Optimizing the Efficiency of Electro-Hydraulic Powertrains

2006 ◽  
Author(s):  
Alexander J. Montgomery ◽  
Andrew G. Alleyne
Keyword(s):  
Intelligent Control ◽  
Operating Conditions ◽  
Control Algorithms ◽  
Prime Mover ◽  
Ic Engine ◽  
Engine Operation ◽  
Hydrostatic Transmission ◽  
Controlled Systems ◽  
Variable Displacement ◽  
Engine Power

The evolution of the hydrostatic transmission system from mechanical systems to electronically controlled systems creates opportunity for improvements in efficiency through the use of intelligent control algorithms. In systems for which the prime mover is an internal combustion (IC) engine, overall system efficiency depends greatly on the prime mover's operating conditions. The use of variable displacement pumps can add a degree of freedom and allow engine operation to be optimized. However, this strategy requires a desired engine power value based on operating states and load references. This paper proposes a novel solution to this problem by using a dynamic engine power demand estimate to meet steady-state load demands using minimal engine power.

Numerical Prediction of CCV in a PFI Engine Using a Parallel LES Approach

2017 ◽  
Author(s):  
Muhsin M. Ameen ◽  
Mohsen Mirzaeian ◽  
Federico Millo ◽  
Sibendu Som
Keyword(s):  
Time Scale ◽  
Early Stage ◽  
Operating Conditions ◽  
Ic Engine ◽  
Engine Operation ◽  
Cyclic Variability ◽  
Eddy Simulation ◽  
Long Time ◽  
Time Required ◽  
Burn Rate

Cycle-to-cycle variability (CCV) is detrimental to IC engine operation and can lead to partial burn, misfire, and knock. Predicting CCV numerically is extremely challenging due to two key reasons. Firstly, high-fidelity methods such as large eddy simulation (LES) are required to accurately resolve the in-cylinder turbulent flowfield both spatially and temporally. Secondly, CCV is experienced over long timescales and hence the simulations need to be performed for hundreds of consecutive cycles. Ameen et al. (Int. J. Eng. Res., 2017) developed a parallel perturbation model (PPM) approach to dissociate this long time-scale problem into several shorter time-scale problems. The strategy is to perform multiple single-cycle simulations in parallel by effectively perturbing the initial velocity field based on the intensity of the in-cylinder turbulence. This strategy was demonstrated for motored engine and it was shown that the mean and variance of the in-cylinder flowfield was captured reasonably well by this approach. In the present study, this PPM approach is extended to simulate the CCV in a fired port-fuel injected (PFI) spark ignition (SI) engine. Two operating conditions are considered — a medium CCV operating case corresponding to 2500 rpm and 16 bar BMEP and a low CCV case corresponding to 4000 rpm and 12 bar BMEP. The predictions from this approach are also shown to be similar to the consecutive LES cycles. Both the consecutive and PPM LES cycles are observed to under-predict the variability in the early stage of combustion. The parallel approach slightly under-predicts the cyclic variability at all stages of combustion as compared to the consecutive LES cycles. However, it is shown that the parallel approach is able to predict the coefficient of variation (COV) of the in-cylinder pressure and burn rate related parameters with sufficient accuracy, and is also able to predict the qualitative trends in CCV with changing operating conditions. The convergence of the statistics predicted by the PPM approach with respect to the number of consecutive cycles required for each parallel simulation is also investigated. It is shown that this new approach is able to give accurate predictions of the CCV in fired engines in less than one-tenth of the time required for the conventional approach of simulating consecutive engine cycles.

On the Energy Efficiency of Dual Prime Mover Pump-Controlled Hydraulic Cylinders

2019 ◽  
Author(s):  
Petter H. Gøytil ◽  
Damiano Padovani ◽  
Michael R. Hansen
Keyword(s):  
Energy Efficiency ◽  
Operating Conditions ◽  
Prime Mover ◽  
Improve Performance ◽  
Servo Valve ◽  
System Parameters ◽  
Component Sizing ◽  
Controlled Systems ◽  
Hydraulic Cylinders ◽  
Prime Movers

