anyone know the mathmatical way to detrimen phase change related stuff

[3vil_l337]

such as but not limited to.
how can you find out the amout of refrigent needed to cool a object. provided we know everything about the refrgent and the blocks. how can we decide flow rate, volumes.

also then how can you detrime the amount of restriction needed and other things

and just about anything else that would apply to phase change cooling

just about anything you can think of would be nice, ive been looking around for the stuff but have been unable to find any equations for this.

im not looking for, "well for about Xwatts use about X meters of captube" or stuff like that. id like things that are alittle more in depth. thanks

evil

[pwnt by pat]

Check over here. There might be some good info waiting for you.
http://www.phase-change.com/phpBB2/index.php

[matttheniceguy]

Some of those things can fairly easily be calculated, others are really complicated and will only give you a decent guess.

The flow rate of refrigerant is a pretty easy one. There is no actual amount that is required, but if you know the flow rate and pressures or temperatures of the refrigerant in and out of the block you can calculate the heat absorbed, and from the processor heat output and amount of insulation get a pretty good guess at the temperature.

Mathematically figuring out what restriction you need (for a cap tube) would be pretty hard. You could do it using fluid dynamics and refrigerant properties, but it would be a whole lot faster and more accurate to just use imperical data. The same can be said for pretty much anything else you would want to calculate. It's possable to describe the entire system mathematically, but it is probably a lot easier and more accurate to use imperical data that has been gathered through many years of testing and experience.

If your building some bazzar new phase change systme unlike anything built before, go ahead and do the math. If your makeing a phase change system using a conventional compressor and restriction, just go with the imperical "for about Xwatts use about X meters of captube" because it's more accurate than anything you could realistically calculate anyway.

[3vil_l337]

lets just say, i like to enginer things, not just slap them togther. so you said there are calculations for this stuff? where might i be able to get my hands on them?
and anyways, i like playing the numbers :)

thank you for the info
3vil

[crimedog]

you're talking about thermodynamics. there is not a page of values and a sheet of equations to get what you want.

[3vil_l337]

oi nevermind, finally found some of the equastions i needed on nasa site. and sense you people are being kinda enough to tell me why i should and cant, sopposedly engiener this stuff, i guess ill just go up to the UW librayer and find all of the equations and laws behind this stuff myself. BUT i figured if anyone hear knew a few bits of these, they would be kind enough to post them up, guess i was wrong :)

well thank you those how did help. and best of luck to yeah
best regareds
3vil

p.s. thank you for the link, it didnt give any equations, BUT it did help on alot of other things, like how to clean my compreser, and alot of other stuff iwas still fuzzy about
p.s.s basic equation for thermodynamcs deltaQ=M*C*DeltaT well theres a start :)

[3vil_l337]

http://www.grc.nasa.gov/WWW/K-12/airplane/guided.htm

see thats all you really had to send me
not to hard was it? look through it, it has all the equations, that arnt one a single page, or cant be used for this :P

[crimedog]

sorry we suck so much. looking forward to your first cascade :rolleyes:

[speed bump]

You mean in two semsters I don't have to worry about thermo then heat transfer then HVAC and thermo 2?

Also what is ther wont help you a whole lot thats basic thermo for rocket scientests not Hvac and thermo for dummies. If you really want to learn how to do that take some junior and senior engineering classes.

Finally you need to realize phase change is an art guided by science no matter how well you know your equations its not going to be perfect despite your math. Mainly becuase equations are a starting point and if you don't know ever single little variable IE you sit down and miss measure a fitting and your compressor just happened to have some slightly higher tolerance component that makes it so you equations is off. Equations are a base to building something the simplest equations work best. However if you really really really want a crash course in HVAC ask chilly1 or ls7corvette over at XS the will probably give you enough equations to make your head spin.

