Browse Topic: Retrofitting
This paper explores the potential of three different hybridization solutions for a medium-sized rotorcraft: an electric tail rotor, an "eco-mode", and a "boost-mode". The solutions were evaluated as a retrofit to a generalized medium lift rotorcraft and the impact on performance across five mission types, representative of the typical use cases for a military rotorcraft, was assessed. Two separate rotorcraft performance modelling tools were used to carry out the assessment, allowing for the results to be cross-examined. The models predicted performance gains for the eco-mode configuration when utilizing the single engine cruise capability for low-speed applications. Likewise, the models predicted improved performance for the boost-mode configuration when operating at hot and high (6,000 ft, 95°F) conditions due to the increased power provided by the battery system. However, all three solutions suffered from increased platform empty weight which negatively impacted performance at certain flight states.
This paper describes the characteristics of the Leonardo Advanced Tiltrotor Aircraft (ATA) concept, focusing on the relationship between goals, targeted improvements and enabling design features. The paper shows the design drivers such as performance, operational capabilities, and maneuverability and it describes how the attributes of the concept originated, showing trade-off and compromises approached during the genesis of the concept. The design drivers are translated into areas of interests, including download, drag, aerodynamic efficiency, rolling and yawing inertia, detectability, maintainability and engine retrofit ability. Finally, these areas are linked to the physical features of the concept, showing how they have been selected and combined to achieve the best overall benefit at platform level.
Electrification could improve full-size rotorcraft performance by reducing peak turbine power demand, reducing transmission system weight and complexity, and reducing operating costs. Integrating electric machines with mechanical powertrains requires careful consideration of the system-level weight and efficiency impacts. This paper presents an optimization framework for evaluating parallel hybrid powertrain configurations using Geometric Programming (GP). Both retrofit and clean-sheet vehicle designs are considered. The results show that high-speed electric motors integrated into a parallel hybrid configuration using batteries can reduce the sized gas turbine power, enabling more efficient engine operation at lower power levels. For retrofit designs, with a fixed vehicle gross weight, adding batteries and motors reduces usable fuel, decreasing mission capability. Clean-sheet designs offer additional flexibility to re-size the vehicle and rotor, resulting in energy savings for an equivalent design mission.
Noise transmission through the vehicle dash panel plays a critical role in isolating passengers from noise sources within the motor bay of the vehicle. Grommets that contain electrical harness routing as well as HVAC lines are examples of dash panel pass-throughs that should be selected with care. Acoustic performance of these components is generally characterized in terms of measured quantities such as noise reduction (NR), sound transmission loss (STL), and insertion loss (IL). These measurements need to be carried out per SAE or ASTM standards in appropriate anechoic or reverberant chambers as this is important for consistency. This work explores an in-situ measurement of the grommet STL performance in the vehicle environment. It utilizes a repurposed vehicle with its cabin retrofitted to serve as an anechoic chamber and its frunk acting as a reverberant chamber. Results of this in-situ measurement are then compared to measurements following industry standards to discuss the differences in results. The data is further analyzed to highlight advantages and disadvantages of this setup. The aim is to understand if this method can be used in the design & selection of pass-through grommets to provide directional input on STL performance.
Defense Innovation Unit Washington D.C. info@DIU.mil
Achieving human-level dexterity during manipulation and grasping has been a long-standing goal in robotics. To accomplish this, having a reliable sense of tactile information and force is essential for robots. A recent study, published in IEEE Robotics and Automation Letters, describes the L3 F-TOUCH sensor that enhances the force sensing capabilities of classic tactile sensors. The sensor is lightweight, low-cost, and wireless, making it an affordable option for retrofitting existing robot hands and graspers.
