J. R. Serrano

• Ph. D. Mechanical Engineer
• Professor (Full) at Polytechnic University of Valencia

Featured Application Jet ejector refrigeration cycles. Abstract Recent advancements in computational and experimental techniques have deepened the understanding of ejector dynamics. Working maps, which depict the relationship between operating conditions and the performance metrics of entrainment and pressure, are commonly used in defining the eje...

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...

This study investigates oxy-fuel combustion (OFC) applied to reciprocating internal combustion engines for a flexible Combined Heat and Power (CHP) plant with carbon capture. Utilizing one-dimensional (1-D) modelling software, the engine and associated components are modelled to generate operating maps based on control strategies. Three control loo...

Worldwide emission standards are now required to cover engine operation under extreme ambient conditions, which affect the raw emissions and the efficiency of the exhaust aftertreatment systems. These regulations also target new combustion technologies for decarbonization, such as neat hydrogen (H2) combustion or dual-fuel strategies, which involve...

Worldwide emission standards are now required to cover engine operation under extreme ambient conditions, which affect the raw emissions and the efficiency of the exhaust aftertreatment systems. These regulations also target new combustion technologies for decarbonization, such as neat hydrogen (H2) combustion or dual-fuel strategies, which involve...

Due to the increasing use of unmanned air vehicles (UAVs) for civil and military purposes, accurate evaluation of this kind of aircraft is becoming a fundamental aim during their development. Particularly, propellers are often the most critical elements influencing a UAV’s performance and noise emission. Therefore, selecting the appropriate tools f...

Considering the concerns for emissions reduction in the maritime sector, the present paper evaluates, through modeling and simulation, oxy-fuel combustion in a two-stroke ship engine (2SE) and the best production system configuration to obtain the required oxygen (O2). An initial model of a ship engine is calibrated with the engine manufacturer’s d...

Considering the concerns for emissions reduction in the maritime sector, the present paper evaluates, through modeling and simulation, the oxy-fuel combustion in a two-stroke ship engine (2SE) and the best production system configuration to obtain the required oxygen (O2). An initial model of a ship engine is calibrated with the engine manufacturer...

In the context of the CO2 challenge, oxy-fuel combustion in internal combustion engines (OFC-ICE) arises as a promising technology for carbon capture and almost zero-NOx solutions. Although the literature shows some experimental and theoretical works on OFC-ICE, there is a lack of systematic studies dealing with dilution strategies or where non-syn...

Oxy-combustion is a promising concept to achieve an extremely clean combustion, independently of the fuel type, because, on the one hand, it is a NOx-free combustion and, on the other hand, the CO2 produced during combustion can be easily captured once the water vapor is removed from the exhaust gases stream, consequently allowing also carbon neutr...

Surge is a phenomenon that limits the operating range of the compressor at low engine speeds and high boost pressure in turbocharged powertrains. This article assesses two prototype turbochargers of variable geometry orifice (VGO) which compensate for the limitation of the boost pressure at low engine speeds. The VGO prototypes modify the inlet com...

The effect of ambient humidity on the performance and pollutant emissions of internal combustion engines is not considered in the literature despite type-approval criteria are moving closer to real driving conditions. This work analyses experimentally the effects of charge air humidity at high warm altitudes, where the use of exhaust gas recirculat...

Among other advances in spark ignited internal combustion engines’ field, the variable geometry turbine (VGT) is being analyzed to achieve further CO2 reduction objectives. This paper analyzes the potential implications of replacing nowadays standard, the waste-gate (WG) technology, with VGT. To do so, after developing a robust and validated model,...

In the context of the CO2 challenge, oxy-fuel combustion in internal combustion engines (OFC-ICE) arises as a promising technology for carbon capture and almost zero-NOx solutions. Although the literature shows some experimental and theoretical works on OFC-ICE, there is a lack of systematic studies dealing with dilution strategies or where non-syn...

A simulation-based assessment of different twin-turbocharging configurations allowing energy recovery from the exhaust gas recirculation flow is performed in a heavy-duty engine from the basis of a single-stage turbocharging architecture. This baseline configuration consists of a single stage turbocharged engine with a low-pressure exhaust gas reci...

The utilization of automotive engine components for the development of a reverse Brayton cycle is shown in this study. The well-known characteristics of turbochargers and electrical centrifugal compressors commonly used in the automotive industry is a starting point for developing an experimental cycle configuration of a reverse Brayton refrigerati...