[3vil_l337]

hey thank you very much, i will be sure to ask chilly1. and yeah well see how well my first system works. *Shrugs* and if it doenst work, then ill admit to it. but hey, i do understnad what your saying about the ball park stuff. so thanks for the info on who to ask. and well over the summer i will more then likely take the enginering courses, however with my curent state, i cant really.
thanks and chears
3vil

[matttheniceguy]

I'm affraid the equations on that nasa site don't even come close to touching the sort of thermodynamics and fluid dynamics you would need to properly describe a phase change system mathematically. And not to seem rude, but quite frankly you have zero chance of being able to understand or use any of the fluid dynamics or thermodynamics that describe this sort of thing anyway. I know this because I have a Mechanical Engineering degree, the degree you need to do this sort of work, and I have no chance of understanding any of those equations without a few years of studying them either.

If you want to engineer a good phase change system, do what a good engineer would do. Study what other people have actually made, and how it actually worked. Real world data and experience always counts for more than anything any equation says. Remember that the real world system creates real world results, and the math is only a tool that tries to guess what the real world outcome might be. Study all the guides to makeing phase change systems, come up with realistic expectations (heat load, desired temperature, noise, etc) and then design a system to meet those expectations using other peoples experience. That is the way to truly engineer a good phase system, not fumbling around trying to get some useless equation to describe what might happen.

Phase Guide 1 (http://www.vr-zone.com/?i=713&s=1)
Phase guide 2 (http://www.vr-zone.com/?i=714&s=1)
insulation (http://www.vr-zone.com/?i=224&s=1)
mounting holes (http://www.vr-zone.com/?i=1356&s=1)
Cap tube size (http://www.xtremesystems.org/forums/showthread.php?t=29694&highlight=cap+tube+rule)
XS phase section, lots of info in stickies and threads (http://www.xtremesystems.org/forums/forumdisplay.php?f=80)

There is a start on what you should be learning. Good luck with it.

[3vil_l337]

ok, jeash everyone starts to freak out on me, i was just posting an example of the kind of thing i was looking for, its not like i really knew what i was looking for, casue if did know would i have been asking for it? now i pmed chilley1 adn hes been kind enough to hook me up with some stuff so ill be going to go play with that. thank you very much for sugesting that, i should have done that from the start

now jsut to let you know, who are you to say if i wont understand it? know your right, i probly wont, but becasue you dont know who i am, nor do i know who you are, how can we really judge this? and on that topic, i have went through every guide on XS and also here on Oc. i even have all my parts, i have the braze, i have jsut about everything(sept refirgent).

and btw my father who is a self employed enginer kinda guy, we do large amounts of work, when we have to fix stuff for people. and time and time again. ive seeen the projects he works on, something that works jsut abit in real life, made by well know companys etc.. then he goes back and rediesns some of the stuff, and it ends up working alot better. now i understand that its no where near the same feils or anything. but its just has shownen me that,becasue everyone does it one way and it works, doesnt mean some one cant do it difrently and make it work better.

whats this mean, it means that i want to see if theres is maybe some way to make one of these run better. i may come up with nothing, i may end up doing it jsut like everyone else. but i would atleast like to try.

lastly i have a link http://www.et.web.mek.dtu.dk/Coolpack/UK/tutorials.html from chilley1 so if anyone else has wondered this go there.

well i will no longer bother replying to this thread. so if you feel like bashing me please send it via PM rather than cluttering a thread with a helpfull link.

chears
3vil

[Time4aMassiveOC]

BUT i figured if anyone hear knew a few bits of these, they would be kind enough to post them up, guess i was wrong



http://www.grc.nasa.gov/WWW/K-12/airplane/guided.htm

see thats all you really had to send me
not to hard was it? look through it, it has all the equations, that arnt one a single page, or cant be used for this :P


after saying these 2 things you are suprised you got a less than warm response?

you do realize they were all trying to help? why be snide and condecending?

im all for what you are trying to do though, once you find the concept of some peice of the puzzle you apply a simple mathmatical eqation to it as a guideline. then move to the next peice.

conceptual math is awesome.

hope you find what you are looking for. sorry i couldnt help