F. J. Arnau

• Doctor of Engineering
• Lecturer at Polytechnic University of Valencia

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...

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...

Literature suggests that driving style and conditions play a major role in vehicle energy consumption. In this sense, this work focuses on vehicle speed planning using information from the environment, through vehicle-to-infrastructure (V2I), and from nearby vehicles, with vehicle-to vehicle (V2V) information to reduce fuel consumption over a signa...

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...

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...

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...

In this work, the Global Energy Balance (GEB) of a 1.6 L compression ignition engine is analyzed during WLTC using a combination of experimental measurements and simulations, by means of a Virtual Engine. The energy split considers all the relevant energy terms at two starting temperatures (20°C and 7°C) and two altitudes (0 and 1000 m). It is show...

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...

As well as new advances in the after-treatment systems are required to achieve the new pollutant emission requirements, new designs of the exhaust line can be considered in order to increase the engine efficiency and the after-treatment effectiveness. In the present work, a one-dimensional gas dynamic model has been used to carry out a simulation s...

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...

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...

Due to the need to achieve a fast warm-up of the after-treatment system in order to fulfill the pollutant emission regulations, a growing interest has arisen to adopt variable valve timing technology for automotive engines. Several variable valve timing strategies can be used to achieve an increment in the after-treatment upstream temperature by in...

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...

In recent years, the interests on transient operation and real driving emissions have increased because of the global concern about environmental pollution that has led to new emissions regulation and new standard testing cycles. In this framework, it is mandatory to focus the engines research on the transient operation, where a Virtual Engine has...

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...

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...

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...

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...

This article presents the experimental validation of a quasi-two-dimensional radial turbine model able to be used in turbocharged reciprocating internal combustion engine simulations. A passenger car variable-geometry turbine has been tested under steady and pulsating flow conditions, instrumented with multiple pressure probes, temperature sensors...

The objective of the study is to determine the behavior of the low pressure exhaust gas recirculation (LP EGR) transport phenomena in the intake manifold during engine transient operation. The investigation also analyzes the influence of the propagation of the pressure waves in the intake manifold on the engine performance. In this sense, there is...

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...

A suitable tool for the design of intake and exhaust systems of internal combustion engines is provided by time-domain non-linear finite volume models. These models, however, are affected by overshoots at discontinuities and numerical dispersion unless some flux limiter is used. In this paper, the effect of the most relevant of such flux limiters o...

The increasing limits of standards on aerosol and gaseous emissions from internal combustion engines have led to the progressive inclusion of different exhaust aftertreatment systems (EATS) as a part of the powertrain. Regulated emissions are generally abated making use of devices based on monolithic structures with different chemical functions. As...

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...

The exhaust energy can represent up to 40% of the fuel chemical energy in turbocharged internal combustion engines. In order to calculate properly the available energy of the exhaust gases, a critical parameter is the temperature downstream the turbine. The prediction of this temperature will also benefit the two-stage turbochargers and after-treat...

This paper presents an experimental analysis on the effect of thermal insulation of engine internal walls on the performance and emissions of a heavy-duty diesel engine. Some parts of the engine, like pistons, cylinder head and exhaust manifold were thermally insulated from gas contact side in order to reduce heat losses through the walls. Each com...

Modelling has proven to be an important tool in the design of manifolds and silencers for internal combustion engines. Although simple 1D models are generally sufficiently precise in the case of manifold models, they would usually fail to predict the high frequency behaviour of modern compact manifold designs and, of course, of a complex-shaped sil...

A lumped capacity heat transfer model has been developed and compared to measurements from a turbocharger operating on a 2.2L Diesel engine under steady and transient conditions ranging from 1000-3000rpm and 2-17bar BMEP. The model parameters have been estimated based on similar devices and this study quantifies the errors associated with this appr...

The behavior of small turbochargers is deeply affected by heat transfer phenomena. The external heat losses of these machines are studied and a simplified model that takes into account both radiation and convective mechanisms has been proposed. The model has been adjusted in a turbocharger test bench for two different turbochargers, later on it has...