The utilization of automotive engine components for the development of a reverse Brayton cycle is shown in this study. The well-known characteristics of turbochargers and electrical centrifugal compressors commonly used in the automotive industry is a starting point for developing an experimental cycle configuration of a reverse Brayton refrigerati...

Nowadays, internal combustion engine (ICE) concerns regarding fuel consumption motivate engine developers to research new technologies, including turbocharging, downsizing and hybridization. Variable geometry turbines (VGT) have been specifically developed for spark-ignited (SI) ICE in recent years. The transient response of such engines, critical...

The widespread trend of pursuing higher efficiencies in radial turbochargers led to the prompting of this work. A 3D-printed model of the static parts of a radial variable geometry turbine, the vaned nozzle, and the volute, was developed. This model was up-scaled from the actual reference turbine to place sensors and characterize the flow around th...

This study uses an optimization approach for developing a combustion system in a compression–ignition engine that is able to operate under oxy-fuel conditions, and produces mainly CO2 and H2O as exhaust gases. This is achieved because the combustion concept uses pure oxygen as an oxidizer, instead of air, avoiding the presence of nitrogen. The O2 f...

Wall-flow particulate filters are key elements to control particulate matter emissions. The stricter emission standards also for non-road mobility machinery makes this device essential to improve the air quality in the short to medium term. However, their high filtration efficiency brings with it an increase in backpressure. This effect becomes mor...

Oxy-fuel combustion is considered an attractive alternative to reduce pollutant emissions, which uses high-purity oxygen mixed instead of air for combustion processes. However, purchasing large amounts of high-purity oxygen may be unprofitable for certain industrial sectors, discouraging its implementation. Considering this, the potential of an oxy...

New propulsive architectures, with high interactions with the aerodynamic performance of the platform, are an attractive option for reducing the power consumption, increasing the resilience, reducing the noise and improving the handling of fixed-wing unmanned air vehicles. Distributed electric propulsion with boundary layer ingestion over the wing...

Oxy-fuel combustion concept is studied in a compression ignition engine (CIE) using Mixed Ionic-electronic Conducting Membranes (MIECs) to separate oxygen (O2) from air in order to achieve a clean combustion eliminating completely nitrogen oxides (NOx) emissions and enabling upcoming carbon dioxide (CO2) capture. Exhaust gas recirculation (EGR), co...

During the last decade, increasingly advanced turbocharger models have been developed for sizing, engine matching and one-dimensional modeling. This work goes further and, instead of using these models for turbocharged engines design or analysis, it implements them in the data acquisition and control system of a turbocharger gas stand. This way, in...

Oxy-fuel combustion concept is one of the most promising technologies not only to avoid NOx emissions, but also to reduce CO, unburned hydrocarbons and soot emissions in combustion-based powerplants. Moreover, the concept facilitates Carbon Capture and Storage (CCS), thus promoting CO2 integration in a circular economy strategy (i.e. e-fuels produc...

New regulations applied to the transportation sector are widening the operation range where the pollutant emissions are evaluated. Besides ambient temperature, the driving altitude is also considered to reduce the gap between regulated and real-life emissions. The altitude effect on the engine performance is usually overcome by acting on the turboc...

Distributed electric propulsion and boundary layer ingestion are two attractive technologies to reduce the power consumption of fixed wing aircraft. Through careful distribution of the propulsive system elements, higher aerodynamic and propulsive efficiency can be achieved, as well as a lower risk of total loss of aircraft due to foreign object dam...

The current paper presents a flow behaviour analysis of twin-entry radial turbines by means of experimental measurements and computational fluid dynamics (CFD) simulations. The experimental data were measured at partial, unequal and full admission conditions, and was used to globally validate CFD simulations. The experimental results hinted towards...

The current paper presents a computational fluid dynamics (CFD) flow behaviour and losses analysis of twin-entry radial turbines in terms of its Mass Flow Ratio ( MFR, the ratio between the flow passing through one of its intake ports and its total mass flow), focusing on the mixing phenomena in the unequal admission conditions cases. The CFD simul...

Turbocharging is one of the foremost ways of engine downsizing and represents the leading technology for reducing the engine CO 2 emission standards in gasoline engine application. Turbocharger turbine always faces high unsteadiness of flow coming from the reciprocating internal combustion engines. Besides, increasing levels of engine downsizing in...

Worldwide emission standards are extending their requirements to cover engine operation under extreme ambient conditions and fill the gap between the type-approval and real driving conditions. The new ambient boundaries affect the engine performance and raw emissions as well as the efficiency of the exhaust aftertreatment systems. This study evalua...

