Pneumatic is used everywhere: It is safe, needs little
maintenance, lasts long...
The Quasiturbine is a pure positive expansion machine.
which can be simulated numerically as expansion in an infinitely long
Quasiturbine Pneumatic Engine
Quasiturbine not a Vane Motor
Unlike vane pumps or motors, which vane extension is important and against which the pressure acts to generate the rotation, the Quasiturbine contour seals have a minimal extension and the rotation does not result from pressure against these seals. The vane geometry does not allow high compression ratio at TDC (top dead center), while Quasiturbine does, and this is why QT is efficient (less pressure charging losses), and this is why there is no vane combustion engine. Quasiturbine publishes « efficiency data » while vane motor manufacturers don't. Premium on « efficient equipment » is rapidely recovered in operational cost, and provide the basis for future QT success...
This is a chainsaw prototype not available for sale.
Remark on Pneumatic Efficiency
An high efficiency pneumatic motor does not guaranty the high efficiency of
the entire pneumatic system. All gas heat up during compression and cool down
during relaxation. The cooling effect must not be under-estimated. As an example,
a typical 200 bar (atm.) cylinder empty adiabatically (without thermalization to
ambient temperature) gives at the end an air so cold that its volume is then
1/4 of that of the air once back to the ambient temperature (isothermal
relaxation). In those temperature conditions at the entrance of a pneumatic
motor, the efficiency is catastrophically low and the lubricant solidifies,
increasing considerably the internal engine friction... Generally, the
reversibility of the compression - relaxation cycle reduces with an increase in
pressure, which favors for high efficiency consideration the use of the lowest
design pressure possible. The measurement of the exhaust temperature gives
generally a good indication of the efficiency, since the minimum of energy lost
into the environment correspond to an exhaust temperature equal (neither
inferior, nor superior) to the ambient temperature. This condition can be
achieved by a slight heating (solar) of the gas before its entry into the
In the case of very high pressure gas tank,
not only one wants to harvest the energy actually in the pressurized air tank,
but also take advantage of the energy amplification possible from using
available external heat. On one side it
is not efficient to make a too important pressure drop into one expander because
the adiabatic cooling will strongly reduce the pushing pressure, and the exhaust
gas will be thrown out at valuable high pressure. On the other side, using a
regulator will dissipate pressure energy, but will allows the reduced pressure
gas to be thermalized, such as to run the expander with much less adiabatic
cooling and less gas pressure energy thrown at exhaust. Both methods are
compromises. Multi-stages with heat input is hardware intensive, but the best
way to get the most mechanical energy out of a high pressure gas tank with an
external available heat source...
The Quasiturbine can
further make internal gas expansion if the dominant restriction is made to be at
the intake, such that the flow is not sufficient to keep the internal pressure
at the level of the pressure intake line. This internal expansion can then be
done without any synchronization valve. Efficiency increases as the involved gas pressure is lower.
Since the Quasiturbine rotates from pressure as low as 1/10 of
atmosphere (bar) (one psi !), the Quasiturbine is well
adapted to high efficiency system... For very high air tank pressure drop (not
necessarily suitable with the
prototype), an intake air heating coil in hot water would be necessary to prevent freezing of the
oil within the Quasiturbine.
For optimum performance, the feed line must be well balanced between the two
intake ports, which must be done by ending the line passed the 2 T by an accumulator
(buffer) tank, on which the pressure gage can be located.
Adiabatic versus Isothermal
Since the Quasiturbine is a pure expansion engine
(which the Wankel is not, neither most of other rotary engines),
it is well suitable as compressed fluid engine - Air engine or air motor.
Since the pneumatic - steam Quasiturbine includes two circuits, these circuits can
be fed in parallel, or in series by connecting the exit of the first
chamber to the entry of second. By placing an exchanger on this conduit one can add heat and
doing so, the total relaxation in the engine approaches an
isothermal relaxation. Notice that in this case, the pressure differential
between the two circuits will be automatically equalized.
In the conventional turbines, such an intermediate heating is often
done in order to increase the total
power of the machine, without necessarily increasing the efficiency. In other
words, to extract the maximum energy from a very high pressure, it
would be necessary to use a cascade of machines starting with the smallest, each one
reducing the pressure a little and feeding the following one through a
heat exchanger... The old steam
engines used up to 3 machines (or more stages in the case of turbines),
the Titanic had steam engines using 4 stages of relaxations... The MDI air
car for its part suggests to use a very high pressure 3 stages piston
engine. Nothing prevents from juxtaposing 3
Quasiturbines of different dimensions to do still better!
In the case of a source of
pressure which becomes exhausted with time, like a compressed air
cylinder, the obvious disadvantage is that it is necessary to keep
useless stages as the pressure becomes less. A high pressure tank cools
gradually when it flows into an intermediate lower pressure tank, but it
is at the entry of the low pressure tank where the relaxation is violent
and where cooling is most considerable.
Quasiturbine pneumatic-steam model QT50SC (Without carriage)
Usable with intake sustained pressure as low as 20 to 50 psi!
