Octavio Armas

• PhD
• Professor (Full) at University of Castilla-La Mancha

This paper deals with minimisation of fuel consumption under real driving conditions using a vehicle speed advisor. The aim is to explore the potential of speed profile optimisation in real driving conditions while assessing the suitability of an application which recommends the driver the optimal vehicle speed sequence that minimises the fuel cons...

This paper presents a fuel injection rate predictive model based on zero-dimensional correlations from experimental results. This model estimates the fuel injection rate behavior with varying parameters such as fuel injection pressure-injector energizing, the injection nozzle geometrical characteristics, and fuel viscosity. The model approach was c...

Sustainable means of transport require the innovation or development of propulsive systems more respectful of the environment. Despite current criticism, modern compression-ignition engines are efficient alternatives also in light aviation and surveillance drones (such as small helicopters), as means of air transport. Currently, the improvement of...

A better understanding of why and how pollutant emissions from compression ignition engines are produced is one of the strategies to reduce them, and to achieve this it is important to understand what happens in the fuel injection inside the combustion chamber and in the combustion process. Experimentally, it is difficult to analyse the fuel spray...

This paper proposes a sensor system for an internal combustion engine based on a new vision-based algorithm supported by the Schlieren sensorization technique, which allows to acquire the macroscopic parameters of the fuel spray injected in a reciprocating internal combustion engine under unmanned aerial vehicle-like conditions. The sensor system p...

Harvesting residual thermal energy from exhaust gases with thermoelectric generators is one of the paths that are currently being explored to achieve more sustainable and environmentally friendly means of transport. In some cases, thermoelectric generators are installed in a by-pass configuration to regulate the mass flow entering the thermoelectri...

This paper investigates the design of a thermoelectric generator for exhaust gases from internal combustion engines. Experimentally validated CFD methodology was employed. Different issues are studied, such as the influence of the replacement of the exhaust pipe for the TEG, the recirculation produced, and the influence of fins. The results show th...

Renewable liquid fuels are a promising alternative solution to decarbonize the transport sector. However, the analysis of emissions of local contaminants coming from the use of such fuels relevant to preserve air quality and related human health issues. Even though the advantages in reducing climate change using renewable fuels appear to be clear,...

The effort to implement more environmental-friendly fuels has been enhanced not only by the desire to reduce the greenhouse effects but also for public health issues. This paper studies the effects on pollutant emissions from a light-duty Euro 6 vehicle with four types of fuel: diesel (fossil origin, used as reference), biodiesel (renewable origin)...

Air pollution and associated particulate matter (PM) affect environmental and human health worldwide. The intense vehicle usage and the high population density in urban areas are the main causes of this public health impact. Epidemiological studies have provided evidence on the effect of air pollution on airborne SARS-CoV-2 transmission and COVID-1...

This work describes an experimental installation for the investigation of the combustion and injection processes. This installation is based on a two-stroke direct injection diesel engine with a total displacement of 3 L and a cylinder head equipped with three quartz windows. The windows are optical accesses that allow studying the process of injec...

In the present study engine/vehicle responses from a standardized transient test cycle are estimated using 13 stationary operating regimes following a previously developed methodology. The main advantage of the methodology tested is that allows obtaining an estimation of transient parameters in a stationary test bench, which requirements are much l...

Significant reduction in fuel consumption and NOx emissions can be achieved just by changing the driving along the road. In this paper, dynamic programming is employed to find two different driving profiles optimized for fuel consumption and NOx creation minimization in a diesel vehicle. Results, show that the fuel reduction driving cycle leads to...

This study presents a new approach to minimize the amount of NOx emitted by diesel engines of Heavy-Duty Vehicles during low engine regimes and low gases temperature conditions. We propose the addition of an electric Exhaust Gas Heater (EGH) to make the SCR system inject the urea solution at low engine regimes. The second part of this study focuses...

Energy savings motivated by economic and environmental reasons have brought attention to waste heat recovery technologies. Thermoelectric generators, previously employed as electric power generators in harsh conditions such as the found in space missions and remote ground locations, have arisen as an option to recover waste energy. Thermoelectric g...