Electrification of transport, together with the decarbonization of energy production are suggested by the European Union for the future quality of air. However, in the medium period, propulsion systems will continue to dominate urban mobility, making mandatory the retrofitting of thermal engines by applying combustion modes able to reduce NOx and PM emissions while maintaining engine performances. Low Temperature Combustion (LTC) is an attractive process to meet this target. This mode relies on premixed mixture and fuel lean in-cylinder charge whatever the fuel type: from conventional through alternative fuels with a minimum carbon footprint. This combustion mode has been subject of numerous modelling approaches in the engine research community. This study provides a theoretical comparative analysis between multi-zone (MZ) and Transported probability density function (TPDF) models applied to LTC combustion process. The generic thermo-kinetic balances for both approaches have been analyzed in term of similarities. Only onion-skin for MZ models have been considered in this study. The governing assumptions linked to sub-models for each approach to describe mixing process for TPDF and interzonal heat and mass transport for MZ are discussed. This step identifies the calibrated model parameters for each approach and their effects on the accuracy in predicting LTC mode simulations. This work shows that the transported probability density function model has fewer parameters to calibrate compared to multi-zone model. Transported probability density function seems easier to use for LTC process.
Ultrafine particles, in particular solid sub-100 nm particles pose high risks to human health due to their high lung deposition efficiency, translocation to all organs including the brain and their harmful chemical composition; due to dense traffic, the population in urban environments is exposed to high concentrations of those toxic air contaminants, despite these facts, they are still widely neglected. Therefore, the EU-Commission set up a program for clean and competitive solutions for different problem areas which are regarded to be hotspots of such particles. HORIZON AeroSolfd is an EU project, co-funded by Switzerland that will deliver affordable, adaptable, and sustainable retrofit solutions to reduce exhaust tailpipe emissions from petrol engines, brake emissions and pollution in semi-closed environments. VERT, a Swiss based international industry organization, has a long research history in the field of nanoparticle filtration and it is in charge of reducing tailpipe emissions of gasoline vehicles by using the best available retrofit filtration technology (BAT). VERT will apply the newest high-efficient GPF technology in three high mileage fleets, in Germany, Switzerland and Israel. The project will also serve as a platform to continue research on PN emissions as well as on secondary emissions from GDI and PFI petrol engines. In addition, the “high emitter phenomena” will be further analysed with a NPTI testing campaign of 1000 gasoline vehicles, including GDI, PFI and GPF equipped vehicles.
The given invention solves the problems associated with the growing greenhouse gases and electric mobility in Indian automobile market using design-thinking approach. It addresses the issue of air pollution, lack of charging infrastructure, limited range of electric vehicles, and high cost of travelling in IC engine vehicles. The problem statement of the project is selected through the process of design thinking. Data for the project is collected from the actual segment of people. The given invention displays the plug-in hybrid electric vehicle kit. The kit retrofits the conventional fuel engine vehicle into plug-in hybrid electric vehicle. As a result, the user can drive on electric mode and when the batteries are exhausted, the user can switch to fuel engine mode. Using the given technology, users can lower the tail pipe pollutants emitted from the vehicle. By using this technology, users can save 73.74% of cost per year.
