×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

cooling time..

cooling time..

cooling time..

(OP)
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!

RE: cooling time..

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: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

RE: cooling time..

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.
 

RE: cooling time..

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.

 

RE: cooling time..

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

RE: cooling time..

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?)  


 

RE: cooling time..

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

RE: cooling time..

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
imagitec.net
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources