Evaporator Design.

[BJClearwater]

Fhqwhgads6680 and I have been working on this Evaporator design. Tell me what you think: The diameter is 46.5 mm and the depth is 30 mm. Made of copper.

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/Evaporator3.gif

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/Evaporator2.gif

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/Evaporator.gif

[tim-]

will proberbly work well but thise "pins" will be a pita to make. even on cnc.

copper is a very soft metal and is hard to work with in miller as well as lathe even with good cooling.

[BJClearwater]

will proberbly work well but thise "pins" will be a pita to make. even on cnc.

copper is a very soft metal and is hard to work with in miller as well as lathe even with good cooling.

Yeah, I was worried about the same thing, and several of the people in my metallurgy lab voiced the same thing. However, I think I have found someone online that said they can make it. I'll cross my fingers. :)

[Sneil]

I cant really see these pins adding any extra cooling capacity anyway. They're so tiny and so few i bet they'd suck next to zero heat from the copper base. Nice design though.:)

[PhilippF]

My guess is the little fins will brake of on milling. And just from the bottom of my heart and stomach: I would use a little more thickness on walls and fins (pins) for optimized heat transfer.

Just my 2 cents...

[{.bLanK} GoD]

Forget milling the pins, machine the design without them.
And if you like, get something like 2mm diameter copper rod, cut them to length, drill a 2.05mm hole where you want the pins and braze them in place.

[[XC] gomeler]

Wonder if you made the inner chamber walls wavy like the middle walls would it help make a more turbulent flow through the block?

[Fhqwhgads6680]

Hey guys, thanks for the replys.

we are playing with several ideas here but yeah the wall and pin thickness etc is something I was concerned with. I am thinking of making just a central mass of copper in the inner chamber, removing the pins, increasing wall thickness and then just sandblasting the inside for surface area. my dad does car paint work so I have access to a sandblaster in house.


gomeler;2389139']Wonder if you made the inner chamber walls wavy like the middle walls would it help make a more turbulent flow through the block?

Gom, we kept it this for two reasons. One, it creates restriction so only a given amount of liquid can pass through the narrower areas, and two the expanding chambers give the gas a place to expand to keep the pressure in the evap during operation as low as possible yet also ensureing as much contact with all the surface area in the evap. My friend can explain a bit better he is the chemical engineer :p:

[[XC] gomeler]

I think we are actually sort of on the same page. I was asking if you could mimic the outside expansion areas that surround the individual pins on the opposite sides of the channels so you'd have a narrow area then a small chamber, narrow area, small chamber. Now sure if it'd do anything but it was just a thought.

[BJClearwater]

gomeler;2389139']Wonder if you made the inner chamber walls wavy like the middle walls would it help make a more turbulent flow through the block?

gomeler, in theory, if you could make the center wavy it would increase turbulence of flow. However, the current design makes the milling significantly easier. Also, I think the goal should be to increase turbulence of flow without restricting flow. Thus, I think it should be best to make a series of waves (~~~~~) rather than channels and chambers (0-0-0-0-0). This is because the channels and chambers approach would restrict flow to that of the refrigerant flowing through a long, narrow channel of the same dimensions as the small channel would be. ex. channel and chambers (0-0-0-0-0) would flow like (--------) and the waves (~~~~~) would have a constant width, larger than the small channel, for flow.

As far as the pins go, people have been talking about them being too thin and possibly bending. I agree, that is possible, but as long as the pin isn't severed from the evaporator, it still serves it's purpose--increased surface area. Furthermore, the main purpose of the pins in the outer circles isn't for surface area. When I designed it, I place them there mainly to disrupt flow and churn the fluid.

The only worry I have is what was mentioned a couple posts ago--that the inside walls may be too thin and may damage during use. Has anyone tested this yet? I'm pretty confident the walls should hold, though. The outside is definately thick enough for withstand the pressure and I figure the walls on the inside don't need to be very thick because there won't be a pressure gradient for it to hold.

