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2017-09-04
Technical Paper
2017-24-0060
Nicolo Cavina, Nahuel Rojo, Lorella Ceschini, Eleonora Balducci, Luca Poggio, Lucio Calogero, Ruggero Cevolani
The recent search for extremely efficient spark-ignition engines has implied a great increase of in-cylinder pressure and temperature levels, and knocking combustion mode has become one of the most relevant limiting factors. This paper reports the main results of a specific project carried out as part of a wider research activity, aimed at modelling and real-time controlling knock-induced damage on aluminium forged pistons. The paper shows how the main damage mechanisms (erosion, plastic deformation, surface roughness, hardness reduction) have been identified and isolated, and how the corresponding symptoms may be measured and quantified. The second part of the work then concentrates on understanding how knocking combustion characteristics affect the level of damage done, and which parameters are mainly responsible for piston failure.
2017-09-04
Technical Paper
2017-24-0039
Daniele Piazzullo, Michela Costa, Youngchul Ra, Vittorio ROCCO, Ankith Ullal
Bio-derived fuels are drawing more and more attention in the internal combustion engine (ICE) research field in recent years. Those interests in use of renewable biofuels in ICE applications derive from energy security issues and, more importantly, from environment pollutant emissions concerns. High fidelity numerical study of engine combustion requires advanced computational fluid dynamics (CFD) to be coupled with detailed chemical kinetic models. This task becomes extremely challenging if real fuels are taken into account, as they include a mixture of hundreds of different hydrocarbons, which prohibitively increases computational cost. Therefore, along with employing surrogate fuel models, reduction of detailed kinetic models for multidimensional engine applications is preferred. In the present work, a reduced mechanism was developed for primary reference fuel (PRF) using the directed relation graph (DRG) approach. The mechanism was generated from an existing detailed mechanism.
2017-09-04
Technical Paper
2017-24-0050
Anjan Rao Puttige, Robin Hamberg, Paul Linschoten, Goutham Reddy, Andreas Cronhjort, Ola Stenlaas
Improving turbocharger performance to increase engine efficiency has the potential to help meet current and upcoming exhaust legislation. One limiting factor is compressor surge, an air flow instability phenomenon capable of causing severe vibration and noise. To avoid surge, the turbocharger is operated with a safety margin (surge margin) which, as well as avoiding surge in steady state operation, unfortunately also lowers engine performance. This paper investigates the possibility of detecting compressor surge with a conventional engine knock sensor. It further recommends a surge detection algorithm based on their signals during transient engine operation. Three knock sensors were mounted on the turbocharger and placed along the axes of three dimensions of movement. The engine was operated in load steps starting from steady state. The steady state points of operation covered the vital parts of the engine speed and load range.
2017-09-04
Technical Paper
2017-24-0027
Nearchos Stylianidis, Ulugbek Azimov, Nobuyuki Kawahara, Eiji Tomita
A chemical kinetics and computational fluid-dynamics (CFD) analysis were performed to evaluate the combustion of syngas derived from biomass and coke-oven solid feedstock in a micro-pilot ignited supercharged dual-fuel engine under lean conditions. For this analysis, a new reduced syngas chemical kinetics mechanism was constructed and validated by comparing the ignition delay and laminar flame speed data with those obtained from experiments and other detail chemical kinetics analysis available in the literature. The reaction sensitivity analysis was conducted for ignition delay at elevated pressures in order to identify important chemical reactions that govern the combustion process. We found that HO2+OH=H2O+O2 and H2O2+H=H2+HO2 reactions showed very high sensitivity during high-pressure ignition delay times and had considerable uncertainty.
2017-09-04
Technical Paper
2017-24-0026
Davide Paredi, Tommaso Lucchini, Gianluca D'Errico, Angelo Onorati, Stefano Golini, Nicola Rapetto
The scope of the work presented in this paper was to apply the latest open source CFD achievements to design a state of art, direct-injection (DI), heavy-duty, natural gas-fueled engine. Within this context, an initial steady-state analysis of the in-cylinder flow was performed by simulating three different intake ducts geometries, each one with seven different valve lift values, chosen according to an estabilished methodology proposed by AVL. The discharge coefficient (Cd) and the Tumble Ratio (TR) were calculated in each case, and an optimal intake ports geometry configuration was assessed in terms of a compromise between the desired intensity of tumble in the chamber and the satisfaction of an adequate value of Cd. Subsequently, full-cycle, cold-flow simulations were performed for three different engine operating points, in order to evaluate the in-cylinder development of TR and turbulent kinetic energy (TKE) under transient conditions.