The potential of plug-in hybrid electric vehicles (PHEV) to reduce greenhouse gas emissions highly depends on the vehicle usage and electricity source. In addition, the high costs of the battery pack and electric components suppose a challenge to the vehicle manufacturers. However, the internal combustion engine complexity can be reduced due to its...

New generation of spark ignition (SI) engines are expected to represent most of the future market share in a context of powertrain hybridization. Nevertheless, the current technology has still critical challenges in front to meet incoming CO2 and pollutant emissions standards, so new technologies are emerging to improve engine efficiency. In parall...

As pollutants and fuel consumption requirements become more constraining, new internal combustion engines generation arise to fulfill future automobile market regulations. In these context spark ignition (SI) engines working under hybridized structures are expected to represent one of the most viable and feasible technical approaches. In parallel t...

Despite the importance of turbocharged engines with dual-volute turbines, their characteristic maps and fully predictive modelling using 1D gas dynamic codes are not well established yet. The complexity of unsteady flow and the unequal admission of these turbines, when operating with pulses of engine exhaust gas, makes them a challenging system. Th...

In this paper, a procedure for the design of a bubble reactor which allows the control of the humidity of a gas stream used as combustion air is presented. This reactor is designed to be used as a component of an altitude simulator test facility for the optimization, homologation and calibration of new hybrid engines. The design has been carried ou...

The earlier activation of the catalytic converters in internal combustion engines is becoming highly challenging due to the reduction in exhaust gas temperature caused by the application of CO2 reduction technologies. In this context, the use of pre-turbine catalysts arises as a potential way to increase the conversion efficiency of the exhaust aft...

Low pressure EGR (LP-EGR) has become recently one of the most investigated technique in the field of internal combustion engines. When LP-EGR is active, two streams with different psychrometric conditions are mixed at the compressor inlet, i.e. fresh air (considered as cold and dry) and EGR (humid and warm). The main objective of the present work i...

The variable geometry turbines (VGT) technology has been proved as beneficious for diesel engines turbocharging, becoming the standard for passenger car diesel engines when high boosting pressure and short transient response are pursued. It has not been until recent times that OEMs and turbocharger manufacturers are able to explore the advantages o...

Despite the importance of turbocharged engines with radial inflow dual-volute turbines, their characteristic maps and fully predictive modelling using 1D gas dynamic codes are not well established yet. The complexity of the unsteady flow and the unequal admission of these turbines, when operating with pulses of engine exhaust gas, makes them a chal...

Growing interest has arisen to adopt Variable Valve Timing (VVT) technology for automotive engines due to the need to fulfill the pollutant emission regulations. Several VVT strategies, such as the exhaust re-opening and the late exhaust closing, can be used to achieve an increment in the after-treatment upstream temperature by increasing the resid...

In this work it is proposed a methodology to standardize turbochargers testing based in measuring the maps twice: in close to adiabatic and in diathermal conditions. Along the paper it is discussed with special detail the impact of the procedure followed to achieve said quasi-adiabatic conditions in both the energy balance of the turbocharger and t...

This paper presents the evaluation of near-future advanced internal combustion engine technologies to reach near zero-emission in vehicles with in the Indian market. Extensive research was carried out to propose the rationalise the most promising, new ICE technologies which can be implemented in the vehicles to reduce CO2 emissions until the year 2...

The current investigation describes in detail a mass flow oriented model for extrapolation of reduced mass flow and adiabatic efficiency of double entry radial inflow turbines under any unequal and partial flow admission conditions. The model is based on a novel approach, which proposes assimilating double entry turbines to two variable geometry tu...

Late fuel post-injections are the most usual strategy to reach high exhaust temperature for the active regeneration of diesel particulate filters. However, it is important to optimise these strategies in order to mitigate their negative effect on the engine fuel consumption. This work aims at understanding the influence of the post-injection parame...

New regulation standards on engine pollutant emissions are widening the engine operating conditions subjected to type approval tests as a way to prevent from the gap between regulated and real-driving emissions. In this regard, ambient temperature and driving altitude are new boundaries to be considered. Although the basis of the impact of these va...

Internal combustion engines (ICE) are the main propulsion systems in road transport [...]

Turbocharged engines are the standard architecture for designing efficient spark ignition and compression ignition reciprocating internal combustion engines (ICE). Turbochargers characterization and modeling are basic tasks for the analysis and prediction of the whole engine system performance and this information is needed in quite early stages of...

Fuel lubricity prevents wear between metallic parts in relative motion inside the injection system of combustion engines. Among diesel fuels, paraffinic (gas-to-liquid or hydrotreated oils) and biodiesel (methyl esters) fuels are emerging since some of them are renewable and, in the case of paraffinic fuels, present excellent properties that can be...

