Computer fan in fridge.

[foxx510]

Thanks Pinhead I kinda get that, but then Me home air conditioner would be useless! with out a fan pushing the cold air out to cool down the occupants.

In this case warm Beer.

Cheers.

It's used in commercial coolers such as this one http://www.sanyobiomedical.com/asset...%20&%20414.pdf so there must be some merit in it.

[foxx510]

a heatsink operates by moving heat by direct contact..a fridge does not.
Does the fridge have a plate coil or a compact finned coil ?

And heatsinks such as those on a computer cpu use a fan to remove the warmed air and replace it with cooler air. It's all the same. The warm beer will be surrounded by a layer of warm air in the fridge as it looses heat, if you put cool air in it's place with a fan it will be able to lose heat more quickly because of the greater temperature differential.

As I said though it will only work to the point where the fridge can no longer keep up and the compressor is running continually.

Also though there will already be air currents in the fridge without a fan because of the temperature differential. The fan will just speed that up.

[Roughasguts]

a heatsink operates by moving heat by direct contact..a fridge does not.
Does the fridge have a plate coil or a compact finned coil ?

Inside it's a large finned aluminium plate about 14 inches long 3 inches wide and the fins 1/34 inchess long about half inch apart.

The fairly small freezer compartment is above that.

[PinHead]

Thanks Pinhead I kinda get that, but then Me home air conditioner would be useless! with out a fan pushing the cold air out to cool down the occupants.

In this case warm Beer.

Cheers.

the fan on your air conditioner is not doing any work by pushing the air into the occupied space..it is working by drawing the warm air over the coil which in turn removes the heat from the air.

anyway..no more comment..try it and see.

[Roughasguts]

And heatsinks such as those on a computer cpu use a fan to remove the warmed air and replace it with cooler air. It's all the same. The warm beer will be surrounded by a layer of warm air in the fridge as it looses heat, if you put cool air in it's place with a fan it will be able to lose heat more quickly because of the greater temperature differential.

As I said though it will only work to the point where the fridge can no longer keep up and the compressor is running continually.

Also though there will already be air currents in the fridge without a fan because of the temperature differential. The fan will just speed that up.

Thanks for your help.

The fridge is one of those Dometic 160 litre 3 way fridges, the amonia and something else, type of absorbtion fridge.

So shes running all the time no compressor but no noise as well so that's all good.

Apparently the fridge can get hot where it vent's out as well, especially if that side is in the sun. I haven't had this happen yet but this outside air temp with these fridges can be a problem. So that's why I'm working on something before the summer holidays.

I'm no Iron man anymore! cold pies, and warm beer, don't go down like when I was younger.

Cheers.

[Roughasguts]

the fan on your air conditioner is not doing any work by pushing the air into the occupied space..it is working by drawing the warm air over the coil which in turn removes the heat from the air.

anyway..no more comment..try it and see.

Yep thats all good This here little fan will be pushing the warm air from the beer cans and sucking it over the colder finned condensor and hopfully cooling down the Beer quicker. Or the shopping for that matter that seems to take forever to get cold as well, just don't go through it as quick.

Cheers.

[baydiesel]

Go for it, I have had a fan in my fridge for months and it works a treat. The best fan to use is a CPU fan and mount it on 4 plastic screw in wall plugs. the ones made to screw into plaster board. It will then mount directly onto the fins inside the fridge. Run a wire out thru the drain hole and connect to the fridge power supply. It will cool your fridge down quicker and the beer. Also you will have to turn the temp down to about 4 when on 240 volt and 5 on 12 volt other wise you will freeze things on the self below the fan. Mine is set on 4 runs at 0 degrees inside most of the time. Be carefull on cold nights it will freeze everything in the fridge, it's best to turn it off.
Cheers pete

[foxx510]

Maybe keep an eye on the temps of the outside vent then and try another or the inside fan there also, could have more of an effect on the outside if it isn't shedding heat quickly enough.

[Roughasguts]

Go for it, I have had a fan in my fridge for months and it works a treat. The best fan to use is a CPU fan and mount it on 4 plastic screw in wall plugs. the ones made to screw into plaster board. It will then mount directly onto the fins inside the fridge. Run a wire out thru the drain hole and connect to the fridge power supply. It will cool your fridge down quicker and the beer. Also you will have to turn the temp down to about 4 when on 240 volt and 5 on 12 volt other wise you will freeze things on the self below the fan. Mine is set on 4 runs at 0 degrees inside most of the time. Be carefull on cold nights it will freeze everything in the fridge, it's best to turn it off.
Cheers pete

Yup it's a cpu Fan! Thanks for the tip on the wall plugs, I haven't got that far yet still at work.

Anyway I guess you have tapped in to the house batteries, or vehicle for running the fridge on the road.

But what about when pluged in to 240v do you still use house batteries for powering up the fan or step down 240 volt.

Cheers.