Thermoelectric generators harvesting energy from exhaust gases usually present a temperature mismatch between modules, due to the gradual cooling of the gases along the flow direction. The way modules that produce unequal voltages are connected has a deep impact on the overall power output. A further step in the prediction of thermoelectric product...

Public transport bus service is extended in big cities and cleaner bus fleets are encouraged to reduce greenhouse and air pollutant emissions in high populated areas. In this work, real driving emissions produced by two Euro VI-C buses, one fueled by diesel fuel and one fueled by compressed natural gas, were measured. Both vehicles with different e...

Current results do not provide conclusive evidence on the effect of BCG vaccination on COVID‐19 alone or in combination with other factors. To address this limitation, in this study we used a citizen science initiative on the COVID‐19 pandemic to collect data worldwide during October 2‐30, 2020 (1,233 individuals) in a structured way for analyzing...

This work presents a computational study about the effect of different fossil fuels (Diesel and GTL) and renewable (Farnesane and Biodiesel) on the characteristics of the nozzle fuel internal flow (speed flow, cavitation, mass flow rate and discharge coefficient). This investigation was focused on the pass of fuel from the volume around the tip of...

Current results do not provide conclusive evidence on the effect of BCG vaccination on COVID-19 alone or in combination with other factors. To address this limitation, in this study we used a citizen science initiative on the COVID-19 pandemic to collect data worldwide during October 2-30, 2020 (1,233 individuals) in a structured way for analyzing...

This book chapter describes, the experiences of different experimental works related to the study of the effect of bioethanol-diesel fuel blends directly used on a study about the integrity of some parts of a diesel injection system, and on performance and regulated emissions of engines and/or vehicles under different transient conditions. The expe...

Due to environmental problems, research on fuel economy and pollutant emissions in internal combustion engines has drawn the attention of automobile manufacturers and researchers. The diesel engine is one of the most efficient alternatives and one of the main areas of the study in these engines is spray mixing, recognized as a critical factor in co...

The inclusion of the measurement of pollutant emissions under real driving conditions for the vehicle certification, together with the restrictive limits in environmental regulations, has motivated an improvement of active and passive pollution control technologies in order to reduce pollution under both urban and extra-urban conditions. In this wo...

The best possible thermal and mechanical energy management is necessary to have more efficient and less pollutant means of transport. This can be accomplished recovering part of the energy lost through exhaust systems in internal combustion engines. One of the devices able to recover this waste thermal energy is a thermoelectric generator. Plenty o...

Parameter identification techniques are applied to find suitable values of unknown key input factors into a mathematical model. Usually, these factors are determined through optimization algorithms. In this case, the establishment of consistent initial values, and their corresponding searching ranges (which are unknown), is quite important to provi...

The use of particle filters, both in diesel and gasoline engines, is increasingly widespread, it being the most used way to reduce the emission of this pollutant into the atmosphere. Predictive knowledge of particle size distributions, both under different operating modes or with fuels of different origin, is increasingly important and necessary. T...

Approximately a third part of the energy intake of a light-duty diesel engine is wasted through the exhaust system. Rising awareness of environmental issues together with fuel economy has encouraged research upon energy recovery in internal combustion engines. This article focuses on the application of thermoelectric generators in light-duty diesel...

Two sugarcane biofuels and mineral diesel fuel are tested under full load conditions, under the same values of performance and under the European Transient Cycle on an engine test bench, without any modifications to the ECU. The target is to compare engine performance and emissions. At full load, engine performance varies due to the variation in LH...

This work focuses on the potential for waste energy recovery from exhaust gases in a diesel light-duty vehicle tested under real driving conditions, fueled with animal fat biodiesel, Gas To Liquid (GTL) and diesel fuels. The vehicle was tested following random velocity profiles under urban driving conditions, while under extra-urban conditions, the...