2017-09-04
Technical Paper
2017-24-0034
Michele Battistoni, Carlo N. Grimaldi, Valentino Cruccolini, Gabriele Discepoli, Matteo De Cesare
Water injection in highly boosted GDI engines has become an attractive area over the last few years as a way of increasing efficiency, enhancing performance and reducing emissions. The technology and its effects are not new, but current gasoline engine trends for passenger vehicles have several motivations for adopting this technology today. Water injection enables higher compression ratios, optimal spark timing and elimination of fuel enrichment at high load, and possibly replacement of EGR. Physically, water reduces charge temperature by evaporation, dilutes combustion, and varies the specific heat ratio of the working fluid, with complex effects. Several of these mutually intertwined aspects are investigated in this paper through CFD simulations, focusing on a turbo-charged GDI engine with port water injection. Different strategies for water injection timing, pressure and spray targeting are investigated.
2017-09-04
Technical Paper
2017-24-0017
Emanuele Servetto, Andrea Bianco, Gennaro Caputo, Giuseppe Lo Iacono
Large pressure pulsations and a non-uniform distribution of charge air temperature along the intake manifold were detected on a large-bore marine Dual-Fuel engine. These two phenomena were found to impact negatively on the knock resistance of individual cylinders, when the engine is operated in gas-mode. As it happens with marine gas engines, the cylinder most prone to knocking drives the engine tuning for all the others, thus reducing the overall fuel conversion efficiency. In order to effectively tackle this issue, a comprehensive study was carried out, which included both experimental testing and fluid-dynamics simulation. A detailed GT-POWER 1D engine model was built, representing the laboratory 8L (i.e. inline eight-cylinder) engine configuration. The model was extensively correlated against measurements at different speeds and loads and it proved capable of closely reproducing both the pressure fluctuations and the temperature gradient along the intake manifold.
2017-09-04
Technical Paper
2017-24-0015
Luigi Teodosio, Vincenzo De Bellis, Fabio Bozza, Daniela Tufano
Nowadays different technical solutions have been proposed to improve the performance of internal combustion engines, especially in terms of Brake Specific Fuel Consumption (BSFC). As known, the latter has to be reduced to comply with the CO2 emissions legislation for vehicle homologation. Concerning the Spark Ignition engines, the downsizing coupled to turbocharging demonstrated a proper effectiveness to improve the fuel economy at part load. On the other hand, at high load, the above solution highly penalizes the fuel consumption mainly because of knock onset, that obliges to degrade the combustion phasing and/or enrich the air/fuel mixture. A promising technique to cope with the above drawbacks consists in the Variable Compression Ratio (VCR) concept. An optimal CR selection, in fact, allows for further improvements of the thermodynamic efficiency at part load, while at high loads, it permits to mitigate knock propensity, resulting in an enhanced fuel economy.
2017-09-04
Technical Paper
2017-24-0162
Harald Stoffels, Jens Dunstheimer, Christian Hofmann
The application of a turbocharger, having an electric motor/generator on the rotor was studied focusing on the electric energy recuperation on a downsized gasoline internal combustion engine, using 1D-calculation approaches. Using state-of-the art optimization techniques, the settings of the valve timing was optimized to cater for a targeted pre-turbine pressure and certain level of residual gases in the combustion chamber to avoid abnormal combustion events. Subsequently, a steady-state map of the potential of electric energy recuperation was performed while considering in parallel different efficiency maps of the potential generator and a certain wastegate actuation strategy. Moreover, the results were taken as input to a WLTP cycle simulation in order to identify any synergies with regard to fuel economy.
2017-09-04
Technical Paper
2017-24-0143
Sathaporn Chuepeng, Kampanart Theinnoi, Manida Tongroon
The combustion in reactivity controlled compression ignition (RCCI) mode of diesel engine have been gained more attention as one among other strategies to increase operating range for premixed combustion and to improve fuel economy. A low reactivity fuel such as high octane number fuel, alcohol blends for example, is early fumigated (or injected) and premixed with air prior to induction to the combustion chamber. Later on adjacent to the end of the compression stroke, the diesel fuel as a high reactivity fuel is directly injected into the homogeneous pre-mixture and ignited. This can also promote lower nitrogen oxides and particulate matter emissions. The main aim of this work is to characterize the combustion phenomena and particulate matter in nano-size from the RCCI engine using neat hydrous ethanol as the low reactivity fuel.
