Post Rad Chiller Concept

[Uncle Jimbo]

I'm trained as a chemist. In grad school, I spent my first two years building interfaces and writing software for computer control of instrumention. Yes, that was a long time ago. In my first real job, I got involved in thermal analysis and helped modernize calorimeters. Fast forward over twenty years and I was building mass spectrometers for measuring airborne pollutants when my boss found out that I'd worked in thermal analysis. So he gave me a pet project of his where he'd been trying to cool a detector cell with TECs. The problem was that the aircraft did not have "air conditioning" until it got up to ~14,000' and because of that, the cooling of the hot side of the TECs was a problem at startup and also when dropping low to do altitude profiles. The detector needed very stable temps. I finally bought a small industrial air conditioner to cool the hot side and the only down side to that was jealousy from other teams on the airplane.

I have similar experience - but I was maintaining constant temperature for sensors on oil rigs. The gear could end up on a north sea platform in the dead of winter, or in Africa in high summer. We needed to maintain 25C plus or minus 2 degrees for the electronics package to assure the stability of readings.

One thing for sure - in a TEC setup, you will not see better than 40% efficiency and probably a lot less. For high efficiency cooling of water, I believe the best way is to just use standard air conditioning or refrigerator components.

The advantage TECs provide is the ability to provide tight temp control, and also to provide cooling with a small physical size and better packaging options. Going way sub-ambient is not an option with water and messy with phase change, but fairly easy to do with TECs - attached is a shot of a cooler I helped my nephew build which delivered air at around 5C to a 100W heat load with hot side air cooling. But it used nearly 300W to do it, so the air cooler had to unload around 400W. The Blue Orb is the cold side - it provided air at 5C to a Vanessa cooler on the CPU and generally cooled the air in the whole case. The hot side has a giant Melcor sink which has .08 C/W with 120CFM. Not shown is the drip pan <G>. An interesting project, but for the small improvement in temp at the CPU, done a whole lot quieter and with a tenth the power using a small phase change unit and WC...