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Challenges of Hydraulic Engine Mount Development for NVH Refinement
- Technical Paper
- 2018-01-0681
- DOI: https://doi.org/10.4271/2018-01-0681
NVH refinement of passenger vehicle is essential to customer acceptance for premium or even mid-size segment passenger cars. Hydraulic engine mount is becoming common for these segments to reduce engine bounce, idle shake and noise transfer to passenger cabin. Modern layout of hydraulic mount with integrated engine-bracket and smaller size insulator has made it cost-effective to use due to reduction of cost gap from conventional elastomeric mounts. However the downsizing and complex internal structure may create some new types of noises in passenger cabin which are very difficult to identify in initial development stage.
Development and Validation of a Submodel for Thermal Exchanges in the Hydraulic Circuits of a Global Engine Model
- Technical Paper
- 2018-01-0160
- DOI: https://doi.org/10.4271/2018-01-0160
To face the current challenges of the automotive industry, there is a need for computational models capable to simulate the engine behavior under low-temperature and low-pressure conditions. Internal combustion engines are complex and have interconnected systems where many processes take place and influence each other. Thus, a global approach to engine simulation is suitable to study the entire engine performance. The circuits that distribute the hydraulic fluids -liquid fuels, coolants and lubricants- are critical subsystems of the engine. This work presents a 0D model which was developed and set up to make possible the simulation of hydraulic circuits in a global engine model. The model is capable of simulating flow and pressure distributions as well as heat transfer processes in a circuit. After its development, the thermo-hydraulic model was implemented in a physical based engine model called Virtual Engine Model (VEMOD), which takes into account all the relevant relations among subsystems. In the present paper, the thermo-hydraulic model is described and then it is used to simulate oil and coolant circuits of a diesel engine. The objective of the work is to validate the model under steady-state and transient operation, with focus on the thermal evolution of oil and coolant. For validation under steady-state conditions, 22 operating points were measured and simulated, some of them in cold environment. In general, good agreement was obtained between simulation and experiments. Next, the WLTP driving cycle was simulated starting from warmed-up conditions and from ambient temperature. Results were compared with the experiment, showing that modeled trends were close to those experimentally measured. Thermal evolutions of oil and coolant were predicted with mean errors between 0.7 °C and 2.1 °C. In particular, the warm-up phase was satisfactorily modeled.
A Study on Real Driving Emissions for India - An Experimental Approach
- Technical Paper
- 2018-01-0339
- DOI: https://doi.org/10.4271/2018-01-0339
Indian automobile industry is set to witness the biggest emission reforms of the last two decades with the implementation of BS6 emission norms from 1st April 2020 and Real Driving Emissions (RDE) from 1st April 2023. However, there are still a lot of unanswered questions regarding the test procedure of RDE for India. For India, adopting European RDE test procedure as it is may be a challenge because of the significant differences between India and Europe in terms of weather, geography, demography, road infrastructure, driving behavior and fuel quality. This paper discusses the detailed experimental results of Real Driving Emission tests analyzing after-treatment system configurations (LNT, sDPF, ufSCR) considering different scenarios such as test routes, test days, driving behavior etc. Variation in trip dynamics (Severity, Softness in driving), trip validity and normality and post-processed results are other key points of interests investigated. The overall activity provided great insights into the possible modifications which may be required for RDE test suitable to Indian conditions. The learning such derived will be of immense value for future design and development.
Symmetric Negative Valve Overlap Effects on Energy Distribution of a Single Cylinder HCCI Engine
- Technical Paper
- 2018-01-1250
- DOI: https://doi.org/10.4271/2018-01-1250
The effects of Variable Valve Timing (VVT) on Homogeneous Charge Compression Ignition (HCCI) engine energy distribution and waste heat recovery are investigated using a fully flexible Electromagnetic Variable Valve Timing (EVVT) system. The experiment is carried out in a single cylinder, 657 cc, port fuel injection engine fueled with n-heptane. Exergy analysis is performed to understand the relative contribution of different loss mechanisms in HCCI engines and how VVT changes these contributions. It is found that HCCI engine brake thermal efficiency, the Combined Heat and Power (CHP) power to heat ratio, the first and the second law efficiencies are improved with proper valve timing. Further analysis is performed by applying the first and second law of thermodynamics to compare HCCI energy and exergy distribution to Spark Ignition (SI) combustion using Primary Reference Fuel (PRF). HCCI demonstrates higher fuel efficiency and power to heat and energy loss ratios compared to SI. The results are applicable for the development of micro-CHP systems using an HCCI engine operating at a constant engine speed with varying loads.
Strategies for Meeting Phase 2 GHG and Ultra-Low NOx Emission Standards for Heavy-Duty Diesel Engines
- Technical Paper
- 2018-01-1429
- DOI: https://doi.org/10.4271/2018-01-1429
When considered along with Phase 2 GHG requirements, the proposed ARB NOx emission limit of 0.02 g/bhp-hr will be very challenging to achieve as the trade-off between fuel consumption and NOx emissions is not favorable. To meet any future ultra-low NOx emission regulation the NOx conversion efficiency during the cold start of the emission test cycles needs to be improved. In such a scenario, apart from changes in aftertreatment layout and formulation, additional heating measures will be required.
