Okay, suppose you have a 5.5 gallon aquarium (16"x9"x8"), and suppose all six faces (including top and bottom) of the aquarium could be allowed to contact air and radiate freely (maybe give it legs, like a table). That's 688 sq inches = 0.444 sq meters of surface area.
Based on conductive and radiative heat loss models I've dug up on the web (see previous posts), here's the the heat loss rate in a room that's maintained at 22 C (71.6 F):
Tank(C) Rad(W) Cond(W) Total (watts)
50 48.4 50.3 98.8
55 58.5 59.3 117.8
60 69.0 68.3 137.4
65 80.1 77.3 157.4
70 91.7 86.3 178.0
75 103.7 95.3 199.0
80 116.3 104.3 220.6
85 129.5 113.2 242.7
So, this tells me that if I have some big honking system that sinks 250 watts into this tank, it is going to settle at a temperature of over 85C, which seems pretty hot. A smaller system that generates only 150 W of heat will settle just below 65C.
As I alluded to last post, I don't know what temperatures are safe for the various devices (GPU, CPU, vid rams, DIMMs, NB, etc).
One thing I have not addressed is the rate at which the system approaches the final temperature. That would be dependent on the thermal mass of the oil-filled aquarium, which relates how much temperature rise results from absorbing a given amount of energy.
Mineral oil has a heat capacity of 1.67 J/gK, and specific gravity of .87 g/cc. 5 gallons of it would be 18927 cc, which is 16.466 kg, which is a thermal mass of 27.5 kJ/K.
So, a 250 watt system running for 1 hour (3600 seconds) produces 250*3600 = 900000 joules of energy, which would change the temperature of that thermal mass by only 32 C. And that assumes the tank loses zero heat during that hour! In reality, as soon as the tank gets above ambient temperature, it starts losing some of its heat. To model the temperature rise as a function of time might require a differential equations solver, or something.
The puget systems people mentioned that it took a long time for their system to reach a stable temperature.
If you've read this far, I salute you, and I apologize. :-)
Again, does anyone know the typical safe operating temperatures for the various devices (GPU, CPU, vid rams, DIMMs, NB, etc)?