2017-09-04
Technical Paper
2017-24-0141
Riccardo Amirante, Elia Distaso, Silvana Di Iorio, Davide Pettinicchio, Paolo Sementa, Paolo Tamburrano, Bianca Maria Vaglieco
It is common knowledge that of all the regulated automotive emissions, particulate emissions are most difficult to quantify as they comprise a complex mixture of particles of varying size and composition, each of which may be influenced by many external factors including engine technology, fuel composition, air-to-fuel ratio, lubricant oil, after-treatment and the act of measurement itself. The aim of the present work is to provide further guidance into better understanding the production mechanisms of such emissions in spark-ignition engines fueled with compressed natural gas. In particular, extensive experimental investigations were designed with the aim to isolate the contribution of the fuel from that of lubricant oil to particle emissions.
2017-09-04
Technical Paper
2017-24-0133
Jelica Pavlovic, Alessandro Tansini, Georgios Fontaras, Biagio Ciuffo, Marcos Garcia Otura, Germana Trentadue, Ricardo Suarez Bertoa, Federico Millo
Plug-in Hybrid Electric Vehicles (PHEVs) are one of the main options for reducing vehicle CO2 emissions and helping vehicle manufacturers (OEMs) to meet the CO2 targets imposed by different Governments from all around the world. In Europe OEMs have introduced a significant number of PHEV models to meet their CO2 target of 95 g/km for passenger cars set for 2021. Fuel consumption and CO2 emissions from PHEVs, however, strongly depend on the way they are used and on the frequency with which their battery is charged by the user. Studies have indeed revealed that in real life, with poor charging behavior from users, PHEV fuel consumption is equivalent to that of conventional vehicles, and in some cases higher, due to the increased mass and the need to keep the battery at a certain charging level.
2017-09-04
Technical Paper
2017-24-0114
Michel Cuijpers, Michael Golombok, Hylke Van Avendonk, Michael Boot
Recently imposed sulfur caps on shipping fuels in so-called sulfur emission control areas (SECA) are forcing shipping companies to sail on more or less automotive grade diesel in lieu of the considerably less expensive but sulfur-laden heavy fuel oil (HFO). This development is an opportunity for a bio-based substitute, given that most biomass is sulfur free by default. Cracking biomass to an HFO substitute will require both lower capital and operational expenditures - currently less viscous automotive grade fuels are the targeted product. Lower production costs should translate directly into higher profits for biorefineries. We demonstrate the principle of producing a bio-based low sulfur HFO (LSHFO) by cracking lignin - a residual phenolic polymer from cellulosic bioethanol production – with a novel subcritical solvolysis reaction in a mixture of water and ethylene glycol monobutyl ether or EGBE.
2017-09-04
Technical Paper
2017-24-0115
Martin Pechout, Jan Czerwinski, Martin Güdel, Michal Vojtisek-Lom
In this study, the combustion of butanol, neat and mixed with gasoline, was investigated on a 0.6 liter two-cylinder spark ignition engine with fully adjustable fuel injection and spark timing, coupled with an eddy current dynamometer. Two isomers of butanol, n-butanol and iso-butanol, were examined. Butanol can be produced from non-food renewable resources and is one of the fuels exploited in the search of energy security and independence and of replacement of fossil fuels. Compared to the traditionally used ethanol, butanol does not exhibit hygroscopic behaviour, is chemically less aggressive and has higher energy density. On other hand, different laminar burning velocity and higher boiling temperature of butanol, compared to gasoline, requires some countermeasures to keep the engine operation reliable and efficient.