In recent times, automotive diesel vehicles are suffering an attack and discrimination at different levels in front of a competitive technology (Electric Vehicles - EV) that is also receiving too much media attention and compliments without a clear scientific support for neither action. Here, an objective comparison of pros and cons has been presen...

New compact engine architectures such as pressure gain combustion require ad-hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the...

This article presents the experimental validation of a complete integrated one-dimensional twin-scroll turbine model able to be used in reciprocating internal combustion engine unsteady simulations. A passenger car with a twin-entry-type turbine has been tested under engine-like pulse conditions by means of a specifically built gas stand. To obtain...

The characterization of tip leakage flow plays an important role for one-dimesional loss modeling and design in radial turbine research. Tip leakage losses can be expressed as function of fluid momentum and mass flow passing through the tip gap. Friction-driven flow and contrariwise oriented pressure gradient-driven flow are highly coupled. However...

This paper aims to build a fuzzy system by means of genetic programming, which is used to extract the relevant function for each rule consequent through symbolic regression. The employed TSK fuzzy system is complemented with a variational Bayesian Gaussian mixture clustering method, which identifies the domain partition, simultaneously specifying t...

New compact engine architectures such as pressure gain combustion require ad-hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the...

Since heat transfer represent an important role in turbochargers’ energy, and due to new technologies being implemented, it becomes necessary to develop new heat transfer models for new turbocharger configurations. The aim of the present work is to show how a compressor heat transfer model has been obtained. The correlation has been formulated in d...

The automotive industry is driven its efforts to cleaner internal combustion engines. As a result, the engine has become conditioned by the exhaust aftertreatment systems. The regeneration of wall-flow particulate filters (PFs)evidences such an interaction. The PFs prevent the soot emission whereas, as a counterpart, the fuel consumption increases....

In an internal combustion engine, twin entry turbine operates under different unequal admission conditions by feeding the turbine with a dissimilar amount of flow in each entry for a majority of the time. Despite the impact on turbine performance, normal characteristic maps of these turbines are usually available only for full admission conditions....

Pulsating flow in automotive turbocharger turbines makes it necessary to know performance characteristics in difficult to measure off-design conditions. Physically based extrapolation models can be used to extrapolate towards unmeasured map regions. However, for model parameter fittings common maps have low numbers of measurement points per speedli...

Worldwide emission regulations are driven the efforts of the automotive industry to meet challenging targets concerning pollution reduction. Nowadays, advances in exhaust aftertreatment systems are primarily required to achieve regulation requirements within the whole engine operating range. Nevertheless, flow parameters, such as the exhaust gas te...

The impact of Euro 4 compression ignition engines over the air quality in Europe has been analyzed in this work by comparing them with Euro 6d emissions regulation. The Euro 6d diesel engine has been chosen as the preferred replacement according to its advantages in global warming potential (GWP) emissions, like methane hydrocarbons (MHC) and CO2,...

According to current worldwide trends for homologation vehicles in real driving conditions is forced to test the engines in altitude and in highly dynamic driving cycles in order to approach nowadays and next future emissions standard. Up to now, there were two main options to perform this type of tests: round-robin tests of the whole vehicle or hy...

Turbocharger performance maps provided by manufacturers are usually far from the assumption of reproducing the isentropic performance. The reason being, those maps are usually measured using a hot gas stand. The definition of the effective turbocharger efficiency maps include the mechanical losses and heat transfer that has occurred during the gas...

As one of the key systems of the marine power plant diesel engine, the turbocharger directly affects whether the diesel engine can continuously and stably provide the power required for the ship. Owing to a number of uncontrollable factors, such as harsh working conditions and complex structures, the turbocharger may have various failures, causing...

Turbocharged engines are the standard powertrain type of internal combustion engines for both spark ignition and compression ignition concepts. Turbochargers modeling traditionally rely in look up tables based on turbocharger manufacturer provided maps. These maps as the only secure source of information. They are used both for the matching between...

According to current worldwide trends for homologation vehicles in real driving conditions, is forced to test the engines in altitude and in highly dynamic driving cycles in order to approach nowadays and next future emissions standard. Up to now, there were two main options to perform this type of tests: round-robin tests of the whole vehicle or h...

In compliance with oncoming emission directives, turbocharging and increasing complexity in the turbocharger system demands a great effort from researchers on the development of effective procedures and tools to cope with the new technological exigencies. This article describes a methodology for studying oil-coking influence in turbocharger perform...

