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Numerical Study of the Maximum Impact on Engine Efficiency When Insulating the Engine Exhaust Manifold and Ports During Steady and Transient Conditions

Universitat Politècnica de València-Alberto Broatch, Pablo Olmeda, Jaime Martin, Amin Dreif
  • Technical Paper
  • 2020-37-0002
To be published on 2020-06-23 by SAE International in United States
In the present work, a study about the impact on engine performance, fuel consumption and turbine inlet and outlet temperatures adding thermal insulation to the exhaust ports, manifold and pipes before the turbocharger of a 1.6L Diesel engine is presented. First, a 0D/1D model of the engine was developed and thoroughly validated by means of an extensive testing campaign. The validation was performed by means of steady state or transient running conditions and in two different room temperatures: 20ºC and -7ºC d. Once the validation was complete, in order to quantify the significance of adding thermal isolations, the simulations were performed setting the exhaust air path before the turbine as adiabatic. This is evaluated the maximum gain of the technology. Results showed that the thermal insulation proved to have a great potential in regard to T4 increase since this would reduce the warm up time of the aftertreatment systems. However, its impact on engine efficiency was limited in both steady and transient conditions.
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A Novel Option for Direct Waste Heat Recovery From Exhaust Gases of Internal Combustion Engines

Universita degli Studi dell Aquila-Davide Di Battista, Roberto Cipollone PhD, Roberto Carapellucci PhD
  • Technical Paper
  • 2020-37-0004
To be published on 2020-06-23 by SAE International in United States
Among the different opportunities to save fuel and reduce Co2 emissions from internal combustion engines, great attention has been done on the waste heat recovery: the energy wasted is, in fact, almost two thirds of the energy input and even a partial recovery into mechanical energy is really promising . Usually, thermal energy recovery has been referred to a direct heat recovery (furtherly expanding the gases expelled by the engine thanks to their high pressure and temperature) or an indirect one (using the thermal energy of the exhaust gases – or of any other thermal streams discharged into the atmosphere – as upper source of a conversion power unit which favour a thermodynamic cycle of a working fluid ). Limiting the attention to the exhaust gases, a novel opportunity can be represented by directly exploiting the residual pressure and temperature of the flue gases through an Inverted Brayton cycle (IBC), in which the gases are expanded at a pressure below the environmental one, cooled down and then recompressed to the environmental pressure. Considering the thermodynamic…
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Study of Friction Reduction Potential in Light- Duty Diesel Engines by Lightweight Crankshaft Design Coupled with Low Viscosity Oil

General Motors-Salvatore Mafrici
  • Technical Paper
  • 2020-37-0006
To be published on 2020-06-23 by SAE International in United States
Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with more stringent homologation cycles and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystem has been one of the most important topics of modern Diesel engine development. The present paper analyzes the crankshaft potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of crankshaft design itself and oil viscosity characteristics (including new ultra-low-viscosity formulations already discussed in SAE Paper 2019-24-0056). For this purpose, a combination of theoretical and experimental tools have been used to design an extremely lightweight crankshaft and to evaluate the effects of main and conrod bearings dimensioning, clearances and oil viscosity, considering not only the impact from a friction perspective but also from a structural and…
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Ammonia Measurement Investigation Using Quantum Cascade Laser and Two Different Fourier Transform Infrared Spectroscopy Methods

Caterpillar UK Ltd-Richard Barrett, Jim Baxter
Loughborough university-Nilton Li, Ashraf El-Hamalawi
  • Technical Paper
  • 2020-01-0365
To be published on 2020-04-14 by SAE International in United States
Most diesel engine exhausts have been fitted with SCR (Selective Catalyst Reduction) in order to reduce NOX (Oxides of Nitrogen) by using NH3 (ammonia). However, both NOX and NH3 have been classified as compounds hazardous for the environment and human health. If the reaction between NOX and NH3 is unbalanced during treatment, it can lead to either NOX or NH3 being released into the environment. Accurate measurement is thus necessary. QCL (Quantum Cascade Laser) and FTIR (Fourier Transform InfraRed) are two methods that have been used to measure NH3 and NOX directly in diesel engine exhausts. However, only a few studies have compared those two methods of NH3 measurement, mainly from diesel engine exhausts. The aim of this paper is to compare the QCL and 2 different FTIR specifications for NH3 measurement directly from diesel engine exhausts under well-controlled laboratory conditions. Researchers have found that as NH3 is reactive, it is absorbed inside the exhaust pipe if the probe location is some distance away from the SCR. The results reported here contradict this and show…
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Real-Time Embedded Models for Simulation and Control of Clean and Fuel-Efficient Heavy-Duty Diesel Engines

