Semi-Finished Evaporator (Pics Inside)

http://www.drcooling.cl/imagenes_foro/eva1.jpg
http://www.drcooling.cl/imagenes_foro/eva2.jpg
http://www.drcooling.cl/imagenes_foro/eva3.jpg

This is my first evaporator, I know it`s not something from another world but I`m really proud of "my" work so far...

Now, I have a question for you PhaseChange Gurus, thisevaporator it`s going to be mounted in a horizontal motherboard... Then which one it`s the best position for the cap. tube? The position for the suction line?

Hope you help me here...

MartO

pics aint working again..

pics ok here :)

They are OK...

Pic's are huge, thats all.

No matter how you put it you need to keep in mind the refrigerant flow you want the refrigerant to go in low and come out high. This will make it work for both horizontal and vertical applications, however you will need to orient the block with the hole between the first chamber and second chamber.. The first chamber should partially flood as long as you have more capacity than you need... http://www.blairwing.com/images/newevap.jpg
pic is sized for 500 pixels wide...

wow chilly u do that pic urselff?;) nice work! easy to relate to

Why not coil the cap tube inside the empty chamber for subcooling?

Yes it would also help boil off any refrigerant that happened to come over the dam ...

Damn I can really tell your are a writer, ever think of doing satire?

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Originally posted by Gary Lloyd
Subcooling is degrees below saturation temp
Superheat is degrees above saturation temp
Subheating is nuking a hoagie
Supercooling is trying to be like me.

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Originally posted by Pimpsho
wow chilly u do that pic urselff?;) nice work! easy to relate to

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Took three min in delta cad its a down and dirty cad, have to print it and then scan it into photoshop and then adj the contrast....

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No matter how you put it you need to keep in mind the refrigerant flow you want the refrigerant to go in low and come out high. This will make it work for both horizontal and vertical applications, however you will need to orient the block with the hole between the first chamber and second chamber.. The first chamber should partially flood as long as you have more capacity than you need...

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So Chilly1, in the middle piece (the one that separates chamber Nº1 from Nº2) How many comunication holes between Chamber 1 and 2 do I need besides the one for the cap tube?

Also in the piece from the TOP, in what position do I locate the Suction line? In the middle or in one of the sides like in your drawing?

Also, is it necessary to have the cap. tube between the heat sink like you it on your drawing? Or just in top of it so it can spray the cool liquid in the hole area?

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Why not coil the cap tube inside the empty chamber for subcooling?

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Is this true?


Bye!

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Damn I can really tell your are a writer, ever think of doing satire?

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Writing talent is a natural occurance, kinda like cancer or the black plague.

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Originally posted by MartO
So Chilly1, in the middle piece (the one that separates chamber Nº1 from Nº2) How many comunication holes between Chamber 1 and 2 do I need besides the one for the cap tube?
Also in the piece from the TOP, in what position do I locate the Suction line? In the middle or in one of the sides like in your drawing?Also, is it necessary to have the cap. tube between the heat sink like you it on your drawing? Or just in top of it so it can spray the cool liquid in the hole area?
Is this true? Bye!

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As in the drawing the hole in the center plate carries the cap tube to the lower chamber and for the dedicated use of it as shown into the top would be fine, If you may use it sans case and lay it flat then in the middle would be better. in that vicinity would be fine either way as the goal is not to use the "spray" but to partially flood and get that to boil continiously, this in turn would cool the entire chamber. You will also want to keep the open space in the first chamber to a minimum like a 1/4 inch. The hole I would drill in the top would be only big enough for the 3/8 id fitting for the hose I would use, and the hole in the middle piece should be almost the same size. Maybe a 1/8 inch smaller. Mark the outside of the block for the direction of the evap both holes toward the top.

So...

Its true that coiling the captube in the top chamber I can help the system's performance?

Chilly1 from what I can understand from your answer (my english it's very limited) I can use the same hole in the middle piece for cap. tube and suction line.

And the objective its not "spraying" here, its FLOODING, right?

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You will also want to keep the open space in the first chamber to a minimum like a 1/4 inch

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Do you mean the TOP chamber? the open space its 1.5cm, is it OK?

Also what kind of fitting do I have to ask for?
Is it a custom made fitting?

Bye, and thanks for your answers.

Ideally you want liquid to contact the entire surface of the pins this will give you the highest capacity and lowest temperature. In the real world the evaporator will never be completely flooded usually the best we can do is have it partially flooded. The captube being coiled in the top chamber will improve performance by subcooling the liquid and making it flood more. The captube will be a lot eaiser to run down the flex line into the evap and into the bottom chamber through the hole in the middle spacer. The middle spacer and the cap tube positioning should be oriented towards the top, [1] to let the liquid cool the pins on the way in ( I usually position it about 1/3 the way from the top)
and [2] to keep th liquid that does collect in the lower chamber from running down the suction line and back to the compressor.
The lower chamber needs to have only 0.5cm clearance from the top of the pins to the middle spacer. This gives you the greatest heat sink area in the evaporator. This ratio of free space to surface area appears to work best if the internal surface in contact with the heatcollecting surface area is slightly greater than the square root of the internal volume. But if you decrease the volume below this the refrigerant does not have enough space to expand and the evaporator will flood back to the compressor before reaching the best temperature.
The fitting and hose size will depend the size of the compressor and the operating temperature you will be operating at, of course the length has something to do with it but we are talking less than five feet so we can discount it. So basically this means if you are running a 1/2 hp compressor at -70 you will need a 5/8 id hose and fittings for that hose, a 1/3 hp compressor at -70 you will need a 1/2 inch id hose and fittings for same , a 1/4 ..1/2inch ,,a 1/5 ,,3/8in a 1/8 ..5/16 ect....

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The middle spacer and the cap tube positioning should be oriented towards the top, [1] to let the liquid cool the pins on the way in ( I usually position it about 1/3 the way from the top)

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This is something I can`t understand so I have posted a drawing with 2 option so you can help me understand it :D

Mounted in a VERTICAL motherboard, wich is closest to your design? nº1 or nº2?

http://usuarios.vtr.net/~marting/model3.jpg

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But if you decrease the volume below this the refrigerant does not have enough space to expand and the evaporator will flood back to the compressor before reaching the best temperature.

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And what happends if I have more than 0.5cm? I have exactly 1.3cm...

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The fitting and hose size will depend the size of the compressor and the operating temperature you will be operating at, of course the length has something to do with it but we are talking less than five feet so we can discount it

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Ok, I will be using a Danfoss NF9FX 1/5HP with R404a so I will use a 3/8 fitting.

Thanks for your answers!

MartO

http://www.blairwing.com/images/blocka.jpg

If it is vertical as in your pic either way would work, horizontal will work a little better this way.
The only reason for reducing the empty space above the fins, is there is little heat dissipating surface in this area.

Ok Chilly1`, now I understand...

Ok Chilly1`, now I understand...

I have a few more questions :D

How many cap. tube "loops" it`s the recommended in the first chamber for sub cooling?


I`ll be using R404a, how much pressure do you think the hose will have to hold? I`m asking this because tomorrow I`ll buy it, so I need to know the caracteristics.

Regards :toast:
MartO

DOn't block off the suction line. I'd put a few in it. Inserting the cap tube doesn't work as well a soldering it to the suctionline but in this case with a flex line there aren't many other options. It will be helpful. The pressure in the suction will have to contain the systems static pressure, A hose with a working pressure of 250 and a burst of 1200 would be good enough. If you have access to a refriigeration supply house a stainless braided hose will more than cover you. I have used stainless corragated gas lines for these and had no problems but you will need to pay attention the the bursy pressure.