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This experimental study investigates the thermal behavior of a 48V lithium-ion battery (LIB) pack comprising three identical modules, each containing 12 prismatic LIB cells. The objective is to investigate the thermal performance of the LIB pack under real-world operating conditions using a worldwide harmonized light duty test cycle and its inverted version. Two cases are tested whose difference is the initial state of charge (SOC), 90% for Case1 and 60% for Case2. The temperature distribution within the battery pack and cooling system is measured using 27 thermocouples. The results show that external surfaces exhibit the lowest temperatures, while the middle cells experience the highest. In addition, an abnormal temperature spike in a specific cell shows external influences or internal irregularities of the LIB cell, emphasizing the need to utilize a high number of thermocouples. Comparing Case1 and Case2, Case2 demonstrates a higher temperature rise at the cycle's beginning.

Gasoline Full Hybrid Electric Vehicles (FHEVs) are considered among good candidates as cost-effective solution to comply with upcoming emissions legislation. However, several studies have highlighted that frequent start-and-stops worsen the hydrocarbon tailpipe emissions, especially when the light-off temperature of the three-way catalyst (TWC) has not been reached. In fact, strategies only addressing the minimization of fuel consumption tend to delay engine activation and hence TWC warming, especially during urban driving. Goal of the present research is therefore to develop an on-line powertrain management strategy accounting also for TWC temperature, in order to reduce the time needed to reach TWC light-off temperature. A catalyst model is incorporated into the model of the powertrain where torque-split is performed by an adaptive equivalent consumption minimization strategy (a-ECMS).

1 Nowadays, In-Cylinder Pressure Sensors (ICPS) have become a mainstream technology that promises to change the way the engine control is performed. Among all the possible applications, the prediction of raw (engine-out) NOX emissions would allow to eliminate the NOX sensor currently used to manage the after-treatment systems. In the current study, a semi-physical model already existing in literature for the prediction of engine-out nitric oxide emissions based on in-cylinder pressure measurement has been improved; in particular, the main focus has been to improve nitric oxide prediction accuracy when injection timing is varied. The main modification introduced in the model lies in taking into account the turbulence induced by fuel spray and enhanced by in-cylinder bulk motion.

The incoming RDE regulation and the on-board diagnostics -OBD- pushes the research activity towards the set-up of a more and more efficient after treatment system. Nowadays, the most common after treatment system for NOx reduction is the selective catalytic reduction -SCR- . This system requires as an input the value of engine out NOx emission -raw- in order to control the Urea dosing strategy. In this work, an already existing grey box NOx raw emission model based on in-cylinder pressure signal (ICPS) is validated on two standard cycles: MNEDC and WLTC using an EU6 engine at the test bench. The overall results show a maximum relative error of the integrated cumulative value of 12.8% and 17.4% for MNEDC and WLTC respectively. In particular, the instantaneous value of relative error is included in the range of ± 10% in the steady state conditions while during transient conditions is less than 20% mainly.

The strategies adopted to control the combustion in Diesel applications play a key role when dealing with current and future requirements of automotive market for Diesel powertrain systems. The traditional “open loop” control approach aims to achieve a desired combustion behaviour by indirect manipulation of the system boundary conditions (e.g. fresh air mass, fuel injection). On the contrary, the direct measurement of the combustion process, e.g. by means of in-cylinder pressure sensor, offers the possibility to achieve the same target “quasi” automatically all over the vehicle lifetime in widely different operating conditions. Beside the traditional combustion control in closed loop (i.e. based on inner torque and/or combustion timing), the exploitation of in-cylinder pressure signal offers a variety of possible further applications, e.g. smart detection of Diesel fuel quality variation, control of combustion noise, modeling engine exhaust emission (e.g. NOx).

An analytical methodology to efficiently evaluate design alternatives in the conversion of a Common Rail Diesel engine to either CNG dedicated or dual fuel engine has been presented in a previous investigation. The simulation of the dual fuel combustion was performed with a modified version of the KIVA3V code including a modified version of the Shell model and a modified Characteristic Time Combustion model. In the present investigation, this methodology has been validated at two levels. The capability of the simulation code in predicting the emissions trends when changing pilot specification, like injected amount, injection pressure and start of injection, and engine configuration parameters, like compression ratio and axial position of the diesel injector has been verified. The second validation was related to the capability of the proposed computer-aided procedure in finding optimal solutions in a reduced computational time.

