WRT to Tata:
... the biggest reason that the assorted "experts",
including a fair number of PhDs have looked like total
fools and jackasses on this one (including moi, to a
lesser extent) is that they naively "assumed" that the
compressed air was being simply "expanded" instead of
being used as a "virtual fuel".
Simple expansion would be pretty dumb and essentially
non-functional. A little knowledge is a dangerous
thing, as they say -- but Tata was also complicit in
holding back some relevant info early-on - as it turns
out in retrospect.
Instead of simple expansion, the MiniCAT runs a normal
4-stroke piston engine that uses a modified "virtual
fuel cycle" of exceptional efficiency. IOW the
compressed air should be considered as liquid fuel
operating at 100% Carnot (when in the engine, but not
the total cycle as the losses are all in the
compression).
As with a diesel, outside air is drawn into the
compression chamber and compressed to a very high
ratio: twenty times or more to ~20 bar (290 psi). This
air reaches 400°C and, at that point, the "virtual
fuel" (air from the storage tank which although
technically not liquid is "virtually" liquid) is
injected into the "combustion" chamber, just as with
the diesel.
Here the fuel actually "explodes" with a large shock
wave ("jerk" perhaps) not unlike real combustion but
in a non-thermodynamic yet violent fashion, giving
about one-fourth the normal amount of net expansion
and torque as if it were "real" diesel fuel. It is
actually only ~ 1/16 as energetic but the Carnot is
essentially four times better.
The exhaust is one fourth or less the temp of fossil
fuel, in degrees K, but the shock wave is not
diminished as much. The exhaust is about 250 K instead
of 1000 K, so the exhaust can actually be used as
air-conditioning - yet in the cylinder, the velocity
of expansion is very high and fuel economy is
therefore rather decent on a "per unit of mass basis"
(not on unit of volume basis).
Who cares if this cycle requires large storage tanks
(except for the danger in a collision), since each
fillup is one tenth the cost of gasoline i.e. about 20
KWhr of grid power ($2 bucks in many places).
Pretty cool, kewl, or cuil ... I'd say...
Jones
