cooling time.. 1

[marBz]

im designing a chiller absorption system with a minimum of 35 F chilling temperature. How much time needed a "can beer" attain 35 F considering it has a room temperature of 70 F.

and one thing, is there any equation to get the number hours that my refrigerant will pass trough my instruments? Ex. the time needed it will pass to evaporator or condenser..

sory for my englsih.tnx a lot!

God bless you!

 

[IRstuff]

Hypothetically, the time is nearly infinite. Newton's law of cooling states that heat loss is proportional to the temperature difference. Therefore, the closer the beer can gets to 35°F, the smaller the heat loss.

Moreover, you've stated bupkis about the cooling capacity of the chiller. What's up with that? How are are you supposed to determine the cooling time if you don't know the cooling capacity. Is it a watt or 100 watts?

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize

 

[MiketheEngineer]

Theoretically it will never get to 35 degrees. For example say you cut the temperature in half every hour and then again half the next hour. You will never reach 35.

Now if the cooler has a large "capacity" (watts as stated above) and is set at say 32 degree- you will get to 35 pretty quickly.

My refrigerator takes about 5-6 hours. BUT if you really want a beer - I would drink one at room temp.

 

[KiwiMace]

Chiller manufacturer should be able to help you with the refrigerant flowrate - capacity is always given.

If it had to be 35deg beer, I'd go as far to put ice in it. Not everyone's favourite idea, but I have done it. If you can settle for a 36deg beer, you need not spent US$600/RT on a new chiller/fridge.

 

[MiketheEngineer]

BTW - A CO2 fire extinguisher will do a pretty good job in a pinch!!!

 

[racookpe1978]

What size "can" of beer? What metal is the can made of? Is the can thermally lined, or pure "whatever metal" is chosen? (Are you supposed to plan for bottles as well?) How many cans are to be cooled? Is the 6-pack wrap also to be cooled?

How thirsty are the beer-drinkers?

What is the tolerance margin of the beer-drinkers' "margin of error"? That is, at what point will the beer drinkers cease to measure the temperature of the can of beer, and merely begin expressing an interest in drinking the beer?

Where is the 35 degrees to be measured at? Water/air/nominal cooler temperature of the thermal mass? Outside surface of the can? Inside surface of the can? Average beer temperature? (Will you agitate the beer before measuring the average? Will you agitate the beer drinkers by agitating the beer to average the beer temperature by agitation?)

 

[MortenA]

There should be lots of emperical data avaiable for this type of problems.

Most early research into transient heat transfer went into autoclaing stuff (canned food) and many heat trasnfer text book will have diagrams where you can solve these special heat transfer problems (always something about infinite rods since the bloddy edges at the end of the cans are a bitch to include - and so if the can are sufficiently long it wont matter wrt centre temperature)

Best regrads

Morten

 

[imagitec]

Let's do an empirical test. We'll take this fine can of Olympia, set it on this chiller, and wait to see how many seconds it takes to get to a consummable temperature.

One...

Two...

Three...

>Pop!<
>Hiss!<
>Glug glug glug!<

Three.

(With apologies to the Tootise Pop Drops owl)

Rob Campbell, PE
Imagitec: Imagination - Expertise - Execution
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