The asymmetric geometry of the Libralato engine not only controls the volumetric properties but also the kinematics.
In reciprocating engines, the torque delivered by the engine is a product of the pressure of the combusting gases expanding in the cylinder and the angle of the connecting rod turning the crankshaft. Maximum pressure is delivered at 0o top-dead-centre and maximum mechanical advantage is delivered at 90o.
Within the Libralato engine, maximum mechanical advantage is delivered straight away because the rotor applies the force directly on the crankshaft. High and relatively constant torque is maintained over 150o despite reducing pressure in the chamber, because of the expanding working surface area of the rotor. A comparison of Unit Torque v Chamber Volume is shown in figure 7.
Figure 7. Unit Torque v Chamber Volume Comparison
The asymmetrical geometry of the Libralato engine produces significantly more torque than the symmetrical arrangement of a conventional piston engine. Note the duration of compression and expansion events are shorter for the Libralato engine. See figure 8.
Figure 8. Torque Comparison
The asymmetrical geometry of the Libralato engine causes a phase shift between the volumetric curve and the Unit Torque curve. A comparison with a symmetrical piston engine is depicted in figure 9.
Figure 9. Volumetric & Torque Curve Comparison
Chamber pressures are generally lower for the Libralato engine, except for the first 15 degrees of the expansion phase. This allows the fuel/air mixture to combust at a higher temperature for a given compression ratio. Due to the greater pressure drop in the expansion phase, the exhaust gases exit the engine cooler, thus fulfilling the first requirement for thermodynamic efficiency. See figure 10.
Figure 10. Chamber Pressure Comparison
These calculations of compression and expansion phases, demonstrate how the Libralato engine could potentially deliver an increase in power of up to 27% using diesel as a fuel. Yet the engine is at most 70% of the weight and volume of a conventional engine. See figure 11. comparison of internal volume of a 2 bank Libralato engine with a conventional ICE right.
Figure 11. Comparison of Internal Volume
It is generally accepted that an ICE burning Hydrogen can never achieve the efficiency of a fuel cell using the same fuel. However an ICE like the Libralato can extract the maximum potential from hydrogen’s properties and in particular circumstances can outperform fuel cell efficiency. The graph overleaf shows the comparative efficiencies of various ICE’s against that of a fuel cell under a complete load spectrum.
It can be seen in figure 12 that a fuel cell is most efficient at low to moderate loads and is more efficient than both the petrol and diesel engines. The Libralato engine can use hydrogen as a fuel without the valve overlap and sealing problems associated with piston engines. Sealing of the rotors against the chamber periphery is excellent because of their circular orbits and large sealing surfaces. This means each chamber within the engine is entirely separated from the others.
Figure 12. Comparative efficiency of Libralato engine