Rotary Pressure Regulator
Gas Pipeline Expander
Gas Pipeline Pressure Energy Recovery - Rotary Pressure Expander
What about an "energy recovery rotary pressure regulator" ? An
interesting application of the pneumatic Quasiturbine is to recover the
pipeline high pressure energy at local distribution stations. Instead of
using a conventional pressure regulator (an energy dissipative device), a
pneumatic Quasiturbine will rotate under the pressure differential and the
flow will be controlled by the rpm, i.e. the torque applied on the
Quasiturbine shaft. It does act as a dynamic active rotary valve. This way, the Quasiturbine can transform the pressure
differential into useful mechanical work to run pump, compressor,
ventilator, electricity generator or locally convert the energy in high
grade heat (better than pre-heating the gas before that
same "rotary expander", to avoid any residual condensation as done with
conventional regulators). Because conventional turbines can not be widely
modulated in rpm and load, they are not suitable for gas flow and pressure
control, while the Quasiturbine is essentially a closed valve at zero rpm,
and has high efficiency at all torque and all flow rpm. Notice that producing high value mechanical or
electrical energy is preferable even if some of the gas has to be burnt to avoid
excessive expansion cooling. With such a system, any heat added before the
Quasiturbine expands the gas and increases the available volumetric flow
with the result that this heat is converted in mechanical energy with a
very high efficiency. All experimental demonstration has to be done only by gas
experts and under all current rules and regulations. Ignoring gas
expansion and considering only the gas pressure flow, a 36 inches diam.
gas pipeline at 700 psi carry typically a pressure power in excess of 30
MW - 25 millions of pound-ft/sec - of zero pollution pure mechanical
energy almost totally recoverable through Quasiturbines in the heart of
cities and industrial parks. This is tens of giant windmills on kW-h basis!.
A survey (M. Dehli, GWF Gas-Erdgas 137/4, p.196, 1996) showed that in
Germany alone, the potential for utilizing this pressure in 1996 was
200-700 MW, and the gas consumption has increased since then... See the
conceptual diagram and a
pipeline technical paper.
Enhance efficiency of LNG liquefaction cycle.
Adsorption Refrigeration Engineering Thermal
Physics. Conventional pressure regulators make all the gas to
expand from the constant high pressure side, and the gas pressure-kinetic energy
at the needle is converted into undesirable heat, reducing accordingly the
amount of cold produced. The Quasiturbine rotary expander allow for individual
chamber to expand at a variable reduced pressure during expansion, and such
reduces the gas kinetic energy transformation into destructive heat.
Furthermore, the Quasiturbine recuperates mechanically the gas differential
pressure energy, which can be used to run more compressors and make more cold...
A double energy efficiency gains! This offers great enhancement of thermodynamic
cooling machine, and specially in high power LNG - Liquid Natural Gas
liquefaction stations. Of course, this efficiency enhancement is also available
for more modest cooling system and air conditioning equipments.
Liquid nitrogen is somewhat a secondary product of oxygen distillation
process, and is consequently relatively affordable. Energy can be produced
by a thermo-pneumatic open cycle, making use of a nitrogen
evaporator (which can be the Quasiturbine itself, which then acts as a "flash
steam generator"), followed or not by an over heater (or overheating the Quasiturbine itself).
The world of new ecological energy often considers sources 2 orders of
magnitude under that offered by petroleum. Assuming that an ambient temperature
heat source is always available for free, a gallon of liquid nitrogen contains
only 10 to 15 times less mechanical energy than a gallon of gasoline used at 10%
efficiency in today's vehicles, and it creates zero pollution! This high
performance cycle is especially simple to built, non-polluting, and appears
highly suitable for mobile units. It also conforms with pure thermal sources,
like solar energy thermal conversion stations (solar hot water systems?) very
well . This concept also allows the design of a working cycle in which the
quantity of heat given to the liquid nitrogen is such that the exhaust
temperature after expansion is equal to the ambient temperature!
The pneumatic Quasiturbine engine does not produce vibration. As an example, a chainsaw with a pneumatic engine
(running from pressure air bottle regulated to less than 100 psi) allows for a
non combustible "all condition" running unit for the fireman and national safety
teams. It does run in heavy smoke and under water as well. Exhaust can even be
inhaled by the fireman ! A must for all civil defense organization ...
Because the Quasiturbine center is free and
available, a jet boat propeller can be inserted inside, and because the
Quasiturbine has no oil pan, it could be submerged to provide direct
underwater boat or recreational pneumatic propulsion.
A small submarine innovative pneumatic Quasiturbine
concept could have a cabin free of any propulsion component, where
the air tank is droppable below, the propulsion Quasiturbine is at the
rear, and the air exhaust of the Quasiturbine goes into the cabin to
be inhaled by the crew.
Powerful hand air tools like mining drills can be
The return of pneumatic vehicles (air car) will
benefit from the Quasiturbine engine.
Pneumatic is well suitable for safety reason like for subway propulsion...
Fuel cells cooled by liquid nitrogen could be teamed with a pneumatic
nitrogen Quasiturbine for a remarkable total output...
Low Pressure Modulated Power Station
Solar radiation varies greatly during the day while most engine keep their
optimum efficiency at design power only. Because the Quasiturbine (steam
or pneumatic) keeps it high efficiency on a large power range, it is well
suitable for modulated (from source or demand) power production like
solar, windmill, ocean wave station... where the pressure is generally
low, and efficiency critical!
A 10 second vehicle Power Booster. Originally, hybrid was intended
for efficiency increase, not for performance increase. More and more
vehicles use 2 engines not for fuel savings, but to increase acceleration
performance: As a 10 seconds Power Booster, benefiting a government grant!
In this regards, the Quasiturbine QT600SC pneumatic with an onboard air
tank and compressor could eventually provide hundreds of additional HP for 10 seconds, and make
an unbeatable acceleration Quasiturbine Hybrid vehicle... the market seem
to ask for? Many others applications require high power bursts, like in
smooth landing parachuting (with fast line-winding in less than 10
Quasiturbine - Comparative
efficiency with other engines
Quasiturbine Pneumatic and Fuel cell :
A perfect Match (using liquid nitrogen)!
A Thermo-Pneumatic Quasiturbine Locomotive (with addendum on subway)
A project intended to make a
Quasiturbine liquid nitrogen
Quasiturbine Air Car (compressed air vehicle)
CRYOCAR from the
Washington State University