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The use of biofuels for spark ignition engines is proposed to diversify fuel sources and reduce fossil fuel consumption, optimize engine performance, and reduce pollutant emissions. Additionally, when these biofuels are produced from low-grade wastes, they constitute valorisation pathways for these otherwise unprofitable wastes. In this study, ethanol and pyrolysis biogasoline made from low-grade wastes were evaluated as additives for commercial gasoline (RON95, RON98) in tests performed in a spark ignition engine. Binary fuel mixtures of ethanol + gasoline or biogasoline + gasoline with biofuel incorporation of 2% (w/w) to 10% (w/w) were evaluated and compared with ternary fuel mixtures of ethanol + biogasoline + gasoline with biofuel incorporation rates from 1% (w/w) to 5% (w/w). The fuel mix performance was assessed by determination of torque and power, fuel consumption and efficiency, and emissions (HC, CO, and NOx). An electronic control unit (ECU) was used to regulate the air–fuel ratio/lambda and the ignition advance for maximum brake torque (MBT), wide-open throttle (WOT)), and two torque loads for different engine speeds representative of typical driving. The additive incorporation up to 10% often improved efficiency and lowered emissions such as CO and HC relative to both straight gasolines, but NOx increased with the addition of a blend.
Joaquim Costa; Jorge Martins; Tiago Arantes; Margarida Gonçalves; Luis Durão; Francisco P. Brito. Experimental Assessment of the Performance and Emissions of a Spark-Ignition Engine Using Waste-Derived Biofuels as Additives. Energies 2021, 14, 5209 .
AMA StyleJoaquim Costa, Jorge Martins, Tiago Arantes, Margarida Gonçalves, Luis Durão, Francisco P. Brito. Experimental Assessment of the Performance and Emissions of a Spark-Ignition Engine Using Waste-Derived Biofuels as Additives. Energies. 2021; 14 (16):5209.
Chicago/Turabian StyleJoaquim Costa; Jorge Martins; Tiago Arantes; Margarida Gonçalves; Luis Durão; Francisco P. Brito. 2021. "Experimental Assessment of the Performance and Emissions of a Spark-Ignition Engine Using Waste-Derived Biofuels as Additives." Energies 14, no. 16: 5209.
This research investigates the effects of a synthetic diesel-like fuel (Fischer-Tropsch diesel) and biofuels (ethanol and biodiesel) fuel blends on the energy-exergy efficiencies and gaseous exhaust emissions characteristics of a compression ignition engine. Two blends of alternative fuels denoted as E15B35FTD50 (15% ethanol, 35% biodiesel, and 50% Fischer-Tropsch diesel) and E15B35D50 (15% ethanol, 35% biodiesel, and 50% diesel) were experimentally studied on a single-cylinder diesel engine and compared to diesel fuel. The results show that the energetic and the exergetic efficiencies of the alternative fuels are comparable to those of the engine fueled with diesel fuel. The unburnt HC, NO, N2O, and NH3 emissions were reduced for the two alternative fuel blends compared to diesel, while CO emissions increased. The light HC species were found to slightly increase for the alternative fuel blends in comparison with diesel fuel. However, the total HC was considerably reduced by the combustion of E15B35FTD50 not only when compared to the diesel fuel combustion, but also when compared to E15B35D50. Overall, these results may contribute to identifying advantages and limitations in terms of energetic-exergetic analysis and emissions for the new generation of conventional diesel and hybrid electric vehicles that aim to achieve future emissions regulations.
Felipe Torres; Omid Doustdar; Jose Herreros; Runzhao Li; Robert Poku; Athanasios Tsolakis; Jorge Martins; Silvio Vieira de Melo. Fischer-Tropsch Diesel and Biofuels Exergy and Energy Analysis for Low Emissions Vehicles. Applied Sciences 2021, 11, 5958 .
AMA StyleFelipe Torres, Omid Doustdar, Jose Herreros, Runzhao Li, Robert Poku, Athanasios Tsolakis, Jorge Martins, Silvio Vieira de Melo. Fischer-Tropsch Diesel and Biofuels Exergy and Energy Analysis for Low Emissions Vehicles. Applied Sciences. 2021; 11 (13):5958.
Chicago/Turabian StyleFelipe Torres; Omid Doustdar; Jose Herreros; Runzhao Li; Robert Poku; Athanasios Tsolakis; Jorge Martins; Silvio Vieira de Melo. 2021. "Fischer-Tropsch Diesel and Biofuels Exergy and Energy Analysis for Low Emissions Vehicles." Applied Sciences 11, no. 13: 5958.
