General Laws of Physics

[Keefe]

At work today we got a huge air tight metal box for a server to go into. SPAMWe also received an air conditioning unit to go inside of the box. SPAMThe air conditioner is not vented outside the box, so no air can escape at all. SPAMHow is this going to keep the servers cool? SPAMFrom general laws of physics I thought that if the entire unit is self contained the temperature will not drop. SPAMActually, wouldn't it heat up from the heat given off from the server and the compressor in the air conditioner? SPAMIf anyone has any ideas let me know...we have a little argument going at work...

Thanks
keefe

[Grinnin Reaper]

Yhea that's kinda the way I see it. SPAMNow one way to make it work would be to take the AC unit and route the condenser (the AC's radiator like unit) on the outside with fans. SPAMJust like on a refrigirator. SPAMI mean even they have it mounted on the back. SPAMAnd yes the temprature would just keep goin' up till somethin' blew. SPAMEventually something would give out from the temp. SPAMBy the way was this a marketing decision??

[Aoshi]

i dont htink the temp would just keep going up if the air conditioner is running as well. SPAMIt is stupid not to have any type of curculation going through it though. SPAMIt would make it harder for the air conditioner to first cool the air before it regurgitates it back out. SPAMIt would be best to have the air conditoiner in the front of the box and have fans in fornt and in back so that the air comming in would get cooled right away and cool the system then the hot air would leave.

[Keefe]

Savage: SPAMNo, sorry it was not a marketing decision. SPAMIt actually was a decision by the owner of the company. SPAMAll I know is that I will be laughing when the server melts...

[Aoshi]

it wont melt keefe, like i said before, the air conditioning unit will cool the air, but it wont cool it effectly.

[Grinnin Reaper]

Aoshi- the whole thing is enclosed.

Even in your house your AC unit needs to be part outside. SPAMif you put the whole thing in the middle of the house it will actually heat up your house. Because of moving parts + friction = heat. SPAMYou have to have outside air involved at some point or your temp will skyrocket. SPAMLike I said above even your refrigirator which is a sealed box has to have the condensor on the back. SPAMIn fact on some allmost the whole back is covered with tubes and cooling fins. SPAMIf you stuffed all that stuff inside you'ld have an oven.

[Aoshi]

hmm... they still should have a windtunnel effect with that air conditoner, it would cool it very nicely

hey keefe shouldnt you tell yoru customer this so that they wont be comming back and argueing with the place you work?

[vee_ess]

Savage, Aoshi is right. first off, take the Ideal Gas Law formula (which I have handy from a friends notes...N=PV/RT). heat does not result from compression, lack of heat does. with the formula you can see at the same R, but increased P(pressure) and decreased V(volume) the temp will increase. then, with the reference to AC units, i live in AZ and help with a lot of work around the house so i gotta know bout this. unlike evaporative coolers, AC's are closed units and do not use outside air except to cool some parts, but...there are AC's that cool themselves and are not external at all, just like the case, and they are just not as efficient.

the reason air cooling and watercooling must be outside is because of the transfer of electron activityfrom very active electrons from the very hot surfaces to moving the air and the water molecules and then those substances transferring it to an outside substance which is almost always air. only thing i've seen.

dont argue with me cuz i am right. SPAM <notice the period

[Keefe]

Where is the heat going to go then? SPAMHeat has to transfer to something else, it cannot just go away. SPAMEnergy cannot be destroyed.

[vee_ess]

it is what is called endothermic...

Main Entry: en·do·ther·mic
Pronunciation: "en-d&-'th&r-mik
Function: adjective
Etymology: International Scientific Vocabulary
Date: 1884
1 : characterized by or formed with absorption of heat


http://www.m-w.com

heat is not energy...all heat is is electron activity and how fast they are moving around...taking melting points for example, it is just the point of activity where molecules can move past each other, and if there is too much pressure, there is not enough room for molecules to move, it freezes, and there is nothing getting warmer. that is the basis for the AC. removing containable space so the stuff cant move as much and BAM you got coldness, and a lot more than the heat produced by other parts.

[MIK3]

Hey guys, just to warn you, dont mess with vee_ess......
SPAMThis guy is a miniature Einstein, no joke. SPAMI will put my money on his word of science any day of the year! SPAMGo ahead and try to fool him..... he knows what he is talking about, kudos to ya man!

[Aoshi]

the (cold) ac would absorb the heat, therfore cooling the air. SPAM

[Keefe]

Heat cannot be "absorbed" by cold air. SPAMWhen air cools, the energy(heat), flows to other air/water/whatever molecules. SPAMIf it is self-contained, the energy will go into the other surrounding air. SPAMIf anything, it will heat up because of the heay given off from the compressor and components of the system.

