Ricardo Novella

• PhD
• Professor at Polytechnic University of Valencia

Ammonia, being 17.6% hydrogen by mass, is regarded as a hydrogen carrier and carbon-free fuel as long as its production methods rely on renewable energy sources. The production and combustion of green ammonia do not generate carbon dioxide, offering a promising avenue for substantial reductions in greenhouse gas (GHG) emissions from a well-to-wake...

Green hydrogen, with its potential to significantly reduce transportation CO2 emissions, emerges as a promising solution to combat human-induced climate change. However, challenges such as flame instability and pre-ignition pose significant obstacles to its integration into internal combustion engines (ICEs). Computational fluid dynamics (CFD) is a...

The Lagrangian-Eulerian Spark Ignition (LESI) model developed by Argonne National Laboratory (ANL) has been integrated into the commercial CFD software CONVERGE. The current implementation contains several options to model the breakdown phase of the spark event, which was not included in the original model. Using Lagrangian particles to deposit ene...

Oxymethylene dimethyl ethers (OMEx), having a chemical formula of CH3O-(CH2O)x-CH3 where x varies from 1 to 5, have been widely considered as a promising fuel to partially replace diesel in CI engines in terms of reducing soot emissions. This work is focused on developing a reduced primary reference fuel (PRF)-OMEx chemical mechanism to better desc...

Since traditional fuels are being phased out, engine conversions to more sustainable fuels are being performed to address local regulations. Due to its potential to reduce CO 2 and local pollutants, liquified petroleum gas (LPG) stands out as an alternative fuel for internal combustion engines. LPG chemical structure allows for higher compression r...

A viable green energy source for heavy industries and transportation is hydrogen. The internal combustion engine (ICE), when powered by hydrogen, offers an economical and adaptable way to quickly decarbonize the transportation industry. In general, two techniques are used to inject hydrogen into the ICE combustion chamber: port injection and direct...

The growing interest in low-impact mobility technologies has elevated the significance of fuel cell electric vehicles (FCEVs) in the automotive sector. Given the complexity of the resulting powertrain, the need for an effective energy management strategy (EMS) becomes essential to optimize efficiency and energy consumption in vehicles with diverse...

This paper proposes a 1D numerical/experimental study on a single-cylinder research ICE equipped with a hydrogen Port Fuel Injection (PFI) system. The experimental campaign covered tests at the fixed speed of 1500 rpm and different levels of load, from 5 bar to 11 bar IMEP, and of air excess, with a relative air-to-fuel ratio ranging from 1.4 to 4....

In the automotive sector, hydrogen is being increasingly explored as an alternative fuel to replace conventional carbon-based fuels. Its combustion characteristics make it well-suited for adaptation to internal combustion engines. The wide flammability range of hydrogen allows for higher dilution conditions, resulting in enhanced combustion efficie...

The solution to the dilemma of carbon footprint of internal combustion engines and pollutant emissions is necessary for the survival of this technology. In this context, alternative fuels have shown great potential in terms of achieving cleaner combustion and compliance with ever increasing pollutant emissions regulations. This work is focused on t...

The present work focuses on the derivation and evaluation of a chemical kinetic mechanism of primary reference fuel [(PRF, binary blends of n-heptane and isooctane)] with a homogeneous reactors approach starting from a detailed one. Results show that the optimized mechanism can replicate the results of the detailed one with high accuracy. The mecha...

Significant efforts are under way to develop innovative ignition systems for spark-ignition engines used in transportation. Within this context, passive pre-chamber technology has emerged as a promising alternative for passenger cars. However, several uncertainties remain regarding the operation of this concept at low engine loads and speeds, as we...

The increase in the overall global temperature and its subsequent impact on extreme weather events are the most critical consequences of human activity. In this scenario, transportation plays a significant role in greenhouse gas (GHG) emissions, which are the main drivers of climate change. The decline of non-renewable energy sources, coupled with...