2017-09-04
Technical Paper
2017-24-0116
Ekarong Sukjit, Pansa Liplap, Somkiat Maithomklang, Weerachai Arjharn
In this study, two oxygenated fuels consisting of butanol and diethyl ether (DEE), both possess same number of carbon, hydrogen and oxygen atom but difference functional group, were blended with the waste plastic pyrolysis oil to use in a 4-cylinder direct injection diesel engine without any engine modification. In addition, the effect of castor oil addition to such fuel blends was also investigated. Four tested fuels with same oxygen content were prepared for engine test, comprising DEE16 (84% waste plastic oil blended with 16% DEE), BU16 (84% waste plastic oil blended with 16% butanol), DEE11.5BIO5 (83.5% waste plastic oil blended with 11.5% DEE and 5% castor oil) and BU11.5BIO5 (83.5% waste plastic oil blended with 11.5% butanol and 5% castor oil). The results found that the DEE addition to waste plastic oil increased more emissions than the butanol addition at low engine operating condition.
2017-09-04
Technical Paper
2017-24-0117
Fabio Scala, Enzo Galloni, Gustavo Fontana
In this paper, the behavior of a downsized spark-ignition engine firing with alcohol/gasoline blends has been analyzed. In particular, different butanol-gasoline and ethanol-gasoline blends have been examined. All the alcohol fuels here considered are derived from biomasses. In the paper, a numerical approach has been followed. A one dimensional model has been tuned in order to simulate the engine operation when it is fueled by alcohol/gasoline mixtures. Numerous operating points, characterized by two different engine speeds and several low-medium load values, have been analyzed. The objective of the numerical analysis is determining the optimum spark advance for different alcohol percentages in the mixtures at the different engine operating points. Once the best spark timing has been selected, the differences, in terms of both indicated torque and efficiency, arising in the different kinds of fueling have been evaluated.
2017-09-04
Technical Paper
2017-24-0119
Jos Feijen, Gerard Klink, Ed Jong, Andreas Schmid, Niels Deen, Michael Boot
Second generation biomass is an attractive renewable feedstock for transport fuels. Its sulfur content is generally negligible and the carbon cycle is reduced from millions to tens of years. One hitherto non-valorized feedstock are so-called humins, a residual product formed in the conversion of sugars to platform chemicals, such as hydroxymethylfurfural and methoxymethylfurfural, intermediates in the production of FDCA, a building block used to produce the polyethylene furanoate (PEF) bottle by Avantium. The focus of this study is to investigate the spray combustion behavior of humins as a renewable alternative for heavy fuel oil (HFO) under large two-stroke engine-like conditions in an optically accessible constant volume chamber.
2017-09-04
Technical Paper
2017-24-0092
Francesco Catapano, Silvana Di Iorio, Paolo Sementa, Bianca Maria Vaglieco
Fuel depletion as well as the growing concerns on environmental issues prompt to the use of more environmental friendly fuels. The natural gas (CNG) is considered one of the most promising alternative fuel for engine applications because of the lower emissions. Nevertheless, recent studies highlighted the presence of ultrafine particle emissions at the exhaust of CNG engines. The present study aims to investigate the effect of CNG on particle formation and emissions when it was direct injected and when it was dual fueled with gasoline. The study was carried out on a transparent small displacement single cylinder SI engine. The engine was fueled with CNG and gasoline, both simultaneously and not. In particular, CNG and gasoline were direct injected in the combustion chamber. For dual fuel configuration, instead, the CNG was direct injected and the gasoline port fuel injected. In-cylinder 2D images of flame evolution were detected. The flame front propagation was calculated.
2017-09-04
Technical Paper
2017-24-0091
Hyun Woo Won, Alexandre Bouet, Joseph KERMANI, Florence Duffour
Reduce the CO2 footprint, limit the pollutant emissions and rebalance the ongoing shift demand toward middle-distillate fuels are major concerns for vehicle manufacturers and oil refiners. In this context, gasoline-like fuels have been recently identified as good candidate. Strait run naphtha, a refinery stream directly derived from the atmospheric crude oil distillation process, allows to reduce both NOx and particulate emissions when used in compression-ignition engines. CO2 benefits are also expected thanks to its higher H/C ratio and energy content compared to diesel. In previous studies, wide ranges of Cetane Number naphtha fuels have been evaluated and CN 35 naphtha fuel has been selected. The assessment and the choice of the required engine hardware adapted to this fuel, such as the compression ratio, bowl pattern, nozzle design and air-path technology have been performed on a light-duty single cylinder compression-ignition engine.
