Unconventional thermal and electric engines

Ever since the first industrial revolution, non-conventional heat engines have been the subject of both breakthrough and breakthrough innovations, both aimed at significantly improving the performance of these engines, whatever their field of application.

As far as disruptive innovations are concerned, they have generally met with mixed success, to say the least, due to the complexity and cost that legitimately accompany these cutting-edge technological advances. Nevertheless, they are resurfacing regularly, and their impact is undeniable at the dawn of 2030, as part of the new, low-carbon energy paradigm that is now unavoidable. For example, one of the key trends for 2030 and beyond is to combine the use of low-carbon fuels with hybrid electric and pneumatic machines on a large scale, to produce the essential energy that everyone needs. Thus, the alliance between combustion, electric and pneumatic engines, and the new range of green fuels of the 21st century, has become unavoidable (biomass, dihydrogen, e-fuels, ammonia, e-methanol...). Breakthrough and breakthrough innovations across the whole spectrum of mobility need to be analyzed in detail, as do their diversified sources of primary energy. These breakthrough innovations demonstrate the effervescence that now reigns across the entire mobility spectrum. Early-stage applications for decarbonated generator sets and polygeneration are part of the same idea.

In this article, we focus primarily on pneumatic engines, which are still widely used today, even though the engine engineer is well aware that optimized performance requires a working fluid compression phase, and simultaneously a combustion phase designed to produce the indispensable mechanical energy with a suitable conversion efficiency.

Camshaftless engines have been the subject of extensive research over the last twenty years, in an attempt to at least partially do away with the traditional conventional camshaft. Variable valve timing processes are being used to replace conventional valve train technology. The ultimate step would be to do away with the camshaft altogether, in favor of electromagnetic actuators.

For its part, the gas turbine applied to automotive propulsion was also the subject of intense research over several decades, but failed to dethrone the supremacy of piston engines. The main argument put forward was that the gas turbine was lighter and had fewer moving parts. In addition, gas turbines could run on several types of fuel - gas, petrol, diesel and kerosene - and would require less maintenance and last longer.

A hybrid thermal-electric demonstrator was investigated for almost 10 years by the Renault group's research center in the early 2000s. The idea was to...