Thermoelectric (TE) generators allow the direct conversion of heat into electricity without moving parts and with little maintenance needs if carefully designed. However, their high cost per unit power produced has prevented their widespread use in waste heat recovery applications. The use of earth-abundant, affordable, non-toxic and performant TE materials such as n-silicide and p-tetrahedrite for TE generators is assessed in the present analysis. A full multiphysics model was used to optimize the geometry of an n-p TE pair/module using these materials and assess its performance. The approach taken implemented the matched load condition automatically and a broad range of conditions was tested and discussed. Several pairs with the optimal geometry were preliminarily manufactured, assembled and characterized. The experimental results were compared against the predictions, allowing to validate the multiphysics model. Power densities up to 5 kW/m2 were predicted for temperatures between 290 K and 620 K, with efficiencies up to 5%. If modules with such performance could be manufactured with electric contact resistances comparable to those found in currently available commercial modules, then a door to the viable recovery of waste heat in industrial and automotive applications could be opened.
F.P. Brito; Rui Vieira; Jorge Martins; L.M. Goncalves; A.P. Goncalves; Rodrigo Coelho; E.B. Lopes; Elli Symeou; Theodora Kyratsi. Analysis of thermoelectric generator incorporating n-magnesium silicide and p-tetrahedrite materials. Energy Conversion and Management 2021, 236, 114003 .
AMA StyleF.P. Brito, Rui Vieira, Jorge Martins, L.M. Goncalves, A.P. Goncalves, Rodrigo Coelho, E.B. Lopes, Elli Symeou, Theodora Kyratsi. Analysis of thermoelectric generator incorporating n-magnesium silicide and p-tetrahedrite materials. Energy Conversion and Management. 2021; 236 ():114003.
Chicago/Turabian StyleF.P. Brito; Rui Vieira; Jorge Martins; L.M. Goncalves; A.P. Goncalves; Rodrigo Coelho; E.B. Lopes; Elli Symeou; Theodora Kyratsi. 2021. "Analysis of thermoelectric generator incorporating n-magnesium silicide and p-tetrahedrite materials." Energy Conversion and Management 236, no. : 114003.
The worldwide consumption of fossil hydrocarbons in the road transport sector in 2020 corresponded to roughly half of the overall consumption. However, biofuels have been discreetly contributing to mitigate gaseous emissions and participating in sustainable development, and thus leading to the extending of the commercial utilization of internal combustion engines. In this scenario, the present work aims at exploring the effects of alternative fuels containing a blend of 15% ethanol and 35% biodiesel with a 50% fossil diesel (E15D50B35) or 50% Fischer–Tropsch (F-T) diesel (E15FTD50B35) on the engine combustion, exhaust emissions (CO, HC, and NOx), particulate emissions characteristics as well as the performance of an aftertreatment system of a common rail diesel engine. It was found that one of the blends (E15FTD50B35) showed more than 30% reduction in PM concentration number, more than 25% reduction in mean particle size, and more than 85% reduction in total PM mass with respect to conventional diesel fuel. Additionally, it was found that the E15FTD50B35 blend reduces gaseous emissions of total hydrocarbons (THC) by more than 25% and NO by 3.8%. The oxidation catalyst was effective in carbonaceous emissions reduction, despite the catalyst light-off being slightly delayed in comparison to diesel fuel blends.
Felipe Andrade Torres; Omid Doustdar; Jose Herreros; Runzhao Li; Robert Poku; Athanasios Tsolakis; Jorge Martins; Silvio Vieira de Melo. A Comparative Study of Biofuels and Fischer–Tropsch Diesel Blends on the Engine Combustion Performance for Reducing Exhaust Gaseous and Particulate Emissions. Energies 2021, 14, 1538 .
AMA StyleFelipe Andrade Torres, Omid Doustdar, Jose Herreros, Runzhao Li, Robert Poku, Athanasios Tsolakis, Jorge Martins, Silvio Vieira de Melo. A Comparative Study of Biofuels and Fischer–Tropsch Diesel Blends on the Engine Combustion Performance for Reducing Exhaust Gaseous and Particulate Emissions. Energies. 2021; 14 (6):1538.
Chicago/Turabian StyleFelipe Andrade Torres; Omid Doustdar; Jose Herreros; Runzhao Li; Robert Poku; Athanasios Tsolakis; Jorge Martins; Silvio Vieira de Melo. 2021. "A Comparative Study of Biofuels and Fischer–Tropsch Diesel Blends on the Engine Combustion Performance for Reducing Exhaust Gaseous and Particulate Emissions." Energies 14, no. 6: 1538.
