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- Análise comparativa do desempenho de motores de combustão interna quando utilizam biocombustíveisPublication . Serrano, Luís Manuel VenturaConsiderando as atuais circunstâncias de dependência energética relativamente ao petróleo, com implicações claras para a sociedade ao nível económico, energético e ambiental e acentuadas no setor dos transportes pela dificuldade em encontrar soluções evidentes, foi elaborado um estudo para avaliar os impactos da utilização de biocombustíveis em motores de combustão interna. A importância do presente trabalho é justificada pela tendência crescente da utilização de biodiesel, quer em Portugal, quer nos outros países europeus. De facto, nas atuais circunstâncias, esta é uma solução efetiva, surgindo com a capacidade de substituir em parte aquele que é o combustível mais utilizado pelos transportes rodoviários em Portugal, o gasóleo. No presente estudo, de cariz essencialmente experimental, utilizou-se um banco de ensaios de motores com um dinamómetro hidráulico, um banco de rolos e ensaios em estrada. Através destas metodologias avaliou-se a forma como a utilização de biodiesel em motores de veículos afeta o consumo, o desempenho e as emissões desses mesmos veículos. Foram consideradas motorizações de veículos ligeiros e pesados, tendo sido realizados estudos comparativos dos resultados de laboratório com os obtidos em estrada, nas condições reais de utilização dos veículos. Relativamente aos veículos pesados, foi feita a análise de dados de uma frota de veículos de transporte de passageiros e a avaliação do comportamento de um motor Volvo de 6 cilindros em banco de ensaios, considerando-se a utilização de diversos combustíveis constituídos por diferentes proporções de biodiesel e gasóleo. No caso dos veículos ligeiros, foi elaborada e implementada uma nova metodologia de ensaios em estrada, considerando a utilização simultânea de dois veículos similares, abastecidos por combustíveis diferentes (B0 e B20). Estes resultados foram comparados com os dados obtidos pelos mesmos veículos no banco de rolos e com os resultados de ensaios de um motor VW 1.9 TDI no banco de ensaios de motores. Concluiu-se que o impacto da utilização de biodiesel em substituição de gasóleo, principalmente quando se considera a utilização de incorporações até 20% de biodiesel, não é significativo ao nível energético. Pode-se admitir uma justificação em termos ambientais, pela redução de emissão de gases com efeito de estufa devido ao caráter renovável do biodiesel e em termos económicos pela diminuição da dependência de petróleo e eventual criação de emprego e riqueza interna. Em termos do consumo de combustível, não é absolutamente claro que a utilização de biodiesel implique um aumento desse consumo pelo facto de possuir menor conteúdo energético por litro de combustível. Atendendo aos dados obtidos, para determinadas situações ocorre um aumento da eficiência energética com a utilização de biodiesel em pequenas proporções de incorporação no gasóleo, sendo verificado que a utilização de um combustível com menor quantidade de energia pode permitir uma maior disponibilidade energética. É também claro que em função do comportamento dos motores quando sujeitos a diferentes tipos de exigência, correspondente a diferentes tipologias de percurso, ocorre uma distinta avaliação em termos de consumo e emissões de NOx, quando o motor é abastecido com uma mistura de biodiesel em gasóleo. O trabalho realizado permitiu estabelecer metodologias de ensaios, aumentando a fiabilidade na avaliação comparativa da utilização de distintos combustíveis em sistemas de propulsão de veículos automóveis.