Daimler Trucks North America-Marc Allain, Siddharth Mahesh
University of Michigan-Saravanan Duraiarasan, Rasoul Salehi, Fucong Wang, Anna Stefanopoulou
  • Technical Paper
  • 2020-01-0257
To be published on 2020-04-14 by SAE International in United States
The ever increasing demand for fuel economy and stringent emission norms drives researchers to continuously innovate and improve engine modes to implement adaptive algorithms, where the engine states are continuously monitored and the control variables are manipulated to operate the engine at the most efficient regime. This paper presents a virtual engine developed by modeling a modern diesel engine and aftertreatment which can be used in real-time on a control unit to predict critical diesel engine variables such as fuel consumption and feed gas conditions including emissions, flow and temperature. A physics-based approach is followed in order to capture vital transient airpath and emission dynamics encountered during real driving condition. A minimal realization of the airpath model is coupled with a cycle averaged NOx emissions predictor to estimate transient feed gas NOx during steady state and transient conditions. The complete airpath and NOx emission model was implemented on a rapid prototyping controller and experimentally validated over steady state and transient emission cycles. The overall performance of the reduced order model was comparable to that of…
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Investigation of Diesel/Natural Gas RCCI Combustion Using Multiple Reaction Mechanisms at Various Engine Operating Conditions

FEV North America Inc.-Mufaddel Dahodwala, Satyum Joshi, Erik Koehler, Michael Franke, Dean Tomazic
Michigan Technological University-Jeffrey Naber
  • Technical Paper
  • 2020-01-0801
To be published on 2020-04-14 by SAE International in United States
Past experimental studies conducted by the current authors on a 13 liter 16.7:1 compression ratio heavy-duty diesel engine have shown that diesel /natural gas Reactivity Controlled Compression Ignition (RCCI) combustion targeting low NOx emissions becomes progressively difficult to control as the engine load is increased due to difficulty in controlling reactivity levels at higher loads. For the current study, CFD investigations were conducted using the SAGE combustion solver in Converge with the application of Rahimi mechanism. Studies were conducted at a load of 5 bar BMEP to validate the simulation results against RCCI test data. In the low load study, it was found that the Rahimi mechanism was not able to predict the RCCI combustion behavior for diesel injection timings advanced beyond 30bTDC. This behavior was found at multiple engine speed and load points. To resolve this, multiple reaction mechanisms were evaluated and a new reaction mechanism that combines the GRI Mech 3.0 mechanism with the Chalmers mechanism was proposed. This mechanism was found to accurately predict the ignition delay and combustion behavior with early…
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Experimental Study on Thermal Management Strategy of the Exhaust Gas of a Heavy-Duty Diesel Engine Based on In-Cylinder Injection Parameters

Tongji University-Piqiang Tan, Lishuang Duan, Erfeng Li, Zhiyuan Hu, Diming Lou
  • Technical Paper
  • 2020-01-0621
To be published on 2020-04-14 by SAE International in United States
The aftertreatment system is indispensable for the removal of the noxious pollutants emitted by diesel engines, whose efficiency depends largely on the exhaust gas temperature. Therefore, this study proposes a thermal management strategy including post injection, intake throttling and late post injection to improve the efficiency of the aftertreatment system for a heavy-duty diesel engine. In the experiments, the effects of main injection, post injection, injection pressure and throttle opening on the exhaust gas temperature at diesel oxidation catalyst (DOC) inlet were studied, with the influence of late post injection on the exhaust gas temperature at DOC outlet also investigated. The results showed that the reasonable control of throttle opening and post injection (such as the adjustment of injection timing and injection quantity) can significantly improve the average temperature at DOC inlet from 237.8°C to 333.6°C in the WHTC, with an increase of 40.3%. On the contrary, the influence of main injection timing on the temperature at DOC inlet was very limited, and reducing injection pressure can slightly raise the temperature at DOC inlet, which,…
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A Holistic Approach to Develop a Modern High Power Density Diesel Engine to Meet Best-in-class NVH levels.

