Air conditioning and refrigeration are both common methods for making an area cooler than the surrounding environment. These two sets of technologies usually employ a liquid or gaseous medium to take in heat from inside the cooled area and use fans to expel it.
Though efficient, these machines require compressors, pumps, and many other devices to function correctly, making them heavy and bulky. What if instead of cooling an entire building or even a pack of sodas, we wanted to cool a single glass of orange juice? For this, we will need another kind of cooling technology, the thermoelectric module.
What is the Thermoelectric Effect?
In short, the thermoelectric effect is the direct conversion of heat to electricity and vice versa. It can be split up into the Seebeck effect, the Peltier effect, and the Thomson effect.
The Seebeck effect is the conversion of a temperature difference into electricity, while the Peltier effect is the conversion of electricity into a temperature difference. These effects can only be experienced with thermoelectric modules. These solid-state heat pumps move heat from one side to the other after a voltage is applied or generate electricity if one side is cold and the other is hot.
The Thomson effect is used to make accurate calculations for the other two effects across various kinds of materials.
Now that you know about the thermoelectric effect, we can focus on Peltier modules, which is what we’ll use in this project.
What is a Peltier Module?
Peltier coolers are thermoelectric modules designed to use the Peltier effect at the junction of N-doped and P-doped semiconductors. They are usually more efficient at being cooling or heating devices (Peltier effect) rather than being generators (Seebeck effect).
We will work with the TEC1-12706 module, a C-sized(standard), 1-stage, 6-amp cooler with 127 PN couples.
Building a Drink Cooling Stand
Now that we know how it works, we can move on to using it in our project. First off, let’s take a look at our materials. In addition to our TEC1-12706 Peltier module we need:
- Thermal pads or paste
- 40cm x 40cm x 11mm aluminum heat sinks (4)
- USB cord with the output connector removed
Once we have our materials, strip the ends of the red and black wires on the USB cable. Since the datasheet for these modules stats a maximum voltage of 12V and we will give it a small current, it is safe to splice the wires directly to the Peltier module.
We can now plug the USB end of the cable to a wall charger or beefy battery pack to make sure it works.
NOTE: Do not plug this into a computer as the high current draw may damage it.
Once it is plugged in, you should feel a hot side and a cold side. Cover the hot side with a thin layer of thermal paste, or thermal pads like the image below. Doing so creates a flatter surface and eliminates any air pockets that would be detrimental for our heatsinks.
Once the hot side of the module is evenly covered by the thermal pads, adhere one of the heat sinks to a corner of the Peltier module. The heatsink should cover one-fourth of the entire module.
Because these devices generate heat quickly, we need more than one small heatsink to dissipate it effectively. Without proper heat dissipation, the heat will flow back into the cold side of the module, nullify its cooling effects, and damage the module.
Now, add one more on each corner for a total of four heat sinks on the module.
With the hot side’s increased surface area, we can rely on passive cooling to remove heat from our device for about ten minutes.
To make this device last longer, the simplest solution is to spray it with water from the sink for a couple of seconds every ten minutes so that it cools down.
To expand this idea, I recommend you research active cooling methods like fans and water pumps. Even without ice, this single drink cooler will preserve the cold, crisp taste of any beverage. The last step in this project is to pour yourself a ice-cold drink and enjoy!