Concept advantages

Making an analysis “Well to wheel” of the main propulsion systems with different paths, it can observe that the total efficiency of various HOPE engines (Diesel, SI- spark ignition and PHE – pneumatic hybrid engine) is placed between the pure electric propulsion (if use only green energy) and the actual Diesel engine.  The hydrogen HOPE with exhaust gas recovery achieved as a pneumatic hybrid engine (PHE) is even more efficient than the fuel cell. For all HOPEs the CO2 emission is low and completely absent if it is used the hydrogen as fuel.

A simple HOPE is cheaper than actual engine even it can achieve a fuel economy and a CO2 reduction superior to 30%.  The vehicle with HOPE and  PHE having exhaust gases heat recovery system is more efficient than an actual hybrid electric vehicle and is not expensive. The client can recover the supplementary cost of around 1500 – 2000 $ in one or two years, which is not the case for the actual hybrid electric vehicle.

Also in the utilization for electric vehicle with extended autonomy or for hybrid electric vehicles the proposed concept reduces the costs and leads to supplementary advantages as the reduced NVH level.

The main advantages of this concept engine are:

• Fully balanced mechanism and very good NVH behavior even with two pistons or four-stroke configuration;
• Having the compressor included in the volume of the engine it offers extreme power density of around 2.5 kW/kg;
• Because is no cylinder head, the heat losses are diminished and the effective efficiency increase a lot, being around 45% for automotive application; This efficiency can be  even bigger for stationary or medium speed marine engines;
• The piston works without touching the cylinder and that diminishes the friction with around 20% and increase substantially the efficiency;  
• For same reason, the reliability of the engine is very much improved;
• Easy to change the compression ratio in the configuration with two crankshafts, respectively modifying the relative position between the one gear and its associated crank;
• The combustion takes place at constant volume (geometrically) minimizing again the heat loses and the incomplete burn rate;
• The fuel injection system, the ignition system, the exhaust manifold and the intake manifold are simplified and that reduces drastically the costs;
• Using extended expansion stroke can improve also the efficiency;
• Comparing with OPOC engine or Achates Power engine is more compact, being very well adapted for automotive applications;
• It represents a real world solution for the portable range extender used by the electric vehicle with extended autonomy, for low cost hybrid electric vehicles or for non electric hybrid vehicles.
• It is very well adapted for the new fuels as CNG, LPG, biofuels and hydrogen doe to the possibility to include a compressor in the volume of the engine.

 For a middle class, gasoline car ( M=1300 kg, Cx= 0.30, S= 2.2 m²), the comparison with the calculated fuel consumptions between conventional and HOPE SI engines is described in the table 1.

Table 1

For a typical diesel truck, the comparison with the calculated fuel consumptions between conventional and HOPE diesel with heat recovery is described in the table 2.

Table 2

For an urban diesel bus, the comparison with the calculated fuel consumptions between conventional and  HOPE diesel is described in the table 3.

Table 3