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration and harshness (NVH) levels. This papers presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4 cylinder diesel engine. The base engine architecture was designed with NVH reduction features such as crank-offset, cast iron crankcase, stiffened ladder frame, structural oil pan and front cover. Piston skirt profile was optimized to reduce the slapping noise by carefully studying the secondary motion and skirt contact pressure. The plastic parts such as cylinder head cover and intake manifold were designed with closely spaced ribs and high wall thickness. Natural frequency targets for different parts were set for the entire engine at component level and system level and confirmed through simulations. High frequency acoustic simulation was carried out to identify and improve the areas of high surface velocity. "Acoustic holography" technology was extensively used to identify the areas of high noise radiation in the running engine. Based on the measurements, it was identified…
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Experimental and Numerical Assessment of Active Pre-chamber Ignition in Heavy Duty Natural Gas Stationary Engine

Istituto Motori CNR-Gessica Onofrio, Carlo Beatrice
Lund University-Changle Li, Pablo Garcia Valladolid, Per Tunestal
  • Technical Paper
  • 2020-01-0819
To be published on 2020-04-14 by SAE International in United States
Gas engines (fuelled with CNG, LNG or Biogas) for generation of power and heat are, to this date, taking up larger shares of the market with respect to diesel engines. In order to meet the limit imposed by the TA-Luft regulations on heavy duty engines, lean combustion represents a viable solution for achieving lower emissions as well as efficiency levels comparable with diesel engines. Leaner mixtures however affect the combustion stability as the flame propagation velocity and consequently heat release rate are slowed down. As a strategy to deliver higher ignition energy, an active pre-chamber may be used. This work focuses on assessing the performance of two pre-chambers with different nozzle orifice diameters, in a stationary heavy-duty engine for power generation, operating at different loads, equivalence ratios and spark timings. The engine was originally a 6-cylinder compression ignition engine which is here employed as a single cylinder engine and then suitably modified to host the pre-chamber (with its natural gas injection system and spark plug) with a new bowl piston to decrease compression ratio. A…
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Effect of Split Injection and Intake Air Humidification on Combustion and Emission Characteristics of a Marine Diesel Engine in Partially Premixed Low-Temperature Combustion Mode

Tianjin University-Yujie Cai, Ke Wang, Shiru Kong, Zhishang Bian
  • Technical Paper
  • 2020-01-0298
To be published on 2020-04-14 by SAE International in United States
The objective of this study was to investigate combined effects of split injection strategies and intake air humidification on combustion and emissions of a partially premixed charge compression ignition (PCCI) marine diesel engine. In this research, a three-dimensional numerical model was established by a commercial code AVL-Fire to explore in-cylinder combustion process and pollutant formation factors in a four-stoke supercharged intercooled marine diesel engine under partial load at 1350 r/min. The novelty of this study is to combine different water-fuel ratios and fuel injection parameters (pilot injection timing and main injection timing) to find the optimized way to improve engine performance as well as NOx-soot emissions, thus meeting the increasingly stringent emissions restriction. The results indicate that as the main injection timing advances (-14°CA to -20°CA aTDC), the in-cylinder peak pressure increases by about 10%, the main injection ignition delay (MI ignition delay) becomes longer, the CA50 is advanced near the top dead center (TDC), which is effective to improve the indicated thermal efficiency (ITE). Meanwhile, soot emissions are reduced by about 50% compared with…