During the intake period in internal combustion engines, it has been noted that the cylinder volume is not completely occupied due to the variation of specific volume and the pressure drop along the supply system. Consequently, the volumetric efficiency in the cylinder is lowered, negatively affecting the engine power output. In this paper, numeric...

Study of a thermoelectric generator in two different types of engines. • Effects of bypassing part of the flow from the thermoelectric generator were studied. • The thermoelectric generator was compared to a turbine-based energy recovery system. • Implementation of a thermoelectric generator in automotive engines was evaluated. A R T I C L E I N F...

Efficiency of internal combustion engines can be improved indirectly using a waste heat recovery system. Thermoelectric generators (TEGs) are employed to convert thermal energy from exhaust gases to electrical energy. Research in this area has been focused on gasoline and heavy-duty engines. The novel purpose of this work is to study the potential...

This paper proposes a methodology for simulating engine/vehicle responses of a non-stationary test cycle by means of few steady-state operating modes, which can greatly reduce testing costs and time. The novelty of the proposed methodology is the application of a mapping from the engine working region to a square domain, which allows testing any de...

The injection rate curve is an important input parameter in the thermodynamic diagnosis and in the predictive models, and it can also be used to simulate fuel sprays under different operating conditions. In this work, a zero-dimensional fuel injection rate model is proposed from experimental data obtained from a common-rail injection system with tw...

The behaviors of a biofuel and a fossil fuel were evaluated by different techniques, namely thermal analysis (Thermogravimetry-TG and Differential Thermal Analysis-DTA) and engine performance tests. From TG and DTA curves, two decomposition phases were identified for diesel fuel with ignition temperature (IT) at 250 °C and three phases for biodiese...

The interest of NOx engine emissions from diesel engines has been increasing during the last years. Particularly, the comparison of the real driving NOx emissions with the results obtained during homologation procedures has received a great attention. The main goal of this paper is to provide a statistical methodology, able to compare two different...

El uso de los métodos numéricos para la solución de problemas de hidrodinámica y aerodinámica ha cobrado interés en años recientes; ha dejado de ser una herramienta en el área de la investigación y la academia para volverse una parte fundamental para el desarrollo de aplicaciones tecnológicas que demandan el conocimiento detallado de los procesos d...

In light-duty internal combustion engines, approximately only the third part of the fuel energy consumed is converted to effective mechanical work. Since waste energy through the exhaust system represents also around a third part of this energy input, it strikes as a remarkable source for energy recovery to reduce fuel consumption and pollutant emi...

From the point of view of energy efficiency of the test bench, a proper design of cooling systems of climatic chambers is also becoming increasingly important for reducing both the investments on the installation and the test costs. This work focuses on the proposal and application of a simple but robust methodology for calculating the thermal load...

This work presents a methodology to adjust the electronic control system of a reciprocating internal combustion engine test bench and the effect of the control parameters on emissions produced by the engine under two extreme situations: unadjusted and adjusted, both under transient operation. The aim is to provide a tuning guide to those in charge...

Low ambient temperatures during start process have a notable influence on the combustion process. A methodology to study parameters as indicated mean pressure and rate of heat release, obtained using on-line thermodynamic diagnosis under cold start, was developed in this work. For this study, the correction of the pressure level from the first cycl...

Thermogravimetric analysis (TGA), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy (RS) and High-resolution transmission electron microscopy (HRTEM) techniques were used to characterize soot gathered from a conventional automotive diesel engine fueled by ultra-low sulfur diesel, gas-to-liquid (GTL), biodie...

The impact of three fuels (a diesel fuel without biodiesel and two Fischer Tropsch low temperature gas to liquid paraffinic fuels from natural gas) on the indicated engine performance and the timing of the combustion process under the engine start has been studied by means of cycle to cycle thermodynamic diagnosis during the first 5–6 cycles along...

Around a third of the energy input in an automotive engine is wasted through the exhaust system. Since numerous technologies to harvest energy from exhaust gases are accessible, it is of great interest to find time- and cost-efficient methods to evaluate available thermal energy under different engine conditions. Computational fluid dynamics (CFD)...