The partial replacement of fossil fuels by biofuels contributes to a reduction of CO2 emissions, alleviating the greenhouse effect and climate changes. Furthermore, fuels produced from waste biomass materials have no impact on agricultural land use and reduce deposition of such wastes in landfills. In this paper we evaluate the addition of pyrolysis biogasoline (pyrogasoline) as an additive for fossil gasoline. Pyrogasoline was produced from used cooking oils unfit to produce biodiesel. This study was based on a set of engine tests using binary and ternary mixtures of gasoline with 0, 2.5, and 5% pyrogasoline and ethanol. The use of ternary blends of gasoline and two different biofuels was tested with the purpose of achieving optimal combustion conditions and lower emissions, taking advantage of synergistic effects due to the different properties and chemical compositions of those biofuels. The tests were performed on a spark-ignition engine, operated at full load (100% throttle, or WOT—wide open throttle) between 2000 and 6000 rpm, while recording engine performance and exhaust gases pollutants data. Binary mixtures with pyrogasoline did not improve or worsen the engine’s performance, but the ternary mixtures (gasoline + pyrogasoline + ethanol) positively improved the engine’s performance with torque gains between 0.8 and 3.1% compared to gasoline. All fuels presented CO and unburned hydrocarbons emissions below those produced by this type of engine operated under normal (fossil) gasoline. On the other hand, NOx emissions from oxygenated fuels had contradictory behaviour compared to gasoline. If we consider the gains achieved by the torque with the ternary mixtures and reductions in polluting emissions obtained by mixtures with pyrogasoline, a future for this fuel can be foreseen as a partial replacement of fossil gasoline.
Luís Durão; Joaquim Costa; Tiago Arantes; F. P. Brito; Jorge Martins; Margarida Gonçalves. Performance and Emissions of a Spark Ignition Engine Operated with Gasoline Supplemented with Pyrogasoline and Ethanol. Energies 2020, 13, 4671 .
AMA StyleLuís Durão, Joaquim Costa, Tiago Arantes, F. P. Brito, Jorge Martins, Margarida Gonçalves. Performance and Emissions of a Spark Ignition Engine Operated with Gasoline Supplemented with Pyrogasoline and Ethanol. Energies. 2020; 13 (18):4671.
Chicago/Turabian StyleLuís Durão; Joaquim Costa; Tiago Arantes; F. P. Brito; Jorge Martins; Margarida Gonçalves. 2020. "Performance and Emissions of a Spark Ignition Engine Operated with Gasoline Supplemented with Pyrogasoline and Ethanol." Energies 13, no. 18: 4671.
The recent transport electrification trend is pushing governments to limit the future use of Internal Combustion Engines (ICEs). However, the rationale for this strong limitation is frequently not sufficiently addressed or justified. The problem does not seem to lie within the engines nor with the combustion by themselves but seemingly, rather with the rise in greenhouse gases (GHG), namely CO2, rejected to the atmosphere. However, it is frequent that the distinction between fossil CO2 and renewable CO2 production is not made, or even between CO2 emissions and pollutant emissions. The present revision paper discusses and introduces different alternative fuels that can be burned in IC Engines and would eliminate, or substantially reduce the emission of fossil CO2 into the atmosphere. These may be non-carbon fuels such as hydrogen or ammonia, or biofuels such as alcohols, ethers or esters, including synthetic fuels. There are also other types of fuels that may be used, such as those based on turpentine or even glycerin which could maintain ICEs as a valuable option for transportation.
Jorge Martins; F. P. Brito. Alternative Fuels for Internal Combustion Engines. Energies 2020, 13, 4086 .
AMA StyleJorge Martins, F. P. Brito. Alternative Fuels for Internal Combustion Engines. Energies. 2020; 13 (16):4086.
Chicago/Turabian StyleJorge Martins; F. P. Brito. 2020. "Alternative Fuels for Internal Combustion Engines." Energies 13, no. 16: 4086.
Biofuels provide high oxygen content for combustion and do modify properties that influence the engine operation process such as viscosity, enthalpy of vaporization, and cetane number. Some requirements of performance, fuel consumption, efficiency, and exhaust emission are necessary for the validation of these biofuels for application in engines. This work studies the effects of the use of diethyl ether (DEE) in biodiesel-ethanol blends in a DI mechanical diesel engine. The blends used in the tests were B80E20 (biodiesel 80%-ethanol 20%) and B76E19DEE5 (biodiesel 76%-ethanol 19%-DEE 5%). Fossil diesel (D100) and biodiesel (B100) were evaluated as reference fuels. The results revealed similar engine efficiencies among tested fuels at all loads. The use of B100 increased CO and NOx and decreased THC compared to D100 at the three loads tested. B80E20 fuel showed an increase in NOx emission in comparison with all fuels tested, which was attributed to higher oxygen content and lower cetane number. THC and CO were also increased for B80E20 compared to B100 and D100. The use of B76E19DEE5 fuel revealed reductions in NOx and CO emissions, while THC emissions increased. The engine efficiency of B76E19DEE5 was also highlighted at intermediate and more elevated engine load conditions.
