Question:
I am sure most people are familiar with gas powered refrigerators. I
was wondering if instead of heat from a flame, you used the heat from the
exaust mainifold of an engine. You could create an air conditioner that used
no mechanical parts and no additional fuel when in use.
I am aware that gas refrigerators use a combination of ammonia and
hydrogen and could create a hazard in an accident. I do not think a gas
refrigerator works too well when it is jostled around either. However, I would
think there would be some combination of materials that could be used.
May someone with a little more knowledge in this area might have some
thoughts.
Answer:
I've harbored such an idea for years. It certainly would save energy by
using otherwise wasted heat. I've heard the objections of the hazards of
the ammonia. I don't think the amount of hydrogen poses a significant
hazard and I doubt that the fire hazards from the ammonia could be all that
much worse than the fire hazards from carrying gasoline around, especially
considering that it's also full of water. A punctured A/C system full of
R-12 isn't exactly safe if you're standing close.
One possible problem: startup time. Imagine the car has been sitting in the
parking lot all day on a hot summer day. The interior of the car is blazing
hot. You come out, start up, and want to cool the car down--FAST. In a
conventional A/C you'd just turn the control to max and point all the vents
at your sweaty shirt. With an absorption A/C you'd have to wait for the
engine to warm up before any cool air came out of the vents. Such a machine
might be more useful for applications where the engine runs all day like
buses or over-the-road trucks.
I have an old absorbtion refrigerator that runs on 110/12V. Handy for
carrying a cool picnic lunch in the back of the car. It would run for hours
connected to the cigarette lighter, even in a moving car. It was position
sensitive but not unreasonably so. It still works after all these years (at
least the last time I checked) but the 110V heater coil is burned out. Now
I use a thermo-electric cooler, another interesting technology