The effects of several operating parameters on dual fuel combustion at light load were investigated by means of direct endoscopic observation of the process. Therefore, an intense experimental campaign was performed on a single cylinder diesel common rail research engine, converted to operate in dual fuel mode and equipped with optical accesses and variable intake configuration. Three bulk flow structures of the charge were induced inside the cylinder by activating/deactivating the two different inlet valves of the engine (i.e. swirl and tumble). Methane was injected into the inlet manifold at different pressure levels and varying the injector position. In order to obtain a stratified-like air-methane mixture, the injector was mounted very close to the inlet valve, while, to obtain a homogeneous-like one, methane was injected more upstream.

In order to study the effects of air bulk motion and methane injection strategies on the development and pollutant levels of dual-fuel combustion, an intense experimental campaign was performed on a diesel common rail research engine with variable inlet configurations. Activating only the swirl or the tumble inlet valve of the engine, or both of them, it was possible to obtain, inside the cylinder, three different bulk flow structures. The air-methane mixture was obtained injecting the gaseous fuel into the inlet manifold varying its pressure and the injector position, either very close to the inlet valves, in order to obtain a stratified-like mixture, or more upstream, to obtain a homogeneous-like mixture. By combining the two different positions of the injector and the three air bulk flow structures, seven different inlet setup have been tested, at different values of engine speed and load.

The maintenance on condition is gaining more and more importance in the field of vehicle pool management. A crucial role in the vehicle maintenance is covered by the changing of the lubricating oil of the gearbox, the differential and the engine. In the lubricating oil different substances dissolve: metal traces from the mechanical parts as well as soot and fuel traces from the leakages unavoidably present in the moving parts of the engine. As well known, the oil loses its lubricating characteristics according to the content of the above contaminants. The aim of the present work is therefore to test a new sensors array whose function is to reveal the diesel fuel content in the lubricating oil. The array consists of different gas microsensors based on different metal oxide thin films deposited by sol-gel technique on silicon substrates.

It is well established that the combustion development and the consequent pollutant emissions in a Diesel engine depend on the fuel spray characteristics. Nowadays, many new injection strategies are being tested, in order to improve the diesel combustion efficiency and so to reduce its environmental impact in terms of pollutant emissions and fuel consumption. Many works have proved that NOx, THC, CO and particulate levels emitted from a Diesel engine, as well as specific fuel consumption, depend, for a given engine speed and load, upon the parameters characterizing any particular injection strategy. Despite the extensive experimental activity analyzing the effects of the previous control parameters on the engine emission and fuel consumption levels, very few are the works dealing with the effect of the same parameters on the fuel spray, and in particular on the droplet dimension distribution. The aim of this work is therefore to study these effect.

The instantaneous power carried out by the frequency components of the in-cylinder pressure results from the rate of energy released during the whole development, and in particular the first stage, of the Diesel combustion. On the other hand, the non-linear pressure fluctuations, caused by the steeped fronted waves that develop after the mixture ignition, characterize predominantly the first stage of the combustion development in Diesel engines. These pressure waves are transmitted to the engine block and then to its surface according to the block damping characteristics. The aim of the present work is then to analyze in detail the relation existing between the block vibration signal and the in-cylinder pressure, and, in this way, to monitor continously the behaviour and the quality of the combustion. Therefore, a series of experiments has been performed on a direct injection common rail Diesel engine, varying the combustion characteristics.

The present work deals with tests on a DI Diesel engine equipped with two different types of Common Rail injectors, the second one allowing a “smoother” fuel rate in the first stage of injection. The work aims at understanding how injection parameters and different injection rates may affect the combustion process in terms of in-cylinder pressure, noise and vibrations of the engine block. The tests performed for the same engine torque generally showed that engine speed, injection pressure and pilot injection duration are the most significant parameters that affect engine noise emissions. As regards the injection rate modulation, experiments showed that it is possible to reduce combustion noise at low engine speeds if the initial rate of injection is lower during the first stage of injection.

The influence of some injection parameters (as main injection timing, pilot injection timing, pilot injection duration) on noise emissions and combustion noise level of a Diesel engine has been evaluated. The noise emissions of an in-line, four cylinder, turbocharged FIAT 1929 cm3 TDI engine were measured using an ambient microphone and accelerometers. The injection system of the engine used was the high-pressure Common Rail system. The experimental results were elaborated using an ANOVA (analysis of variance) technique, to evaluate the influence of the control parameters on the controlled ones. Moreover, a multi-layer neural network was used to predict noise emissions and vibration level. It was found that the accelerometer mounted on the top of the engine bolt, which clamped the head of the cylinder to the crankcase, gave the best coherence of the results.