This study presents a novel approach specifically designed for real-world driving scenarios of heavy-duty fuel cell vehicles, named P-ECMS. The P-ECMS addresses both charge-sustaining and charge-depleting modes of the battery to optimize the vehicle’s energy management. To this aim, the P-ECMS integrates a velocity prediction layer and a SOC planni...

div class="section abstract"> This study proposes a predictive equivalent consumption minimization strategy (P-ECMS), based on short-term velocity prediction for a heavy-duty fuel cell vehicle while considering fuel cell degradation. The long-short term memory (LSTM) based predictor has been trained on data deriving from realistic driving cycles. T...

div class="section abstract"> Hydrogen-fueled internal combustion engines are highly susceptible to pre-ignition from external sources due to its low minimum ignition energy despite the hydrogen’s good auto-ignition resistance. Pre-ignition leads to uncontrolled abnormal combustion events resulting in knocking and / or backfire (flashback) which ma...

div class="section abstract"> Mitigating human-made climate change means cutting greenhouse gas (GHG) emissions, especially carbon dioxide (CO₂), which causes climate change. One approach to achieving this is to move to a carbon-free economy where carbon emissions are offset by carbon removal or sequestration. Transportation is a signifi...

The employment of hydrogen as energy carrier for transportation sector represents a significant challenge for powertrains. Spark-ignition (SI) engines are feasible and low-cost devices to convert the hydrogen chemical energy into mechanical work. However, significant efforts are needed to successfully retrofit the available configurations. The comp...

Shipping is one of the most efficient transportation modes for moving freight globally. International regulations concerning decarbonization and emission reduction goals drive rapid innovations to meet the 2030 and 2050 greenhouse gas reduction targets. The internal combustion engines used for marine vessels are among the most efficient energy conv...

Aiming at reducing pollutant emissions, hydrogen and fuel cell hybrid electric vehicles (FCVs) represent a promising technological solution. In this scenario, this paper proposes an adaptive energy management strategy (A-EMS) based on speed forecasting for a heavy-duty FCV, in order to achieve stable battery charge sustenance in realistic driving c...

SI engines fueled with hydrogen represent a promising powertrain solution to meet the ambitious target of carbon-free emissions at the tailpipe. Therefore, fast and reliable numerical tools can significantly support the automotive industry in the optimization of such technology. In this work, a 1D-3D methodology is presented to simulate in detail t...

Hydrogen substitution in applications fueled by compressed natural gas arises as a potential alternative to fossil fuels, and it may be the key to an effective hydrogen economy transition. The reduction of greenhouse gas emissions, especially carbon dioxide and unburned methane, as hydrogen is used in transport and industry applications, makes its...

The importance of new alternative fuels has assumed great relevance in the last decades to face the issues of global warming and pollutant emissions from energy production. The scientific community is responsible for developing solutions to achieve the necessary environmental restriction policies. In this context, ammonia appears as a potential fue...

In recent decades, the importance of emerging alternative fuels has increased significantly as a solution to the problems of global warming and air pollution from energy production. In this context, ammonia (NH3) is seen as a potential option and energy vector that may be able to overcome the technical challenges associated with the use of other ca...

div class="section abstract"> Fuel film deposits on combustion chamber walls are understood to be the main source of particle emissions in GDI engines under homogenous charge operation. More precisely, the liquid film that remains on the injector tip after the end of injection is a fuel rich zone that undergoes pyrolysis reactions leading to the fo...

div class="section abstract"> Pre-chamber spark ignition (PCSI) systems have been proven to improve combustion stability in highly-diluted and ultra-lean natural gas (NG) engine operation by providing spatially distributed ignition initiated by multiple turbulent flame-jets that lead to faster combustion compared to conventional spark ignition. Thi...

div class="section abstract"> Despite recent advances towards powertrain electrification as a solution to mitigate pollutant emissions from road transport, synthetic fuels (especially e- fuels) still have a major role to play in applications where electrification will not be viable in short-medium term. Among e-fuels, oxymethylene ethers are gettin...