2017-09-04
Technical Paper
2017-24-0096
Laura Sophie Baumgartner, Stephan Karmann, Fabian Backes, Andreas Stadler, Georg Wachtmeister
Due to its molecular structure, methane provides several advantages as fuel for internal combustion engines. First, owing to the single carbon atom per molecule, a formation of particular matter becomes drastically more unlikely and second the carbon to hydrogen ratio of methane reduces the amount of carbon dioxide by 20 % at the same energy output. To cope with nitrogen oxide emissions a high level of excess air is beneficial, which on the other hand deteriorates the flammability and combustion duration of the mixture. One approach to meet these challenges and ensure a stable combustion process are fuel scavenged prechambers. The flow and combustion processes within these prechambers are highly influenced by the position, orientation, number and overall cross-sectional area of the orifices connecting the prechamber and the main combustion chamber.
2017-09-04
Technical Paper
2017-24-0098
Christophe Barro, Curdin Nani, Richard Hutter, Konstantinos Boulouchos
The operation of dual fuel engines, operated with natural gas as main fuel, offers the potential of substantial savings in CO2. Nevertheless, the operating map area where low pollutant emissions are produced is very narrow. Especially at low load, the raw exhaust gas contains high concentrations of unburned methane and, with high pilot fuel portions due to ignition limitations, also soot. The analysis of the combustion in those conditions in particular is not trivial, since multiple combustion modes are present concurrently. The present work focuses on the evaluation of the individual combustion modes of a dual fuel engine, operated with natural gas as main and diesel as pilot fuel, using a combustion model. The combustion has been split in two partwise concurrent combustion phases: the auto-ignition phase and the premixed flame propagation phase.
2017-09-04
Technical Paper
2017-24-0099
Francesco Catapano, Paolo Sementa, Bianca Maria Vaglieco
Gasoline direct injection (GDI) allows knock tendency reduction in spark-ignition engines mainly due to the cooling effect of the in-cylinder fuel evaporation. However, the charge formation and thus the injection timing and strategies deeply affect the flame propagation and consequently the knock occurrence probability and intensity. Present work investigates the tendency to knock of a GDI engine at 1500 rpm full load under different injection strategies, single and double injections, obtained delivering the same amount of gasoline in two equal parts, the first during intake, the second during compression stroke. In these conditions, conventional and non-conventional measurements are performed on a 4-stroke, 4-cylinder, turbocharged GDI engine endowed of optical accesses to the combustion chamber.
2017-09-04
Technical Paper
2017-24-0081
Luigi De Simio, Michele Gambino, Sabato Iannaccone
In recent years the use of alternative fuels for internal combustion engines has had a strong push coming from both technical and economic-environmental aspects. Among these, gaseous fuels such as liquefied petroleum gas and natural gas have occupied a segment no longer negligible in the automotive industry, thanks to their adaptability, anti-knock capacity, lower toxicity of pollutants, reduced CO2 emissions and cost effectiveness. On the other hand, diesel engines still represent the reference category among the internal combustion engines in terms of consumptions. The possibility offered by the dual fuel (DF) systems, to combine the efficiency and performance of a diesel engine with the advantages offered by the gaseous fuels, has been long investigated. However the simple replacement of diesel fuel with natural gas does not allow to optimize the performance of the engine due to the high THC emissions particularly at lower loads.
2017-09-04
Technical Paper
2017-24-0080
Ross Ryskamp, Gregory Thompson, Daniel Carder, John Nuszkowski
Reactivity controlled compression ignition (RCCI) is a form of dual-fuel combustion that exploits the reactivity difference between two fuels to control combustion phasing. This combustion approach limits the formation of oxides of nitrogen (NOX) and soot while retaining high thermal efficiency. The research presented herein was performed to determine the influences that high reactivity (diesel) fuel properties have on RCCI combustion characteristics, exhaust emissions, fuel efficiency, and the operable load range. A 4-cylinder, 1.9 liter, light-duty CI engine was converted to run on diesel fuel (high reactivity fuel) and compressed natural gas (CNG) (low reactivity fuel). The engine was operated at 2100 revolutions per minute (RPM), and at two different loads, 3.6 bar brake mean effective pressure (BMEP) and 6 bar BMEP.