The altitude effect on performance, emissions and thermodynamic diagnosis under real world driving conditions has been evaluated using two alternative fuels and a diesel fuel. Three places, at different altitudes, were selected for the tests, from 0 to 2500 m above the sea level. Besides, two type of circuits (Urban and Extra-urban) have been selec...

In this study a comparative experimental work about the sooting tendency of different fuel blends has been carried out. Three groups of alternative fuels, blended with diesel fuel, were tested: (1) an animal fat biodiesel; (2) two paraffinic fuels: a hydro-treated vegetable oil (HVO) and a gas-to-liquid (GTL) from natural gas and (3) two alcohols:...

In this paper, a new methodology to adjust the control system of a test bench, formed by an Internal Combustion Engine (ICE) and a dynamometer brake has been developed. The aim of this proposed method is to provide a guide to help researchers that work with this type of platform but they aren’t experts in control engineering. This methodology prese...

Three fatty acid methyl ester fuels (from rapeseed, sunflower and soybean vegetable oils) and their blends (30% v/v) with diesel fuel were tested under New European Driving Cycle (NEDC) on an engine test bench. This allowed comparing engine pollutant emissions trends under transient operation. FAME fuels and their blends produced higher specifics e...

This work addresses the potential for waste energy recovery from exhaust gases in a diesel passenger car mounted in a chassis dynamometer. The New European Driving Cycle was followed, while recording relevant operating variables. Tests were performed under three temperature conditions, and exergy analysis was included to find the potential of exhau...

In terms of energy efficiency and exhaust emissions control, an appropriate design of cooling systems of climatic chambers destined to vehicle certification and/or perform scientific research is becoming increasingly important. European vehicle emissions certification (New European Driving Cycle, NEDC) stablishes the position of the wind-simulation...

The prediction of pollutant emissions and fuel consumption under real operating conditions of any motor vehicle requires the use 8 of complex mathematical models and experimental tools. In the present research, biharmonic maps (BM) were used to predict NOx (nitrogen 9 oxides) emissions and relative fuel–air ratio (Fr) of a passenger city bus. For t...

The increasing interest for using alternative fuels, more environmentally friendly compared to fossil fuels, has motivated this research work. The knowlegde of the combustion process with these fuels provides an important tool for increasing performance and for reducing pollutant emissions. This knowledge allows a better calibration of engine param...

Engine start is a critical process of diesel engine operation with respect to the stability of the combustion process, specific fuel consumption, and pollutant emissions among others. Additionally, the starting is a transient process included into the New European Driving Cycle (NEDC) established for the certification of light-duty vehicles. In thi...

Tire pyrolysis liquid (TPL)/diesel fuel blend (50/50 vol.%) was fed in a residential boiler unit of 29.1 kW of nominal power, assessing its potential use as alternative heating fuel oil (HFO) for domestic heating. Process performance was compared to that observed for conventional diesel fuel. Both, 50/50 blend and reference diesel fuel were tested...

The major regulated pollutants emitted by a diesel urban bus are nitrogen oxides (NOx) and particulate matter (PM). These emissions depend on the engine and its strategies (injection, exhaust-gas recirculation, after-treatment devices, etc.), altitude, weather con- ditions, route, and driver. This work studies the effect of two fuels, one of them o...

This paper presents the performance, combustion, and emissions characteristics of a light-duty vehicle equipped with a Euro 4 diesel engine, operating with animal fat biodiesel, gas to liquid (GTL), hydrotreated vegetable oil (HVO), and a commercial diesel fuel (with 5.8% of biodiesel) as reference. Tests were carried out in on a chassis dynamomete...

This paper presents the chemical composition, oxidation reactivity and nanostructural characteristics of the particulate matter (PM) produced by a diesel engine operating with crude palm oil, crude jatropha oil and commercial diesel fuel. The engine was operated under a stationary mode of 25 N m and 1800 min−1. Non-diluted PM was collected through...