Márcio Carvalho; Felipe Torres; Vitor Ferreira; Júlio Silva; Jorge Martins; Ednildo Torres; Vitor Pinheiro. Effects of Diethyl Ether Introduction in Emissions and Performance of a Diesel Engine Fueled with Biodiesel-Ethanol Blends. Energies 2020, 13, 3787 .
AMA StyleMárcio Carvalho, Felipe Torres, Vitor Ferreira, Júlio Silva, Jorge Martins, Ednildo Torres, Vitor Pinheiro. Effects of Diethyl Ether Introduction in Emissions and Performance of a Diesel Engine Fueled with Biodiesel-Ethanol Blends. Energies. 2020; 13 (15):3787.
Chicago/Turabian StyleMárcio Carvalho; Felipe Torres; Vitor Ferreira; Júlio Silva; Jorge Martins; Ednildo Torres; Vitor Pinheiro. 2020. "Effects of Diethyl Ether Introduction in Emissions and Performance of a Diesel Engine Fueled with Biodiesel-Ethanol Blends." Energies 13, no. 15: 3787.
Currently, the automotive industry faces challenges to implement solutions that provide reductions in energy consumption, pollutants and greenhouse-gas (GHG) emissions. Exhaust heat recovery employing Thermoelectric generators (TEGs) enables the direct conversion of heat into electric energy without moving parts and little to no maintenance. On-board electrical production is especially useful given the growing electrification trend of road vehicles. The present work assesses the performance of a novel temperature-controlled thermoelectric generator (TCTG) concept in a light duty vehicle and its impact on fuel economy and GHG emissions under realistic driving conditions. The novel exhaust heat exchanger (HE) concept consists of corrugated pipes embedded in a cast aluminium matrix along with variable conductance heat pipes (VCHPs) acting as spreaders of excess heat along the longitudinal direction. This concept seems to have a quite good potential for highly variable thermal load applications, as it is able to avoid overheating by spreading heat instead of wasting it through by-pass systems. Furthermore, when compared to previous concepts by the group, it does not need gravity assistance and has a form factor similar to conventional generators. It also appears to be capable of delivering a breakthrough electric output for TEG systems in such light vehicles, with as much as 572 W and 1538 W of average and maximum electric powers during a driving cycle, respectively, and showing a quite promising reduction of 5.4% in fuel consumption and CO2 emissions.
N. Pacheco; F.P. Brito; R. Vieira; J. Martins; H. Barbosa; L.M. Goncalves. Compact automotive thermoelectric generator with embedded heat pipes for thermal control. Energy 2020, 197, 117154 .
AMA StyleN. Pacheco, F.P. Brito, R. Vieira, J. Martins, H. Barbosa, L.M. Goncalves. Compact automotive thermoelectric generator with embedded heat pipes for thermal control. Energy. 2020; 197 ():117154.
Chicago/Turabian StyleN. Pacheco; F.P. Brito; R. Vieira; J. Martins; H. Barbosa; L.M. Goncalves. 2020. "Compact automotive thermoelectric generator with embedded heat pipes for thermal control." Energy 197, no. : 117154.
A range extender (RE) is a device used in electric vehicles (EVs) to generate electricity on-board, enabling them to significantly reduce the number of required batteries and/or extend the vehicle driving range to allow occasional long trips. In the present work, an efficiency-oriented RE based on a small motorcycle engine modified to the efficient over-expanded cycle, was analyzed, tested and simulated in a driving cycle. The RE was developed to have two points of operation, ECO: 3000 rpm, very high efficiency with only 15 kW; and BOOST: 7000 rpm with 35 kW. While the ECO strategy was a straightforward development for the over-expansion concept (less trapped air and a much higher compression ratio) the BOOST strategy was more complicated to implement and involved the need for throttle operation. Initially the concepts were evaluated in an in-house model and AVL Boost® (AVL List Gmbh, Graz, Austria), and proved feasible. Then, a BMW K75 engine was altered and tested on a brake dynamometer. The running engine proved the initial concept, by improving the efficiency for the ECO condition in almost 40% in relation to the stock engine and getting well over the required BOOST power, getting to 35 kW, while keeping an efficiency similar to the stock engine at the wide open throttle (WOT). In order to protect the engine during BOOST, the mixture was enriched, while at ECO the mixture was leaned to further improve efficiency. The fixed operation configuration allows the reduction, not only of complexity and cost of the RE, but also the set point optimization for the engine and generator. When integrated as a RE into a typical European light duty vehicle, it provided a breakthrough consumption reduction relatively to existing plug-in hybrid electric vehicles (PHEVs) in the market in the charge sustaining mode. The very high efficiency of the power generation seems to compensate for the loss of efficiency due to the excess electricity production, which must be stored in the battery. The results indicate that indeed it is possible to have an efficient solution, in-line with the electric mobility sustainability paradigm, which can solve most of the shortcomings of current EVs, notably those associated with batteries (range, cost and charging time) in a sustainable way.
