Solid-State RF Energy for Engines & Ignition Systems

Solid-state RF energy enables completely new ignition systems that work far more efficiently, with lower emissions of pollutants. Biogas plants and mini-combined heat and power (mini-CHP) plants could be the first to benefit from the new technology.

“It is already clear today that the new RF spark plugs will be installed in stationary engines over the next few years,” says Professor Holger Heuermann of the University of Applied Sciences Aachen, Germany. This is where, they could show that they significantly reduce emissions of pollutants, work reliably and are suitable for real use. The production costs should then be brought to a level which makes them an appropriate alternative for use in other engines.

After all, anyone who thinks of RF energy in ignition systems - that is, ignition of the gas mixture by plasma, which power transistors generate - the first thing that comes to mind is the car. Here, the new technology can make gasoline engines as efficient as diesel engines, fuel consumption and emissions of pollutants would be reduced - not just by a few percentage points, this would be a huge leap forward.

At the moment, RF energy ignition systems are on the verge of being adopted in the real world of engines. Promising prototypes already work. According to Professor Heuermann, the system is on the brink of a breakthrough: “We started developing RF ignition systems in 2006. We have now developed a very well thought out overall concept from the formerly large and less practical feasibility studies.” Because the RF spark plugs were constructed with very fast control electronics, they could be finely and flexibly controlled after installation. This is very important for practical use. In addition, they are constructed from a few production-friendly components, thus making them simple and relatively inexpensive to manufacture.

However, wherever help is needed to achieve the breakthrough of a new technology, high costs at the beginning are inseparably linked with small quantities. Therefore, in the first step on the way to commercialization, the primary goal is to find a market in which the new RF energy spark plugs can fully exploit their advantages, despite an initially higher price. The quantities then increase and penetrate into sectors, which make them suitable for use in cars and consumer devices.

Professor Heuermann has found this market: “Our system is ideally suited for use in stationary gas engines for biogas plants and mini-CHP plants. Those who reduce emissions of pollutants in their plant are immediately rewarded by German legislators with money. A mini-CHP engine, whose ignition system costs EUR 400, is not a problem in this market, because users can very quickly recover the money back again,” says Professor Heuermann.

It is no wonder that he has found a partner: Within the framework of a sponsored project, Professor Heuermann is already working closely with a medium-sized company, which specializes in ignition systems for all types of engines, in the development of practical systems.

Some small teething problems in the system still have to be solved. The plasma is generated at a frequency of 2.5 GHz, it is therefore very cool, achieves however a high energy density. The great thing about it: “We have achieved a very precise square wave voltage, which everyone can immediately hear. The square wave voltage produces a very individual sound that is clearly different from the sinusoidal voltage,” says Professor Heuermann. Unfortunately, in this initial approach, the frequency had shifted slightly so that the required performance was no longer achieved. According to Professor Heuermann, such small difficulties are repeatedly encountered when new concepts are to put into practice. It is, however, an easy problem to solve and to compensate for the frequency shift is the aim of a new project, which has just been approved.

Professor Holger Heuermann, University of Applied Sciences Aachen, Germany: “It is already clear today that the new RF spark plugs will be installed in stationary engines over the next few years.”