- Roads as sources of heavy metals in urban areas. The Covões catchment experiment, Coimbra, PortugalPublication . Ferreira, António J. D.; Soares, Daniel; Serrano, Luis; Walsh, Rory P. D.; Dias-Ferreira, Celia; Ferreira, Carla S. S.Purpose This work studies the implications of different traffic patterns for heavy metal and solid pollution generation processes following rainfall events with contrasting antecedent meteorological conditions, at a periurban catchment. The aim is to provide information on the pollution processes and their potential environmental impacts for urban areas. Materials and methods Seven campaigns were performed covering winter, spring, and summer conditions, for rainfall events with different antecedent conditions. Four types of roads were monitored: low traffic, average traffic, heavy traffic with demanding driving situations (break and turning), and heavy traffic with high vehicle speed (motorway profile). Samples were taken at the beginning, middle and end of the events to measure within event variation in concentration. Analytical standard procedures were used to quantify pH, conductivity, turbidity, total solids, volatile solids, suspended solids, volatile suspended solids and heavy metals (Cd, Cu, Pb and Zn) in the total and dissolved forms (as to infer the particulate fraction), namely copper, zinc, cadmium and lead. Results and discussion The collected data show a direct relation among the number of vehicles and/or the driving manoeuvres performed by them and the amount of solids and heavy metals present in the wash out overland flow collected. An important fraction of the heavy metals is washed off in the particulate form, which represents an increased problem since the road overland flow is directed to green/brown areas and for the local aquatic ecosystems. Maximum copper values recorded exceed 0.6 mh L−1, zinc exceeds 5 mg L−1, lead 0.1 mg L−1 and cadmium 0.01 mg L−1. Values are higher after long dry spells and reduce concentration throughout the rainfall events. Conclusions An important part of the heavy metals (with relevance for zinc and lead) are washed off in the particulate form, pollutants are typically related to the amount of traffic, and especially to the existence of driving manoeuvres. The summer events show the highest values, due to the accumulation of pollutants during the long dry spells.
- Energy audit as an input for energy management and energy efficiency improvement in a gypsum manufacturing plantPublication . Bernardo, Hermano; Oliveira, Filipe Tadeu; Serrano, LuisThis paper aims at presenting the main results of an energy audit performed to a gypsum production plant, in Portugal, which due to the amount of energy consumed must comply with the Portuguese program SGCIE (Intensive Energy Consumption Management System). The program was created in 2008 to promote energy efficiency and energy consumption monitoring in intensive energy consuming facilities (energy consumption higher than 500 toe per year). Facilities operators are required to perform energy audits and take actions to draw up an action plan for energy efficiency, establishing targets for energy consumption reduction and greenhouse gases emissions indexes. An energy audit was carried out to identify potential energy conservation measures for improving energy efficiency, and also typical energy consumption patterns, sector/equipment load profiles and thermal equipment performance. This tool gives managers the information to support decision making on improving energy performance and reducing greenhouse gas emissions. A number of tangible targets and measures were devised and set to be implemented in the next few years. Results show that there is a considerable potential for reduction in the energy consumption and greenhouse gases emissions of gypsum manufacturing plants. Here, as elsewhere in the industrial sector, energy efficiency can only be achieved through a continuous energy monitoring and management system.
- Optimization of engine performance for ethanol consumptionPublication . Serrano, Luis; Chalaça, DulioEthanol is a fuel obtained from vegetable by-products becoming a promising substitute for gasoline in internal combustion engines. It is obtained by plants, which convert carbon dioxide into oxygen through photosynthesis, what implies that the carbon dioxide cycle is very short, since that the CO2 released by combustion can be withdrawn from the atmosphere on ethanol production. This is absolutely contrary to the fossil fuels consumption, which introduce carbon dioxide into the atmosphere that will only be taken off in billions of years cycle. The incentive for the present work had the genesis in the Student Formula team of the Polytechnic Institute of Leiria (FSIPLeiria) which has interest in get the advantages and disadvantages of the use of ethanol (E85) as fuel in the development of the next car prototype. The basis of this work is to optimize the engine of the FSIPLeiria team to run with ethanol. To attain this objective, it was used software to model the engine and to compare the final result with the experimental tests developed in order to obtain the validation of that model. This allow to find the best engine parameterization in order to get the best of it when he was fueled with E85, a mixture of 85% of ethanol and 15% of petrol. Taking into account the objectives of the team FSIPLeiria, a computational model using Ricardo Wave based on gasoline was developed to simulate the behavior of the engine and later study not only the influence of the ethanol but also other parameters that was necessary in view of the optimization of the engine when fueled by E85. Together with the software modeling, an experimental set-up was established to acquire data from the gsxr-600 engine under study in a chassis dynamometer, in order to validate the developed model and make able to draw conclusions about the use of ethanol as fuel. It was possible to develop software models with a relative error below 10% of the initial objective. A torque curve with a maximum deviation of 6.2% in the gasoline model and 8.5% in the model E85 was obtained, in relation to the experimental tests. Regarding the optimization process, it was possible to evaluate the effects of the increased compression ratio and the ignition timing, which revealed that it will be possible to obtain an increase in engine performance with the use of ethanol by correct adjustment of these parameters.