F. P. Brito; Jorge Martins; Francisco Lopes; Carlos Castro; Luís Martins; A. L. N. Moreira. Development and Assessment of an Over-Expanded Engine to be Used as an Efficiency-Oriented Range Extender for Electric Vehicles. Energies 2020, 13, 430 .
AMA StyleF. P. Brito, Jorge Martins, Francisco Lopes, Carlos Castro, Luís Martins, A. L. N. Moreira. Development and Assessment of an Over-Expanded Engine to be Used as an Efficiency-Oriented Range Extender for Electric Vehicles. Energies. 2020; 13 (2):430.
Chicago/Turabian StyleF. P. Brito; Jorge Martins; Francisco Lopes; Carlos Castro; Luís Martins; A. L. N. Moreira. 2020. "Development and Assessment of an Over-Expanded Engine to be Used as an Efficiency-Oriented Range Extender for Electric Vehicles." Energies 13, no. 2: 430.
This paper exhibits an outline of the piston rings operational characteristics and consequently, of their main functional challenges. The basic geometrical shapes, materials and manufacturing technologies used to produce compression rings for up to date diesel engines are summarized. Based on this description, each technological solution to enhance the behavior of the piston rings is fully described and explained. The state-of-the-art solutions such as a DLC (diamond-like carbon) layer, multi-layered coatings and compound coatings are tersely presented and discussed. New approaches suggest surface textures, which are expected to be a major improvement in the development of optimized surface coatings of the piston rings, and the latest progress in that area is examined and debated. Also, a novel solution for the enhancement of the behavior of ring coatings is presented, using a proposed and previously tested solution for a different application. This solution attempts to optimize most of the properties in relation to friction, wear, mechanical stresses, heat dissipation and self-lubrication. The overall idea is to use specific materials in specified positions over the surface to individually enhance the referred properties, creating a multifunctional surface.
Rita Ferreira; Jorge Martins; Óscar Carvalho; Luis Sobral; Sandra Carvalho; Filipe Silva. Tribological solutions for engine piston ring surfaces: an overview on the materials and manufacturing. Materials and Manufacturing Processes 2019, 35, 498 -520.
AMA StyleRita Ferreira, Jorge Martins, Óscar Carvalho, Luis Sobral, Sandra Carvalho, Filipe Silva. Tribological solutions for engine piston ring surfaces: an overview on the materials and manufacturing. Materials and Manufacturing Processes. 2019; 35 (5):498-520.
Chicago/Turabian StyleRita Ferreira; Jorge Martins; Óscar Carvalho; Luis Sobral; Sandra Carvalho; Filipe Silva. 2019. "Tribological solutions for engine piston ring surfaces: an overview on the materials and manufacturing." Materials and Manufacturing Processes 35, no. 5: 498-520.
One of the main obstacles for the use of thermoelectric generators (TEGs) in vehicles is the highly variable thermal loads typical of driving cycles. Under these conditions it will be virtually impossible for a conventional heat exchanger to avoid both thermal dilution under low thermal loads and TEG overheating under high thermal loads. The authors have been exploring an original heat exchanger concept able to address the aforementioned problems. It uses a variable conductance thermosiphon-based phase-change buffer between the heat source and the TEGs so that a nearly constant, optimized temperature is obtained regardless of operating conditions. To the best of the authors’ knowledge, the thermal control feature of the system is unique among existing TEG concepts. The novelty of the present work is the actual computation of operating pressure and temperature and the corresponding vaporization and condensation rates inside the thermosiphon system during driving cycles along with the assessment of the influence of the volumes and pre-charge pressure on electrical output. The global energy and emission savings were also computed for a typical yearly driving profile. It was observed that indeed the concept has unparalleled potential for improving the efficiency of vehicles using TEGs, with around 6% fuel and CO2 emissions savings using the system. This seems a breakthrough for such light duty applications since the efficiency of conventional (passive) systems is strongly deprecated by thermal dilution under low thermal loads and the need to by-pass high thermal load events to avoid overheating. On the contrary, the present concept allows the control of the hot face temperature of the TEGs even under highly variable thermal load (i.e. driving cycle) environments.
