Chiller Adventures Part 1

Looking at all the temperatures the Prometeia users were getting, not to mention the overclocks they were getting, I could not help but feel jealous. As the high price-tag of the Prometeias made them out of my reach, I decided to go about building my own phase-change cooler…

I went into phase-change cooling starting out with modding fridges. Below is
an account of the journey.

Looking at all the temperatures the Prometeia users were getting, not to mention
the overclocks they were getting, I could not help but feel jealous. As the
high price-tag of the Prometeias made them out of my reach, I decided to go
about building my own phase-change cooler. I had 2 options, build a liquiid
chiller thant chills the liquid that runs through my water-cooling setup, or
build a direct-die cooler that directly uses refrigerant to cool the processor.
As direct-die set up involves the acquisition of refrigeration tools which will
come up to a large sum of money, I decided to build liquid chiller. So I went
onto the internet sourcing for cheap second-hand fridges to mod.

Here’s the old Acma Fridge I bought from Yahoo Auctions Singapore.

The nice fellow sold it to me for $ 30 and had it delivered to my place. First
thing I did was of course to check if it was working properly. Connected the
power cord, and I was pleased to find it working like a fridge should. The next
step was to spot the crucial components and try to get them out of the shell.
Now there is always the misconception that one could easily throw the PC inside
the fridge and things would cool themselves nicely. This is very niave due to
many reasons, one of which is thermal resistance when so many mediums have to
be bridged to cool the PC. You are using the refrigerant to cool the evaporator
and the evaporator to cool the air and the air to cool the water. Air is a very
unideal medium and so a lot of efficiency and performance is lost due to this.

Anyway, I opened up the fridge.

The evaporator is of course inside the fridge. It is an aluminum heat-exchanger
with very flat parallel running tubes. Unscrewing the top nylon screws loosened
the evaporator. I had to attack it from the back next.

Here’s the main component, the compressor at the bottom of the fridge.
This fridge is at least 8 years old, so it i no surprise this area is so dirty.
Wiping off the dust on the compressor, I was disappointed with what I saw written
on it. It runs refrigerant R12 and is rated 90w. That is a little too small
for a water chiller. It will be able to chill the water but might not be able
hold very cold water temps for long under a high CPU heat load. Moreover, refrigerant
R12, which is now phased out, is not as cold as R22, etc.

Anyhow, I removed all the screws and nuts, which took quite a lot of effort
since most of them are rusted pretty bad. The condenser, which is the long winding
pipe at the back of the fridge was removed in the process. I took care not to
kink any part of the pipes as I wanted to remove the whole phase-change system
intact.

I also removed the back plate behind the evaporator and you can see the pipe
from the condenser going to the evaporator.

And here it is, finally removed without cutting any lines, except for the electrical
wires leading to the thermostat which I decided to skip. I connected the power
lines of the compressor and connected them straight to the plug, skipping the
thermostat and started the compressor to see if anything was amiss.

.

The evaporator frosted up in no time so its still good. The passive condenser
also got very hot.

I knew it wasn’t going to be really up to the task with the relatively
weak compressor on it. Thus, I decided to look for another small compressor
so that I can have 2 evaporators chilling the water in the same reservoir. M
friend Visionary of VR-Zone happened to own a mini bar fridge which he wasn’t
using. He was kind enough to let me have it.

Here’s the Samsung mini bar fridge. The compressor is just behind.

The compressor runs R134a and is rated- Cooling capacity: 69 Kcal/hr, 274 BTU/hr.
I knew before hand it was rather weak, as are all mini fridges so it was fine
as together with my other compressor, it should be able to handle at least a
CPU.
It looks easy to dismantle compared to my other fridge but looks can be very
deceiving.
After half an hour of prying, I’ve only gotten the back plate off.

The foam seen here at the back is very hard and it was going to be hell removing
it.

After a long time of scraping, it looked like it was snowing in my house.

And then after some more hours of scrapping, I finally got to the evaporator.
But that was the easy part. Removing the condenser was the finale. It was just
a pipe running around the interior perimeter of the fridge, but was well-hidden
behind metal plates and foam. After struggling for another few hours, I was
very frustrated and decided to cut the lines. I used a small pipe-cutter and
the line going to the condenser and the pipe cutter frosted up quickly as the
refrigerant escapes with a bit of oil.