I have read about a potential new combustion technology known as Homogeneous Compression Charge Ignition (HCCI). According to some researchers, it can help diesel engines simultaneously satisfy emissions requirements for NOx and particulates. How does this technology relate to CGI?

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HCCI is one of a large number of new technologies that are continuously being evaluated by the automotive industry to improve fuel economy and performance while reducing emissions. In comparison to technologies such as exhaust gas treatment or new engine management techniques such as cylinder deactivation, or even longer-term developments such as fuel cells, HCCI can be of interest to SinterCast due to the likelihood of increased mechanical and thermal loading.

The HCCI concept can be applied to both diesel and petrol engines. Some researchers are also investigating the use of HCCI technologies for Combined Combustion Systems (CCS) which would use spark ignition under extreme operating conditions such as full acceleration or when the engine is cold and would otherwise use the HCCI diesel cycle as often as possible.

In general, the HCCI combustion technology uses leaner fuel mixtures and requires more turbocharging to reach the performance levels of conventional petrol or diesel engines. Compared to conventional engines, the ignition is very rapid and the peak cylinder pressures become very high, in excess of 200 bar and possibly up to 250 bar. These conditions place severe mechanical loads on the cylinder block and both thermal and mechanical loads on the cylinder head. At present, the rapid combustion also results in relatively loud engine operation.

The development of the HCCI concept is still relatively new and most automotive forecasters view this as a technology for the 2015 timeframe. In the meantime, researchers will undoubtedly try to control the speed and intensity of the HCCI combustion by introducing technologies such as exhaust gas recirculation (EGR). Further development will also include the need for prolonged durability testing which will serve to identify the material requirements.

Regardless of the future for HCCI, many novel engine technologies will continue to be presented and developed. The common objective among these new technologies will continue to be increased performance and reduced emissions from smaller packages. Stronger engine materials will certainly contribute to the realisation of the new technologies and trends, and this will continue to provide new opportunities for CGI beyond our current Five Wave perspective.