I was sick this week, so not much work or modding got done. However, I refined the new plans to the point that I can not start working with full-size model. As you can see, I went for the bottom-heavy design:
As this a bit confusing picture shows, the top decoration element is gone. What is harder to see is that I scaled the case up in size some 8% per direction, resulting in 25% more colume to fill with parts. This made it easier to fit parts and still cool them properly and retain desired case size. Now the total dimensions are 800×470x330mm.
The light magenta part between drives and backplate heatsink marks air guide for back fans.
Basic idea in cooling is that all the heat is transferred to backplate heatsink and then when necessary, fans will spin to provide additional cooling. There is two water loops, one that flows in direct thermal contact with backplate and another that’s cooled down with peltier elements.
Here you can see the two waterloops:
Dark blue marks cool water loop, dark red the warm one. Light cyan marks the cool loop reservoir/TEC block and light magenta the warm ones.
At the top, in the “horns”, are the two reservoirs. Water flows through the sides of the chassis to the bottom where the two pumps reside. Peltier elements are located between the side flow areas. When flowing downwards, the cool loop water get cooled down by peltiers and the warm water loop cools hot sides of the peltiers and further transfers the heat to the backplate.
I reasoning behind this is that as the backplate is huge and made of aluminium, which is not the best thermal conductor there is, there will be substantial temperature differences between different parts of the backplate, unless I design cooling properly. The traditional approach has been to thicken the backplate (the part that’s not fins, but mounts them), but it would need to be very thick to effeciently transfer heat through the 900mm cross length of the heatsink.
So I ended up having warm water loop flow in thin and wide layer over the backplate. This should reduce the temperature gradient significantly and thus allow better cooling.
In addition to the passive convection cooling of the backplate heatsink, there is three portions of heatsinks that can be cooled actively.
First of all, the two back (up to 110CFM) fans protrude through the backplate and when spinning, move air over both external (mostly passive) and internal heatsink. The external heatsink is massive and with thick and sparse fins, to support passive cooling.
The internal heatsink is above back fans and is attached partly to backplate and partly to HDDs. It has thinner and more tightly packed fins as it’s mainly cooled with airflow.
The third heatsink is at the bottom front and gets heat from copper tubes transporting water of the warm loop. The three front fans (slow and silent) pull air through the heatsink and then over the mainboard and display adapter.
The reason why I push _warm_ air over the mainboard is that, first of all, it doesn’t really matter, as the parts producing most heat are anyway watercooled and second, I want to keep condensation temperature as low as possible. Naturally I will utilize some thermal insulation when going to sub-zero temps, but it does not hurt to have warm air heating up the outside of the insulation layer.
The two PSUs (one for the computer parts, another for the peltiers) will be bolted to the backplate, so they should stay rather cool even without any active airflow. In case they do not, the two back fans pull air through them to be evacuated from the top of the case.
Here is image illustrating the “show” parts, ie. parts that will be constructed to look good and be visible:
The rest, naturally, will be hidden.
And finally, here is image showing the base structural elements:
These plates will mostly be 2mm thick aluminium sheet attached to each other with L-shaped brackets. They should provide robust backbone to keep the pieces of the heavy case together.
I am also planning to have double middle-plates and have hinge at the back between them. This way I could basicly split the case to two halfs, should it be necessary. As case is mostly symmetric anyway and I will have to construct the heatsink from two pieces, this halving should not weaken the case too much. And it would enable me to do maintenance to the internal parts without tearing the whole case apart.
Now I need to wait for the replies from the sellers of ready heatsinks to know whether I want to use ready one or make one myself. And get my hands on 0.5mm and 2mm thick aluminium sheets.