Quasiturbine> Type> Compressors


Atmospheric pressure is the relatively weak force filling compressor intake.
Slow sine-wave crankshaft movement wastes precious intake time.
Quasiturbine allows to better shape the intake vacuum volume pulse!

Quasiturbine Compressors

The Ratio: Flow to Compressor Volume and Weight

Why is the Quasiturbine compressor more compact? Considerer the frontier case of  the perfect skating rink Quasiturbine design:

The flow correspond to 8 chambers per revolution, which in this case is exactly the rotor inner volume, for an exceptional flow (cfm) to machine size and weight ratio, while still running at relatively low rpm. Model QT-SC are slightly less performing in this regard, but still quite unique.

Double Circuits

The Quasiturbine has 2 intakes and 2 exits related to 2 quasi-distinct circuits. Each circuit can be used to compress gas. The Quasiturbine is a positive displacement compressor, and does not make use of aero- or hydro-dynamic flow consideration.

Quasiturbine SC (Without Carriage) Model

Reciprocal compressor reverses the flow while they compress, which is a severe inertia, turbulent and heat generation limitation for high rpm. Because the flow is peripheral and nearly unidirectional, the Quasiturbine is much less sensitive to flow reversal, turbulence and heat generation, which improves it efficiency. Check valves are generally suitable when used with compressible fluid, but the Quasiturbine could as well work without it. Check valve is never required with incompressible fluid like liquid.

Position of intake and exhaust ports can be slightly deported to account for high rpm pressure lag time. The Quasiturbine does not produce vibration. The Quasiturbine could be made of plastic for compressor application. The 2 circuits are of the same stage, and can not be mounted in serial for a 2 stages effects, because they are of equal flow capacity. However, they can both be used as a first stage into a buffer tank, and one circuit could intake this buffer tank pressure say every 10 turns, in order to get a double stages effect...

Improved Air Intake

Because of the crankshaft sine wave, the piston stays a long time at the top, which prevents active early intake into the compressor. The Quasiturbine (specially the model AC -With carriages) allows to shape the intake vacuum pulse such as to create a much faster depression in the chamber and to maintain it much longer. This increases the intake capability from naturally aspirated air, and allows for much faster rpm, and consequently better specific compression performance.

Centrifugal Compressor

The Quasiturbine air intake can be done from the center through check valves located within the blades. This way at high rpm, the Quasiturbine compressor can cumulates both characteristics from the the positive displacement compressor and the centrifugal compressor.

Compressor versus Air Motor

Both are in theory very alike. However, because of the flow inertia, optimization of both mode may require a slightly different set of ports, which can exist simultaneously.

Switching Air Motor-Compressor

Turning in reverse a Quasiturbine air motor will make it act as a compressor. However, the direction of rotation can be keep the same, if both exhausts are plug by a small check valve line taking the exhaust pressure exit as the compressor output. Then, to prevent the air motor intake two lines to be vacuumed, a check valve on them allowing-in atmospheric air will suffice. This kind of switching motor-compressor mode without changing the direction of rotation is useful for application like windmill back up pneumatic air storage or vehicle breaking energy recovery device.

Higher Efficiency

Notwithstanding other advantages (including the fact that QT has 2 compressor circuits, one at the top and one at the bottom), the Quasiturbine compressor has a unique property resulting from the sequential chambers geometry. In piston or Wankel compressors, the residual compressed volume at top dead center which does not make it through the check-valve, re-expand in the cylinder at the beginning of the next intake process, destroying the early intake vacuum much needed for a good chamber loading. In the Quasiturbine, early vacuum loading is not affected, because the residual high pressure gas not making it through the check-valve is made to flow into the following compression chamber at the end of the intake process (and not forward into the other starting intake cycle), improving this way substantially the pressure loading intake factor of the compressor. Furthermore, the Quasiturbine compressor has the ability to run without any check-valve, neither at intake or exit (some oscillating flow with compressible fluids).

This extra-dynamic-loading property is a major compressor improvement, unachievable with piston compressors, and allows for the Quasiturbine compressor to run at relatively higher rpm with optimum efficiency. Consequently, not only the efficiency is improved, but the specific compression capability which result in smaller and lighter compressors. Similar argument also applies to the Quasiturbine used as a vacuum pump.


As for any other compressor, pressure differential is limited by adiabatic temperature and heat produced during compression, and the ability to remove this heat from the compressor.

From the basic QT75SC of 75 cc per chamber engine bloc, an air compressor prototype has been built making use of 2 parallel compression circuits of 300 cc per revolution each, for a total of about 15 cubic feet per minute at 1000 rpm (zero psi differential).

The Quasiturbine is very compact and light, still allows to compress large volumes at low rpm with no vibration.

Refrigeration: Conventional pressure regulators cause all the gas from the constant high pressure side to expand, and the gas pressure-kinetic energy at the needle is converted into undesirable heat, thereby reducing the amount of cold produced. The Quasiturbine rotary expander allows for individual chambers to expand at a variable reduced pressure during expansion, and therefore reduces the transformation of the gas' kinetic energy into destructive heat. Furthermore, the Quasiturbine mechanically recuperates the gas' differential pressure energy, which can be used to run more compressors and make more refrigeration... for double the energy efficiency gain! This offers a great enhancement to the thermodynamic cooling machine, especially in high power LNG - Liquid Natural Gas liquefaction stations. Of course, this efficiency enhancement is also available for more modest cooling systems and air conditioning equipment. With Quasiturbine rotary expander, the efficiency of a gaseous only (like dry air) system reaches almost the efficiency of a phase change liquid-gaseous system, and sophisticated phase change chemical products often environmentally unwelcome are not anymore needed.

Essentially, the extra cooling power will be equal to the extracted power on the Quasiturbine expander shaft. More pressure power you remove mechanically, less heat power there is in the gas flow to warms it up during relaxation!
As an example, the QT600SC expands 600 cc per chamber and 8 chambers per revolution. At 500 rpm, this is 2,4 cubic meters per minute at intake, for up to 12 kW of output shaft power under 60 psi differential. Every second, the Quasiturbine expander removes (12 kW-sec) 12000 joules of thermal energy out of (2,4/60) 40 liters of 60 psi intake gas (at the expander exit, this volume is about 5 x 40 = 200 liters, if expanded to the atmospheric pressure). This is a removal of 300 joules of heat per liter (or 300 watts out of a 1 liter/sec flow) at intake (60 psi); or 60 joules of heat per liter (or 60 watts out of a 1 liter/sec flow) at exhaust (atmospheric pressure). The cooling temperature gain depends of the gas specific heat capacity. The exhaust gas cooling efficiency is consequently enhanced (and could be even somewhat more, by using intake valve cut-off cycle) compared to the use of a simple valve or pin hole, even if the Quasiturbine expander shaft output power is simply dissipated and lost. However, this shaft power can be re-used, possibly to recompress part of the gas, for a double efficiency gain!

More Technical

Quasiturbine Theory Concept

Quasiturbine Rotary Expander

Quasiturbine Pump and Turbo-Pump