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Intake noise has become one the main concerns in the design of highly-supercharged downsized engines, which are expected to play a significant role in the upcoming years. Apart from the low frequencies associated with engine breathing, in these engines other frequency bands are also relevant which are related to the turbocharger operation, and which may radiate from the high-pressure side from the compressor outlet to the charge air cooler. Medium frequencies may be controlled with the use of different typologies of resonators, but these are not so effective for relatively high frequencies. In this paper, the potential of the use of multi-layer porous materials to control those high frequencies is explored. The material sheets are located in the side chamber of an otherwise conventional resonator, thus providing a compact, lightweight and convenient arrangement.

It is challenging to develop highly efficient and clean engines while meeting user expectations in terms of performance, comfort, and drivability. One of the critical aspects in this regard is combustion noise control. Combustion noise accounts for about 40 percent of the overall engine noise in typical turbocharged diesel engines. The experimental investigation of noise generation is difficult due to its inherent complexity and measurement limitations. Therefore, it is important to develop efficient numerical strategies in order to gain a better understanding of the combustion noise mechanisms. In this work, a novel methodology was developed, combining computational fluid dynamics (CFD) modeling and genetic algorithm (GA) technique to optimize the combustion system hardware design of a high-speed direct injection (HSDI) diesel engine, with respect to various emissions and performance targets including combustion noise.

Traditionally, combustion noise in Diesel engines has been quantified by means of a global noise level determined in many cases through the estimation of the attenuation curve of the block using the traditional discrete Fourier transform technique. In this work, the wavelet transform is used to establish a more reliable correlation between in-cylinder pressure (sources) and noise (effect) during the combustion of a new generation 2 liter DI Diesel engine. Then, in a qualitative sense, the contribution of each source intrinsic to the combustion process is determined for four engine operating conditions and two injection laws. The results have shown high variations in both the in-cylinder pressure and noise power harmonics along the time, which indicates the non-stationary character of this process.

Compared to the gasoline engine, the diesel engine has the advantage of being more efficient and hence achieving a reduction of CO₂ levels. Unfortunately, particulate matter (PM) and nitrogen oxides (NOx) emissions from diesel engines are high. To overcome these drawbacks, several new combustion concepts have been developed, including the PCCI (Premixed Charge Compression Ignition) combustion mode. This strategy allows a simultaneous reduction of NOx and soot emissions through the reduction of local combustion temperatures and the enhancement of the fuel/air mixing. In spite of PCCI benefits, the concept is characterized by its high combustion noise levels. Currently, a promising way to improve the PCCI disadvantages is being investigated. It is related with the use of low cetane fuels such as gasoline and diesel-gasoline blends.

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.

In this paper, a numerical model is used to study the influence of several relevant parameters on the behaviour of a turbocharged Diesel engine as an exhaust noise source, with two main objectives: first, determine if it is possible to reduce exhaust noise at the source itself, thus simplifying the task of exhaust system design; and secondly, to asses up to which extent simple linear source models may be used to predict exhaust noise in these engines. The results obtained indicate that, on the one hand, exhaust noise is sensitive to the variation of certain engine design parameters and, on the other hand, that for certain running conditions simple source models may give an acceptable estimation of the actual engine behaviour as a noise source.

The influence of manifold geometry on exhaust noise is studied. First, a linear description of the problem is presented, so that potential relevant factors may be identified. Then a full non-linear simulation is performed, for a simple geometry, in order to check, in more realistic conditions, the ideas obtained from the linear theory. The results indicate that, although some qualitative trends may be obtained from the linear analysis, the role of back-reaction of the manifold on the engine (a non-linear coupling effect) may be determinant.

In modeling an Internal Combustion Engine, the combustion sub-model plays a critical role in the overall simulation of the engine as it provides the Mass Fraction Burned (MFB). Analytically, the Heat Release Rate (HRR) can be obtained using the Wiebe function, which is nothing more than a mathematical formulation of the MFB. The mentioned function depends on the following four parameters: efficiency parameter, shape factor, crankshaft angle, and duration of the combustion. In this way, the Wiebe function can be adjusted to experimentally measured values of the mass fraction burned at various operating points using a least-squares regression, and thus obtaining specific values for the unknown parameters. Nevertheless, the main drawback of this approach is the requirement of testing the engine at a given engine load/speed condition. Furthermore, the main objective of this study is to propose a predictive model of the Wiebe parameters for any operating point of the tested SI engine.

Altitude simulators for internal combustion engines are broadly used in order to simulate different atmospheric pressure and temperatures on a test bench. One of the main problems of these devices is their outlet temperature and in order to control it, at least one heat exchanger is needed. A methodology to define, select and analyses the best heat exchanger that fulfill the requirements is presented. The methodology combines CFD and 0D models with experimental test. The combination of these tools allows to adjust both the 0D and the CFD models. The adjusted 0D model will be used to perform parametric analysis that will help to select the best geometrical combinations considering heat transfer and pressure losses while the CFD model will help to find possible local deficiencies on the designed Heat Exchanger and, therefore, try to improve it.

New technologies are required to improve engine thermal efficiency. For this it is necessary to use all the tools available nowadays, in particular computational tools, which allow testing the viability of different solutions at reduced cost. In addition, numerical simulations often provide more detailed information than experimental tests. Such is the case for the study of the heat transfer through the walls of an engine. Conjugate Heat Transfer (CHT) simulations permit precise calculations of the heat transfer from gas to walls throughout the whole engine cycle, and thus it is possible to know such details as the instantaneous heat losses and wall temperature distribution on the walls, which no experiment can give. Nevertheless, it is important to validate CHT calculations, either with some experimental measurements or with some other reliable tool, such as 0D-1D modelling known to work well.

In the present work, a study about the impact on engine performance, fuel consumption and turbine inlet and outlet temperatures with the addition of 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 and transient running conditions and in two different room temperatures: 20°C and -7°C. Once the validation was complete, in order to evaluate the maximum gain by means of insulating materials, the exhaust air path before the turbine was simulated as adiabatic. Results showed that the thermal insulation proved to have a great potential in regard to T4 increase that would lead to a reduction of the warm up time of the aftertreatment systems. However, its impact on engine efficiency was limited in both steady and transient conditions.

Rising concern towards environment and decarbonization has increased the demand of EVs. However, one of the major challenges for these vehicles is to achieve the same driving ranges as that of ICEs. This can be attained by increasing the power of cells without altering their sizes; conversely, this has important effects on the cell thermal behaviour. The focus of this paper is to analyse the impact of changing the characterizing materials thicknesses of collectors and electrodes of a cylindrical cell on its thermal response and to determine an optimal configuration. The CFD software considered to conduct this research uses the equivalent circuit model (ECM) to represent a cell and requires material physical properties to calculate the thermal response. In the calculations presented, resistance, capacitance, and Open Circuit Voltage (OCV) needed for the ECM are obtained from experimental measurements.

This article proposes a novel methodology for the definition of an optimized immersion cooling fluid for lithium-ion battery applications aimed to minimize maximum temperature and temperature gradient during most critical battery operations. The battery electric behavior is predicted by a first order equivalent circuit model, whose parameters are experimentally determined. Thermal behavior is described by a nodal network, assigning to each node thermal characteristics. Hence, the electro-thermal model of a battery is coupled with a thermal management model of an immersion cooling circuit developed in MATLAB/Simulink. A first characterization of the physical properties of an optimal dielectric liquid is obtained by means of a design of experiment. The optimal values of density, thermal conductivity, kinematic viscosity, and specific heat are defined to minimize the maximum temperature and temperature gradient during a complete discharge of the battery at 2.5C.