Monday, July 20, 2009

Finishing the refrigerator conversion project

In my last post, I had just finished charging the "new" refrigerator with R134a. I was surprised that it worked at all, and it was still working the next day, so something must be correct. I used some expanding foam to fill up the large square hole left by the thermoelectric module in the bottom of the fridge. The clear vinyl tube is a hose that I connected to a drain on the inside of the fridge. If (when) the evaporator defrosts, I am sure there will be a fair bit of condensate dripped out. I put a small stainless tray on top of the compressor to catch the water.

I also used the fridge's existing thermostat (the white tube on the right). The manufacturer setup the thermostat so that it would regulate the temperature on the evaporator itself. The thermostat has a capillary tube that is clipped onto the evaporator and a large knob with numbers 1 to 7 (like any refrigerator). I also filled up the hole through which the refrigerant lines and thermostat enter the fridge with expanding foam.

While the existing thermostat works well, the table has a nice cutout for a two-digit 7-segment display and four buttons. The thermoelectric fridge came with a digital thermostat, and I made the cutout in the tabletop specifically for it. I would like to keep the digital thermostat feature, so I am building one with an Arduino microprocessor.

Here is the rear of the completed table with white thermostat control knob at lower left. I've already written some Arduino code for the digital thermostat, and will probably be implementing that soon. In the meantime, my table refrigerator is now frosty cold, and using less power than the thermoelectric model.

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