Modeling and Validation of a Roots-type Supercharger Using GT-SUITE
- Technical Paper
- 2018-01-0164
- DOI: https://doi.org/10.4271/2018-01-0164
Superchargers are engine driven positive displacement devices which increase the air mass flow into the engine, thereby leading to a better combustion efficiency. This gives an advantage of extracting more power from the same engine [
Experimental Investigation of Novel Ammonia Mixer Designs for SCR Systems
- Technical Paper
- 2018-01-0343
- DOI: https://doi.org/10.4271/2018-01-0343
Meeting Euro 6d NOx emission regulations lower than 80 mg/km for light duty diesel (60 mg/km gasoline) vehicles remains a challenge, especially during cold-start tests at which the selective catalyst reduction (SCR) system does not work because of low exhaust gas temperatures (light-off temperature around 200 °C). While several exhaust aftertreatment system (EATS) designs are suggested in literature, solutions with gaseous ammonia injections seem to be an efficient and cost-effective way to enhance the NOx abatement at low temperature. Compared to standard SCR systems using urea water solution (UWS) injection, gaseous NH3 systems allow an earlier injection, prevent deposit formation and increase the NH3 content density. However non-uniform ammonia mixture distribution upstream of the SCR catalyst remains an issue. These exhaust gas/ NH3 inhomogeneities lead to a non-optimal NOx reduction performance, resulting in higher than expected NOx emissions and/or ammonia slip. Thus, efficient mixers upstream of the SCR are crucial for the overall EATS performance. In the experimental study reported in this article, planar laser induced fluorescence (PLIF) is used to quantify mixing performance of four novel CFD optimized static mixers in an optically accessible flow bench. The variation of boundary conditions and the change of exhaust line configurations (
Autoignition of isooctane beyond RON and MON conditions
- Technical Paper
- 2018-01-1254
- DOI: https://doi.org/10.4271/2018-01-1254
The present study experimentally examines the low temperature autoignition area of isooctane within the in-cylinder pressure - in-cylinder temperature map.
Numerical and Experimental Research on Flow Resistance of Cool Medium from Heat Dissipation System for Construction Vehicles
- Technical Paper
- 2018-01-0088
- DOI: https://doi.org/10.4271/2018-01-0088
Construction vehicles own some inherent characteristics, such as low velocity, high power and following heavy heat flux et al. Aiming at decreasing flow resistance and managing airflow, a 39 ton single drum road roller from one of the biggest manufactures in China was employed as a research target to seek out the effect of air flow resistance on the performance of its heat dissipation system. For a start, a simplified 3D model of the road roller in a virtual wind tunnel was established with a commercial software, which was pre-processed in Gambit later. The radiators were set with heat exchanger boundary condition based on the analysis on the air-side elementary unit, as for the cooling fan, the experimental results in the wind tunnel were transformed into the corresponding boundary condition. Following that, a new design scheme was offered to assign the air flow inside the engine cabin, detail flow trajectories of which were introduced by velocity vector and path line acquired from the simulation results in FLUENT. At last, a field experiment was carried out to validate the correctness of the CFD simulation. The results showed that the outlet temperature of thermal fluid from the simulation could agree with experimental data over an acceptable range. The outlet temperature of coolant maintained around 78°C under the new scheme as ambient temperature was at 30°C, the assignment of air flow path could descend flow resistance, which could improve the heat dissipation performance for construction vehicles as well.
Cloud-Based Vehicle Velocity Prediction Based on Seasonal Autoregressive Integrated Moving Average Processes
- Technical Paper
- 2018-01-1178
- DOI: https://doi.org/10.4271/2018-01-1178
Intelligent transportation systems (ITSs) and advanced driver assistance systems (ADASs) are considered as key technologies for improving road safety, fuel economy and driving comfort. For various ITSs and ADASs, e.g. for energy management systems in hybrid electric vehicles and adaptive cruise control systems, the velocity prediction of the ego vehicle and the target vehicles can substantially improve the system performance and is therefore an important building block. In this paper a novel concept for cloud-based vehicle velocity prediction using seasonal autoregressive integrated moving average (SARIMA) processes is proposed. The concept relies on collecting velocity profiles and estimating SARIMA processes using the collected velocity profiles for distinct road segments in a cloud (offboard). When a vehicle enters a road segment, the SARIMA model for the road segment is transmitted from the cloud to the vehicle for velocity prediction (onboard). The actual velocity profiles are transmitted from the vehicle back to the cloud for updating the SARIMA models. For quantifying the prediction uncertainty, an analytical formulation of the prediction bounds is provided. Such an analytical formulation is essential for robust control design but not available in most existing concepts. Throughout the paper the theoretical findings are evaluated utilizing real measurement data from highway driving. Moreover, the proposed concept is compared with a concept from the literature relying on artificial neural networks. The evaluation and comparison indicate that the concept based on SARIMA processes provides a good compromise between prediction accuracy and computational effort. Particularly real-time requirements on velocity prediction in many ITSs and ADASs can be satisfied.