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Accelerating rate calorimetry (ARC) has emerged as a powerful tool for evaluating the thermal behavior of Li-ion cells and identifying potential safety hazards. In this work, a new physical thermal model has been developed based on the first law of thermodynamics for analyzing heat and mass generated by Lithium-ion battery cells under thermal abuse conditions during EV-ARC tests. The analysis is based on the experimental data gathered from an ARC, including different temperatures and pressure inside a gas-tight canister located in the calorimeter chamber, as well as the gas composition at the end of the test. The energy balance of the battery cell includes: the energy released by the cell, the internal energy of the elements inside the canister, heat transfer between elements inside the canister, as well as the mass transfer between the cell and the gases inside the canister.

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.

In order to face the new challenges, spark ignition engines are evolving by following some strategies and technologies. Among them, alternative combustion processes based on the dilution of the homogeneous mixture, either with fresh air or with Exhaust Gas Recirculation (EGR), are being explored. In a higher or lower extent, these changes modify in-cylinder thermodynamic conditions during the engine operation (pressure, temperature and gas composition) thus conditioning the spark ignition system requirements that will have to evolve to become more reliable and powerful. In this framework, an experimental study on the effect of the key in-cylinder conditions on the ignition system performance has been carried out in a single-cylinder spark-ignition (SI) research engine. The study includes EGR, lambda and energizing time sweeps to assess the behavior of the engine in different operating conditions.

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.

The combination of more strict regulation for pollutant and CO2 emissions and the new testing cycles, covering a wider range of transient conditions, makes very interesting the development of predictive tools for engine design and pre-calibration. This paper describes a new integrated Virtual Engine Model (VEMOD) that has been developed as a standalone tool to simulate new standard testing cycles. The VEMOD is based on a wave-action model that carries out the thermo-and fluid dynamics calculation of the gas in each part of the engine. In the model, the engine is represented by means of 1D ducts, while the volumes, such as cylinders and reservoirs, are considered as 0D elements. Different sub-models are included in the VEMOD to take into account all the relevant phenomena. Thus, the combustion process is calculated by the Apparent Combustion Time (ACT) 1D model, responsible for the prediction of the rate of heat release and NOx formation.

Growing awareness about CO2 emissions and their environmental implications are leading to an increase in the importance of thermal efficiency as criteria to design internal combustion engines (ICE). Heat transfer to the combustion chamber walls contributes to a decrease in the indicated efficiency. A strategy explored in this study to mitigate this efficiency loss is to promote low swirl conditions in the combustion chamber by using low swirl ratios. A decrease in swirl ratio leads to a reduction in heat transfer, but unfortunately, it can also lead to worsening of combustion development and a decrease in the gross indicated efficiency. Moreover, pumping work plays also an important role due to the effect of reduced intake restriction to generate the swirl motion. Current research evaluates the effect of a dedicated injection strategy to enhance combustion process when low swirl is used.

Engine-out soot emissions are the result of a complex balance between in-cylinder soot formation and oxidation. Soot is formed in the diffusion flame, just after the lift-off length (LOL). Size and mass of soot particles increase through the diffusion flame and finally they are partially oxidized at the flame front. Therefore, engine-out soot emissions depend on the amount of soot formed and oxidized inside the combustion chamber. There is a considerable amount of work in the literature on characterization of soot formation. However, there is a clear lack of published research related to the characterization of soot oxidation. Thus, the main objective of the current research is to provide more knowledge and insight into the soot oxidation processes. For this purpose, a combination of theoretical and experimental tools were used. In particular, in-cylinder optical thickness (KL) was quantified with an optoelectronic sensor that uses two-color pyrometry.

Regulated emissions and fuel consumption are the main constraints affecting internal combustion engine (ICE) design. Over the years, many techniques have been used with the aim of meeting these limitations. In particular, exhaust gas recirculation (EGR) has proved to be an invaluable solution to reduce NOx emissions in Diesel engines, becoming a widely used technique in production engines. However, its application has a direct effect on fuel consumption due to both the changes in the in-cylinder processes, affecting indicated efficiency, and also on the air management. An analysis, based on the engine Global Energy Balance, is presented to thoroughly assess the behavior of a HSDI Diesel engine under variable EGR conditions at different operating points. The tests have been carried out keeping constant the conditions at the IVC and the combustion centering.

In the last two decades engine research has been mainly focused on reducing pollutant emissions. This fact together with growing awareness about the impacts of climate change are leading to an increase in the importance of thermal efficiency over other criteria in the design of internal combustion engines (ICE). In this framework, the heat transfer to the combustion chamber walls can be considered as one of the main sources of indicated efficiency diminution. In particular, in modern direct-injection diesel engines, the radiation emission from soot particles can constitute a significant component of the efficiency losses. Thus, the main of objective of the current research was to evaluate the amount of energy lost to soot radiation relative to the input fuel chemical energy during the combustion event under several representative engine loads and speeds. Moreover, the current research characterized the impact of different engine operating conditions on radiation heat transfer.

This paper presents an experimental analysis on the effect of thermal insulation of engine internal walls on the performance and emissions of a heavy-duty diesel engine. Some parts of the engine, like pistons, cylinder head and exhaust manifold were thermally insulated from gas contact side in order to reduce heat losses through the walls. Each component has been analyzed, independently, and in combination with others. The results have been compared with that of the original engine configuration. The analysis focuses on NOx and, smoke emissions along with brake specific fuel consumption. In order to take advantage of the engine insulation, an optimization of the air management and injection settings was finally performed, which provided the best combination for each engine configuration.

