View Full Version : calcing capillary tube lenght
ok..here is my cooler http://koti.mbnet.fi/gjunnu/0kompura/14cm3/
i measured evap max cold temp and it was -42c most, and i'm
consider to extend capillary tube to get evap colder...into -65c~
so is there some kind formula which i can calc needed extra capillary tube to get that -65c~ temp?
is there anyone can help me?
Calm down, its early stateside still.
The simple answer is no.
The indepth answer is no, and you wont get -65 with a single stage system with any sort of capacity, if at all.
Need more information also, refrigerant? compressor size? etc...
I see you have run the cap tube inside the suction line, what ID is the suction line? If its a fill line off a set of guages its probably too small to run the cap tube through the middle.
]JR[
compressor is electrolux 14cm3 low-stage r404a.
cap tube is 1.5m long and it's diameter is 0.66mm
suctionline diameter is 8mm...
-65c impossible at single stage?..i'dont think so
Marci
12-11-2003, 07:32 AM
tis with r404a... no amount of cap tube modding would gain an additional 20 degrees off yer temp...
ok maybe -65c is too far but atleast -55c is reasonable?
Marci
12-11-2003, 08:28 AM
All depends how well suited the current cap tube is to the setup. If current captube is optimum length already then no, it probably isn't. Only way to find out is to try it. -50 probable, but more than that purely from captube tweakin seems a little unlikely...
chilly1
12-11-2003, 02:15 PM
You could lose 2/3 your cap tube and install a Constant pressure expansion valve. That would make it adjustable under load and you could optimize the temperatures, you will have to payattention to the superheat though...
Zejtan
12-12-2003, 12:48 PM
i made a repair on a friends mach 1 and then laborated with R134a for the fun of it, after a while i got down to -55 c but then the display got some kind of virus ( showing only error messages )
even if this was unloaded i think it was ok,
after that i tweaked it with R507, and got down to -55 fast....
but still that damn display yanked my chain so i gave up and gave it a blow jobb with a hair dryer =)
Originally posted by Marci
All depends how well suited the current cap tube is to the setup. If current captube is optimum length already then no, it probably isn't. Only way to find out is to try it. -50 probable, but more than that purely from captube tweakin seems a little unlikely...
i visit local "freezer & fridge repairer" and he
sayed there is no enough small valve these outputs..
smallest was desing to 500w loads...,and optimal my system
were 100-200w?
if put that 500w valve , it would leasing gas too much or too little..
i guess i gotta put ..say 1.0m more cab tube and
test it..
bowman1964
12-12-2003, 02:21 PM
I have a program that can get you close.but i need wattage to be cooled.
but cap tub tweeking is a art,and a pain.
and i have done more cap tube tweeking than most have looked at.most techs understand cap tubing,but until you spend countless hours lenghing and shortening the lenghts and see how it affects the heat load and temps.you cannt know.
you can shorten the tube in 12 "lenghts to get one close.but since you are lenghtening to get colder temps,you will see 2 things happen.
at one point you will see the low side start to drop lower,because of less refrigerant passing into the evap,so less boil off to compress and move,hence less work,more vacuum,lower boiling point.
but then you will get to the point were there isnt enought refrigerant to keep the heat load cooled the evap temps will suddenly skyrocket,fast and hard.
ok when you reach that point,shorten the tubing 6 to 8 inches.and that will be the max that system can handle.period.
you will then have max tuning to the cap tubing per heat load you have,
there you have cap tube adjustment 101 from a hands on guy,not a text book reader.
cooler is optimize over 200w heatwattage now...i tested
with p4 3.6ghz 1.85v = heatload 110-140w
result = "suction line" is totally frozen all to way into compressor...
evap temp droped only -39c...
bowman: well calc to 150w load?
btw. i finded out that system has 110g of r404a