[Horse]

Moving air chills much faster. this is why in cold areas you factor in the "wind chill" in calculations for insulation. The same principle applies to "blast freezers". Most commercial refrigeration requires moving air as do many marine installations where pulling fish down quickly is important (smaller ice crystals in flesh when freezing)

[Roughasguts]

Maybe keep an eye on the temps of the outside vent then and try another or the inside fan there also, could have more of an effect on the outside if it isn't shedding heat quickly enough.

Yeah I better take a look in the back of the fridge. The vans only 18 months old but it could probably do with a clean! and see how air circulation could be better improved.

Cheers.

[Roughasguts]

Moving air chills much faster. this is why in cold areas you factor in the "wind chill" in calculations for insulation. The same principle applies to "blast freezers". Most commercial refrigeration requires moving air as do many marine installations where pulling fish down quickly is important (smaller ice crystals in flesh when freezing)

Thanks Horse looks like I'm on the money then and not wasting my time.

Cheers.

[oldboot]

A couple of points.

1/ never get a "fridgy" involved in a discussion about airflow, they have very fixxed ideas about how things work....and in the stuff they work with things are pretty fixed... sorry pinhead...... mostly these guys are preocuppied with what breaks and what they have to screw to the wall.... and that is the box..... a mate of mine is even worse he is an airhandling engineer dscuions with him are a pain... even if you are right... he will find something else to argue about

Clasiclay.... this blowing cold V's sucking hot concept.... who cares as long as the beer gets cold

2/ most DC brushless fans are quite happy to run for extended periods under voltage, It is common in all sorts of equipment.....12 volt fans are typicaly reliably fine down to about 6 volts and 24 down to about 12 volts..... then it depends on the size and particular fan how far you can push it below that...I have had 12 volters run fine down as far as 5 & 5.5 volts particularly if they have good bearings or are mag levitation bearings....some will run as low as 4.5 volts but wont start reliably......I would no get too concerned with protecting any of these fand with a fuse, they are generaly short circuit protected and can be stalled at full power with little or no damage.....never seen one with a fuse of its own in any item of oem equipment.

as a general rule... half the voltage , half the current, half the speed, half the airflow and much less than half the noise... much less.

3/ if you are talking about a 3way or amonia cycle fridge....they do not cool down rapidly and they are incapable of producing as big a temperature gradient as a compressor bassed machine, and therefore can not cool stuff down as fast.

I would expect the best part of a day to properly chill a slab of tinnies in a typical 3 way van fridge... you would probaly do the same job in a proper fridge of the same size in 2 to 3 hours... especilay iff you tickle it up and remove the crisper.

4/ a large portion of modern domestic fridges have fan forced airflow and this does make them more efficient ( in theory) ... the idea is that the air is circulated and thus carrying the hot air back to the heat exchanger and minimising dead spots in the pack.

5/ while many "fridgies" thing the main function of a fan in an airconditioner is to pass air over the heat exchanger, the function of distributing cold air arround the room is equally important.......if the AC unit did not thrust the air far enough from the intake or return.... the airflow would short cycle in front of the unit and the room would not be cooled.

cheers

[Roughasguts]

Hi Oldboot yup that is me problem just getting the Beer cold.

And trying to get these stupid Dometic 3 way fridges a little more efficiant. I was starting to think it was just my imagination that they don't cool very fast! but at least you have confirmed my thoughts on that.

There Useless for the first half day after a fresh stock of anything! can't beleive there so exspensive and theres nothing in them. Geez a 6 dollar fan might just make it better and even a bloody light inside wouldn't hurt either.

Maybe even a LED to let you know that 12 volt is being used or 240 Etc.

Just going to have to do that meself I guess.

Cheers

[finga]

Ah, the fridge is in a van...the plot thickens.
Chuck a thermometer in the space at the back of the fridge.
If there is not enough air circulation the fridge will not work efficiently.
The flue needs a good flow of cool clean air over it.
They are sometimes called heat exchange units for good reason.
Take particular attention of where the top vent is. This needs to be above the height of the flue, the bottom vent needs to be lower then the heat source and the size of the vents is important.
I sometimes put computer fans in the void to assist air circulation which improves recovery rates of the fridge.

I would stick to the rated voltage of the fan. The rating is there for a reason. Whether it be longevity, heat buildup, air flow rates or what-ever.
You don't want the fan to fail (if it works) on a really hot summers day when you've just placed another 6 pack in.
The $6 on the initial purchase of the correct fan would seem stupid if the fan fails when it's most needed. Especially seeing that you, most probably, would not be close to a computer shop when/if it fails.

PS an efficient ammonia fridge will cool only fractionally slower or just as fast as a compressor type IMO.
They both work pretty well on the same principle.

As a side note...wind chill will not work on stubbies or cans of beer usless they are wet.
Wind chill is just an extension of sweating (but at a lower temperature)...same principle, same result. Things that have moisture getting sucked out (or pumped out as in sweating) and removed cools down. That's why good been hit with the blast freezing have smaller ice crystals. The moisture was sucked out before it could freeze in big blobs in the flesh.
Wind chill needs moisture to become wind chill and fairly strong winds. Stronger winds then a computer fan could pump out IMO
Here's a good link to work out wind chill
http://www.csgnetwork.com/windchillcalc.html
Google is good