There has always been lots of questions concerning using thermoelectric cooling for Cp's
A while back I bought a 300watt peltier chip. It didnt take long to realize that this was the easy part. The hard part would be a power supply for the thing as it would require a 12vdc/25amp power supply (and massive heatsinks) LOL.... cha-ching
Recently I came across a 50(?) watt chip, now the power supply becomes more resonable. This one only needs 4amps at 12vdc. With a couple heat sinks, a fan and a couple power supplies some of my students and I were ready to give it a try.
Here are the results of a simple bench top test
The DVOM meter is indicating voltage, the adjustable power supply's display is showing current in amps.
The large power supply is powering the peltier and the small power supply is for the fan.
Immediately it became obvious that the bench top power supply could not carry the load. The best it would do is about 3 amps at approx 12vdc. This was maxed out, the power supply's heat sink (not visible in the pic) could fry an egg.
The top heat sink of the peltier is the hot side and the lower heat sink the cold. Peltier's are very inefficent to begin with. Without the fanI belive the top heatsink would be hot enough to blister your finger.
Initially it seemed to take about 30 mins for the peltier temp drop to reach maximum. As the delta T max is reached efficiency drops even lower.
Room temperature is 68-70f
It wasnt long before condensation was obvious:
Input power levels:
After a half hour or so, temps stabilize:
I was curious if a greater delta T max could be acheived if I used a power supply capable of driving the peltier at full load.
I found one and hooked it up, current jumped to above 6 amps and voltage levels were regulated at 13.8vdc
Amazingly, it had very little effect on performance. Evidently somewhere around 3 amps a point of diminishing return was reached. Any additional temperature drop would come at a significant price in efficiency, power consumption and wear and tear on all components.
So, where does all this lead me... I believe that a small terrarium would be an ideal application. Maybe a 5 or 10 gallon aquarium. But beyond that and beyond a 50 watt peltier... the disadvantages far out weigh the advantages. In that application a typical vapor cycle cooling system would be far superior.
Having said all this, I will build a 5 gallon temperature controlled terrarium version using the setup shown. It should be the perfect nursery for N. villosa and other difficult Cp children. I have little doubt that I could use this to lower a 5 gallon aquarium to 50f, maybe even a 10 gallon.
Hope this helps shed some light on the debate