A tire pyrolysis liquid (TPL) has been blended in 5 vol.% with commercial diesel fuel (5TPL) and tested in a light-duty diesel Euro 4 engine (with all technologies for meeting Euro 5) under transient operation by means of Road Load Simulation (RLS) and simulating the New European Driving Cycle (NEDC). Commercial diesel fuel has also been tested for...

Starting is a special transient process of engine operation. Due to its relevance on the overall emissions, it was included in the New European Driving Cycle (NEDC) for certification of light duty vehicles. In this work, a turbocharged, direct injection (DI), diesel engine equipped with common rail injection system and exhaust gas recirculation (EG...

Regulated gaseous emissions and particle concentrations, with commercial diesel fuel, animal fat biodiesel and gas to liquid (GTL) fuel from a Low Temperature Fischer-Tropsch process, have been studied. Tests were carried out in a light duty vehicle (Nissan Qashqai, 110 kW, Euro 4) equipped with variable geometry turbocharger (VGT), cooled exhaust...

The present work focuses on the impacts of engine operating conditions and combustion phasing on diesel soot properties. The study was carried out in a 2.5 L direct injection common-rail turbodiesel engine using an ultra low sulfur diesel fuel (BP15). The study has two objectives. The first objective is to investigate the reactivity difference of t...

The work focuses on the impact of fuel on soot reactivity and nanostructure. A 2.5 L, 4-cylinder, turbocharged, common rail, direct injection light-duty diesel engine was used in generating soot samples. Three test fuels were used: an ultra low sulfur diesel fuel (BP15), a pure soybean methyl-ester (B100), and a synthetic Fischer-Tropsch fuel (FT)...

Urban buses with diesel engines produce NOx and particulate matter emissions thus affecting local city pollution. During stops, due to traffic lights, programmed stops, etc., pollutants are emitted close to people, being damaging to their health. This paper studies the effects on particle size distributions caused by the use of oxygenated fuels dur...

The study of the diesel combustion process is a current topic by the need of thermal efficiency improving and the reduction of pollutant emissions. This circumstance has forced researchers and manufacturers to optimize this process not only in steady state operating conditions but also during transient operation. A zero dimensional thermodynamic di...

This work describes an experimental setup for obtaining pressure variation and rate of injection profiles per engine stroke. This study focuses on the following experimental parameters: flow meter's backpressure, injection pressure, and duration of the process. An IAV EVI-2-type flow meter is used to measure the rate of injection. The work has been...

In this work, an experimental method for the estimation of the volatile organic emission (VOE) of diesel particles is proposed. This method involves a minitunnel (MT) diluted exhaust sample, which is sent through a thermal denuder (TD) to a scanning mobility particle sizer (SMPS). VOE was estimated by the difference in particle mass concentration w...

The starting is a special transient process of engine operation, which is included in the New European Driving Cycle of light duty vehicles (NEDC). This is a critical operation mode of diesel engines with respect to pollutant emissions and to stability of the combustion process. In this work, a turbocharged, direct injection (DI), diesel engine equ...

In this work a methodology is proposed for measurement and analysis of gaseous emissions and particle size distributions emitted by a diesel city bus during its typical operation under urban driving conditions. As test circuit, a passenger transportation line at a Spanish city was used. Different ways for data processing and representation were stu...

This research paper presents a comparative experimental study for determining the functionality of a common-rail injection system used in light-duty diesel vehicles. Two Bosch fuel-injection systems were chosen to be tested using a low sulphur diesel fuel and an ethanol–diesel blend (7.7% v/v). Both systems were composed of a high-pressure injectio...

The study of particulate matter (PM) and nitrogen oxides emissions of diesel engines is nowadays a necessary step towards pollutant emission reduction. For a complete evaluation of PM emissions and its size characterization, one of the most challenging goals is to adapt the available techniques and the data acquisition procedures to the measurement...

The present work is focused on a comparative experimental study for determining the effect of fuel properties on the constructive characteristics of some pieces of a current common rail injection system used in light duty diesel vehicles. Two Bosch fuel injection systems, each composed by a high pressure injection pump Bosch (270 CDI), the common r...

