Peltiers are notoriously inefficient. Hideously. Reasonable numbers are in the 10% range. So in order to remove say 5kW of heat from the skin (1.5 tons of refrigeration) which is pretty conservative would require say 50kW of power. Most of which would end up as heat in the metal of the structure of the tank.
If you figure the chassis and armor are say, 50 tons, and steel, you can do a little math to figure out how quickly it would heat up. 50 tons is 50,000 kg and the specific heat of steel is about 0.5kJ/kgK. We're putting heat into the chassis at the rate of 50kJ/sec and things cancel out pretty nicely. You'd heat it up at about half a degree C per second, or about one degree F per second.
In the best possible scenario you're talking about no more than two minutes worth of stealth (perhaps only 30 seconds in reality) and that's with the tank not moving and only idling its engine, just enough to produce the necessary 50kW. It's a neat trick, but I'm not sure it's worth writing home about.
Storing the heat chemically, in an easily reversible endothermic reaction including but not limited to phase-change, could be much more efficient than using Peltiers to cook the crewmwmbers
If you figure the chassis and armor are say, 50 tons, and steel, you can do a little math to figure out how quickly it would heat up. 50 tons is 50,000 kg and the specific heat of steel is about 0.5kJ/kgK. We're putting heat into the chassis at the rate of 50kJ/sec and things cancel out pretty nicely. You'd heat it up at about half a degree C per second, or about one degree F per second.
In the best possible scenario you're talking about no more than two minutes worth of stealth (perhaps only 30 seconds in reality) and that's with the tank not moving and only idling its engine, just enough to produce the necessary 50kW. It's a neat trick, but I'm not sure it's worth writing home about.