The combustion process in spark-ignition engines can vary considerably cycle by cycle, which may result in unstable engine operation. The phenomena amplify in natural gas (NG) spark-ignition (SI) engines due to the lower NG laminar flame speed compared to gasoline, and more so under lean burn conditions. The main goal of this study was to investigate the main sources and the characteristics of the cycle-by-cycle variation in heavy-duty compression ignition (CI) engines converted to NG SI operation. The experiments were conducted in a single-cylinder optically-accessible CI engine with a flat bowl-in piston that was converted to NG SI. The engine was operated at medium load under lean operating conditions, using pure methane as a natural gas surrogate. The CI to SI conversion was made through the addition of a low-pressure NG injector in the intake manifold and of a NG spark plug in place of the diesel injector. Flame luminosity images of the whole combustion event inside the piston bowl were used to analyze the major sources of cyclic variation. The optical measurements were combined with in-cylinder pressure measurements to infer the characteristics of the cycle-by-cycle variation. The results suggested that the spark intensity, arc continuity, and arc location affected the flame kernel inception. The gas motion and the mixture equivalence ratio around the spark location also influenced it. Then, the intake swirl and the turbulence during the compression stroke determined the flame propagation speed and direction. The variation in the fast burning between individual cycles compounded the cyclic variation caused by the ignition event. In addition, the reduction in flame propagation near the bowl wall decreased the cyclic variation. Moreover, the complex phenomena at the entrance of the squish region increased the cycle-by-cycle variations but it seems to not have a strong influence on the power output difference between cycles. Furthermore, the large surface-to-volume ratio in the squish region resulted in a large variation in the heat loss, then producing large differences in the flame development in the squish, which in turn affected the heat loss variation, and so on. But the COVIMEP was less than 4%, despite the extremely lean burn operation (ϕ = 0.66). It was probably due to the high turbulence intensity inside the bowl that helped with the rapid burning process inside the bowl. The strong turbulence was generated by the squish during the compression stoke. The reasonable COVIMEP suggest that the significant cycle-by-cycle variation in the burn inside the squish region had little impact on the COVIMEP. However, a large cycle-by-cycle variation in the squish burn would cause unstable CO and HC emissions, which is a concern for efficient engine operation.
The ceramic wall-flow filter has now been globally commercialized for aftertreatment systems in light-duty gasoline engine powered vehicles. This technology, known as the gasoline particulate filter (GPF), represents a durable solution for particulate emissions control. The goal of this study was to track the evolution of tailpipe particulate and gaseous emissions of a 4-cylinder gasoline turbocharged direct injected (GTDI) 2018 North American (NA) mild-hybrid light-duty SUV, from a fresh state to the 4,000-mile, EPA certification mileage level. For this purpose, a production TWC + GPF aftertreatment system designed for a China 6b-compliant variant of this test vehicle was retrofitted in place of the North American Tier 3 Bin 85 TWC-only system. Chassis dyno emissions testing was performed at predetermined mileage points with real-world, on-road driving conducted for the necessary mileage accumulation. The vehicle was tested at 0, 500, 1000, 1800, 3000, and 4000-mile points in order to characterize the evolution of tailpipe particulate emissions: particulate mass (PM), particulate number (PN), and particulate size distribution (PSD). Industry standard methods were applied throughout this study to align with future NA particulate measurements under CARB LEV III and US EPA Tier 3 standards. Correlations are presented, specific to the nature of FTP chassis testing strategy. The impact of drive cycle during the mileage accumulation for soot particulate emission capture within the GPF aftertreatment of new mild-hybrid GTDI powered vehicles is also evaluated. Tailpipe emission results showed a decrease in PM along with shifts in the particle count and size range as the vehicle accumulated mileage. Turbo out and TP gaseous emissions demonstrated trends consistent with engine and aftertreatment system break-in throughout the 4,000-mile period.
Ducted fuel injection (DFI) was tested for the first time in a heavy-duty diesel metal engine. It was implemented on a Caterpillar 2.5-liter single-cylinder heavy-duty diesel engine fitted with a common rail fuel system and a Tier 4 final production piston. Engine tests consisted of single-injection timing sweeps at A100 and C100, where rail pressure and exhaust gas recirculation (EGR) were also varied. A 6-hole fuel injector tip with 205 am orifices was used with a 130° spray angle and rail pressures up to 250 MPa. The ducts were 14 mm long, had a 2.5 mm inner diameter, and were placed 3.8 mm away from the orifice exits. The ducts were attached to a base, which in turn was attached to the cylinder head with bolts. Furthermore, alignment of the ducts and their corresponding fuel jets was accomplished. The objectives of this study were to compare performance and emissions trade-off curves for DFI and conventional diesel combustion (CDC) at high load and evaluate whether DFI could be successfully retrofitted into a production-like combustion system. Results suggest that a combustion system may need to be designed for DFI - retrofitting without base engine hardware modifications may not work. At these high load operating conditions DFI generally yielded increased PM emissions. Unburned hydrocarbons and carbon monoxide also generally increased with DFI. Fuel consumption with DFI matched CDC at some injection timing locations, but generally increased. DFI generally performed better at retarded injection timing and higher rail pressures, possibly suggesting that DFI favors lower combustion temperatures.
