View Full Version : Phase-change calculations?
naTTen
05-05-2003, 10:33 AM
Anyone got any formulas so i can do some calculations. Any formulas will do. Like how to calculate cop or something about the gases or whatever?
naTTen
05-06-2003, 05:38 AM
Tried to calculate how much btu it can handle but i'm not sure that i got it all right
Q = 205 * (0,055/0,304)^2 * ((52 * 1,8) + 32)
and i got Q to 853,43 BTU's
This is the formula
Q = U x A x TD
Q = heat gain, Btuh (btu’s/hour)
U = overall heat transfer coefficient of the exposure
A = area in square feet of the exposure
TD = difference between outside air temperature and air temperature of the refrigerated air space, deg F
I'm not sure about the U but i guessed that it is how much heat the compresor can handle. And i also asumed that the evap was -32 c(boiling point for r134a?) and the room temp was 20 so i get i delta T that is 52. i had to convert al metric units to fahrenheit and foot.
http://www.phase-change.com/phpBB2/viewtopic.php?t=316
might find some useful software on the link in this thread... dunno tho still have not looked thru it
]JR[
ellsworth
05-06-2003, 10:41 AM
does anyone know where to find software to calculate cap tube size?
bowman1964
05-06-2003, 04:32 PM
yea as most of you know i have a program and have been to the site where it isnt avalible to the general public anymore, but it came from tecumseh. but check these out maybe it will help you some.tecumseh (http://www.tpc-nacg.com/ref-sdh.htm)
ellsworth
05-06-2003, 05:11 PM
i found some programs on the copeland site, which requires membership, but their server seems to be down and i can't seem to download them.
naTTen
05-07-2003, 08:37 AM
I would love to find out how much refrigant comes to the evap every second. then you have the mass of it and can make all kinds of calculations like how much heat it can absorb and the pressure and perhaps temperature. this must have something to do with the cap tube because its that that regulate the refrigant.
Bowman. can you calculate how much refrigant that streams in to the evap every sec with that program of yours. it must be somewhere because i guess that it is necessary to need how much rfridagnt is needed to cool down a cretain amount of heat to a cretain temp
Method Man
05-07-2003, 10:38 AM
Hey bowman1964 can you zip that program and post it up here so we can use it?:cool:
bowman1964
05-07-2003, 11:51 AM
well i can try but i would need someone to host it.you will need a host first to download from.if anyone wants to or can host it. i can work something out with them.my server wont let me host a file other than pics and such.
but if someone wants it i can get it to them if they will post it.
naTTen
05-07-2003, 12:32 PM
Can you calculate the amount of refrigant that comes to the evap with that program
bowman1964
05-07-2003, 12:59 PM
Originally posted by naTTen
Can you calculate the amount of refrigant that comes to the evap with that program
nope not that i can see.
it must calculate it somehow,but i can only access it though the interface screen
Originally posted by bowman1964
well i can try but i would need someone to host it.you will need a host first to download from.if anyone wants to or can host it. i can work something out with them.my server wont let me host a file other than pics and such.
but if someone wants it i can get it to them if they will post it.
how big is it? my hosting will allow it, although ive only got 1gb/month traffic iirc and itll get kained pretty quickly if i put it up im sure :)
]JR[
or alternatively, rename the exe to jpg and upload it to your webspace, then simply rename it back afterwards :)
]JR[
naTTen
05-08-2003, 02:59 AM
They have probably a 1mb limit too :) my old account had that
Anyway. I have found a book that is called "Värmepumpboken" and that's swedish for heatpump book. I have found some nice formulas here and i will be back later for results and stuff
naTTen
05-08-2003, 04:47 AM
By the way. does anyone have the entalphy when r134a evaporate. The engergy that it consumes when it goes from liquid to vapor form
Method Man
05-08-2003, 03:10 PM
Originally posted by bowman1964
well i can try but i would need someone to host it.you will need a host first to download from.if anyone wants to or can host it. i can work something out with them.my server wont let me host a file other than pics and such.
but if someone wants it i can get it to them if they will post it.
I might be able to host it....how big is it zipped?
bowman1964
05-08-2003, 05:17 PM
its a small program only a little over 2 mg.
i tried again today to host it.i can upload to my server but i cannt download it because of the file type.