F.P. Brito; N. Pacheco; Rui Daniel De Sousa Vieira; J. Martins; J. Teixeira; L.M. Goncalves; J. Oliveira; M.J. Hall. Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators. Energy Conversion and Management 2019, 203, 112255 .
AMA StyleF.P. Brito, N. Pacheco, Rui Daniel De Sousa Vieira, J. Martins, J. Teixeira, L.M. Goncalves, J. Oliveira, M.J. Hall. Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators. Energy Conversion and Management. 2019; 203 ():112255.
Chicago/Turabian StyleF.P. Brito; N. Pacheco; Rui Daniel De Sousa Vieira; J. Martins; J. Teixeira; L.M. Goncalves; J. Oliveira; M.J. Hall. 2019. "Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators." Energy Conversion and Management 203, no. : 112255.
Jorge Martins; Afonso Baptista; Rui Pinto; Francisco Brito; Tiago J. Costa. Analysis of a New VVT Trapezoidal Rotary Valve. SAE Technical Paper Series 2019, 1 .
AMA StyleJorge Martins, Afonso Baptista, Rui Pinto, Francisco Brito, Tiago J. Costa. Analysis of a New VVT Trapezoidal Rotary Valve. SAE Technical Paper Series. 2019; ():1.
Chicago/Turabian StyleJorge Martins; Afonso Baptista; Rui Pinto; Francisco Brito; Tiago J. Costa. 2019. "Analysis of a New VVT Trapezoidal Rotary Valve." SAE Technical Paper Series , no. : 1.
Adriano Sousa; Jorge Martins; Francisco Brito; Tiago J. Costa. Improvement of Engine Performance through Intake Port Modifications Including Dimpling. SAE Technical Paper Series 2019, 1 .
AMA StyleAdriano Sousa, Jorge Martins, Francisco Brito, Tiago J. Costa. Improvement of Engine Performance through Intake Port Modifications Including Dimpling. SAE Technical Paper Series. 2019; ():1.
Chicago/Turabian StyleAdriano Sousa; Jorge Martins; Francisco Brito; Tiago J. Costa. 2019. "Improvement of Engine Performance through Intake Port Modifications Including Dimpling." SAE Technical Paper Series , no. : 1.
Guilherme Capela; Tiago J. Costa; José Meireles; Jorge Martins; Francisco Brito. Native Over-Expanded Engine Based on a Planetary Crankshaft with Enhanced Balancing. SAE Technical Paper Series 2019, 1 .
AMA StyleGuilherme Capela, Tiago J. Costa, José Meireles, Jorge Martins, Francisco Brito. Native Over-Expanded Engine Based on a Planetary Crankshaft with Enhanced Balancing. SAE Technical Paper Series. 2019; ():1.
Chicago/Turabian StyleGuilherme Capela; Tiago J. Costa; José Meireles; Jorge Martins; Francisco Brito. 2019. "Native Over-Expanded Engine Based on a Planetary Crankshaft with Enhanced Balancing." SAE Technical Paper Series , no. : 1.
The present work is aimed at quantifying the effects of ambient pressure in the heat transfer at single injections of a full cone spray over a hot metal surface. The experimental configuration is that of a spray impinging down perpendicularly onto a flat surface located at 55mm inside an injection chamber. The experiments were conducted for prescribed initial wall temperatures ranging from single phase to local nucleate boiling and transition regimes of heat transfer. Ambient pressures ranged from atmospheric to 30bar. The analysis is based on spatial resolved measurements of the instantaneous surface temperature during the injection period. The measurements are then processed in order to obtain estimates of the time-averaged values of the local heat flux. The overall cooling rate is also obtained by integrating the local values within the total area of the spray impact. Results show that the amount of heat extracted by the impinging spray increases 3.4 times when ambient pressure is increased from atmospheric to 20bar at the same superheating degree at the wall of 45∘C. This corresponds to an increase from 13.3% to 47.7% in the ratio between the actual cooling and the theoretical maximum cooling, defined here as cooling efficiency. This is a result of a better spreading of the liquid film at the wall, covering a larger footprint upon impact . Instantaneous peak heat flux is also increased, as a clear indication of the improved heat transfer between the impinging droplets and the wall. The work presented herein derives from a broader research program devised to develop a system for in-cylinder cooling of internal combustion engines using high pressure water sprays produced by gasoline direct injectors.
