[Bicycle Bob]

Originally Posted by stonebreaker

OK, I'm not understanding your position, since you're effectively arguing for driving around with a boiler in your car but not doing anything with the steam once you generate it.

Thermal efficiency is not the only consideration in an engineering solution. Regular tank, phase change tank, doesn't matter. The energy density of that solution is way too low to work.

A phase change for water would release about 2,200 joules per liter of liquid water (where are you going to store the steam while you're driving, BTW?). Compare that to the WORST battery in terms of energy density, the lead acid car battery. The lead acid battery has an energy density of about 180,000 joules per liter. In other words, you'd need 80 liters of water to equal 1 liter of battery. From a weight standpoint, it's almost the same - 70 kilograms of water for every 1 kilogram of battery.

You see, even if your solution is more thermally efficient, it's simply not practical. Whereas, adding a "low efficiency" generator will still recover lost energy without turning the car into a rolling tank truck.

OK, I see the disconnect. I'm talking about the phase change from solid to liquid in wax or a similar substance - no steam involved. The last time I ran the numbers on it, a modest weight would handle an average day's waste heat. The system delivers exactly what we buy for houses with low cost hardware.