In the present work, a numerical methodology based on three-dimensional (3D) computational fluid dynamics (CFD) was developed to predict knock in a 2-Stroke engine operating with gasoline Partially Premixed Combustion (PPC) concept. Single-cycle Unsteady Reynolds-Averaged Navier Stokes (URANS) simulations using the renormalization group (RNG) k−ε m...

Tip leakage loss characterization and modeling plays an important role in small size radial turbine research. The momentum of the flow passing through the tip gap is highly related with the tip leakage losses. The ratio of fluid momentum driven by the pressure gradient between suction side and pressure side and the fluid momentum caused by the shro...

One dimensional modeling can give important insights into the needs of engine and turbocharger design. In this paper a holistic turbocharger model that calculates besides transient effects also heat transfer, friction losses, extrapolated adiabatic turbine and compressor maps has been validated over the range of an entire diesel engine map. Due to...

The heat transfer model can be used in a one-dimensional (1-D) engine simulation. When the engine speed is reduced to zero, the codes have been upgraded to calculate transient turbocharger thermal conditions. The turbocharger model has been used as an external plugin. Analysis of the temperature evolution at different parts of the turbocharger is d...

Due to the power consumption restriction of the turbocharger compressor, common turbine maps are rather narrow. To extrapolate them, reliable physical submodels are needed that are valid for broad ranges. Plenty of research has been done referring to tip leakage losses in axial and traditional radial turbomachinery. However, less effort has been pu...

Bulk flow condensation caused by the mixing of air streams at different temperatures and humidities is a thermodynamic process that requires strong assumptions to be calculated with low computational effort. The applicability of a model that correctly predicts this phenomenon has grown recently due in part to the deployment of the Long Route Exhaus...

Nowadays, the turbocharger has become one of the key components for automotive spark-ignition engine improvements (fed with both liquid and gaseous fuels), as a support for the boosting and downsizing concept to reduce fuel consumption and exhaust emission. In gasoline engines, the usage of the waste-gate valve typically regulates the maximum boost...

Internal Combustion Engines (ICEs) are the main propulsion systems for ground transport, both in on-road and off-road applications [...]

In the current work a computational study to evaluate the effect of the DPF downsizing on filtration efficiency is performed. The DPF is conventionally placed downstream of the turbine. However, its placement upstream of the turbine is growing in interest because of the benefits in specific fuel consumption, passive regeneration and aptitude to dow...

Current key technologies to meet the future emission standards for internal combustion engines are downsizing, downspeeding, and advanced charging concepts. While turbocharging already combines high specific rated engine power with low fuel consumption, there is still potential for optimization to achieve prospective demands for fuel efficiency wit...

State of the art car engines are fed by compressed air, coming from a turbocharger compressor, to increase the power to weight ratio and to allow downsizing the combustion engine. The used compressor is driven by a radial turbine taking advantage of the hot and pressurized exhaust gases of the engine. Thus, the turbine acts under highly unsteady co...

During automotive urban driving conditions and future homologation cycles, automotive radial turbines experience transient conditions, whereby the same operate at very high blade speed ratios and, thus, at very low power outputs. Under those conditions, the turbine power output might not be enough to feed the mechanical power needs of the compresso...

Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted particle sizes, the porous sub...

Forthcoming directives from European Commission will force homologation in altitude to approach standards to actual driving conditions in order to reduce the gap between regulated and real-life emissions. This work presents the use of a dedicated atmosphere simulator to analyse the impact of altitude on performance and emissions of a turbocharged d...

The implementation of tight vehicle emission standards has forced manufactures to use aftertreatment systems extensively. In addition to pollutant emissions abatement, these devices have a noticeable impact on the wave pattern. This fact affects the muffler design criteria. All monolithic aftertreatment devices produces a damping effect because of...

Turbine performance at extreme off-design conditions is growing in importance for properly computing turbocharged reciprocating internal combustion engines behaviour during urban driving conditions at current and future homologation cycles. In these cases, the turbine operates at very low flow rates and power outputs and at very high blade to jet s...

A filtration model for wall-flow particulate filters based on the theory of packed beds of spherical particles is presented to diagnose the combined response of filtration efficiency and pressure drop from a reliable computation of the flow field and the porous media properties. The model takes as main assumption the experimentally well-known low s...

A novel experimental procedure is presented which allows simultaneous identification of heat and work transfer parameters for turbocharger compressor models. The method introduces a thermally transient condition and uses temperature measurements to extract the adiabatic efficiency and internal convective heat transfer coefficient simultaneously, th...