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.Main purpose of hydraulic mount is to provide high damping at low-frequency range (6~15 Hz) and to isolate noise transfer from combustion engine to passenger cabin within wide frequency range (15~600 Hz).This paper emphasizes on challenges and problems related to hydraulic mount development. Tuning of Hydraulic mount is required to avoid cavitation noise at low-frequency and also any abnormal noise due to hydraulic unit resonance at higher frequency. Design measures to curb NVH problems, e.g. cavitation noise, bump noise of mount stopper, resonance from…

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.…

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…

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.

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.In this paper, a physics-based model for an advanced aftertreatment system comprising of a DOC, an SDPF, a standalone SCR and an ammonia slip catalyst were calibrated against experimental data. The calibrated model was then used to evaluate various advanced aftertreatment system configurations that included the application of an electrically heated catalyst, mini-burner, fuel dosing, passive NOx adsorber and ammonia injection. The advanced aftertreatment system capable of meeting the 0.02 g/bhp-hr NOx emission limit with minimum fuel consumption penalty was then coupled to two different advanced engine models. Each of these engine models met the 2027 Phase 2…

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 [1], thereby reducing emissions and achieving a better fuel economy [2]. With emission norms getting more and more stringent, the need for boosting engine intake air becomes very important [3]. There are many types of superchargers based on design [4], out of which, the roots-type positive displacement supercharger, is discussed in here. A 1-dimensional model of supercharger gives flexibility of choosing the right aspect ratio (length to the diameter of the rotor), deciding on the clearances (a tradeoff between volumetric efficiency and manufacturing capabilities) and arriving at the inlet and discharge port dimensions. The dependency of the above parameters on mass flow rate of air and volumetric efficiency of the supercharger can be studied in good depth with a simplified one dimensional model [3]. This paper aims to present a one dimensional model of roots-type twin rotor (each 3 lobed)…

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…

The present study experimentally examines the low temperature autoignition area of isooctane within the in-cylinder pressure - in-cylinder temperature map.Experiments were run with the help of a CFR engine. The boundaries of this engine were extended so that experiments could be performed outside the domain delimited by RON and MON traces. Since HCCI combustion is governed by kinetics, the rotation speed for all the experiments was set at 600 rpm to allow time for low temperature heat release (LTHR). All the other parameters (intake pressure, intake temperature, compression ratio and equivalence ratio), were scanned, such as the occurrence of isooctane combustion.The principal results showed that LTHR for isooctane occurs effortlessly under high intake pressure (1.3 bar) and low intake temperature (25 °C). Increasing the intake temperature leads to the loss of the LTHR, and therefore to a smaller domain on the pressure-temperature trace. In such a case, the LTHR domain is restricted from 20 to 50 bar in pressure and from 600 to 850 K in temperature. By slightly decreasing the intake pressure, the LTHR…

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…

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…