[wildcard]

hmm, interesting thread-

I understand endothermic and exothermic, had a few semesters of Physics in college.

I wrote up a huge post on the basics of the heat transfer process of this 'cooling machine'. SPAMI opted to just narrow it to this:

Even ignoring the heat the computer creates, the 'machine' will use power. SPAMI believe anything that uses power, also expends heat.

So let's say the machine uses 100 watts of power, how much cooling could you expect? SPAMThere is no such thing as a perfectly efficient machine, so at best you could only achieve heat absorbtion of 99.9999%, or abosrbing 99.9999watts worth of heat.

with only the cooler working, over time even assuming a high rate of efficiency, the box would heat to a high point. SPAMWhen you take the computer into consideration, which uses 300 watts or more (it's a big server), then I feel it's obvious that the computer is headed to an inevitable meltdown.

As example, if you could create this sort of situation, why don't they make CPUs that don't exhale heat? SPAMAnd why do air conditioners at home and work have to burp out the heat to the outside?

As a good example of endothermic heat transfer, look at peltier CPU coolers. SPAMCurrent goes thru the peltier to super cool one side, the other side gets superhot. SPAMIf you just let the current go at it, overtime the hot side would permeate to the cold side overtaking it and sending it to a meltdown.

I could be very wrong here, I am just trying to use my logic and understanding of physics of the real world to explain this situation. SPAMIf I am wrong and you can logically explain that to me, I would love to hear it. SPAMPlease be polite about it. SPAM

Thanks- SPAM
SPAM-Eric-

[Aoshi]

keefe, trust me here, i'm in honors physics right now and we jsut did this stuff a little while ago. SPAMWhen you ahve two objects a hot one and a cold one wheater its air or not they will mix and eventually even out at a certain temp. SPAMThe cool air takes in teh heat from the hot air, therefore cooling the hot air.
This can be explained in another way: When you live near a lake of a body of water during winter its warmer because heat from the lake is being taken into the atmosphere, and during summer the cool lake take heat from the atmosphere causing the temp to be cooler for a while in spring. SPAMIt also explains why its not going to be 70's in spring until the snow is gone.


sorry vee_ess, i know your on my side but heat is energy, movement of electrons or any type of molecules is defined as energy. SPAMIt is also included when your calculating energy in a system. SPAMYes everything is not 100% efficient, thats becuase some of the energy is released as heat, although your right on the gas laws and compression :)

[Grinnin Reaper]

Okay I know when you compress the gas it will result in a heat loss a.k.a. cooling. SPAMYou can't just keep compressing it. SPAMSomewhere, sometime it will expand and it results in heat. SPAMIn a car this is expelled in a radiator type device that is mounted to the main radiator, in a refrigerator it is done on the back, in window mounted a/c's it's done out the back side and is exhausted outside, and in central air conditioning it's done either through the roof mounted a/c's or through a small device beside the building. SPAMIf the entire a/c device is mounted in the sealed server case then its exhaust will remain in there. SPAMSure the a/c will cool some air but its exhaust will cancel this out. SPAMThe only device I've ever saw that defy's this is a peltie cooler. SPAMIt uses electricity in some way to cool the surrounding air. SPAMI really don't know how it works but I used to work on machines that used them for cooling. SPAMEven fairly large ones only dissipate a fair amount of heat. SPAMI forget the specs but the ones we used could barely keep 30 to 40 ounces of liquid cooled 15 to 20 degree's Fahrenheit running all the time with no introduction of heat. SPAMWe was just trying to keep the liquid cool. SPAMA/C's only move heat they do not destroy it. SPAMIf you only move it to another part of the sealed case then the case will countinue to heat up. SPAM

[Aoshi]

what keefe forgot to mention to us is that the ac has a nice sticker that says exhast here or soemthing like that on it.

thx keefe!! SPAM;)

[jinx]

Well, after reading this entire thread, I would suggest considering the " huge metal box " as the radiator. If it is " airtight " SPAMwith no exhaust vents, then it probally has been calculated by size to dissipate the heat which will be generated in side by the air cond exhausted heat.

The air cond unit itself has been calculated by size to cool the generated heat from the server's electronic components. As long as the server is on, ( up and running ) a certain calculated amount of heat will be generated - calculated from the amount of current it is drawing. With the air cond pumping heat from the electronic devices, the huge metal box will act as a radiator to dissipate it's heat in to the ambient area, which could be inside a bldg or outside.

Just my opinion ( without knowing all of the facts ) which is based on my 40 years experience as an Electrical Engineer. ( now retired )
But I would love to hear an official explanation of why a huge metal box if other answers are true. Also would love to know the outcome of it's operation when it is placed in service.