These days great effort is devoted to the study of turbocharging in order to minimize fuel consumption and pollutant emissions of turbocharged reciprocating engines. Among all the processes taking place in small automotive turbochargers, the heat transfer phenomenon is one of the least analysed in a systematic way. However turbocharger heat transfe...

Nowadays turbocharging the internal combustion engine has become an essential tool in the automotive industry to meet downsizing technique requirements. In that context turbocharger unsteadiness is huge since both turbine and compressor work under high pulsating flow conditions, being turbocharger behavior prediction more difficult but still key fo...

In this paper, a student evaluation methodology which applies the concept of continuous assessment proposed by Bologna is presented for new degrees in higher education. An important part of the student's final grade is based on the performance of several individual works throughout the semester. The paper shows the correction system used which is b...

In the present work a comprehensive study of turbocharger heat transfer phenomena is discussed, showing their relevance compared to gas enthalpy variations through the turbomachinery. The study provides an experimental methodology to consider the different heat fluxes in the turbocharger and modeling them by means of a lumped capacitance heat trans...

Gas dynamic codes are computational tools applied to the analysis of air management in internal combustion engines. The governing equations in one-dimensional elements are approached assuming compressible unsteady non-homentropic flow and are commonly solved applying finite difference numerical methods. These techniques can also be applied to the c...

The soot loading process in wall-flow DPFs (diesel particulate filters) affects the substrate structure depending on the filtration regime and produces the increase of pressure drop. Deep bed filtration regime produces the decrease of the porous wall permeability because of the soot particulates deposition inside it. Additionally, a layer of soot p...

Nowadays turbocharging the internal combustion engine has become a key point in both the reduction of pollutant emissions and the improvement of engine performance. The matching between turbocharger and engine is difficult; some of the reasons are the highly unsteady flow and the variety of diabatic and off-design conditions the turbocharger works...

In the present paper, a methodology to calculate the heat fluxes inside a turbocharger from diesel passenger car is presented. The heat transfer phenomenon is solved by using a one dimensional lumped model that takes into account both the heat fluxes between the different turbocharger elements, as well as the heat fluxes between the working fluids...

Nowadays turbochargers play an important role in improving internal combustion engines (ICE) performance. Usually, engine manufacturers use computer codes to predict the behavior of both engine and turbocharger, the later by means of measured look-up maps. Using look-up maps different problems arise, being one of the most important the difference i...

This paper describes in detail a novel formulation of the method of characteristics for its application to solve one-dimensional compressible unsteady non-homentropic flow advected along porous wall channels. In particular, the method is implemented into a wall-flow monolith Diesel particulate filter model whose purpose is the pressure drop predict...

In the present paper an unsteady approach to determine the performance of a small radial inflow turbine working under cold pulsating flow is presented. It has been concluded that a reasonably good characterization of turbine behavior working with pulsating flow can be obtained using in a quasi-steady way models of the turbine isentropic efficiency...

An acoustic one-dimensional compressor model has been developed. This model is based on compressor map information and it is able to predict how the pressure waves are transmitted and reflected by the compressor. This is later on necessary to predict radiated noise at the intake orifice. The fluid-dynamic behavior of the compressor has been reprodu...

Solution of governing equations for one-dimensional compressible unsteady flow has been performed traditionally using a homogenously distributed spatial mesh. In the resulting node structure, the internal nodes are solved by applying a shock capturing finite difference numerical method whereas the solution of the end nodes, which define the boundar...

Surge occurrence in automotive engine turbochargers is known to be dependent on the installation conditions. It is proven that the flow pattern produced by the inlet ducting at the compressor inducer modifies surge margin. But also the engine intake line acoustics, both compressor upstream and downstream, affects turbocharger surge. In the paper th...

In this article a new experimental technique is presented to measure the turbocharger surge limit in a regular engine test bench. It is known that the surge margin on engine tests may be very different from that obtained in a steady-flow gas-stand. In particular, surge is very dependent on the flow pattern produced by the compressor inlet duct and...

The use of particulate filters (DPF) in Diesel engines has become in recent years the standard technology for the control of soot aerosol emissions. Once emissions reduction through the management of filtration and regeneration aspects has reached its maturity, the effect of the system location on engine performance and acoustics are key topics to...

