Automotive Industry Development Trend

         Internal combustion engines (ICEs) came into existence quite a long time ago; their efficiency factor, however, hasn’t changed much since. To date, the efficiency factor of a gasoline ICE is 25-30%, while a diesel ICE is 40-45%.

         From a physics standpoint, the operational principles of gasoline and diesel engines are not all that different. From a mechanical standpoint, gasoline ICEs have a higher rotation speed and lower torque. Diesel ICEs, on the other hand, have a lower rotation speed and a higher torque. This is exactly why gasoline engines are used predominately in passenger cars, while diesel engines are more common in trucks and tractors.

         Substantial loses in ICE-produced energy can be observed during the mechanical transfer of torque to the wheels. For example, transmission loss can reach 10-20% of the engine’s overall power, depending on gear ratio and vehicle speed.

         An uneven load during ICE operation can contribute to a drop in efficiency (up to 50%). Auto manufacturers cover these losses by applying different fuel-usage models for city and freeway driving. For city driving, acceleration and braking is very typical, which leads to higher fuel consumption (which may double in some cases).

         As a result, the actual efficiency of a gasoline ICE is 16.6-20%, while a diesel ICE registers between 26.6-30%. The rest is smoke, heat, noise, and odor.

         The battle against transmission loss and uneven ICE performance was won when the hybrid engine car was invented. In essence, the engineering solution they provide is an ICE onboard computer that not only works under constant load, but also rotates electrical generators. Motors mounted on the wheels take electrical energy from the generator and battery. When a vehicle is going uphill, energy is taken from the batteries and evenly distributed to the wheels. When a vehicle is going downhill, momentum is transferred back to the batteries. Think of it as a complex, yet natural, recharging process. Ultimately, however, everything relates back to ICE efficiency.

         Turbine ICEs are a little different from piston ICEs. The engine is essentially the same, but the compressor, combustion chamber, and energy converter are three completely different devices. In a piston engine, all operations occur in one place. In a turbine engine, efficiency is heavily dependent upon the turbine’s power capacity. Based on experimental data and calculations, the following unofficial recommendation is made: for power generation up to 800 kWs, use a piston ICE; for higher capacities, use a gas turbine unit (GTU).

         Theoretically, a GTU can be installed in any car. The unit is small and light, and there’s no need for cooling. However, there are some significant disadvantages (perhaps even more than ICEs have):

1)  A lower efficiency factor (15-25%)

2)  High rotation speed and low torque, all leading to larger transmission losses

3)  Low motor power potential

4)  Higher costs

5)  Lower range of power control

         Because of these disadvantages, GTUs in cars never caught on. A few prototypes were created – mass production was even attempted – but the idea was never widely accepted.

         NRGLab Pte Ltd, along with an Israeli group of scientists, has developed a new GTU concept.  The main difference between our GTU and a traditional GTU is its efficiency of 75%! Speed rotation is almost as high as observed in gasoline engines, i.e. 3,000-3,600 rpms. Among the disadvantages of the new GTU are an absence of power control and restrictions in fuel consumption. Possible fuels that can be used are methane, propane-butane, and methanol.

Measure	Gasoline car	Hybrid car with GTU
Consumption, liter/100 km	10	5
Kind of fuel	non-leaden gasoline	methanol
Cost of fuel	$1.00	$0.40
Motor potential, h	35,000	100,000
Engine power, kW	100	100
Engine weight, kg	100	25
Cost of engine	$1,000	$1,000

         From an engineering standpoint, such GTUs can be used in hybrid cars. This way, fuel consumption per mile is reduced. Consider the above example of a conventional gasoline engine versus a proposed hybrid with one of our new GTUs:

         The new GTU (unlike the traditional GTU) needs a radiator. As it so happens, so does the gasoline engine. The table above gives an example of using methanol versus gasoline. The same results will be produced if liquefied natural gas (LNG) is used, too. When converting natural gas into cubic meters, the rate is 3 m³ for every 100 km.  All values are conditional, and were taken based on average car parameters.  

By Zeev Drori

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