While I was in China I worked with a number of manufacturers to design and assemble parts that could work together to form a temperature controlled fermentor. Many nights were spent working on CAD designs and I spent a lot of time chatting with engineers who could help turn my designs into a reality. Today I had some spare time which I put to good use test fitting the parts and running some simple tests on their performance.
Unfortunately I only had some weak TEC1-12706 (6 amp) thermoelectric coolers (TECs) on hand to test with but most importantly, the CNC machined parts all mated together nicely and the results were promising.
A picture tells a thousand words so here are some pics of the assembly process…
The heat spreader is machined from a solid block of aluminium. It’s got a curved edge on one side to mate up with the keg and a flat edge on the other side to mate up with the TECs and provide good thermal contact on both sides. In this picture you can see a 1mm thermal conductive sheet that’s used to fill any imperfections between the block and the keg and I’m torquing it down with some M6 bolts. On the keg you can see one of the M6 weld nuts that were attached during manufacture before the pickling and passivation process.
Here’s a picture with the spreader block attached. I ended up trimming the grey silicone pad with a Stanley knife so it finished flush with the spreader block.
I’ve had two heatsink prototypes made up. One has heat pipes (pictured) and the other is bare aluminium. The difference in cost is considerable but since this is just a prototype I decided to use the more expensive heat pipe version. I’m still not completely sold on the heat pipes yet since the way I see it, they are only really carrying the heat a few cm outwards to the edges of the heatsink and they probably don’t justify the extra cost. They were a suggestion from the heatsink manufacturer.
In this pic I’ve already added thermal paste to the underside of the TECs and I’m adding the paste to the heatsink side now. You can also see I’ve 3D printed a template that holds them evenly spaced while I put everything together.
In this pic you can see the heatsink being attached. It’s held in place with six M4 bolts and all the holes lined up nicely. Its great when things go together as designed.
Here you can see the wires coming from the evenly spaced TECs. The heatsink has been screwed down and it’s all holding together very solidly.
I also had an aluminium shroud folded up. This is used to hold the fan in place and duct the air through the heatsink’s fins. I designed it so there will be enough room for some circuitry and a small display.
Finally with all these parts attached I was able to get some testing underway. Today I just tested using a bench top power supply seeing how cold I could get the cold side on a hot 26C day.
All is looking well for now but I’ve got some TEC1-12715 TECs on order that should really show what this large heatsink is capable of!