, they are smaller, lighter and capable of handling extreme pressures.
But they are new, expensive and not yet available at the scrap yard.
Im hoping it will work, if im not mistaken its rated for 6.5 bar, but will stand 10 easylly (the safety margin), i think they work @ 5V so if they dont want to open i can always overvolt them to 12V (remember its cooled down to ~ -40C beacause it has direct contact with the evap, even without that it shouldnt burn) + its pulse operated...
Right now i feel preety damn misereble and i have a 2maths lesson in ~20min, after that ill start making the rest of the evap if i feel strong enough..
You are ill pretty often, aren't you? Too bad :(
Anyway, I expect the best performance with peak-and-hold type injectors. Literature (Bosch) I just read talks about leakage above 65 psi fuel pressure. That's bad.
This page sums some injectors and their factory flow rate. To get flow rate and required duty cycle at our conditions, keep in mind that flow increases with the square root of the pressure drop over the orifice. Thus, a 4 times increase in pressure doubles the flow rate. With a factory designed pressure drop of 3 bar, our refrigerant flow at 10 bar pressure drop will thus be approximately sqrt(10/3)=1.82 times the given flow rate in the table. Assuming that we need 4kg/hr of R404a (will be close, but I didn't calculate it) at load, we pass about 3240cc of refrigerant per hour through the injector, which is 54cc/minute. A fairly standard 240cc/minute injector will thus operate at approximately 22% duty cycle. This can be done. At idle our load drops, and the duty cycle drops below the 10%-15% range, where it gets hard to control.
I wonder if you are better off with an (eventually modified with stronger spring and overvolted coil) solenoid valve made for refrigeration and a piece of captube. That would solve the temperature rating problem, the pressure rating problem, and the additional heat load on the evaporator problem. This way you can also keep duty cycle into the 80% range for full load.
this could be very powerful if you could write software that changes the throttle of the injector according to cpu load. it would be like a txv but more practical to our use. i cant wait to see some results.
kinda off topic, but how did you make that copper base?
i think he used a dremel
OK, one of our systems was testes for the first time with a injector...
Short summary: injectors tend to "freeze up" when they spray freon so we had to give them a shock @ 22V. They also dont like to close, thats all i know right now from my friend Radek, he'll perform additional tests today if he didnt kill his compressor.
So u guys, pray for his compressor to live :(
Compressors don't die so easily. But I would have added an accumulator anyway while testing, and so should you.
As soon as I finished my apartment I will try to repeat this, but then with an Alco valve. Let's see how that works.
Ok, got some stainless steel banjo connectors and copper orings today:
This is a preety bad pic but you can see the custom made connector (its made of epoxy glue and cyanoakrylate glue)
A shot of the banjo joint ready to assemble ;]