Peltier devices

[Glot]

Has anyone played around with Peltier type thermoelectric heating/ cooling devices?

 

[QldKev]

Yep, I scored 3 car fridges quite a while back. Kept one and ended up playing with the other two. Easy to setup and use, but they are extremely inefficient. I even tried increasing the capacity using a large heat sink and it still sucked the power for the amount of heat/cool it produced.

 

[Beerisyummy]

+1 on Kev's summary.

They can work if used properly, but they are way too power hungry compared to a compressor unit. They also struggle to pull very low beyond ambient.

http://www.novatecproducts.com/iceprobe.htm you can mount something like this directly into a fermenter, but they only work so well.

 

[Ducatiboy stu]

Good for things like wine fridges. I have one but its not big enough to fit a ferm in. Unit only draws 80wbut not really enough to pull them temp down and hold it.

Make a good cheese fridge.

 

[Glot]

They are only a couple of dollars to buy a 60 watt one. I was just thinking about the cooling and then heating all in one device.

 

[Ducatiboy stu]

They dont work fast like a compressor. But no harm in trying

 

[Beerisyummy]

Hey Glot,

Are you talking about just buying a chip and making your own device, or a ready made camping fridge unit?

Also, what sort of use will it have?

 

[Glot]

I was just looking at the ceramic chip. Bolting it to a bit of solar mounting rail and adding an old computer style fan. I just like to play around. Maybe I should try golf

 

[Ducatiboy stu]

They need a reasonable sized heatsink to work efficiently. You have to take into account the amount of heat they transfer and the amount they produce operating. So you need a heatsink for the cold side and the hot side. The higher the temp diff between the hot and cold side the less efficient they become.Ambient temp also affects how eff they work

 

[Ducatiboy stu]

They need a reasonable sized heatsink to work efficiently. You have to take into account the amount of heat they transfer and the amount they produce operating. So you need a heatsink for the cold side and the hot side. The higher the temp diff between the hot and cold side the less efficient they become.Ambient temp also affects how eff they work. A standard fridge type compressor is roughly 4 x more efficient and are more instantanious.

Would work great conected to a solar panel.

 

[zarniwoop]

What everyone else has said. They are primarily used in applications where the complexity or cost of a compressor cooling system is too much or where you need high reliability owing to the lack of moving parts. Not only are they not very efficient they don't actually have that much cooling (or heating) capacity when compared to a compressor system for the type of cooling we're talking about. They're quite good at maintaining temperatures over time where you don't have much mass to cool (e.g. cheese fridge as stu already mentioned).

Some of my work is connected to thermal systems for high power electronics and I looked at them some time ago as I think they're quite cool as devices but decided they didn't really have a place in brewing (or at least I haven't though of one yet....)

 

[Glot]

yeah, but a fridge compressor cost more than $2.50

 

[Beerisyummy]

Some of my work is connected to thermal systems for high power electronics and I looked at them some time ago as I think they're quite cool as devices but decided they didn't really have a place in brewing (or at least I haven't though of one yet....)

I was using a spare 85w chip water cooler/heater when I first started using temp control. It worked just fine, but had difficulty at the lower end of the scale.

It does make me wonder how well it would work in a small jacketed fermenter. If I go back through my old note books I'm sure I recorded results somewhere. From memory it maxed out around 1c.

Glot, find a free fridge on the side of the road instead. I've grabbed a couple that have been free and work just fine.

If not I'm keen to see what you do with the chip.

 

[Ducatiboy stu]

If you had a peltier fridge in your shed at 35* and you wanted to get a fridge to get down to say 15* its a big ask. Not only do you have to get a drop of 20*, but as it is cooling it is also heating up, might get up to 60*. Now your are looking at a 45* temp difference accross the device. The device may be able to achieve a 20* drop, but as it operates and heats up to 60* it will only cool the fridge to 40*.. It doesnt produce cold like a compressor fridge but a temp difference from one side to the other. Hence you need big heatsinks on it.

Hope that make sense in a rather muddy water kind of way.

 

[Beerisyummy]

If you had a peltier fridge in your shed at 35* and you wanted to get a fridge to get down to say 15* its a big ask. Not only do you have to get a drop of 20*, but as it is cooling it is also heating up, might get up to 60*. Now your are looking at a 45* temp difference accross the device. The device may be able to achieve a 20* drop, but as it operates and heats up to 60* it will only cool the fridge to 40*.. It doesnt produce cold like a compressor fridge but a temp difference from one side to the other. Hence you need big heatsinks on it.

Just found some of the results I had with an 85w chip. Not the perfect setup, but it worked.
Ambient temperature of 23c. 26l in the esky as coolant and 23l in the FV @24c combined temp. Nearly 29 hours to pull that lot down to 9c.

Those figures really highlight how piss poor peltier efficiency is. From memory it's something ridiculous like 10%.

 

[QldKev]

yeah, but a fridge compressor cost more than $2.50

but the cost of running a peltier over a year will start costing more than a cheap fridge would cost to buy and run.

 

[Feldon]

This US fermentor system (yet to be launched) uses peltier technology .

Link: http://www.brewjacket.com/the-lagerjacket-homebrew-lager-without-refrigerator/

 

[Ducatiboy stu]

yeah, but a fridge compressor cost more than $2.50

And the power supply,heatsinks,control ccts, housing...

And its going to use 4x more power than a similar size fridge...

 

[Glot]

I as just after any feedback for a side interest. I am just mucking about with some.
Definitely the best source of a ferment fridge is to go to your local appliance retailer and ask them is they ever get any fridges. Some have a regular buyer that sells them at an auction
Some are more than willing to sell you a fridge in unknown condition as it costs them money to take them to the tip.
Don't be afraid. Just be polite and don't annoy them in peak times. ie weekends. Don't be scared to ask. They are people. Just don't stuff them around at all. They have a job to do.