- A methodology to evaluate the performance and consumption of vehicles in comparative on-road testsPublication . Ghodsirad, Mohammadhossein; Teixeira, Joao; Breda, Paulo; Campos, Cristina; Serrano, Luis; Silva, Manuel Gameiro daThe main objective of the reported work was to develop a methodology to assess the fuel consumption and the efficiency of the propulsion system of passenger cars equipped with internal combustion engines in road tests carried out to compare the performance of fuels with different formulations. The examination has been done out in highway travels. A Peugeot 407 HDI station wagon, with a 2,0 liter engine, has been equipped with different measurement systems. The measurement equipment is based upon two vehicle data loggers. A real-time fuel consumption metering system is combined with a GPS logger in order to analyze trip fuel consumption with different conditions in speed and altitude. An OBD II data logger is also mounted and the analog outputs of two pressure sensor are also connected to it. OBD II provides the vehicle and engine information available at the CPU unit, while the pressure sensors are connected to three pressure taps placed on the front of the vehicle to provide information about the relative velocity between the car and the air and the flow angularity. In the test, the impacts of speed, acceleration, road slope and wind disturbance on fuel consumption were analyzed for different fuel formulations. The developed system revealed to be well adapted to the requirements of the research project, allowing an accurate measurement of the fuel consumption and all the relevant parameters related to the vehicle movement. The best compromise in terms of sampling parameters has been achieved with a data acquisition frequency of 10 Hz, being the values decimated to 1 Hz, with the exception of the fuel consumption that is analyzed for 10 s integration intervals.
- Development of a distributed electronic system for low-cost heavy-duty engine test benchPublication . Rodrigues Gouveia, Olivier; Borges, Alexandre; Costa, Diogo; Coelho, Diogo; Lopes, Paulo; Perpétua, Hugo; Serrano, Luis; Ferreira, CarlosTest benches are important tools for the optimization and diagnosis of internal combustion engines. This paper presents the work done to develop a low-cost tech bench for heavy-duty engines, which uses an electromagnetic brake, to apply load to the engine, and a distributed electronic system for control and data acquisition. Signal noise contamination in test benches represents a problematic aspect of the engine testing. Moreover, a distributed control and monitoring electronic systems, allied with a Controller Area Network (CAN) communication bus for signal transmission, was used to mitigate and ultimately immunize signals from noise sources such as electric or electromagnetic fields. Overall, a heavy-duty test bench aiming the engines diagnostics was obtained, where all control and data acquisition is performed via an USB serial port, interfacing with two CAN bus networks, in a complete distributed control system.
- Adjustment parameters of an internal combustion engine working with methanePublication . Dimitrov, R.; Bogdanov, K.; Wrobel, R.; Mihaylov, V.; Serrano, Luis; Institute of Physics PublishingThe paper presents a study of the variation of ignition advance when the engine works with methane and a comparison with values when the engine runs on gasoline. It is known that methane has a lower burning velocity than gasoline, and therefore, to obtain a maximal efficiency from the working process (the maximum value of cylinder pressure pz should be 7-15 degrees after TDC), ignition advance should be increased, as for different operating regimes this angle should be increased with different values. A gasoline engine has been studied and were measured and analysed the ignition advance at work with gasoline and methane, with optimal air-fuel ratio (α) for both fuels. Three-dimensional graphics of ignition advance variation across the rpm and load range were made. In conclusion, on the basis of the experiments, a table is produced, which presents the values of coefficients for change of base parameters of ignition advance for all engine operating modes, in dependence on rpm and load of the engine.
