ENERXICO develops and validates predictive combustion simulation tools in order to optimise fuel design and fuel performance towards more sustainable and greener propulsion systems.

The prediction of the combustion performance biofuels in practical applications is very challenging as some of the fuel characteristics are dependent on the country of origin and where the blending components come from. As a consequence, the performance and emission behavior of engines operated with these fuels also show a strong variability. The main factors that affect the combustion behavior are mainly related to the fuel properties, injection timing, feedstocks, type of engine and operating conditions. In particular, emissions are mainly driven by the efficiency of the atomization process and the heat loss. Those are parameters of major relevance to take into account for the prediction of NOx and soot, which are the main pollutants to target during the course of the project. Therefore, the use of exascale computing using high-fidelity simulations can represent an important step forward to provide further understanding on the combustion process and emissions characteristics of these new fuels and industrial guidelines for engine operation and maintenance.

ENERXICO´s objectives in combustion:

  • Develop and validate predictive simulation tools to optimise fuel design and performance.
  • Develop combustion and emission models for new industrial guidelines for engine operation and maintenance.


Collaborating institutions UPV, BSC, IMP
Software involved Alya 
Main mission High-fidelity numerical simulations of high-pressure spray flames of sustainable fuels for transportation
Target TRL TRL 3
Relevant stakeholders Repsol, Engine Combustion Network
Achievements up to M24 Development of a virtual platform for testing alternative fuels under engine-like conditions.
Related work and further information Two conference papers are in preparation


Exascale outlook

Exascale target 

We expect HPC to enable large-scale simulations of spray flames at engine-relevant conditions by allowing scale resolving simulations.
Main benefits expected from large increase in compute resources We should be able to solve more scales in the flow and add higher fidelity to the models.
Main challenges in harnessing large compute resources Performance portability is a major issue here and also the use of accelerators to speed up the calculations.
Specific actions towards exascale at present time Use of accelerators and load balancing of multiphase simulations using an Eulerian-Lagrangian framework are key aspects to optimize


Computational details

  Number of Cores/GPUs Storage (GB) both temporary and permanent #Files written both temporary and permanent 
Minimum 480 10 TB 500
Average 960 10 TB 1000
Maximum 1920 10 TB 3000



Caption: High-pressure ndodecane spray flame in hot air

Taoufik Ait-Ettajer, Subsurface Manager and Technology Projects E&P at Repsol "One of the main goals of the ENERXICO project in the Combustion research is to evaluate some of the most promising renewable fuels to deliver computational tools that can predict the behavior of such fuels under technologically relevant conditions. This is highly crucial since the availability of these tools will ensure the development of more sustainable and carbon-neutral combustion systems and powertrains to boost a successful energy transition. Repsol participation in Enerxico is focused on renewable fuel formulation, characterization and collaboration in the combustion process analysis to correlate the different renewable fuel composition with the fuel performance, combustion and emissions formation. Being part of the project guarantees us an early adopters position for the next generation of HPC capacities, which will be key in the roadmap in the continuous evolution of our ‘virtual laboratories’.”