In this page we will keep all information regarding the design and development of the clamping mechanism
Problem
As our vacuum table draws out the cold air from the box, the temperature rises, compromising the samples. As a result we have to add a way of supplying cool air into the box.
Idea
Our idea for solving this is recycling the air drawn out, back into the box. But as the vacuum heats the air, we want to send it through metal pipes in a cooling box before it goes back into the box. We want to cool the box the pipes sit in with dry ice.
Development
We have created a makeshift metal pipe and found a tube that fits. We will fetch an insulated box and some dry ice to test if it cools the air enough.
This was further improved with a styrofoam box.
We tried using an air pump to pump in air through our tubes, but the air coming out of the air pump was simply too warm. The spiral was not able to cool it enough. Using air from our environment became the most viable solution.
The problem was then that our freezer box wasn't air tight. We first modified the seal of the lid, and tried closing all the visible gaps with vacuum tape, but somehow the box was still leaking. We found that the seal simply was not tight enough, so we doubled the mass of the seal, and now the box is close to air tight. When the vacuum runs, the lid is pulled on by vacuum, so it feels quite air tight now.
With a tight box we saw that we were able to maintain a stable temperature of -7.6 degrees. And this was with perhaps 1/4 of maximum dry ice capacity. We also have the option of running more of a plastic tube through the ice box, further extending how far the air has to pass through our cold environment
Further development
We have two ideas on how to build this better at a later stage
Varmeveksler
Using a "varmeveksler" will recycle a lot of the cold from the box back into the box.
Instead of drawing out air that is -20 and drawing in air that is +20, we will draw out air that is -20 and draw in air that is ~0. This will still lead to loss of cold, but at a slower pace.
The advantage of this solution is that it is possible to buy, which makes fast to implement.
Self-made cooling system
Another idea is to create our own vacuum pump where the engine is further away from the fan. Recycling the air internally in the freezer, while the engine driving the air-flow is separated from the cold environment.