In recent years, the spread use of after-treatment systems together with the growing awareness about the climate change is leading to an increase in the importance of the efficiency over other criteria during the design of internal combustion engines. In this sense, it has been demonstrated that performing an energy balance is a suitable methodology to assess the potential of different injection or air management strategies, to reduce consumption as well as determining the more relevant energy terms that could be improved. In this work, an experimental energy balance with the corresponding comprehensive analysis is presented. The main objective is the identification of how the energy is split, considering internal and external balances. For this purpose, some parametric studies varying the coolant temperature, the intake air temperature and the start of the injection timing have been performed. The results quantify the effect of each parametrical study on engine efficiency.

The generalization of exhaust aftertreatment systems along with the growing awareness about climate change is leading to an increasing importance of the efficiency over other criteria during the design of reciprocating engines. Using experimental and theoretical tools to perform detailed global energy balance (GEB) of the engine is a key issue for assessing the potential of different strategies to reduce consumption. With the objective of improving the analysis of GEB, this paper describes a tool that allows calculating the detailed internal repartition of the fuel energy in DI Diesel engines. Starting from the instantaneous in-cylinder pressure, the tool is able to describe the different energy paths thanks to specific submodels for all the relevant subsystems.

In the present work, an automotive Diesel engine has been experimentally tested under a New European Driving Cycle (NEDC) with the aim of getting experimental plots of time dependent partitioning of energy injected during the warm-up process. An additional objective of this work is to assess the energy recovery capacity installed in the engine, i.e., to assess how much of the energy that leaves the engine with the exhaust gasses and the coolant is being employed. With this target, mean values of some parameters (intake and exhaust pressures and temperatures, coolant flow and coolant inlet and outlet temperatures, engine speed and torque) together with instantaneous variables (crankshaft angle, in-cylinder gas pressure, intake and exhaust mass flows) were continuously recorded during the warm-up of the engine. As a result of the work, the dynamics of the thermal balance of the Diesel engine under transient road conditions during the warm-up period was obtained.

Partially Premixed Combustion (PPC) of fuels in the gasoline octane range has proven its potential to achieve simultaneous reduction in soot and NOX emissions, combined with high indicated efficiencies, while still retaining control over combustion phasing with the injection event. However, the octane range where the ignition properties of a given fuel are optimum depends on the engine running conditions. Thus, low octane fuels present problems for extending the ignition delay at medium to high engine loads; while too high octane fuels have ignition problems at low engine loads. Two-stroke engines arise as a promising solution to extend the load range of the PPC concept, since it intrinsically provides equivalent torque response with only half the IMEP required in a four-stroke engine.

Soot radiation has an important contribution to the overall heat losses in a combustion chamber of a DI diesel engine. The aim of this study was to develop a soot radiation model coupled to a soot formation/oxidation sub-model, which is also described in the paper. On the one hand, the soot radiation model is based on the available knowledge of the radiation of a soot cloud commonly used to apply the two-color method to diesel sprays. On the other hand, it was tuned and validated with experimental data: the optical thickness, KL, obtained from the laser extinction method, and the radiation intensity at two different wavelengths. Once the model was validated, the overall radiated power was calculated taking into account the radiation absorption caused by the spray itself. This power was compared to the one released by the spray combustion process, and the results were in agreement with other studies available in the literature.

Although in combustion diagnosis models the uncertainty in the trapped mass is not critical, different authors have reported non negligible effects on the rate of heat release. Usually, an emptying-and-filling model is used to estimate the residual mass, whence the trapped mass is obtained. Generally, the instantaneous pressure at the intake and exhaust ports are not measured for combustion diagnosis applications and hence, it is difficult to estimate accurate values of the residual mass. The objective of this work is to propose a simple physical model to estimate the residual mass in a DI Diesel engine for a combustion diagnosis model. The proposed model specially focuses on the exhaust port conditions, because they appear to be the most important factor affecting the residual mass estimation.

The aim of this work is to develop a combustion and emissions (NOx and soot) predictive tool that allows rapid parametric explorations of operating conditions and geometric configurations in diesel engines. This paper will present the mixing and combustion models used. All the models are constructed around a spray-mixing model. This mixing model is based on the gaseous steady jets theory. The transient behavior description of the initial and final phases of the injection-combustion process is obtained from CFD studies. The mixing model allows the determination of the instantaneous local conditions of temperature and species mass fraction, used by the ignition, premixed and diffusion combustion models. The ignition and premixed combustion models are based on a simplification and parameterization of a complete n-heptane chemical kinetics description. Some constants of the models are adjusted by a genetic algorithm with experimental information from different engines.

In this paper the heat transfer of the hot gases to the cylinder walls of DI Diesel engines is analyzed using Computational Fluid Dynamics (CFD) and compared to the predictions obtained with a zero-dimensional thermodynamic model based on a variant of the Woschni equation. The final objective is to improve the simple model by modifying the original equations to better take into account the influence of important parameters, such as swirl, on the heat transfer. CFD calculations of the compression and expansion strokes have been made for two real DI Diesel engine geometries, a small one with a displacement of 0.4 l. and a heavy duty one of 2.0 l., and for different working points. The total heat transfer rate to the cylinder surfaces is highly dependent on the mean flow behavior and turbulence levels.