Btw, incase anyone is interested, Whirlpool made one of the most efficient home freezers ever mass produced which actually used the metal top ( freezer cover - top door ) SPAMas a radiator, at times it would be warm and nothing could ever be placed on top of the cover- lid- door. This was in the early 70's.

[Eric C]

Hello all-

I work with Keefe, I posted a post a few posts ago. SPAMHere is some more pertinent info about the system:

The box is about 3 feet wide, 3 feet deep and 4 feet tall. SPAMThe reason this company wants to put the server into a locked box is due to it being in a dirty factory setting and for security reasons (it will be locked and houses their whole database). SPAMThe box is plain, not air tight, but it will be locked and I imagine it is close enough given our discussion.

The computer is a server with dual processors (forget specs), 4 100 GB HDs and unknown power supply rating. SPAMI mention this so you can imagine that one HD gets warm, 4 HDs and 2 processors will create significant heat.

The cooler was opened when I saw it, and I don't know any power specs, brandname or anything. SPAMIt appeared like any ordinary space heater, 12 inches wide, 9 deep, 24-30 high. SPAMWhen I asked why they had a heater, I was told it was a cooler. SPAMI noticed there didn't appear to have any outward vent. SPAM

The previous posts have all been good, but I am disappointed in the guy that feels we should just trust young einstein. SPAMThere are smart people reading this post, a real einstein would know the answer and be able to explain it so a majority of us could understand and agree with it. SPAM:)

Note that this box was picked only for its sealability from dust and thieves. SPAMThe box itself will not act as a radiator given that I believe there was a lining inside that didn't look like a perfect insulator, but it wasn't bare metal either.

My knowledge of physics leads me to believe that even without the server and only the air conditioner in the box, eventually the box would reach a very high temp and the conditioner would burn out. SPAMI base that on the fact that no machine is 100% efficent yet, so there would be a slightly greater heating action than cooling action.

That's assuming that only the conditioner will be used in the box. SPAMNow add a server case with probably a 350 or 400 watt power supply, dual pentium 4 processors, 4 100 gig hard drives and the bit of heat the motherboard makes (chipset and such). SPAM

It's headed for meltdown, and I don't think it's going to take too long to get there. SPAMIf the AC was vented out of the box, then it would be a wholly different story and probably work awesomely.

I look forward to seeing the post that can tell me I am wrong and give logical reasoning or back it up with physics laws that disprove me! SPAM:D

-Eric-

[vee_ess]

(1) Here's what will happen...the heat (which is not energy itself [usually it is but we are not talking about types of energy, we are talking about just the concept of energy] but a result of the energy: the molecules will be moving around faster and bouncing around faster because of the energy [i should of explained myself further the first time]) will be spreading itself throughout the air in the case (molecules bouncing off each other hit other molecules and make them start moving faster too) and then the warmer air will come to the container of compressed refrigerant. When this happens the molecules going faster will start colliding with the container of the refrigerant and will start slowing down because the molecules of the container will not move much faster (but when it does startgetting heated up it will cool down because of the refrigerant not having room to bounce around much), resulting in the air around being cooled. This energy doesnt just disapear, it excites the coolant from the case excitng the molecules, and the coolant tries to expand (the molecules try bouncing around and push each other away from each other), but as it expand the compressor kicks in and pushes it right back. the energy doesn't get get transfered from hot to cold or cold to hot, it gets transferred from "heat" which is sort of kinetic for the way we are describing it, to stored energy or potential energy (as soon as the compressor releases, it will expand and start baking in there). It will probably need a very strong compressor cuz otherwise, it will burn-out because of the pressure being pushed back. * I apologise for some of the phrasings, as I am very bad with words and find it hard to describe what I am thinking.

(2) If this method of cooling is to keep the dirt out, I might suggest another method using an off-shoot of water cooling:
i. seal off your unit, except make 2 holes for tubes to pass through
ii. put watercooling heatsinks on any components to be cooled
iii. run all tubing for the water through these heatsinks
iv. have these tubes connected to 1 intake and 1 exhaust tube
v. place these 2 tubes through the 2 holes in the case and seal it
vi. on the outside place the radiator with the 2 tubes connected
vii. place the pump inbetween radiator and first heatsink, either on inside or outside and if you want put your A/C unit where the fan is supposed to be on the radiator and you have an effective A/C cooling system (no dirt inside computer!)

(3) A/C units dont burp out heat or anything as a requirement, they just use it as a method of cooling without having to cool themselves too. I will remind you that there are A/C units that I have seen in the middle of houses, they just have to cool themselves too, that's all.