The increasing concern about Greenhouse Gas (GHG) emissions led the European Union to introduce increasingly stringent limits to the CO2 from road vehicles, with an impact on the sales of passenger cars. Vehicles equipped with Spark-Ignition (SI) engines became more numerous than those equipped with Compression-Ignition (CI) engines, due to the exp...

Flamelet Generated Manifold (FGM) is an example of a chemistry tabulation or a flamelet method that is under attention because of its accuracy and speed in predicting combustion characteristics. However, the main problem in applying the model is a large amount of memory required. One way to solve this problem is to apply machine learning (ML) to re...

In the Computational Fluid Dynamics (CFD) simulation of advanced combustion systems, the chemical kinetics must be examined in detail to predict the emissions and performance characteristics accurately. Nevertheless, the combustion simulation with detailed chemical kinetics is complicated because of the number of equations and a broad timescale spe...

During the last years, the sales of vehicles equipped with Spark-Ignition (SI) engines have increased, to the detriment of those powered by Compression-Ignition (CI) engines. However, SI engines provide lower efficiency than CI engines, due to the low compression ratio and stoichiometric mixture operation. A way to increase the efficiency of SI eng...

The effects of passive pre-chamber (PC) geometry and nozzle pattern as well as the use of either conventional spark or non-equilibrium plasma PC ignition system on knocking events were studied in an optically-accessible single-cylinder gasoline research engine. The equivalence ratio of the charge in the main chamber (MC) was maintained equal to 0.9...

In this study, an innovative Low Temperature Combustion (LTC) system named Temperature Controlled Reactivity Compression Ignition (TCRCI) is presented, and a numerical optimization of the hardware and the operating parameters is proposed. The studied combustion system aims to reduce the complexity of the Reaction Controlled Compression Ignition eng...

The impact of passive pre-chamber (PC) internal volume, nozzle hole pattern (i.e. with and without a central axial nozzle), and PC igniter plug type on performance and emissions was investigated in an optically accessible, single-cylinder, gasoline research engine. The two PC igniter plugs investigated were a conventional inductive coil spark plug...

Aiming at increasing fuel cell (FC) stack durability in driving conditions, part of the scientific community has focused its efforts on developing energy management strategies (EMS) for fuel cell hybrid vehicles (FCV). Nonetheless, most of these studies do not explicitly explain the effect of constraining the EMS in both degradation and performance...

Mitigation of the carbon footprint of internal combustion engines is mandatory to ensure a future for this technology. Within this scope, e-fuels are considered a potential solution to replace conventional fossil fuels. However, in some cases, their physical and chemical properties are so different that its application in conventional engines is co...

In this study, durability and performance prediction were integrated in the sizing process of the FC stack of a fuel cell range-extender (FCREx) vehicle together with the design of a dynamics-limited control strategy. For that purpose, a FCREx vehicle model integrating a FC stack, balance of plant, battery, H2 tank and vehicle body (C-class SUV) va...

The reduction of the carbon footprint of internal combustion engines and the pollutant emissions is mandatory for the survival of this technology. In this sense, e-fuels are considered as a potential pathway to achieve this reduction and even remarkable carbon footprint mitigation in compression ignition engines. Among numerous e-fuels, oxymethylen...

Among the possible electric powerplants currently driving low-payload UAVs (up to around 10 kg of payload), batteries offer certain clear benefits, but for medium-payload operation such as aerotaxis and heavy-cargo transportation UAVs, battery capacity requirements restrict their usage due to high weight and volume. In light of this situation, fuel...

The use of advanced ignition concepts and enhanced combustion strategies is being widely studied for modern engine applications. In this framework, the passive pre-chamber ignition system is gaining popularity for its mechanical simplicity. However, in order to implement this ignition system in passenger car vehicles, the concept must be able to op...

Economy decarbonization will be one of the main goals for the following years. Research efforts are being focused on reducing carbon-based emissions, by increasing the efficiency of the transport power plants while developing new fuel production methods that reduce the environmental footprint of the refinement process. Consequently, the depletion o...

