Then, I went on to make the evaporators for the CPU and GPU. Instead of going
the copper block drilling method which I had always relied on, I decided to
use many copper caps to save time and effort. I bought many copper end caps
from smallest to bigger ones in steps.
I used a copper base plate 50 x 50mm and a copper base plate 42 x 42mm for
CPU and GPU evap respectively. They are 3mm thick. I drilled appropriately positioned
holes for the refrigerant to flow through as seen:
The top hole is for the capillary tube to go through and the side for the refrigerant
to flow out. The idea is for refrigerant to flood the inner most copper cap
first then goes out to the second cap, and then to the third and so on. Here
is a paint pic to illustrate better.
As usual, I brazed on the caps on a cooking stove to keep the copper hot as
I braze. I plan to use a blend of R410A, R22 and R290 and I used about 1.7m
of 0.026″ cap tube for CPU evap and 1.85m of 0.026″ for GPU evap.
This works well with my condensing pressure of 250 PSI in 24C room temp under
load. The proportion is quite vital as the lion’s share of the refrigerant should
go to the CPU evap as there’s gonna be a bigger heat load there.
The completed GPU evap:
It is elbowed as the plan was to run it in a casing. The cap tube is ran through
the suction hose.
Here it is brazed onto a stainless steel hose:
And the CPU evap:
The cap tube was ran through the suction at first but I found that it got brazed
shut in the evap so I cut it off, drilled a hole at the side of the evap and
put in a new length of cap tube:
I pressure tested the evap for leaks with shraeder valves: