Need help for troubleshooting a SS

[Stelios]

I have a single stage with the following parts :
Compressor : Electolux GD30MB R134A , charged with R507A
Condenser : Original from Prometeia Mach2
Cap tube : 2.5m 0.031"
Evap from Eleven .


The Compressor is 1/12HP and i'm planning to use it for cooling my X1900XTX . There is some strange behaviour that bothers me .

For heatload tester i have an 170W peltier . I put some AS ceramique on it's hot side . Next i put a cold plate & finally the evaporator .

Peltier Voltage| Pressures |Plate temp |Suction temp|
--------------+----------+-----------+------------+
0V |20/200PSI| -29C | 17C |
5V |24/215PSI| -17C | 14C |
12V |42/260PSI| +3C | 25C |
-----------------------------------------------------

Now ... if i remove some refrigerant i get the following ...

Peltier Voltage| Pressures |Plate temp |Suction temp|
--------------+----------+-----------+------------+
0V |6/190PSI | -36C | 29C |
5V |12/210PSI| -27C | 29C |
12V |36/255PSI| -2C | 29C |
----------------------------------------------------

What do you think it's wrong ??? The temperatures are 100% right.

So , when i put more refrigerant , the evap temp goes up and the suction line gets colder ...

I'm not sure but i have 2-3 things in mind ... But first i would like to read some opinions .

Thanks .

[n00b 0f l337]

Peltier is a terrible source for heat under cold. Your decreasing the resistance and the peltier is going to suck large amounts more electricity than at its normal temperature.

EDIT: I thought I read 1/12hp as well, damn man. Thats a tiny compressor. That won't hold a x1900 much less 150+watts of heat.

[Unknown_road]

your captube is pretty short voor a vgpu. I would go for 3,5 - 4 meter or something. why do you think something is wrong btw? where do you measure suction temp?

[Stelios]

@ n00b 0f l337 ... What happens when u put a peltier in cold ? Does it dissipate more watts ?
About the compressor ... the spec sheet is this :http://elektronika-sa.com.pl/Ie/perf...?MID=95&SID=14

It can hold 100W at -20C with R134 (Evap temp) ... so with R507 i would guess something like -30C/-35C (evap temp) which is correct to what i'm measuring .
I also tried 3 differend condensers . The best job did the smaller one (The prommie one) . With this condenser i got the lowest evap & suction line temp .

Also ... the X1900XTX has 120W power consumption and thats for the whole card . How much heat would the GPU only dissipate ? About 80W ?

@ Unknown_road ...The suction temp is about 7-10cm from the compressor .
The reason i believe something is wrong is that when you put more refrigerant you expect to see the suction line freeze . It just don't happen here .

About the captube , i know that i could use something longer (i wanted to begin with 4m) but this is what some friends recommend to me .

[n00b 0f l337]

When you cool a pelts hot side it will start sucking lots more energy.

[Stelios]

And that means that it will generate more heat . Right ?

[mindnumb1]

The thing with higher temp on evap when more refrigerant in system: I am no expert at this, but theory says that the pressure on evap side determines the temp the liquid evaporates at. so the higher the pressure on evap side, the higher you have to expect the temp to be. So ... say your compressor can keep a difference in pressure of XX bars... when you load more refrigerant into the system, the pressure on condenser side gets higher, xx+y. pressure on low side will allso get the y in addition , because the comp cant get it lower because of its compression ratio.

Experts, please correct me if I am wrong...

Best regards, Bernt.

[Stelios]

Bernt , maybe you are correct . I would like to hear some more opinions.

So far , i have an option to lengthen the cap tube (which i'm gonna do in 1-2 days) .

The other thing that i'm thinking is if the tubing is very long for this small motor . Suction length (from evap to motor) is about 150 cm .
If i shorten it , it will need less refrigerant .

Last thing ... static pressure is about 8 bars ( ) . Surely not low .

[[XC] MarioMaster]

it's pretty much how phase works, more refrigerant = more capacity but higher temperatures, less refrigerant = lower capacity but also lower temperatures

[Stelios]

it's pretty much how phase works, more refrigerant = more capacity but higher temperatures, less refrigerant = lower capacity but also lower temperatures

Yep . I know ...
One thing that makes me feel better is that with more refrigerant i have better superheat , so colder compressor .

I'm trying to find out what is the better insulation for my GPU . I hope in a few days to post some benchmarks .