Abstract This paper concerns the energy efficiency of a special class of pump-controlled hydraulic cylinders utilizing two prime movers. The performance of such circuits has been studied previously motivated by their capability of providing an actuator stiffness similar to that of servo valve-controlled systems. This characteristic may improve performance and robustness in applications requiring feedback control. In this paper, the presence of losses similar to that of fluid throttling, in the sense that they occur even in the absence of component inefficiencies, are demonstrated for such circuits and shown to degrade the overall energy efficiency of the system. The conditions under which such losses occur are derived analytically as a function of system parameters and operating conditions and two solutions for their elimination are proposed and verified analytically and numerically. Several implementation options are compared in terms of energy efficiency and component sizing and benchmarked to a conventional servo valve solution. It is shown that with the appropriate implementation, an energy efficiency up to ten times greater than that of a conventional servo valve system may be expected.

scholarly journals Investigation of Valve Tip End Wear Mechanism of a Four-Cylinder Automotive Engine Under High-Speed Application

2021 ◽  
Author(s):  
Yashkumar Gandhi ◽  
Ninad Pawar ◽  
Nanasaheb Zoal ◽  
Gurunathan Ramnathan
Keyword(s):  
Surface Roughness ◽  
Wear Mechanism ◽  
High Speed ◽  
Development Stage ◽  
Operating Conditions ◽  
Fatigue Wear ◽  
Ic Engine ◽  
Engine Operation ◽  
Automotive Engine ◽  
Worn Surfaces

AbstractThis work investigates the causes of wear occurring at the engine valve tip end after 400 hours of engine operation. Fatigue wear was observed on the valve tip at the product development stage of the engine, which is going to be used in an automotive vehicle. Valves were assembled on a gasoline/CNG fuel-based four-cylinder IC engine. In this engine, tip end wear was prominent during high-speed testing conditions as compared to other types of engine tests. The chemical composition of worn surfaces was verified by spectroscopy. The microstructures, grain sizes and surface roughness were determined by optical microscopy and surface roughness tester. To evaluate the wear mechanism, valve tip end worn surfaces were analyzed using Scanning electron microscopy. The SEM analysis indicates the initiation of micropits and subsequent propagation of the fatigue wear during engine operating conditions. The residual stresses were measured at valve tip end surfaces and subsurfaces using X-ray diffraction techniques. Several investigations employing multiple techniques were carried out to identify the root cause of failure while comparing results against those of untested valves. Parameters that can affect valve tip end properties were identified in the study and countermeasures provided, and that lead to successful completion of the testing with the same operating condition.

Methodologies to Compare IC Engine Power Assembly Interface Materials

2018 ◽  
Author(s):  
M R Sridhar ◽  
K A Harsha ◽  
Savio Sebastian ◽  
Souvik Math
Keyword(s):  
Ic Engine ◽  
Interface Materials ◽  
Engine Power

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jinlong Liu ◽  
Hemanth Kumar Bommisetty ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Cycle Variation ◽  
Spark Timing ◽  
Ci Engines

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

High-efficiency hybrid PV-TEG system with intelligent control to harvest maximum energy under various non-static operating conditions

2021 ◽  
pp. 128643
Author(s):  
Adeel Feroz Mirza ◽  
Majad Mansoor ◽  
Kamal Zerbakht ◽  
Muhammad Yaqoob Javed ◽  
Muhammad Hamza Zafar ◽  
...  
Keyword(s):  
Intelligent Control ◽  
High Efficiency ◽  
Maximum Energy ◽  
Operating Conditions

Ethers and esters as alternative fuels for internal combustion engine: A review

2021 ◽  
pp. 146808742110464
Author(s):  
Yang Hua
Keyword(s):  
Alternative Fuels ◽  
Combustion Engine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Engine Performance ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Future Research ◽  
Particulate Emissions ◽  
Ic Engine

Ether and ester fuels can work in the existing internal combustion (IC) engine with some important advantages. This work comprehensively reviews and summarizes the literatures on ether fuels represented by DME, DEE, DBE, DGM, and DMM, and ester fuels represented by DMC and biodiesel from three aspects of properties, production and engine application, so as to prove their feasibility and prospects as alternative fuels for compression ignition (CI) and spark ignition (SI) engines. These studies cover the effects of ether and ester fuels applied in the form of single fuel, mixed fuel, dual-fuel, and multi-fuel on engine performance, combustion and emission characteristics. The evaluation indexes mainly include torque, power, BTE, BSFC, ignition delay, heat release rate, pressure rise rate, combustion duration, exhaust gas temperature, CO, HC, NOx, PM, and smoke. The results show that ethers and esters have varying degrees of impact on engine performance, combustion and emissions. They can basically improve the thermal efficiency of the engine and reduce particulate emissions, but their effects on power, fuel consumption, combustion process, and CO, HC, and NOx emissions are uncertain, which is due to the coupling of operating conditions, fuel molecular structure, in-cylinder environment and application methods. By changing the injection strategy, adjusting the EGR rate, adopting a new combustion mode, adding improvers or synergizing multiple fuels, adverse effects can be avoided and the benefits of oxygenated fuel can be maximized. Finally, some challenges faced by alternative fuels and future research directions are analyzed.