Tiago Costa; Jorge Martins; F.P. Brito; Miguel R. Oliveira Panão; Antóio L.N. Moreira. The effect of ambient pressure on the heat transfer of a water spray. Applied Thermal Engineering 2019, 152, 490 -498.
AMA StyleTiago Costa, Jorge Martins, F.P. Brito, Miguel R. Oliveira Panão, Antóio L.N. Moreira. The effect of ambient pressure on the heat transfer of a water spray. Applied Thermal Engineering. 2019; 152 ():490-498.
Chicago/Turabian StyleTiago Costa; Jorge Martins; F.P. Brito; Miguel R. Oliveira Panão; Antóio L.N. Moreira. 2019. "The effect of ambient pressure on the heat transfer of a water spray." Applied Thermal Engineering 152, no. : 490-498.
Tiago Costa; Jorge Martins; Francisco Brito. UMotor - PERFORMANCE EVALUATION OF A SMALL OVER-EXPANDED ENGINE USING 3D-CFD AND 1D ENGINE MODELS. Anais do X Congresso Nacional de Engenharia Mecânica 2018, 1 .
AMA StyleTiago Costa, Jorge Martins, Francisco Brito. UMotor - PERFORMANCE EVALUATION OF A SMALL OVER-EXPANDED ENGINE USING 3D-CFD AND 1D ENGINE MODELS. Anais do X Congresso Nacional de Engenharia Mecânica. 2018; ():1.
Chicago/Turabian StyleTiago Costa; Jorge Martins; Francisco Brito. 2018. "UMotor - PERFORMANCE EVALUATION OF A SMALL OVER-EXPANDED ENGINE USING 3D-CFD AND 1D ENGINE MODELS." Anais do X Congresso Nacional de Engenharia Mecânica , no. : 1.
Tiago J. Costa; Mark Nickerson; Daniele Littera; Jorge Martins; Alexander Shkolnik; Nikolay Shkolnik; Francisco Brito. Measurement and Prediction of Heat Transfer Losses on the XMv3 Rotary Engine. SAE International Journal of Engines 2016, 9, 2368 -2380.
AMA StyleTiago J. Costa, Mark Nickerson, Daniele Littera, Jorge Martins, Alexander Shkolnik, Nikolay Shkolnik, Francisco Brito. Measurement and Prediction of Heat Transfer Losses on the XMv3 Rotary Engine. SAE International Journal of Engines. 2016; 9 (4):2368-2380.
Chicago/Turabian StyleTiago J. Costa; Mark Nickerson; Daniele Littera; Jorge Martins; Alexander Shkolnik; Nikolay Shkolnik; Francisco Brito. 2016. "Measurement and Prediction of Heat Transfer Losses on the XMv3 Rotary Engine." SAE International Journal of Engines 9, no. 4: 2368-2380.
One way to increase efficiency and performance of 2-stroke engines is the addition of an exhaust valve to control the opening/closure of the exhaust port. With this implementation it is possible to change the exhaust timing for different conditions. However, conventional systems cannot change the exhaust opening and closure timings independently. The work herein presented shows the development of a new exhaust rotary valve enabling the control of the opening independently from the control of the closure of the exhaust port. The study is based on kinetic and thermodynamic analysis. Some manufacturers use exhaust rotary valves but none of them performs a fully rotary motion. This kind of motion has various benefits such as smoothness and most notably the ability to control both the opening and the closure timing of the exhaust independently. Regarding the kinematic analysis, a simple model was created to determine the most suitable valve angles. This combines the kinematic of the piston with the kinematic of the valve in order to determine the required valve angles to perform the required exhaust timing. With this model the authors were able to obtain the valve parameters for different engine conditions and visualize geometry limitations of the valve for each engine event. For the thermodynamic analysis the authors were able to use the data from the referred kinematic model to create a 3D model of the engine. The 3D model was then implemented using the software CONVERGE CFD which simulated the flow and thermal effect of the valve on the engine behaviour. The simulations were performed for a single engine geometry but with different valve conditions/geometry and different compression ratios. It was concluded that indeed it is possible to effectively implement this kind of valve and achieve the intended over-expansion effect.
Jorge Martins; Carlos Pereira; F.P. Brito. A New Rotary Valve for 2-Stroke Engines Enabling Over-Expansion. SAE Technical Paper Series 2016, 1, 1 .
