New diesel engines could deliver near-zero NOx

Welcoming the project, Science and Innovation Minister Malcolm Wicks said: "The UK has a proud history of innovation in science and technology. We believe that we must work with industry to develop the marketable products and services of tomorrow, so that we can maintain our position as a leading global economy. That is why we are supporting this project, not to mention it having great potential to help the environment. It provides an opportunity to harness the UK's world-class expertise."

Dr Derek Wallis of Cambridge Consultants added: "The benefits of developing HCCI technology are potentially enormous. HCCI diesel engines will deliver near-zero NOx and particulate emissions, with minimal requirement for exhaust gas treatment" says .

Applications

Diesel engines are used in buses, trucks and other large vehicles and around a quarter of the carbon dioxide (CO2) is generated by UK road transportation. In today's diesel engines, combustion takes place at high temperatures, generating nitrogen oxides (NOx) and particulates. In an HCCI engine, the fuel disperses very evenly throughout the combustion chamber as a vapour mist. This process allows it to burn extremely efficiently at a lower temperature, resulting in exceptionally low emissions. But, although the HCCI combustion principle has been demonstrated, there are many design problems and so far nobody has managed to build an engine that can sustain HCCI efficiently over the range of real-world operating conditions.

This project, which runs until December 2008, will study the complete combustion cycle, focussing on the injection system, the in-cylinder design and combustion processes and the turbocharger systems. New, dedicated three-dimensional modelling tools will be developed to understand the complex air flow, fuel spray and in-cylinder processes, to help the designers to bring HCCI to market more quickly.

The impact of HCCI could be hugely significant, as more stringent emissions regulations for diesel engines come into force in Europe over the next few years. Alternative approaches to meet these future standards require exhaust gas filtering or treatment, resulting in a substantial increase in both fuel consumption and CO2 emissions. HCCI can deliver very low emissions and would also be able to operate on bio-based fuels, further supporting countries' commitments to reduce greenhouse gases. For example, the UK government has recently announced that it is targeting a 60 per cent reduction of CO2 by 2050, compared with 1990 levels.

Each of the team members is contributing expertise in a range of engine design areas. Cambridge Consultants will develop a predictive controller for management of the engine's air system. Loughborough University is working on the design of the fuel injector flow path and nozzle. City University is working on a model to simulate the nozzle flow and the spray characteristics inside the engine cylinder. Sussex University will model and control the combustion process and the exhaust gas temperature to better understand how HCCI combustion can be implemented on a commercial engine.

Caterpillar UK is the lead partner in the project, and will integrate the models into its own system simulator at its engine manufacturing plant in Peterborough, as well as evaluating the design ideas.

Cambridge Consultants' input will enable an adaptive, predictive, control strategy to operate in real-time on a commercial engine control unit (ECU). The company's experience in this field includes a patented transient EGR/VGT (exhaust gas recirculation/variable geometry turbine) controller for use in meeting the highly dynamic requirements of HCCI charge air delivery. The technology employs a self-learning algorithm to predict requirements and tune air control parameters for combustion efficiency. CCL will also employ its rapid-prototyping skills to help the speed and efficiency of the project.