reflex

Hi all,

I now this isn't really overclocking related, but I need some help.

Uncle Jimbo I have been reading some of your posts on xtremesystems, but I am having trouble registering there.

I need to make a cooler box to cool 2 six packs.

I was running some tests in a plastic tupperware with a hole cut in it with a heatsink(cold side) extruding inside the tupperware. The hot side I was using a heatsink too cool. The ambient temperature when I was testing was about 16C. After leaving it on for about 2hours the 2 cans I put in there were 14C. The cans were not in direct contact. I thought this may be because of bad insulation, as the hot side was only reaching about 47C. I am running this TEC of the 12V rail on a computer power supply.


http://cgi.ebay.com/91-2W-TEC-Thermo...QQcmdZViewItem

Obviously I am not using the full power of the TEC at 12V, but I think it should be good enough to get a small tupperware to 0C. Also will a decent Heatsink and fan be able too cool the hot side if I wish to have a temp of about 3C in the cooler with a 30C ambient?

Thanks in advance

Scarlet Infidel

A photo would be helpful here.

How much pressure is there on the peltier? There needs to be a lot and it needs to be even.

Can you measure the current draw of the peltiers and check the voltage level is staying high?

How are you connecting the cans to the cold heatsink? Are you using a fan to blow cold air? Maybe filling the Tupperware with liquid (e.g. water) would be a good way of allowing heat conduction (this of course adds more thermal mass to cool initially).

reflex

I have a photo, but not the camera at the moment. The peltier isn't under much pressure at the moment, but I have now taken an old stainless steel pot and wrapped it in polystyrene. The pot has a bracket on it so I can put the peltier under pressure. The can will only be able to lie sideways in the pot, I am hoping to mainly cool the air inside the box. Should I have a heatsink and fan inside the box aswell?

reflex

Ah, the voltage is staying at roughly 11.9V and is drawing about 5 amps

reflex

How much pressure is alot? I rather new too this stuff.

The problem seems to lie in transferring the cool from the peltier to the air. The cold side is getting well below 0C

Yesterday I experiments with the pot, I covered the whole thing in polystyrene and left a small open square at the bottom for the peltier. It has a copper base. Any I turned it on and only the middle of the pot got cold, cold enough to freeze water but the rest of the pot stay quite warm.

So I closed it up and left it for about half an hour. The temperature had only dropped by 2C from ambient.

Scarlet Infidel

Air is a very poor conductor of heat. A fan circulating air may help, enlarging the surface area above the peltier cold side should too (though this is a little awkward).

As I mentioned before, try putting some water in the pot and see what happens to the temperature of the water,

reflex

I will try some water tonight. After that I will attempt using a small heatsink and fan on the cold side, inside the pot.

Thanks for the help

reflex

Ok, I have finally obtained some decent results. I went and bought one of those foam coolers for a six pack today.

I cut a hole in the side and mounted a heatsink with fan inside and one of the outside. It cooled 2 cans (340ml) from room temp 19C to 3.5C in about 45mins. I don't know if this is any good, but it is better than anything I have achieved so far.

Scarlet Infidel

Sounds very promising, that's the same temperature as a normal fridge in a pretty reasonable time. Well done.

reflex

Anyway, I am going to post on xtremesystems, I think the TEC community there is perhaps a bit better. Thanks for the advice, I will continue to experiment