[Fhqwhgads6680]

@ gom: Oh i see what you mean. I thought you were saying make the channels wavy but the same width throughout. I'm playing around with some ideas like that actually. here is a quick remake of the one without the pins and thickend walls. In this one I'd sandblast it to hopefully make up for the lost surface area by getting rid of the pins. the inner walls are about 1.5mm thick. the inner chamber walls thinnest areas are about 1.5mm while the thicker areas are 1.8mm

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/evap2.jpg

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/evap3-1.jpg

[DetroitAC]

Yeah, I was worried about the same thing, and several of the people in my metallurgy lab voiced the same thing. However, I think I have found someone online that said they can make it. I'll cross my fingers. :)
I can't see how to make it. I roughly scaled it off the screen, and it looks as if you can use no bigger than 1/8 inch diamter end mill, and 1 in depth of channel. 3/4 inch is the longest length of cut I can find in catalogs, and I think have one of those at home. They are almost useless at that length, it's like machining with a wet noodle, flexes all over unless you take very small passes, slow feed rates. I predict 6 hours machining time, no kidding!

I don't even know how to handle something like that with some guy machining it that you've found online. If his quote is something like 6 hours time, then fine. If he's given you a great price, he may get 1 hour, or 2 broken tools into it and figure it's best to quit and keep your money for his pain and suffering.

edit- Get rid of the tiny pins, drill and braze them back in you want, machining time will get cut by 80% if your guy can use a reasonable end mill

edit again, ok, I missed your update

[ak_47_boy]

I like the new center, it should suck the heat away from the core and get rid of it with that large surface area.

[Unseen]

Guys we have tried many designs. No need for so complex. A simple maze is doing the job.

[Duh]

@ unseen:not that I have a basis to justify my opinion but if we have a bigger variety of designs and all those designs are tested, we can start to infer which things make it better.. although there must be some theory on the subject I guess it is not enough, as otherwise everyone would follow it...

nice work dude.. are those elevens??

[Fhqwhgads6680]

ok here is the lastest I have come up with. The only thing I have thought about changing is the height of the entire evap. I keep going back and forth. This one I have at 20mm high with a 3.5mm base.

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/evap5.jpg

[Fhqwhgads6680]

Here is our final design, we will be sending this to get machined in less than a week! Alot of time and thought went into this design and I am pretty confident it is going to perform very well. When we get some in we will be looking for people to test it for us so stay tuned.

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/newevap3.jpg

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/final.jpg

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/top.jpg

[Freddie123]

Looks good. Will look forward to seeing it post machined

[killermiller]

Looks good. Will look forward to seeing it post machined

Yeah me too. I would really like to watch the evap come to life.

[BJClearwater]

Dat shiz da bmob dizzel!

[Fhqwhgads6680]

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/final32.jpg

http://i206.photobucket.com/albums/bb194/fhqwhgads6680/final3.jpg

Final design! off to Machine shop tomorrow! getting 15 in the first batch.

Edit:

total height: 20mm
base: 3.5mm
channel depth: 16.5mm
diameter: 50mm

[Freddie123]

I hope they turn out good. Will you do any comparisons?

[Fhqwhgads6680]

I have a kayl stepper here that I can test against, I was going to get a cyrostar, but I wanted to put the $ into getting these milled. once they come in I will be looking for testers.

[BJClearwater]

This thing's gonna rock.

[killermiller]

What is the ETA on these?

[Fhqwhgads6680]

about 25 days to machine and shipped to our door. then we have to work on mounting. I cannot WAIT until the get here!

[killermiller]

Are the chewing the design in the copper in their teeth? Yeah, must be pretty exciting. You have to have the evap in hand to work on mounting?

[Fhqwhgads6680]

well the only thing we need to work on is the enclosure part of the mounting and we are trying to find a cheap way to do it to keep cost down. I am also playing with some different ideas to make mounting hardware removable. I will keep this post updates in the thread.

and yeah it is a while to wait.... I hate knowing that I am just waiting now... lol.... I want to test these SOOO badly....

[teyber]

if you don't mind me asking, what was the cost to have these machined? not including the metal or anything, just the labor/tool use?

[Fhqwhgads6680]

if you don't mind me asking, what was the cost to have these machined? not including the metal or anything, just the labor/tool use?


For an order of 20 it came out around $50 a piece. most places charge a base fee for tooling then so much a piece, the more you get the cheap it is obviously.