A Bunch Of ?s On A Custom Chiller Unit.

Unregistered

Hi everyone! I'll greatly appreciate the time and patience put into my newbie questions

My project consists of a refrigeration unit chilling the water of a computer watercooling system (I know...insulation EVERYWHERE to prevent condensation). I will be modifying a small refrigeration unit, originally designed to cool down a laser diode, by installing an evaporator consisting of a 10-15' 1/4" ID long copper tube installed in an insulated 2-3 gallon reservoir with a lid. The unit has a 1/6hp compressor using R134

I would like to have the water down to anywhere beteen 20-30f. Yes, I'll be using an antifreeze mixture. Mind you, the water will have a heatload on it of about 80-90f since it will be cooling down the CPU and the graphics processing unit. Ambient in the room is ususally about 75F.

And now for the questions
1) Is it better to use a TXV or a capillary tube?

2) If I should use a TXV, how do I know which one to get?
A) Adjustability of the evaportor temp would be nice to
fine tune the unit. Is this possible with a TXV?

3) If a capillary tube is better, how do I know how long it should be and what ID?

4) When I construct my evaporator, which is more efficient? Just one long copper tube spiralling around or a grid? By a
grid I'm thinking of 1 long copper tube on each side with several Ts on it connecting to Ts on the other tube. I guess you could say it will look something like this:

In
|
|
|-------|
|-------|
|-------|
|-------|
|-------|
|-------|-----------out


5) Is 1/4"ID sufficient for an evaporator? I have also found refrigeration grade copper.


6) When torching the pipes together, should I use flux AND solder or just solder?

and last but not least:
7) When I repressurize the system, how do I know what pressures are best on the low and high side, and what do the differance in pressures mean? For example: which gives you a colder evaporator temp, a higher or lower pressure on the low side? Yes, I'll be getting some cheap little R134 gauges just for this project.

Oh,I was planning on taking the unit to a shop, having them dispose of the R134 properly, then I'll begin to take it apart and construct the evaporator I want. Finally, I'll pressure/vacuum test it to ensure I have no leaks, and then I'll have it filled up again. In my area, you can buy R134 off the shelf of any regular autoparts stores. I don't want anyone to think I'm doing anything illegal


Thanks guys!

Unregistered

ya know ya cant solder them tubes with a solderin gun.

Unregistered

sounds like ya got a lot to learn about refrigerant, and the refrigeration cycle. firs you wont achieve the temp that you want from 134a. second a txv is much better that a fixed orfice or cap tubes. third the more joints you have in a refrigeration cycle the more chances of leaks. fourth you cant use regular solder on refrigeration applications. this is for vibration purposes regular solder will not hold you need to braze the joints with silver solder wich melts at around 1500 degrees f. and a butane torch will not reach that temp. you will need a oxy. accetalyne torch to achieve this. fifth r-134a is a ozone safe refrigerant. that is why you can buy it over the counter with no liscense and do not need to recover it. next you better pull a good vaccume on the system after you leak check it. this is to remove all the noncondensibles wich if not removed will turn into a acid when mixed with refrigerant and refrigerant oil, and eventually eat up the windings on your compressor. I think the best thing to do is get off your wallet and let a refrigeration mechanic build your system before you spend a lot more money than you need to.

Unregistered

and this thing will do what ? make cool green water ? will it light up too ?
any sounds ?