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How to Design a Peltier Cooler

Many applications require a cooling source that is small, with no moving parts. The Peltier module is a solid state device that works similar to a diode, however, current is able to flow in both ways. The module is a flat waferlike device with a red and black wire connected to it. Wired to a battery, one side of the plate will become cold and the other side of the plate will heat up. By making use of this property, a small electric cooler can be made to keep items cool while traveling.

Things You'll Need

Cooler
Peltier module
Drill
Hole saw
Heat sink
Epoxy cement
Heat sinking paste
Aluminum plate
Brace
Fan
Power cable
Butt splices
Wire clamp
Self-tapping screws
Cigarette lighter plug

Instructions

- 1
  Drill an access hole near the bottom of a small plastic cooler. Using the drilled hole as an access point for a hole saw, cut out a square hole large enough for the Peltier module to fit. Attach a heat sink, the same size as the module, to the hot plate side of the module using an epoxy cement. Allow to set. Apply epoxy along the sides of the heat sink and insert the module into the hole. Bring the cool plate side of the module flush with the inside wall of the cooler.
- 2
  Cut an aluminum plate to fit the inside wall of the cooler where the Peltier module is installed. Apply a heat sinking paste to the module's cooling side. Apply epoxy around the outside rim of the aluminum plate. Press the plate against the inner wall to assure the module is making contact with the aluminum plate. Place a brace from the opposite inside wall of the cooler to the plate to prevent it from moving while the epoxy is setting.
- 3
  Attach a small, 12-volt computer fan on the outside of the cooler over the cut out area to draw heat away from the heat sink. The two leads from the Peltier module should be extended from the back of the cooler in such a way as to avoid getting in the way of the fan. Mount the fan over the heat sink and attach to the cooler using four small, self-tapping screws.
- 4
  Remove the brace holding the aluminum plate after the epoxy has set. Join the power cable, using butt splices, to the two leads extending from the module. Clamp the cable to the cooler using a cable clamp and a self-tapping screw. Attach the cigarette lighter plug, with a built-in fuse, to the other end of the cable making sure the positive (red) wire is connected to the center pin of the plug and the negative (black) wire to the outer casing.
- 5
  Take the cooler to the car and plug the cigarette lighter plug into the car's socket. The fan should begin running. Leave the lid off the cooler and place your hand over the center of the aluminum plate. Within a few minutes the plate should begin cooling. If it is heating, you will have to reverse the wiring to the cigarette lighter plug.

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