AMA StyleJorge Martins, Carlos Pereira, F.P. Brito. A New Rotary Valve for 2-Stroke Engines Enabling Over-Expansion. SAE Technical Paper Series. 2016; 1 ():1.
Chicago/Turabian StyleJorge Martins; Carlos Pereira; F.P. Brito. 2016. "A New Rotary Valve for 2-Stroke Engines Enabling Over-Expansion." SAE Technical Paper Series 1, no. : 1.
The main source for the estimation of stiffness coefficients to be used in accident reconstruction calculations is a very large database of crash-test related information from NHTSA. However, that database includes only car models sold in the USA. Unfortunately, there is no such information for European-only cars besides the raw video recordings of EuroNCAP crash tests. In the present work a methodology is proposed to estimate the stiffness coefficients of European-only models from video images of EuroNCAP crash tests. However, these images are intricate to assess, because the car front is crushed into a deformable barrier at 40% of the front width and usually the bonnet (hood) hides most of the crash damage. Therefore, the top images could not be used straightforward, so a procedure was envisaged to circumvent this difficulty and still allow to calculate stiffness coefficients for European-only cars. The methodology for stiffness coefficients estimation involves: 1calculation of an average value for rebound based on NHTSA tests; 2calculation of the deformation of the deformable barrier as a function of vehicle class; 3measurement of the maximum deformation, using the superposition of video images of the crash-test; calculation of an average value for rebound based on NHTSA tests; calculation of the deformation of the deformable barrier as a function of vehicle class; measurement of the maximum deformation, using the superposition of video images of the crash-test; Since the video images are subject to error, such as parallax, a method to reduce these errors was established and used. Then, from the video image it was possible to calculate the permanent deformation by subtracting the rebound (1) and the deformation of the barrier (2) from the maximum deformation (3) that was measured from the image. This methodology allowed to extend the existing database of US cars to European models and to significantly improve the calculation of the dissipated energies associated to the permanent damage caused by accidents.
Jorge Martins; Ricardo Ribeiro; Pedro Neves; F. P. Brito. Accident Reconstruction Using Data Retrieval from Crash-Test Video Images. SAE Technical Paper Series 2016, 1 .
AMA StyleJorge Martins, Ricardo Ribeiro, Pedro Neves, F. P. Brito. Accident Reconstruction Using Data Retrieval from Crash-Test Video Images. SAE Technical Paper Series. 2016; ():1.
Chicago/Turabian StyleJorge Martins; Ricardo Ribeiro; Pedro Neves; F. P. Brito. 2016. "Accident Reconstruction Using Data Retrieval from Crash-Test Video Images." SAE Technical Paper Series , no. : 1.
A network of conveniently located fast charging stations is one of the possibilities to facilitate the adoption of Electric Vehicles (EVs). This paper assesses the use of fast charging stations for EVs in conjunction with VRFBs (Vanadium Redox Flow Batteries). These batteries are charged during low electricity demand periods and then supply electricity for the fast charging of EVs during day, thus implementing a power peak shaving process. Flow batteries have unique characteristics which make them especially attractive when compared with conventional batteries, such as their ability to decouple rated power from rated capacity, as well as their greater design flexibility and nearly unlimited life. Moreover, their liquid nature allows their installation inside deactivated underground gas tanks located at gas stations, enabling a smooth transition of gas stations' business model towards the emerging electric mobility paradigm. A project of a VRFB system to fast charge EVs taking advantage of existing gas stations infrastructures is presented. An energy and cost analysis of this concept is performed, which shows that, for the conditions tested, the project is technologically and economically viable, although being highly sensitive to the investment costs and to the electricity market conditions.
Álvaro Cunha; F.P. Brito; Jorge Martins; Nuno Rodrigues; Vitor Monteiro; João L. Afonso; Paula Ferreira. Assessment of the use of vanadium redox flow batteries for energy storage and fast charging of electric vehicles in gas stations. Energy 2016, 115, 1478 -1494.
AMA StyleÁlvaro Cunha, F.P. Brito, Jorge Martins, Nuno Rodrigues, Vitor Monteiro, João L. Afonso, Paula Ferreira. Assessment of the use of vanadium redox flow batteries for energy storage and fast charging of electric vehicles in gas stations. Energy. 2016; 115 ():1478-1494.
Chicago/Turabian StyleÁlvaro Cunha; F.P. Brito; Jorge Martins; Nuno Rodrigues; Vitor Monteiro; João L. Afonso; Paula Ferreira. 2016. "Assessment of the use of vanadium redox flow batteries for energy storage and fast charging of electric vehicles in gas stations." Energy 115, no. : 1478-1494.