Peltier Mini Fridge For Class By Class

December 30, 2023 by Al Williams 13 Comments

How do you keep a few sodas in your classroom cool? Well, if you are teacher [Ethan Hunt], you have your students design and build a solid-state mini refrigerator that can beat his prototype fridge. The prototype uses a Peltier effect module to get three cans down to 11 C (52 F), with a final goal of reaching 5 C (41 F). It’s not all fun and games either — [Ethan] provides a suggested lesson plan with a total of thirteen modules made to fit in an hour each.

Peltier effect modules, also known as solid-state heat pumps, used to be exotic tech but are now quite common. They are actually the reverse of the Kelvin effect. Thermocouples exploit the Kelvin effect by measuring current flowing due to temperature differences.

Solid-state heat pumps use current flowing to create a comparable temperature difference. However, that’s also the catch. One side of the heat pump gets cold, but the other side gets equally hot. That heat has to go somewhere. The same is true, of course, of a “real” refrigerator or an air conditioner.

The lessons would be perfect to adapt for a class, a kid’s club, or even homeschooling. We’d love to see what your students build. You probably won’t be making liquid nitrogen with this setup. But we have seen more than one mini-fridge.

Salty Refrigeration Is Friendly To The Environment

January 6, 2023 by Al Williams 34 Comments

Widespread use of refrigerators is a hallmark of modern society, allowing people to store food and enjoy ice and cold beverages. However, a typical refrigerator uses gasses that are not always good for the environment. Now the Berkeley National Lab says they can change that using ioncaloric cooling, a new technique that uses salt as a refrigerant.

The new technique involves using ions to drive a solid-to-liquid phase change which is endothermic. Unlike some similar proposals, the resulting liquid material would be easy to pump through a heat exchanger. In simple terms, it is the same process as salting a road to change the melting point of ice. In this case, an iodine-sodium salt and an organic solvent combine. Passing current through the material moves ions which changes the material’s melting point. When it melts, it absorbs heat. When it resolidifies, it releases heat.

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Repair Your Ice Maker Motor Without Buying A Whole New Assembly

December 17, 2012 by Mike Szczys 28 Comments

ice-maker-repair

There are a number of things that can go wrong with an automatic ice maker. But one of the more common problems is that the motor which scoops the ice out of the integrated trays can burn out after years of use. [Dave] recently repaired a common ice maker motor and shows us how cheap and easy it can be. See how he did it in the video after the break.

Pictured above is the motor and gear box from the ice maker. Before disassembly he verified that the problem is with the motor by placing a piece of paper in the path of the fingers that move the newly formed ice. After removing the sensor arm and three screws he was able to pull this front portion from the unit. The two wires are clipped as near to the motor as possible and the motor itself comes out with just a twist. After verifying that the gears are not broken he sourced a $2.50 motor replacement by Googling the part number (M004 3W in this case). Once the new unit arrived the motor wires are connect in much the same way that a punch down Ethernet jack makes a connecting with insulated wires.

This is something worth looking into if your ice maker is not working. The manufacturer may suggest replacing the entire unit which can be well north of a hundred bucks… this is a worthwhile gambit to save some cash. Well, we guess you could always build your own non-electrical ice maker.

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Tunes In The Icebox

June 4, 2012 by Mike Szczys 29 Comments

A couple of years back [Bryan’s] iPod went on the fritz. It wasn’t completely broken, as long as he kept it really cold it still worked. So what was he to do with the crippled device? We’ve all heard of elevator music. [Bryan] decided to invent refrigerator music.

First he needed some speakers. A trip to the Goodwill store netted him a pair for under $5. They need A/C power, and the project depends on sensing when the door to the refrigerator is open. He killed two birds with one stone by adding a light socket outlet adapter. This provides a place to plug in the speakers’ power adapter, and it only gets juice when the door is opened. The gimpy iPod just constantly loops through the tracks stored within, but you’ll only hear it when the door is open and the speakers receive power. Of course the iPod will eventually run its own battery down so [Bryan] ran an extension cord out the side of the door to a wall outlet. This interrupts the door seal and we wish there were another way to keep it contained within.