Condenser- Cap tube ratio

[naTTen]

I have a 205w compressor that will run on r134a(instead of propane as i first thought). I plan to make the condenser 1 meter long and have a ID of 10mm. How long cap tube will i need
?

[bowman1964]

Originally posted by naTTen
I have a 205w compressor that will run on r134a(instead of propane as i first thought). I plan to make the condenser 1 meter long and have a ID of 10mm. How long cap tube will i need
?

not sure what you mean 205w compressor?
for capillary tube size ,i need to know how many watts of heat do you want to remove.tell me the watts of heat you need and refrigerant you want to use. 134a i am guessing by the post.
then i can figure it up for you.

[naTTen]

Well. the people at danfoss said that it can remove 205w at -15 degres celsius and i am aiming to remove so much heat at possible at -20 - -40 c.
I hope you can calculate the length.
I'm going to use r134a.
What length should i have for the condenser or are you going to base your calculations on the length i wanted?

If you got any mathematical formulas please post them here. Or is it just based om some universal chart?

[bowman1964]

Originally posted by naTTen
Well. the people at danfoss said that it can remove 205w at -15 degres celsius and i am aiming to remove so much heat at possible at -20 - -40 c.
I hope you can calculate the length.
I'm going to use r134a.
What length should i have for the condenser or are you going to base your calculations on the length i wanted?

If you got any mathematical formulas please post them here. Or is it just based om some universal chart?

OK i loaded the spec you gave me.210watt of heat removal.
i decieded to just print it for you.this is a program i have that will caculate the proper lenght.
look at the bottom for the cap tube size and lenght ,it is in metric just convert it for proper size over here.

[naTTen]

Thanks

Where can you get the program?

What if i want to have 0.5mm cap tube instead. Is it based on the condenser lenght?

[bowman1964]

Well program came from TECUMSEH EUROPE but is no longer on the web site for public download.i tried to host it on my web page but with todays restrictions i cannt.

to anser your question.no capillary size or lenght is based on condensor size. a condensor has but one general rule.remove enough heat to allow for proper condesation.each refrigerant has a basic temp that is needed to reach to alow it to condense under a certan pressure,into a liquid.too short of condensor and you wont get any condensation because the gas will not be cool enough.


and the only thing that would happen if you have too short of evaperator lenght is you may get flooding of the compressor because the liquid hasnt all evaperated into a gas

[will_perdikakis]

bowman,

Would sub-cooling the capillary tube decrease the length of the capillary tube needed to move 210W?

[bowman1964]

Originally posted by will_perdikakis
bowman,

Would sub-cooling the capillary tube decrease the length of the capillary tube needed to move 210W?

well if you subcooled the capillary you would in effect increase the amount of watts of heat you can remove,or it would decrease the evaperator temps slightly.
so if you wanted to remove 210 watts of heat with 2.61m of .800 capillary tubing.now if you subcooled the capillary you would need to INCREASE the lenght of the capillary to keep the same watts of heat removed.
the main reason all of us subcool,is to drop the evaperator temps as far as possable.the overall evaperator becomes much more effeciant.

[will_perdikakis]

So it would be an equal amount of capacity but a lower evaporator temp if you did a little subcooling on a longer tube, correct?

[bowman1964]

Well if it was me. i would build the evaperator to handle 150 to 170 watts (direct block)then caculate the capillary.

then subcool the hxll out of it.this is what i think works the best.leaving the cap lenght alone helps my pull down time.

because the subcooling wont come into the picture untill the evap is already setting at a low temp and then the extra liquid not boiling off is returning with the gas.this cools the suction side down.and that is were most of all the subcooling comes from in the first place.so then you start to see the effect of subcooling.

so subcooling doesnt come into the picture untill minutes after the evap has cooled down.

[naTTen]

if i use a 0.5mm cap tube instead will it then change the lenght of the cap tube.

Do you think that 1m condenser will be enough? it will be mae of copper

[bowman1964]

Originally posted by naTTen
if i use a 0.5mm cap tube instead will it then change the lenght of the cap tube.

Do you think that 1m condenser will be enough? it will be mae of copper

First off yes it will make a big differance on the tube.i dont show a .5 but i show a .600mm tube.and as you see in this pic it will take 2 .600 tubes not one to do the job then.

and i think 1m condensor is too short,unless you are going to water cool the condensor( you are talking about 1m of copper tubing?).i would say more like 3m air cooled may work.all depends on how well the air cools the tubbing.1 meter may work if it had fins and such to help in the heat transfer.

[naTTen]

Ok.

Sat and thought about the condenser in school today and i thought it was to short too.