Oxygenated fuels in diesel engines represent an alternative to conventional petroleum-derived fuel to achieve current European emissions standards (EURO 5), especially with regard to particulate matter (PM), where the reduction of the limit in mass concentration is 80% compared to that for the previous EURO 4 standard. Among these oxygenated fuels,...

A gas-to-liquid (GTL) fuel derived from Low Temperature Fischer–Tropsch process has been tested in an automotive diesel engine fulfilling Euro 4 emissions regulations. Both regulated and non-regulated emissions have been compared with those of a commercial diesel fuel, a commercial biodiesel fuel and a GTL–biodiesel fuel (30% and 70% v/v, respectiv...

The use of oxygenated and renewable fuels has potential to reduce regulated pollutant emissions from diesel engines, as well as to reduce the greenhouse impact of transportation. Aside from the particulate and NOx emissions, the size of the particles composing the particulate matter emitted by diesel engines is considered essential due to its effec...

Biodiesel fuels (methyl or ethyl esters derived from vegetables oils and animal fats) are currently being used as a means to diminish the crude oil dependency and to limit the greenhouse gas emissions of the transportation sector. However, their physical properties are different from traditional fossil fuels, this making uncertain their effect on n...

The present work focuses on an experimental comparison of diesel emissions produced by three fuels: an ultra low sulfur diesel fuel (BP15), a pure soybean methyl-ester biodiesel fuel (B100), and a synthetic Fischer–Tropsch fuel (FT), practically free of sulfur and aromatic compounds, and produced in a gas-to-liquid process. The study was carried ou...

Few factors affect diesel combustion and emissions more significantly than the composition of the fuel and the fuel injection process. In this paper, both of these factors are considered by comparing conventional, synthetic and vegetable oil-derived diesel fuels and by comparing a single pulse injection and a split (pilot and main) injection proces...

This work is focused on the measurement and analysis of biodiesel emissions resulting from two commercial diesel engines derived from the same baseline engine. One of the engines was equipped with a rotary fuel injection pump electronically controlled. Another engine was equipped with a common-rail injection system. Both engines were tuned by the m...

The stability diagrams of ethanol (e)−biodiesel (b)−diesel blends were studied at different temperatures. It was found that biodiesel acts as a stabilizer component in e−diesel blends, except at low temperatures, where it favors the formation of a gelatinous phase. Three blends (two e−diesel and an e−b−diesel) were selected to be tested in a diesel...

The present work has been focused on the measurement and analysis of diesel emissions produced by a construction machinery (vibrating roller) fuelled with conventional fuel and an ethanol−diesel blend under the typical operations in railways construction. A commercial pure diesel fuel and a blend with 7.7% v/v of anhydrous ethanol (99.7%) were used...

Owing to the negative effects that aerosols have on human health, the interest in knowing the size and the amount of particulate matter emitted by diesel engines is increasing. The measurement of this kind of aerosol is mainly influenced by three parameters: the ambient conditions, the sampling method used to characterize the emissions together wit...

The effect of the biodiesel feedstock on the engine performance and emissions is expected to become increasingly important as the emissions regulations become more stringent (Euro 5). This work aims to study the effect of the degree of unsaturation of a biodiesel fuel (which is a characteristic of the original oil), this being quantified by the iod...

The call for the use of biofuels which is being made by most governments following international energy policies is presently finding some resistance from car and components manufacturing companies, private users and local administrations. This opposition makes it more difficult to reach the targets of increased shares of use of biofuels in interna...

Diesel emissions have been measured from an automotive engine using anhydrous bioethanol blended with conventional diesel, with 10% ethanol in volume and no additives. The resulting emissions have been compared with those from pure diesel. A stationary engine test bed, together with the instrumentation for measuring the most stringent regulated emi...

Bioethanol is an attractive fuel due to its renewable origin and its oxygen content, but it is unable to be used directly in diesel engines. Although biodiesel can be produced with bioethanol through ethanolisis, direct blending of ethanol and diesel fuel, called e-diesel, has at least the same potential to reduce particulate emissions, despite the...