Thermal Management of Diesel Engine Emissions

Diesel engines remain a cornerstone of heavy-duty transport and off-road machinery, yet their emissions of nitrogen oxides, particulate matter and unburnt hydrocarbons pose significant environmental and health challenges. To meet tightening regulations and reduce urban air pollution, advanced exhaust after-treatment systems—comprising diesel oxidation catalysts, particulate filters and selective catalytic reduction units—must reach and maintain critical operating temperatures rapidly. Thermal management strategies therefore play a pivotal role in accelerating catalyst light-off during cold starts, sustaining conversion efficiency under variable loads and minimising the fuel penalty associated with heating. These strategies encompass engine-based controls such as cylinder deactivation, ignition timing adjustment and variable valve timing, alongside dedicated heating technologies including electrically heated catalysts, microwave or burner-based regeneration and phase-change materials. Insulation techniques further reduce heat loss from exhaust piping and after-treatment housings. The optimal integration of these methods balances rapid temperature rise against energy consumption, delivering substantial reductions in cold-start emissions and enhancing overall fuel economy. Innovations in catalyst formulations and adaptive control algorithms are extending the thermal resilience of systems across diverse duty cycles, offering pathways to decarbonise diesel powertrains and improve air quality on a global scale.

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Thermal Management of Diesel Engine Emissions publication trend

The graph below shows the total number of articles in thermal management of diesel engine emissions across all publications each year (not limited to Nature Index journals).

Technical terms

Diesel Oxidation Catalyst (DOC): A catalytic converter that oxidises carbon monoxide and hydrocarbons into carbon dioxide and water once sufficient temperature is reached.

Diesel Particulate Filter (DPF): A device that traps soot particles from exhaust gases and requires periodic high-temperature regeneration to oxidise the collected particulate.

Selective Catalytic Reduction (SCR): A system that injects a urea-based reductant into the exhaust stream to convert nitrogen oxides into nitrogen and water over a catalyst at optimal temperature.

Electrically Heated Catalyst (EHC): A heating element integrated with the catalyst substrate that uses electrical power to raise catalyst temperature rapidly during cold starts.

Light-off Temperature: The exhaust gas temperature at which a catalyst achieves 50% conversion efficiency of target pollutants.

Cylinder Deactivation: An engine control strategy that temporarily disables fuel injection and valve motion in selected cylinders to increase exhaust gas temperature and accelerate catalyst warm-up.

References

1. A Review of Thermal Energy Management of Diesel Exhaust after-Treatment Systems Technology and Efficiency Enhancement Approaches. Energies (2024).
2. Fuel Consumption and Emission Reduction for Non-Road Diesel Engines with Electrically Heated Catalysts. Catalysts (2023).