- Evaluation on effects of using low biodiesel blends in a EURO 5 passenger vehicle equipped with a common-rail diesel enginePublication . Serrano, L.; Lopes, M.; Pires, N.; Ribeiro, I.; Cascão, P.; Tarelho, L.; Monteiro, A.; Nielsen, O.; Silva, M. Gameiro da; Borrego, C.The effects of the use of low biodiesel blends in performance, fuel consumption and NOx emissions was investigated during tests carried out with a Renault Megane 1.5dCi equipped with recent injection and exhaust emission control technologies. To accomplish this goal, several tests were performed using the European homologation cycle concerning CO2 emissions of vehicles, known as the New European Driving Cycle (NEDC). This was executed using a chassis dynamometer, a fuel weighting equipment, an exhaust emissions analyzer and the software developed to acquire data and control the execution of the cycle. Besides the accomplishment of the NEDC cycle tests with three diverse fuel blends, performance tests were also realized, enabling to get the full load engine response considering the use of different fuels.The chosen biodiesel produced from original oils of soybean (84%) and palm (16%), was mixed in proportions of 0%, 7%, and 20% on a volumetric basis, allowing to test comparatively the results for these different fuel blends (B0, B7 and B20).The obtained results reveal some interesting findings regarding all the involved aspects. The consumption was not consistently increased with the use of biodiesel, revealing the existence of other factors besides the lower heating value to explain the fuel consumption differences. Likewise, the NOx emissions with biodiesel use does not present significant raise. In fact, when B20 was used, the levels of NOx emitted by the vehicle present a reduction in all the NEDC, which was more pronounced in the urban part of the NEDC. The performance analysis did not reveal any relevant differences, however the use of B7 promote an improvement on torque and power in the order of 2% relatively to B0.
- On-road performance comparison of two identical cars consuming petrodiesel and biodieselPublication . Serrano, L.; Carreira, V.; Câmara, R.; Gameiro da Silva, M.The present work studies the impact on vehicle performance and fuel consumption when using 100% diesel with petroleum origin (fossil diesel), compared to a mixture of 20% biodiesel in 80% of fossil diesel fuel (B20). For the accomplishment of this work an assessment was made using some primary tests on a chassis dynamometer, measuring vehicle performance and consumption. Subsequently a methodology was developed to conduct road tests. These considered the simultaneous circulation of two identical vehicles, fed with the two different fuels, but running on the same traffic and road conditions. Both vehicles were equippedwith geo-referencing systems (GPS) and datameasured by the Electronic Control Unit (ECU) were acquired. A precision balance was used in fuel consumption measurements of an auxiliary reservoir. The results demonstrate that the use of biodiesel has a penalizing effect on themass fuel consumption and on vehicle's performance, but this is largely dependent on the type of circuit used. One can also conclude that the methodology implemented on the study of fuel alternatives is extremely important. It is noticeable that for different route needs, different energetic solutions are more suitable than others, which can only be properly assessed by conducting road tests.
- Performance study about biodiesel impact on buses engines using dynamometer tests and fleet consumption dataPublication . Serrano, Luis M.V.; Câmara, Rui M.O.; Carreira, Vasco J.R.; Gameiro da Silva, M.C.The problem of reducing harmful emissions, mainly particulate matter (PM) and nitrogen oxides (NOxs) originated in compression ignition combustion engines, and also the mandatory intention of lowering the CO2 impacts of road transportation define the need to improve our knowledge on biodiesel use in engines. A 6 in line cylinders Volvo engine was submitted to a 100 min cycle with 27 stabilized steps for seven different fuel blends from pure fossil diesel (B0) to pure biodiesel (B100), considering also B10, B15, B20, B30, B50 fuel blends. The cycle imposed tries to simulate a normal use of a bus in an urban and extraurban circuit, considering different engine rotation and loads applied. An analysis on consumption data obtained of a fleet was made. The fleet had near 200 buses, used different fuel blends, and operated in the north of Portugal. Results reveal that the cycle imposed reflects very well the tendency of consumption, allowing to confirm the methodology and also to check influences on consumption, mainly associated with possibilities to decrease CO2 emissions by using some biodiesel blends on buses. This allows increasing the quality of data in vehicle real use and tightening the uncertainties on the actual effects of using biodiesel.