The combination of computational fluid dynamics (CFD) and evolutionary methods has been a breakthrough in the development of internal combustion engines (ICE) in the last three decades. The continuous evolution of computational methods, together with the impressive growth of computer performance, has allowed large-scale and massive engine simulatio...

In this study, a numerical methodology for the optimization of the combustion chamber in compression ignited engines using OME as fuel is presented. The objective is to obtain a dedicated combustion system for an engine that is fueled with this alternative fuel improving the efficiency and reducing the emissions of NOx. This article proposes the in...

Systems electrification in the unmanned aerial vehicle (UAV) and short-range aircraft industries is a trend that is becoming consolidated as the foundation for the future of this part of the aerospace sector. Among the possible electric powerplants currently driving low-payload UAVs (up to around 10 kg of payload), batteries offer clear benefits wi...

Fuel cell (FC) technologies for mobility are gaining interest as promising options to decarbonize the transport sector in line with the current progress towards the H2 economy. Previous studies show how the fuel cell range extender (FCREx) powertrain architecture can offer flexible and efficient operation along with the potentially low total cost o...

The achievement of a carbon-free emissions economy is one of the main goals to reduce climate change and its negative effects. Scientists and technological improvements have followed this trend, improving efficiency, and reducing carbon and other compounds that foment climate change. Since the main contributor of these emissions is transportation,...

In transport applications, reciprocating internal combustion engines still have important advantages in terms of endurance and refueling time and available infrastructure when compared against fuel cell or battery-based powertrains. Although conventional internal combustion engine configurations produce important amounts of greenhouse gases and pol...

The pre-blending of low- and high-reactivity fuels for a single direct injection system has been proven to be an effective way to control the reactivity of mixtures in compression ignition engines, having the potential to simultaneously reduce fuel consumption and pollutant emissions. However, there is not much knowledge about the complex physical–...

A R T I C L E I N F O Keywords: Pre-chamber spark ignition 1-D gas jet model cycle-to-cycle variability infrared imaging high-speed visualization A B S T R A C T Experimental results from a study on the evolution of gas jets ejected through the orifices of a pre-chamber in a heavy-duty optical engine are presented. The work examines conditions with...

Soot production (including formation and oxidation) is studied in the transient, high-pressure and turbulent n-dodecane Spray A flames from the Engine Combustion Network (ECN) using computational fluid dynamics (CFD) simulations. A two-equation soot-in-flamelet modeling approach is applied within the framework of the Unsteady Flamelet Progress Vari...

div class="section abstract"> Computational fluid dynamics (CFD) modeling has many potentials for the design and calibration of modern and future engine concepts, including facilitating the exploration of operation conditions and casting light on the involved physical and chemical phenomena. As more attention is paid to the matching of different fu...

Passive pre-chamber ignition concept has been proven to be an excellent strategy to increase the ignition energy and enhance the combustion velocity even when spark-ignition engines are operating in diluted conditions. Other benefits of this system are the increased combustion stability and combustion efficiency, reducing hydrocarbons and carbon mo...

Aiming to reduce global warming and emissions in general, cleaner technologies are the spotlight of research and industry development. Among them, fuel cell vehicles (FCV) are gaining interest to decarbonize the transport sector. Plug-in FCV or FCV in range-extender configuration (FCREx) is an interesting option to reduce the total cost of ownershi...

Hydrogen is one of the most promising alternative fuels for the transportation industry. The use of hydrogen to enable lean burn in internal combustion engines is an attractive solution for reducing CO2 emissions from two points of views: the substitution of carbon‐based fuels and the increased thermal efficiency due to lean operation. Combining th...

Adverse effects of global warming due to the greenhouse gas emissions is changing the actual paradigm for the use energy resources. In the absence of a mid-term solution for reducing these emissions in transportation, internal combustion (IC) engines are going to coexist in the social spheres in the foreseeable future. Therefore, the study of other...