Marine Gas Turbine Performance Model for More Electric Ships

2011 ◽  
Author(s):  
George M. Koutsothanasis ◽  
Anestis I. Kalfas ◽  
Georgios Doulgeris
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Diesel Engines ◽  
Gas Turbines ◽  
Electric Propulsion ◽  
Operating Conditions ◽  
Prime Mover ◽  
Creep Life ◽  
Hull Fouling ◽  
Turbine Performance

This paper presents the benefits of the more electric vessels powered by hybrid engines and investigates the suitability of a particular prime-mover for a specific ship type using a simulation environment which can approach the actual operating conditions. The performance of a mega yacht (70m), powered by two 4.5MW recuperated gas turbines is examined in different voyage scenarios. The analysis is accomplished for a variety of weather and hull fouling conditions using a marine gas turbine performance software which is constituted by six modules based on analytical methods. In the present study, the marine simulation model is used to predict the fuel consumption and emission levels for various conditions of sea state, ambient and sea temperatures and hull fouling profiles. In addition, using the aforementioned parameters, the variation of engine and propeller efficiency can be estimated. Finally, the software is coupled to a creep life prediction tool, able to calculate the consumption of creep life of the high pressure turbine blading for the predefined missions. The results of the performance analysis show that a mega yacht powered by gas turbines can have comparable fuel consumption with the same vessel powered by high speed Diesel engines in the range of 10MW. In such Integrated Full Electric Propulsion (IFEP) environment the gas turbine provides a comprehensive candidate as a prime mover, mainly due to its compactness being highly valued in such application and its eco-friendly operation. The simulation of different voyage cases shows that cleaning the hull of the vessel, the fuel consumption reduces up to 16%. The benefit of the clean hull becomes even greater when adverse weather condition is considered. Additionally, the specific mega yacht when powered by two 4.2MW Diesel engines has a cruising speed of 15 knots with an average fuel consumption of 10.5 [tonne/day]. The same ship powered by two 4.5MW gas turbines has a cruising speed of 22 knots which means that a journey can be completed 31.8% faster, which reduces impressively the total steaming time. However the gas turbine powered yacht consumes 9 [tonne/day] more fuel. Considering the above, Gas Turbine looks to be the only solution which fulfills the next generation sophisticated high powered ship engine requirements.

scholarly journals Repair and maintenance costs of 4WD tractors and self propelled combine harvesters in Italy

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Aldo Calcante ◽  
Luca Fontanini ◽  
Fabrizio Mazzetto
Keyword(s):  
Cost Estimation ◽  
Working Hours ◽  
The United States ◽  
Operating Conditions ◽  
List Price ◽  
Optimal Time ◽  
Model Parameters ◽  
Maintenance Costs ◽  
Combine Harvesters ◽  
Engine Power

Purchasing and maintaining tractors and operating machines are two of the most considerable costs of the agricultural sector, which includes farm equipment manufacturers, farm contractors and farms. In this context, repair and maintenance costs (R&M costs) generally constitute 10-15% of the total costs related to agricultural equipment and tend to increase with the age of the equipment; hence, an important consideration in farm management is the optimal time for equipment replacement. Classical, R&M cost estimation models, calculated as a function of accumulated working hours, are usually developed by ASAE/ASABE for the United States operating conditions. However, R&M costs are strongly influenced by farming practices, operative conditions, crop and soil type, climatic conditions, etc. which can be specific for individual countries. In this study, R&M cost model parameters were recalculated for the current Italian situation. For this purpose, data related to the R&M costs of 100 4WD tractors with engine power ranging from 59 to 198 kW, and of 20 SP combine harvesters (10 straw walkers combines and 10 axial flow combines) with engine power ranging from 159 to 368 kW working in Italy were collected. According to the model, which was obtained by interpolating the data through a two-parameter power function (proposed by ASAE/ASABE), the R&M cost incidence on the list price of Italian tractors at 12,000 working hours (estimated life of the machines) was 48.6%, as compared with 43.2% calculated through the most recent U.S. model while, for self propelled combine harvesters, the R&M cost incidence at 3,000 working hours was 23.1 % as compared with 40.2% calculated through the same U.S. model.

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