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gjordan · 07-12-2016, 08:28

I just stumbled across this thread and will go back and study all of it, but I was surprised to see you are using R12. Unless I am mistaken, R12 has been unavailable (illegal to sell) in the states for years. Is it still available in Canada on the open market? You do great work and thanks for posting. _____Grant.

ColdEH · 07-12-2016, 08:41

Hey Grant ,
I am actually using R12A which is a hydro carbon refrigerant . The system takes about 15 ounces of the stuff , about what is in your average spray can . Since it looks like the days of R134a are numbered .

Here's a little info on them .

http://www.engas.com.au/about/about-...-refrigerants/

Regards

UNCIVILIZED · 07-12-2016, 08:53

Nice thread. Though thanks to the OP I now have something new to study/get schooled on

Actually, I love that. Thanks!

BTW, to help keep your fridge cool, an old racer trick is to line it with beer, especially the bottom

ColdEH · 07-12-2016, 13:11

Quote:

Originally Posted by UNCIVILIZED

Nice thread. Though thanks to the OP I now have something new to study/get schooled on

Actually, I love that. Thanks!

BTW, to help keep your fridge cool, an old racer trick is to line it with beer, especially the bottom

Thanks for the tip LOL. The cans will blow up ! this thing is way to cold . But I have lots in my fridge and it works well

Gonna let the system run for the next 24 hrs and log the amp hrs , so far it looks excellent, 1 amp, per hour . Not bad for a deep freeze , the final box this is going in is a little smaller and better insulated then the test box . O yes I, I showed that at the beginning of this thread

Regards

ErikFinn · 07-12-2016, 21:19

I really enjoy reading your fridge/freezer posts Typhoon, thank you for sharing all this!

If you don't mind me asking what made you choose evaporator plate design over cold plates? I'd be interested to learn your reasons.
Furthermore, is that a standard Danfoss/Secop electronic control unit or do you have something special on that front?
Cheers
Oh, "Cheers" reminded me; I believe 5%vol beer freezes at around 7-8ºC / 18F, if memory serves me right..

ColdEH · 08-12-2016, 07:00

Quote:

Originally Posted by ErikFinn

I really enjoy reading your fridge/freezer posts Typhoon, thank you for sharing all this!

If you don't mind me asking what made you choose evaporator plate design over cold plates? I'd be interested to learn your reasons.
Furthermore, is that a standard Danfoss/Secop electronic control unit or do you have something special on that front?
Cheers
Oh, "Cheers" reminded me; I believe 5%vol beer freezes at around 7-8ºC / 18F, if memory serves me right..

Hey Erik, thanks for the comments . I like to share my crazy .

The controller is a standard Danfoss 101N0210.

The evaporator vs holding plate conversation has been going on for as long as 12v systems have been on the market . Which one is more efficient ??????. Just as many arguments there as well. If I had a holding plate I would do the testing and post the results here , but as I don't , I can really only comment on my testing.
The problem with holding plates for me, is the bulk , I don't want to give up the space for them , and I can build my plates any size and shape to fit any box, and multi plates as well . Also Im not really keen on cooling down all that liquid , and then the phase change as well , plus compared to copper, stainless steel and aluminum are less efficient thermal conductors , thats what most of the holding plates are made of . I want to put the BTU's in the box not into the plates. I also wanted better control over box temperature swings , I have my test box and my fridge that is installed on my boat cycling between 2 degrees C , try that with a holding plate!

The argument against flat thin aluminum plate evaporators is that they are fragile and will hole if hit with something sharp , that happens all the time as can be seen by other posts on this forum. I make mine out of 14 gauge copper plate they are as tough as any holding plate and do not corrode as the aluminum plates do , I see them lasting many many years.

The compressors in my systems are controlled by the box temperature not by the evaporator temps so the entire box and the contents becomes your holding plate . This also cuts down drastically the number of times the compressor cycles on and off.

"""Warning . don't do this with a cap tube system or one that uses a constant pressure valve to control refrigerant flow. !!

I have just run the 24 hr test on this test box system and will be posting results shortly .

The beer floor in my fridge on my boat is working just fine stabilizing temperatures .

Regards

ColdEH · 08-12-2016, 09:40

24 Hr test data.

I was hoping for 20 ah battery usage per 24 hr period . But 25.52 amp hrs in a test box is just great !

As seen below the meter shows ah used and hours run . You can tell which one by which LED is lit.

First photo show the number of hours since reset and the second photo show amp hours used , and of course the voltage above.

The unit was running on low speed , or no resistor in the system , 2000 RPM .

Temperatures were set at -18 C to -16C or 0 F to 3.2 F The gap is easily adjusted at the thermostat.

Box is 2.5 square feet of R30 or 6 " blueboard XPS insulation . the top is only R20 or 4"

Ambient temperatures are a steady 72 F

I am happy with the results , things that will improve the performance would be better insulation , larger plates with more surface area , the ones I am using are 160 sq" combined . I built these to fit my box on the boat which is slightly smaller and better insulted with Polyiso to R40 , and obviously my test box does not have a liner and was not built with the same care . I predict that this unit will meet my expectations of 20 amp hours per 24 hrs use at true deep freezer temperatures.

Next test will be hot weather temp test. I will run the unit as it is set up now in an oven set at a constant 120F . I will make a video of this and post it on my You-tube channel that is linked below .

Oh and just to add one more reason I went to a thin plate design , it takes so long to defrost holding plates , hours instead of minutes , So you tend not to do it as often as you should , and that results in more energy lost.

Regards

ColdEH · 08-12-2016, 10:53

Forgot to mention the duty cycle . Unit cycled 35 times in 24 hrs . 560 minutes off and 875 minutes on . Not quite 50% but not bad . Bigger plates in the test box and I'm sure it would be closer to ideal . These plates in the permanent smaller better insulated box on my boat should be a good match .

Regards

ColdEH · 12-12-2016, 13:13

You should sit down for this one .

Just in case anyone is following my endless rambles .

I used the same box and turned up the temps to refrigeration levels .

24 hrs ,
4.3 amp hrs
71 degrees ambient

Same box as last test , i will run this for another 24 hrs to make sure these measurements are right .
Remember this is a small box 2.5 sq feet and not in the tropics , But WOW 4.3 Amp Hrs

Regards

ColdEH · 13-12-2016, 12:54

Confirmed .

10.23 amp hrs in a 48 hour period .

Not bad .

Now to install and do more tests aboard .

Regards

ErikFinn · 13-12-2016, 17:09

wow. what did you have inside the box or was it empty?

ColdEH · 13-12-2016, 17:44

Quote:

Originally Posted by ErikFinn

wow. what did you have inside the box or was it empty?

Hey Erik .
The box was empty . Other then a few rags at the bottom to soak up the melting frost off the plates after the deep freeze test. Can you amagine how good it would have been if it was half full of chilled beer 🍻 😳

Regards

ColdEH · 14-12-2016, 10:27

I did actually do a test with the ambient temperatures at 120 f . I used an automotive spray booth that bakes cars at 160f so 120f Was not a problem . Took a couple of photos
The first pic shows the condensing temp on top and the evaporator temp on bottom . The second shows the pressures . It actually went up 165psig but was dropping when I snapped the pic . System ran for two hours at these temperatures and stabilized nicely . It actually got up to 136f before the booth settled into 120f . This was a deep freeze test .