Diesel-powered engines are used worldwide for efficient transportation and stationary power generation. The significant drawback of a diesel engine is its harmful emissions. The stringent emission norms enforced by the different organization demands effective catalyst system to control the gaseous emissions. Diesel oxidation catalysts are the extensively used technique for diesel engines to control HC and CO emissions. Currently the catalyst in the diesel oxidation system employs precious metals such as Pt/Pd/Rh to reduce the emissions and makes the DOC system expensive. This paper presents a cost-effective catalyst prepared to employ non-noble mixed oxides of copper and nickel supported on non-conventional support (i.e.) ceria doped calcium borophosphates (Ce-SCaPB). Initially, ceramic beads (5mm X 5mm) were coated with (Ce-SCaPB) support material. Secondly, the copper and nickel salts were deposited on the Ce-SCaPB coated ceramic beads and subsequently reduced and calcined. The crystallinity and phase formation was studied using XRD technique and SEM image showed particle size ranging between 40 - 50 nm. These catalyst coated beads were loaded into the fabricated DOC reactor and was retrofitted into the tailpipe of the engine exhaust. The experimental emission testing was carried out in a single-cylinder diesel engine coupled with eddy current dynamometer. In engine testing, catalytic material are tested individually to evaluate his reduction percentage. The engine test was conducted under different engine loads (0-100%) and the emission readings were taken for each load. Uncertainty analysis is calculated for the results and the results showed a higher reduction in CO, HC and smoke emissions.
The interest of long-hauling companies about the conversion of their fleets into low-emission and fuel-efficient vehicles is growing, and retrofitting options may represent a suitable solution. Powertrain hybridization and waste heat recovery are considered among the most promising methods to further improve the fuel economy of road vehicles powered by internal combustion engines. In this article, not only the effect of retrofitting a heavy-duty truck with an electrification-oriented ORC unit or with a series hybrid system is investigated, but also the possibility of implementing both at the same time. The conventional vehicle is powered by a heavy-duty 12.6 liters diesel engine. It is shown that, despite such a large engine has high potential for waste heat recovery, on the other hand it represents a very challenging constraint when designing a hybrid retrofitting. Four powertrain options are considered: conventional vehicle (engine-only powered), waste heat recovery retrofit, hybrid retrofit, waste heat recovery+hybrid retrofit. For the hybrid powertrains, the optimal control strategy is analyzed and used as a starting point to develop an online implementable rule-based control strategy. The performance of the different powertrains have been numerically simulated over a set of driving cycles. The results show that, compared to the conventional powertrain, the hybrid retrofit allows the greatest reduction in fuel consumption (up to 17%), and the best employment of the waste heat recovery system.
The conversion of existing diesel engines to natural gas with the least amount of modifications can reduce the dependence on conventional oil and enhance national energy security. This study investigated such engine conversion using an experimental platform that consisted of a single-cylinder diesel engine modified for lean-burn natural-gas spark-ignition operation through the addition of a gas injector and a spark plug. Following steady-state experiments at several operating conditions that changed spark timing, mixture equivalence ratio, and engine speed, the experimental results suggested that the combustion phenomena in diesel engines retrofitted to lean-burn natural gas spark ignition presents significant differences compared to that in a conventional stoichiometric spark ignition engine. For example, the apparent heat release rate inferred from recorded pressure data is the addition of two separate, sequential combustion events: a fast burn inside the piston bowl and a slow event inside the squish region. To model the heat release in such converted engine, each combustion event was approximated to a Gaussian curve, with the total heat release during the engine cycle being the superimposition of the two curves. While this double-peak curve fitting might not accurately capture the physics of the combustion behaviors, it supported the investigation of two distinct combustion stages in such engines.
Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of the year and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to NG spark ignition simulated lean-combustion engine operation at low speed and medium load conditions. The work investigated three NG blends with similar lower heating value (i.e., similar energy density) but different Methane Number (MN). The results indicated that a lower MN increased flame propagation speed and thus increased in-cylinder pressure and indicated mean effective pressure. In addition, a low MN increased the thermal efficiency despite the higher heat transfer to the surroundings. Also, a higher MN reduced the nitrogen-oxides emissions but increased unburned hydrocarbons (UHC) emissions. Moreover, while UHC emissions had a similar H/C ratio as the NG, there was no correlation between the carbon monoxide emissions and the fuel H/C ratio.
The present work describes the numerical modeling of medium-speed marine engines, operating in a fumigated dual-fuel mode, i.e. with the second fuel injected in the ports. This engine technology allows reducing engine-out emissions while maintaining the engine efficiency and can be fairly easily retrofitted from current diesel engines. The main premixed fuel that is added can be a low-carbon one and can additionally be of a renewable nature, thereby reducing or even completely removing the global warming impact. To fully optimize the operational parameters of such a large marine engine, computational fluid dynamics can be very helpful. Accurately describing the combustion process in such an engine is key, as the prediction of the heat release and the pollutant formation is crucial. Auto-ignition of the diesel fuel needs to be captured, followed by the combustion and flame propagation of the premixed fuel. In this work, an approach based on tabulated kinetics has been used, to include detailed chemistry while still maintaining acceptable computation times. To allow for the modeling of a fumigated dual-fuel engine, this approach has been extended with a Coherent Flame Model (CFM), capable of tracking the premixed flame surface. This methodology has been validated for standard diesel operation, dual-fuel diesel/natural gas and diesel/methanol operation. The model has been applied under a variety of different loads, speeds, diesel substitution ratios and equivalence ratios to capture and study a large operating range. While still observing some discrepancies between certain simulations and the corresponding experiments, already a large improvement in the prediction of fumigated dual-fuel engine operation was observed with the proposed method.
Recent development in hydraulic fracking made natural gas (NG) to be a promising alternative gaseous fuel for heavy-duty diesel engines. The existing compression ignition (CI) engine can be retrofitted to NG spark ignition (SI) operation by replacing the diesel injector with a spark plug and fumigating NG into the intake manifold. However, the original diesel piston geometry (flat head and bowl-in-piston chamber) was usually retained to reduce modification cost. The goal of this study was to increase the understanding of the NG lean-burn characteristics in a diesel-like, fast-burn SI combustion chamber. The experimental platform can operate in conventional (i.e., all engine parts are metal) or in optical configuration (i.e., the stock piston and cylinder block are replaced with a see-through piston and an extended cylinder block). The optical data indicated a fast-propagated flame inside the piston bowl. However, this rapid-burning process did not shorten the combustion duration, which can be explained by an important fuel mass trapped in the squish that burned slowly during the expansion stroke. Steady-state experiments that operated at the metal engine configuration suggested that operating conditions controlled the phasing difference between inside- and outside-bowl burn processes. Advancing the spark timing can increase the phasing separation between these two combustion events to a point that a secondary peak will appear in the heat release rate. Moreover, changing the spark timing had a negligible effect on the end of combustion, probably due to the complex combustion of the charged squish. Overall, natural gas combustion in such retrofitted engines presents differences compared to that in conventional spark ignited engines.
Inaugural workshop for new AutoDrive Challenge student competition held at SAE World Headquarters. WITHOUT A PROPERLY EDUCATED engineering workforce, the road to automated vehicles could be a rocky one. Helping take the bumps out are SAE International and General Motors with AutoDrive Challenge, SAE's newest Collegiate Design Series competition now being rolled out. AutoDrive Challenge took a bold step forward this week at SAE's Pittsburgh-area headquarters with its first workshop. About 65 participating students, faculty, SAE staff and corporate sponsors met to review Year 1 Competition Rules and discuss the basic technical and safety elements involved in retrofitting a conventional car for autonomous driving.
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