Nowadays, turbocharged engines are widely used in cars and trucks. Gas-dynamic codes are an important tool in design and optimization of these types of engines. These codes solve the one-dimensional governing equations in ducts for compressible, unsteady and non-homoentropic flow. The ducts are generally solved using finite difference schemes, the...

A calculation methodology to solve the one-dimensional governing equations system is presented. This calculation methodology is based on the Independent Time Discretisation (ITD) of the ducts composing the system. The purpose is the improvement of the trade-off between the accuracy and the computational cost that the current 1D gas dynamic models c...

Modeling has become an essential technique in design and optimization processes of internal combustion engines. As a consequence, the development of accurate modeling tools is, in this moment, an important research topic. In this paper, a gasdynamics modeling tool is presented. The model is able to reproduce the global behavior of complete engines....

A detailed analysis of mass non-conservation in the proximity of thermal contact discontinuities, when solving 1-D gas dynamic flow equations with finite difference numerical methods, is carried out in this paper. A wide spectrum of finite difference numerical methods has been applied to solve such conditions. Thermal contact discontinuities are ve...

Compliance with oncoming emission directives demands a great effort from researchers on the development of effective procedures and tools to cope with the technological exigencies. The first aim of this work focuses on the development of methodologies and tools related to the combustion characterisation in turbocharged diesel engines with EGR syste...

The paper presents a model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with zero- and one-dimensional gas dynamic codes.The model is based from its very conception on the measured characteristics of the turbine. Nevertheless, it is cap...

This article presents a two-stage turbocharged heavy-duty diesel (HDD) engine designed to fulfil the US2007 anti-pollution directive. This directive imposes very restrictive limits on the NOx and particle emissions of HDD engines. In this work, the possibility of combining particle traps in the exhaust line to reduce soot emissions with very high E...

This paper presents an improvement in the conservation element–solution element (CE–SE) scheme for calculating one-dimensional flow through tapered ducts. This new CE–SE scheme has been validated against experiments in tapered ducts with non-steady flow using pressure impulses. This validation analyses scheme's ability to reproduce instantaneous pr...

Modeling has become an essential technique in design and optimization processes of internal combustion engines. As a consequence, the development of accurate modeling tools is, in this moment, an important research topic. In this paper, a gas-dynamics modeling tool is presented. The model is able to reproduce the global behavior of complete engines...

A comparative study of the performance of different schemes used to solve one-dimensional gas flow equations when applied to the computation of the frequency response of exhaust mufflers is presented. Simple but representative systems with well-known acoustic behaviour were considered. Apart from the classical Lax–Wendroff and MacCormack schemes, t...

Although in combustion diagnosis models the uncertainty in the trapped mass is not critical, different authors have reported non negligible effects on the rate of heat release. Usually, an emptying-and-filling model is used to estimate the residual mass, whence the trapped mass is obtained. Generally, the instantaneous pressure at the intake and ex...

The paper presents a fluid dynamic model of fixed and variable geometry turbines. The aim of this model is to provide an efficient boundary condition to model turbocharged internal combustion engines with one-dimensional gas dynamic codes. The model is based on the measured characteristics of the turbine from its very conception. Nevertheless, it i...

In this paper, an analytica-numerical approximation of the one-dimensional gas flow Euler equations in conical ducts, is obtained by an iterative method based on the Cauchy-Kovalev-skaya theorem. This method has been applied in [1] for the constant ducts case. In this paper, the algorithm and the theoretical results are adapted and some examples fo...

In this work, we present a semi-implicit method based on the CE-SE numerical scheme (space time conservation-element and solution-element). In particular, we apply this method to a hyperbolic system that models the dynamics of an unsteady flow along a tapered duct with friction and heat transfer. Conditions on the scheme in order to get real numeri...

A comparative study of different schemes to solve one-dimensional (1-D) gas flow equations in tapered pipes was conducted in this paper. The total variation diminishing schemes, flux corrected transport techniques or the innovative space–time conservation element and solution element method have been contrasted with experimental data. The experimen...