[Grinnin Reaper]

I still don't buy it and until you can explain those "in the middle of the house units I won't" SPAMI've seen a lot of A/c's mounted in the middle of the house. SPAMIt's called central air and usually used in connection with central heat and air. SPAMAnd every one of them have had a condensor outside to get rid of the heat. SPAMYour right compressed refrigerant does slow down the molecules and it does result in lower tempratures. SPAMHowever you can't just keep compressing it to make it cooler. SPAMThe refrigerant will have to go through a condensor where the pressure is bled off and the heat can escape. SPAMYou can't just keep compressing it or you will blow hoses out and I don't care how big of a compressor you have it will burn out. SPAMAnd as proof here is a list of places you can find condensors. SPAM"In a car this is expelled in a radiator type device that is mounted to the main radiator, in a refrigerator it is done on the back, in window mounted a/c's it's done out the back side and is exhausted outside, and in central air conditioning it's done either through the roof mounted a/c's or through a small device beside the building. " SPAMIf you don't need these devices why have they been built for over 40 years as ways to bleed the heat off the refrigerant.

[Grinnin Reaper]

And since I did some research I have found out more http://www.howstuffworks.com/ac.htm SPAMIt is explained in detail and in actuallity you find that the Freon is compressed SPAMfirst and this results in heat. SPAMIt is then ran through the cooling coils to become cold. SPAMThen it starts to absorb heat. SPAMAnd yes that is right compressing things result in heat. SPAMI'm sorry I was in error to even agree earlier about compressing results in cold. SPAMIt doesn't anyone that's work around industial air compressors can tell you that when you compress air it gets hotter. SPAMJust the way it is.

[jinx]

Well, I don't see it as a 'physics' problem entirely. The answers to the questions will probally be in 'Ohms Law' where power is calculated, P=IXE, once the wattage of usage is calculated, then the BTU's are calculated. Next the cooling system- whatever type it is- will be based on how many BTU's -etc.
Also it is a matter of heat transfer, since Freon12 boils at 30 degrees F, the heat 'transfered' will need to be 'exchanged' somewhere. Then we have 'condensation' SPAMas a byproduct of heat transfer.
So the questions are:
A-) Where will the heat exchange take place ?
B-) Where will the condensation drain to ?

If 'Ammonia' type systems are used, an exhaust pipe and usually a flame are required.
If a 'Peltier junction' method is used, heat will still need to be vented, and this method is not at all very efficient for large projects.
A method could be used that is not so far addressed in this thread, or a melt down may be in the making.
Keep us updated on the project- please !

[Grinnin Reaper]

More proof of hole in theory. SPAMIf cold was the result of compression then heat would be the result of decompression or expansion right? SPAMWell if you've ever used canned air you would know that as you squeeze the trigger and the gas escaped (Pressure Loss) that the can gets colder. SPAMTo the point frost can form on the can. SPAMSo if decompression results in heat loss the compression would have to lead to heat production. SPAMAm I right??

[akimoto]

All you need to know is PV=nRT

[Keefe]

So the server died from overheating the other day. SPAMThe boss called up the company and they re-evaluated how to install it. SPAMI guess it is suppose to be mounted to the back of the large box, with a hole cut into it.

I love being right...

[jinx]

So do I , and thanks for the update. You would think that any Company, corp, firm, whatever that had enough sense to set up computer equip would know that the heat generated from it will need to be exchanged somewhere, guess they just had to learn the hard way !
Water flows downhill, earth is round, gravity pulls down, and heat has to be exchanged. Period.

[thetechfreak]

we should of setup a pool on when it was gonna go down...whoever won got admin for a week SPAM;D

was a pretty good debate... shame the server didn't last abit longer

[Grinnin Reaper]

Just goes to prove that theory is one thing and the real world is a whole diffrent ball of wax.

[vee_ess]

yeah i still think the compressor just couldn't press hard enought to compress to keep it cool SPAM>:(

just playin y'all

[jinx]

What compressor ?

[vee_ess]

that compresses the coolant

[Grinnin Reaper]

Did you read any of the other stuff I posted. SPAMCompressing stuff causes heat. SPAMIf you don't beleive meafter you followed the links on the other pages think about this. SPAMA diesel enginehas no spark plugs and diesel fuel isn't flammable it's combustible (a diffrence in the ignition temps). SPAMThe diesel engine runs off of compression. SPAMWhen the fuel/air mixture is compressed it heats up until it explodes. SPAMSorry man but compression causes heat and that's all there is to it. SPAMAnd like I said I have the links on page 2 to back it up.

[vee_ess]

agreed. and i did read what you said, as i read everything on this thread. but the compression indirectly causes the cooling. i didn't want to go in to details that you already said. sorry about the lack of clarity. i have a hard time speakin cuz people dont understand me. i find it funny. SPAM;)

i figured you were gonna say somethin about diesels earlier, but the you didn't but then you came through and didn't disappoint me. kudos to you fellow grease monkey (well if you even call me a grease monkey...dont even have a car)