Introduction: How to Make a Mini Usb Air Conditioner

In this tutorial i will be making a mini Usb air conditioner. The air conditioner can be made for less then 15$.

The entire video and the test can be found on my youtube video https://www.youtube.com/watch?v=h_KX-qGl_JI

Here are the materials used:

-2 peltier elements

-2 heat sinks

-Styrofoam

-a motor

-a propeller

-a Usb cable

-a peanut butter container

Step 1: The Science Behind Peltier Elements

Peltier elements have a property that when you apply a voltage to them, one side will get colder and one side will become hotter. To make this air conditioner we will use the cold side and blow the cold air from it to cool the room, while the heat from the hot side will be dispersed elsewhere

In the demonstration in the pictures above, you can see that the air temperature is 82 degrees. When i apply voltage to the peltier element, the cold side cools to 76 degrees and the hot side heats up to 110 degree.

Peltier elements can also be used in the opposite direction. A heat difference between both side, ie one side hotter then the other will create a voltage.

Step 2: Assembling the Core

To start off the build i first get 2 computer heat sinks. If you don't have heat sinks you can flatten out copper tube and use that as a heat sink. Next i put the 2 heat sinks together and hold them together with elastic bands. Then i slide the peltier elements in, one on each side. The elastic bands will ensure the heat sinks are pressed against the peltier elements so that the heat will be quickly dispersed into the heat sinks. For wiring i simply wire the peltier elements in parallel with each other and make sure the same side is facing up, so the same side on each peltier element will get cold

Step 3: Dividing the Hot and Cold Side

Next i cut a piece of Styrofoam out in the shape of the core. I then glue the Styrofoam around the core so that the hot and cold sides are separated by the Styrofoam.

Step 4: Attaching the Fan

I now glue the propeller to the motor. This will be used to blow the air from the cold side.

To attach the motor, i cut a slot out of the Styrofoam and glue the motor into the slot. I then grab the wires from the motor and wire it in parallel with the peltier elements

Step 5: Adding a Case

For the case of the air conditioner i use a peanut butter container with the bottom cut out. I then insert the core into the middle of the container and glue it in place

Step 6: Adding a Cord

For the cord any Usb charging cable will work. I cut the end off of the cable and strip it back to expose the wires. I then use the red and black wire and attach them to the positive and negative of the node where the peltier elements and motor combine. Be sure that when it is plugged in, one side gets cold, one side gets hot, and the air blows through the case. If something is in the wrong direction, reverse it's wires

Step 7: Closing Off the Hot Side

Because the fan will be blowing through the case. it will be blowing the hot air as well. If this was allowed to escape, it would be counterproductive because we would be cooling and heating the air. To prevent this, i seal off the hot side so that the air cannot escape. i then put a hole in it and attach a tube so that the warm air can be vented elsewhere. The hot air should be vented outside so that it does not heat the air that it is supposed to cool

Step 8: Test

Now to test it, i measure the outdoor temperate. Outside gives a temperature reading of 84 to 83 degrees. Once i turn the air conditioner on, it cools the air to 78 degrees. this is a total cooling of 5 degrees. When i place the temperature probe against the peltier elements, they read a bit colder. This is because the heat sinks and peltier elements can only cool the air so fast before it leaves. The result of this is that the air gets cooled 5 degrees but does not have enough time to cool more before being pushed out of the Air conditioner

I hope you enjoy this project, peltier elements can be bought on ebay for fairly cheap. If you decide to build it, you should check out the full video https://www.youtube.com/watch?v=h_KX-qGl_JI

Comments

author
PhilS86 made it! (author)2016-08-06

That element shifts heat from one side to the other. It is not absorbing any heat and discharging it elsewhere. Refrigerant/freon works on a directly proportional heat/pressure relationship - the warmer the freon, the higher the pressure and vice versa. In an air conditioner, the metering device (thermal expansion valve or capillary tubes) drops the pressure of the refrigerant thus dropping the temperature. The refrigerant then flows through the evaporator which absorbs heat from the air in your house as the fan draws air across it's coils. The refrigerant is superheated 10-15 degrees above it's saturation point and is moved to the compressor as a vapor, where it is compressed into a high pressure vapor and it then flows through a condenser and is subcooled below it's saturation point and turned from a vapor into a liquid, rejecting the heat it absorbed from the evaporator in the process, before it goes through the metering device again.

There is no absorption of heat and subsequent superheat followed by a rejection/discharge of heat and subcool happening. Plus that little tube does not have enough of a capacity to carry an adequate volume of air.

It's a super cool project to be sure, but I'm not sure it works the way it needs to. I welcome any corrections to my logic here though!
author
deluges made it! (author)2016-07-21

Right so the heat is still there, I don't think you can "blow it out" in such a small tube (fluid mechanics are annoying with that. Having a conic connector would help, better even would be a tube the size of the half bottle). And what's really sad is that by the laws of thermodynamics, you are actually producing more heat than cold. Congrats on your new radiator ;) With improvement (and a sizeable scale-up) it could be functional

author
agulesin made it! (author)2016-07-18

An interesting project, but I'm not sure about routing air down a thin tube like that. it won't flow, and all the heat you've extracted from the air will pass back through the walls of the tube before it reaches anywhere useful! :-)

author
doctormerlin made it! (author)2016-07-15

Nicely done! Might want to consider adding a small exhaust fan on the "hot" side to improve the efficiency.

author
DylanD581 made it! (author)2016-07-15

Great DIY Air Conditioner. Is there any escaping heat from the peltier junction?

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