My Evap Design

[p8ntslinger676]

I was just wondering what yall think of my evap design, im going to mill it using my cnc machine (50mm dia.) Please Critique This is not the final drawing, there will be revisions, this is just the basic layout.

[Fhqwhgads6680]

good working basic design, alot like elevens that are know to be great performers but having the suction exit protrude like that wouldn't work out very well because it would be harder to insulate well, and cost a bit more to machine. just make the last channel wide enough to accommidate the 3/8in suction line.

[Freddie123]

Pretty much the same evap I did in Ricky's thread. I was told it would be really hard to machine.

[Fhqwhgads6680]

not really, if you make wall thickness about 1.5mm that is plent strong enough. I am not sure how many channels you could fit, but that doesn't look impossible. I am not a machinist tho he may have to remove a wall or 2 and make the channel width a bit wider.

[Kizmo]

That is not hard to machine at all with cnc milling machine. I would try with 2-flute 3mm endmill, 10000rpm, slow feed and Z -0.5 ... -0.8mm / pass and LOTS of coolant. It will take some time but at least you wont break tools

Copper is pretty though to machine because it is so 'sticky'

[Exahertz]

I'm speculating, what would the benefit be if the cold-head was machined so as each concentric channel would progressively get smaller or larger as it goes out from the center entry point, ultimately giving a more uniform cooling capacity profile.

I wonder this on the basis that the liquid in the center would begin to change phase to its vapor state as it reaches the outer edges of the cold-head, thus less liquid cooling capacity on the larger outer rings.

just a thought...
nice design though!!!

[edit]
Although now that I'm thinking about it, changing the size of the channels throughout the flow would cause a pressure differential. If the outer rings were smaller then the liquid refrigerant would boil at a “slightly” higher temperature causing a gradient from the center out. However it would help to re-condense “some” of the vapor back into liquid which may give better load handling properties.

[p8ntslinger676]

First of all, im going to be milling this on MY cnc mill so it wont cost me anything and second, i have already done a lot of milling so i dont need any help with that, im just asking about the basic design nothing more