2017-09-04
Technical Paper
2017-24-0087
Maxime Pochet, Ida Truedsson, Fabrice Foucher, Hervé Jeanmart, Francesco Contino
Ammonia and hydrogen can be produced from water, air and excess electricity using power-to-fuel and are therefore a promising step in the transition from fossil fuel energy to cleaner energy sources. Indeed, produced from excess renewable electricity these two fuels can provide mid- and long-term energy storage. An HCCI engine can be used to convert those two energy vectors to electricity and heat. The purpose of the study was to see the possible range of ammonia concentrations that could be used in a conventional 16:1 compression ratio HCCI engine. Due to the high ignition resistance of ammonia, hydrogen was used to promote and stabilize the combustion. Equivalence ratios of 0.2 to 0.3 were utilized to limit the pressure rise rate. Engine speed was kept constant at 1500 rpm at an intake pressure from 1 to 1.5 bar and with intake temperatures from 428 to 473 K.
2017-09-04
Technical Paper
2017-24-0069
Hyunwook Park, Jugon Shin, Choongsik Bae
Spray and combustion characteristics of diesel fuel were investigated in order to get a better understanding of the evaporation and combustion behavior under simulated cold-start conditions of a diesel engine. The experiment was conducted in a constant volume combustion chamber and the target ambient conditions were selected as the engine cranking. Mie scattering and shadowgraph techniques were conducted to visualize the liquid and vapor phase of the fuel under non-combustion condition (O2 concentration=0%). In-chamber pressure and direct flame visualization were acquired for spray combustion condition (O2 concentration=21%). The fuel was injected with an injection pressure of 30MPa, which is a typical value during cranking period. The liquid penetration of the fuel was increased at 573K of ambient temperature compared to that at 663K due to the poor evaporation characteristic and the increased fuel viscosity from the lower fuel temperature.
2017-09-04
Journal Article
2017-24-0118
Marius Zubel, Stefan Pischinger, Benedikt Heuser
Within the cluster of excellence “Tailor-Made Fuels from Biomass” at the RWTH Aachen University, two novel biogenic fuels, namely 1-octanol and its isomer dibutyl ether (DBE), were identified and extensively analyzed in respect of their suitability for Diesel engine combustion. Both biofuels feature very different properties, especially regarding their ignitability. In previous works of the research cluster, promising synthesis routes with excellent yields for both fuels were found, using lignocellulosic biomass as source material. Both fuels were investigated as pure components in optical and thermodynamic single cylinder engines. For 1-octanol at lower part load, almost no soot emission could be measured, while with DBE the soot emissions were only about a quarter of that with conventional Diesel fuel. At high part load, the soot reduction of 1-octanol was more than 50% and for DBE more than 80 % respectively.
2017-09-04
Technical Paper
2017-24-0059
Massimo Ferrera
The 2020+ CO2 and noxious emission limits will impose drastic technological choices. Even though in 2030 65% of road transportation vehicles will be still powered by an Internal Combustion Engine, a progressive increase of hybrids and battery electric vehicles will be confirmed. In parallel, the use of Low-Carbon Alternative Fuels, such as Natural Gas/Biomethane, will play a fundamental role in accelerating the process of de-carbonisation of the transportation sector supporting the virtuous Circular Economy. Since the nineties FCA invested in Compressed Natural Gas (CNG) powered vehicles becoming Market leader with one of the largest related product portfolios in Europe. A progressive improvement of this technology has been always pursued but, facing the next decades, a further improvement of the current CNG powertrain technology is mandatory to achieve even higher efficiency and remove residual gaps versus conventional fuels.
2017-09-04
Technical Paper
2017-24-0065
Helmut Ruhland, Thomas Lorenz, Jens Dunstheimer, Albert Breuer, Maziar Khosravi
An integral part of combustion system development for previous NA gasoline engines was the optimization of charge motion towards the best compromise in terms of full load performance, part load stability, emissions and, last but not least, fuel economy. This situation might have changed with the introduction of GTDI engines. While it is generally accepted that an increased charge motion level improves the mixture preparation of a direct injection gasoline engine, the tradeoff in terms of performance seems to become less dominant as the boosting systems of modern engines are typically sound enough to compensate the flow losses generated by the more restrictive ports. Certainly the increased boost level does not come for free. Increased charge motion generates higher pumping- and wall heat losses. Hence it is questionable and engine dependent, whether more charge motion is always better.
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