Turbulent jet ignition (TJI) engines might substantially improve the efficiency of spark ignition (SI) engines by locating the spark in a pre-chamber. Concretely, the passive pre-chamber concept could be directly applied in commercial SI engines with minor modifications. The pre-chamber burns a small quantity of fuel providing the rest of the chamb...

In this paper, the acoustic response of a combustion chamber is studied by assuming different pressure field excitation. The viscous effects on the combustion chamber and the finite impedance of the walls have been modeled with a first-order system, which damps the resonance oscillation created by combustion. The characterization of the acoustic re...

In view of the increasing restrictions for CO2 mitigation, the evaluation of alternative fuels to ensure sustainability of transportation is becoming increasingly important. Since some of these alternatives can be refined from renewable sources, they are interesting from the perspective of both: the use of the current power-plants and the CO2 emiss...

The combustion process of the Engine Combustion Network (ECN) Spray A and Spray D is studied over a wide range of ambient temperatures from 750 K to 900 K. With nominal diameters of 89.4 μm for the Spray A and 190.3 μm for the Spray D, these n-dodecane sprays are representative for light- and heavy-duty compression ignition engine applications, res...

To further understand the processes and phenomena taking place in the pre-chamber (PC) ignition concept, many studies under simplified conditions have been carried out in different experimental facilities (e.g. constant volume chambers and rapid compression machines). However limited information is provided about how the volume, orifice diameter an...

This paper proposes an educational methodology for the development of the specific instrumental soft skill in Aerospace Engineering degree students. This methodology uses an autonomous and active learning approach to measure, through two different techniques, the local flow velocities around a circular cylinder in a subsonic wind tunnel. The studen...

This work evaluates the performance of Computational Fluid Dynamics modeling using a Reynolds Average Navier-Stokes turbulence approach and the coupling of an Eulerian diffuse-interface (Ʃ-Y) spray model and an Unsteady Flamelet Progress Variable combustion model. All models are implemented using the open-source CFD software OpenFOAM. The approach...

With the rise of cleaner technologies for transport and the emergence of H2 as a fuel, most of the emissions in the well-to-wheel process are shifting towards the energy carrier production (fuel or electricity). The objective of this study is to perform a simplified cradle-to-grave Life Cycle Assessment (LCA) that compares the greenhouse gases (GHG...

As computational capabilities continue to grow, exploring the limits of computational fluid dynamics to capture complex and elusive phenomena, which are otherwise difficult to study by experimental techniques, is one of the main targets for the research community. This paper presents a detailed analysis of the physical processes that lead to combus...

In this paper, a computational study was performed using a combination of several numerical tools to better understand the limiting aspects of combustion in a passive pre-chamber ignition system when operating at lean conditions. A specific methodology was developed to analyze in detail the scavenging and combustion processes of this ignition conce...

Fuel efficiency improvement and harmful emissions reduction are the main motivations for the development of gas turbine combustors. Numerical computational fluid dynamics (CFD) simulations of these devices are usually computationally expensive since they imply a multi-scale problem. In this work, gaseous non-reactive unsteady Reynolds-Averaged Navi...

Nowadays the combination of strict regulations for pollutant and CO2 emissions, together with the irruption of electric vehicles in the automotive market, is arising many concerns for internal combustion engine community. For this purpose, many research efforts are being devoted to the development of a new generation of high-performance spark-ignit...

div class="section abstract"> An existing one-dimensional (1D) spray model, which successfully captures inert spray processes, has been extended to enable prediction of ignition delay and lift-off length under reacting conditions. For that purpose, an additional transport equation for the progress variable has been incorporated, which includes deta...

In order to face the new challenges, spark ignition engines are evolving by following some strategies and technologies. Among them, alternative combustion processes based on the dilution of the homogeneous mixture, either with fresh air or with Exhaust Gas Recirculation (EGR), are being explored. In a higher or lower extent, these changes modify in...