1st stage is cap tube, im gunna throw a txv on there. we'll see what happens
Printable View
1st stage is cap tube, im gunna throw a txv on there. we'll see what happens
Ive been working on tons of information. Its not done yet, but its still a very useful resourse right now.
come check out my forum
http://www.captaincascade.com/forums/index.php?act=idx
I forgot to mention my forum is having a contest to see who can submit the most useful refrigration information.
the winner gets 2 1hp copeland low-temp cascade compressors!
just wanted to let you guys know, im not dead. And i am still working right along.
Heres a new one im almost done with.http://www.captaincascade.com/forums...1078263799.jpg
I have decided, that for every 200Btu/h of rated capacity (THR - including motor cooling and superheat) that 1' per 200btuh of (2 pieces) of 3/8" copper soldered together (side by side in a helix) should handle an interstage load at about a 110deg TD .... derived from what I did. ;)Quote:
Originally posted by captaincascade
ok, as you may or may not know. my three stage is not working properly. And i think i have gotten to the bottom of it. This was something very stupid of me not to antisapate. In making my own heat exchangers, i have not asured the where equal in size. What is happening is my 2nd to 3rd stage heat exchanger is much larger than my 1st to 2nd. so, my2nd stage is picking up alot more heat than it can reject to my first stage. it kills my first stage innerstage. and the 2nd and 3rd stage pressures rise astronomicly. this also aplies to autocascades. they dont have to be exact, but the heat exchangers should be close in size. when using a multi stage system.
lmao......hold on a sec...........hmmm
PS - the first stage load will be higher than the second stage load, and the second stage load will be higher than the third stage load. I think you would use a multiplier of about 1.25 to 1.35 to calculate the THR. The multiplier decreases as the evaporating temperature increases. Probably 1.5x for the third stage!
Cheers!
Take your lowest stage evap heat load (plus a little for insulation gain). Add heat of compression (25% or so). That is the heat load for its condenser, which is the heat load for the next stage's evaporator. Add heat of compression to determine that stage's condenser load, which is the evap load for the next stage up. Etc., etc., etc...
If I could figure out what you said, I would be happy to translate. :DQuote:
I have decided, that for every 200Btu/h of rated capacity (THR - including motor cooling and superheat) that 1' per 200btuh of (2 pieces) of 3/8" copper soldered together (side by side in a helix) should handle an interstage load at about a 110deg TD .... derived from what I did.
for every 200Btu/H of required THR in an interstage, 1' of copper (length) is required for the interstage heat exchanger (at 110degF TD)...
Is that better? :D:
PS... nice sig, Gary... :p:
Yep, it's pretty cool. You do nice work, Mark. Thanks. :DQuote:
PS... nice sig, Gary...
Okay, let's see if we can figure this out.Quote:
for every 200Btu/H of required THR in an interstage, 1' of copper (length) is required for the interstage heat exchanger (at 110degF TD)...
If we have an evap heat load of say 400btu, add 25% for heat of compression, for a total of 500btu, then we need about 2.5 feet of 3/8OD copper tubing for one side of the heat exchanger. Does that sound about right?
What do you mean by TD? Surely you can't be suggesting 110F difference between the two refrigerants?
Yes, that is what I was suggesting. If you wanted, say a 55deF TD, you would double the length. I propose that he relaitonship is proportional.Quote:
Originally posted by Gary Lloyd
What do you mean by TD? Surely you can't be suggesting 110F difference between the two refrigerants?
I was running a -10F suction temperature (not SST, but acutal) with an R-13 SCT of about.. OH! :eek: I take that back... the R-13 was at a saturation temperature of about 15degF... so about a 25degF TD...
Thanks, Gary...
Does that sound better?
Cheers!
That's much more like it. Now cut that in half (10-15F SCT/SST TD), and this is what we normally see in commercial systems.
Do you recall what the SST was?Quote:
I was running a -10F suction temperature (not SST, but acutal)
SST? of the first stage? or second stage? The 25degF TD was under a good load with my 160W water condensate heater, that I actrually think is more like 300watts, if you consider the total suface area of the pan, plus the heat output of the heater.
:D
In any case, I think any rule of thumb coming from this would only apply to tubes soldered in helix. Other types of heat exchangers would have different rates of heat exchange, contact surface area, wall thickness, etc.
Quote:
Originally posted by Gary Lloyd
In any case, I think any rule of thumb coming from this would only apply to tubes soldered in helix. Other types of heat exchangers would have different rates of heat exchange, contact surface area, wall thickness, etc.
Absolutely.. ;)
I am in full agreement....
Cheers!
man, im gone for five minutes.......you guys...
Time for Kommando to do alot of reading on cascade systems as he wants to try it some time next year :)
beware!
Theres a new creation lurking. I am calling her "captainCascades Revenge".
Tell you one thing, It aint energy efficient....:D:D:D:D
anxious to see THAT!!! :slobber:Quote:
Originally posted by captaincascade
beware!
Theres a new creation lurking. I am calling her "captainCascades Revenge".
Tell you one thing, It aint energy efficient....:D:D:D:D
C
Anyone got a pic of what the cascade thing cools the heat exchanger or something?
what?Quote:
Originally posted by kommando
Anyone got a pic of what the cascade thing cools the heat exchanger or something?
LMAO :rotf: :rotf:Quote:
Originally posted by captaincascade
what?
Imagines captaincascade reading that sentance and being just plain puzzled.
I really just dont understand. I read the sentence like 4 times, thats pretty much the way it happened russel lol.
pics dont work