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Thermoelectric Cooling Cabinet Project

David Murray

Nov 26, 2015
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Hi, let me start by saying I dont know much about electronics, which is why im here!

Im a product designer and im working on a new device. A breif overview of the device is a cabinet that is placed over a radiator to dry clothes in. I want to condense the warm moist air given off by the drying clothes into water, to prevent it from creating mould indoors. This will be essentially a cooling cabinet with a heat sink inside it.

I want to use the heat of the radiator and a thermoelectric generator to produce electricity to then go on to power another Thermo electric plate, making use of its cool side to cool down the cabinet.

Firstly, I know this is an inefficent method, but really want to avoid any external electric input. Secondly, could i literally just connect one TEG up to another?
Im assuming that it gives off an AC and that this would not need to be inverted. If it was an AC i thought that there would be a direct relationship between the heat input and the final cooling output.

Thanks for taking the time to read, I apologise for my electronics illiteracy.

Cheers,

David
 

Harald Kapp

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Nov 17, 2011
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I want to use the heat of the radiator and a thermoelectric generator to produce electricity
The electric energy a thermoelectric generator (TEG) produces comes from the thermal energy of the source, the hot air in your case. By giving up energy to the thermolelectric generator, the air will cool down and water will start to condense on the thermoelectric generator.

Firstly, I know this is an inefficent method,
"Inefficient" is an understatement. Immensely inneficient is more to the point.
The efficiency of a TEG is less than 10%, so the energy output you can expect is rather low. Using the little energy produced to cool a plate/heatsink by e.g. a Peltier element again has an efficiency fo < 15%.
Overall efficiency is then 10%*15%=1.5%.
I think you'll have a bettter effect by funneling the hot air through a tube or something similar attached to a big heatsink (essentially a big hunk of metal, preferably finned to be cooled by the surrrounding air). You could use the power of the fan within the dryer to force the air through the cooler.

could i literally just connect one TEG up to another?
That will depend on the parameters (voltage, current) of the components you select.

Im assuming that it gives off an AC
Unless you buy a TEG module with built in inverter that is designed to deliver AC, your assumption is, sorry to say, wrong. Both components will operate on DC, so this is not an issue.
 

GPG

Sep 18, 2015
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You need a heat pump, certainly the most efficient way of doing this. Ditch the heater and use the condenser instead. The evaporator does the cooling.
 

David Murray

Nov 26, 2015
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"By giving up the energy to the thermolelectric generator, the air will cool down and water will start to condense" - The TEG will be placed directly on the heater surface not inside the cabinet, so it wont create a cold spot.
""Inefficient" is an understatement" - Could i use a joule thief circuit to overcome this? If the energy is built up to cool more dramatically over a shorter period and contained within an insulated cooling box could this be more effective?

"You need a heat pump" I have looked at using absorption heat pumps like those found in older style fridges but looks like it would be very difficult to make one/find one that fits. I dont want any external inputs to run a compressor or anything, just the heat energy given off by the heater.

I am planning to use a condenser/heat sink to passively cool the air but was concerned this might not be enough. This is why i was looking at a secondary cool box that the air is passed through. I imagined the cool box to be build around a aluminum heat sink which was cooled with TEGs

Thanks for taking the time to reply!
 

Harald Kapp

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Could i use a joule thief circuit to overcome this?
A joule thief will not increase efficiency, On the contrary, it will introduce additional losses.

I am planning to use a condenser/heat sink to passively cool the air but was concerned this might not be enough.
Did you try it? Passive cooling would be the most efficient way of cooling in my opinion.
 

David Murray

Nov 26, 2015
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No not yet, I'm still in the research phase of the project. It's for university so it's quite linear. I look forward to testing it though. I think your correct about passive being the most suitable. It looks like TEG cooling is out of the question but I could always resort to using them to move air around with fans. Do you think TEGs are going to be more efficient in the future? As I could mention them in the project for future scoping. Thanks for your help - it's been really useful.
 
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