Engine simulation software has become synonymous with automotive design and component development. An integral part of any engine simulation is the correct modeling of the air flow at the intake. This air flow, which is highly compressible and unsteady, has a first order influence on the trapped air mass inside the cylinder and therefore on the behavior of the engine (torque response and emissions). The non-linear modeling of the air paths at the intake is done using a space-time meshing and by solving the 1D equations with a proper time scheme. Such methods are the bases of today’s engine simulation codes [1]. The main constraint with these methods is the time needed to model complex geometries, whether being the simulation time or the time spent on calibrating the said models with experimental measurements. These complicated geometries become problematic to accurately predict, particularly the charge air cooler (CAC) which is responsible for cooling the air flow on a turbocharged engine. Another approach is to use frequency domain models to describe the fluctuating pressure and mass flow [2]. Although this approach is simpler, faster in terms of computing time and offers many experimental techniques to characterize complicated geometries; important limitations can appear when it is confronted to the effects of high pressure levels and pulsating mass flow. Furthermore, the models behind such methods are designed to be used in the frequency domain, contrary to an engine simulation that works solely with time domain variables. In this article, a linear frequency domain model known as a transfer matrix is used. This concept is nothing new in acoustics; however here it was developed by experimentally measuring the transfer matrix [3] for a simple tube on a dedicated bench under conditions similar to those encountered on an engine [4]. The approach is then extended to measure the transfer matrix of a charge air cooler (CAC) on a real engine test bench. The measured discrete transfer matrix, defined in terms of fluctuating pressure and mass flow, is then transformed to a continuous frequency model and coded in Simulink®. The latter is coupled to the non-linear engine simulation software GT-Power®. The objective is to accurately model the pressure and mass flow of a complicated geometry using experimental measurements and a linear frequency model then to couple the transfer matrix to an engine simulation code, thus replacing the need for a meshed model.

The exploitation of renewable sources is an opportunity to increase the number of people who have access to electricity. To assure better living conditions, the free and simple access to water is another fundamental key point in many developing countries. Stand-alone photovoltaic pumping systems are often installed in remote areas where the grid is not available: they are used for irrigation and/or other local water needs and can supply also electricity to small consumers. In this paper a system aimed at supplying electricity and water to an isolated small village has been studied. Ground water is pumped into a storage reservoir and can be used both for irrigation and domestic use. The system is composed by a photovoltaic plant, a pump as turbine (PAT), a diesel internal combustion engine for integration purposes and a battery storage. By means of an optimization model based on the Particle Swarm Theory, the size of the system and its managing strategy have been optimized in order to fulfill the requirement of the users, to improve the system efficiency and minimize the overall costs. The most suitable hourly-based profile of the flow rates of a pump-as-turbine as well was found.

Development of IC engines with low emissions and low fuel consumption causes interest in direct injection engine, especially diesel engines that work with lean mixture. This goal may be achieved with separation of mixture formation and combustion processes, in diesel engines. A practicable way to reach this target is the use of porous medium (PM) inside the combustion chamber. The PM has benefits to enhance the evaporation of droplets in liquid-fuel burners, reduce emissions and minimize instabilities. This paper represents the numerical study of liquid-fuel injection and combustion inside constant-volume chemically inert PM to stabilize lean mixture. 3D numerical results have obtained based on a modified version of KIVA-3V code. Diesel was directly sprayed inside hot and high pressure PM chamber. Complete evaporation and self-ignited was achieved due to the initial temperature of PM. The results in an especial condition have compared with an experimental data in the literature. Effect of injection in cold condition has investigated. Contours of diesel vapor, fluid and solid temperature of PM in a cross section, have shown. Also, effects of pore density on a constant high-porosity PM and mass of spray fuel were studied. The results show considerable reduction in carbon monoxide, nitrogen monoxide and elimination of soot.

Power management systems are one of the most important components in modern hybrid vehicles. They are needed to optimize the operation of the hybrid system components. In this paper, a model for a fuel cell/battery vehicle is developed using PSAT and then tested with four power management control strategies utilizing the driving cycle of Amman city, the capital of Jordan. The main components of the hybrid vehicle are a PEM fuel cell, battery, and a brushless dc motor. PEM fuel cells are popular due to their good start up, high power density, and low operating temperature. The role of the battery in a hybrid system is to boost the system power during start-up and transient events in addition to storing the energy recovered from the braking process. The developed hybrid vehicle model is designed and configured so that it matches the power, acceleration, and maximum speed of a midsized vehicle powered by an internal combustion engine. The proposed control strategies are the thermostat strategy, fuel cell optimized strategy, load following strategy and fuzzy logic strategy. All four control strategies are implemented in simulation utilizing PSAT. The simulation results indicate that the best performance in terms of fuel economy is achieved by the load following control strategy.

The “gear rattle” phenomenon is a research topic of great interest for the NVH (Noise, Vibration and Harshness) automotive sector, concerning driveline noise and vibrations coming from the manual gear boxes. It is due to the internal combustion engine variable torque producing impacts and rebounds, and consequently noise, between the teeth of the unloaded gear pairs of the gear box because of the unavoidable presence of backlashes. Discrete Wavelet Transform (DWT) is used to decompose the angular relative motion signal and the wavelet decomposition details are adopted to analyze the dynamic behaviour of gears under rattle conditions. The DWT has been chosen because it is a particularly suitable instrument to recognize discontinuities, such as jumps or instantaneous changes in the slope of the signals, due to their localization in the time domain. Wavelet analysis allows to characterize an event by the localization, the kind, and the amplitude of the event. This technique enables, moreover, to define new indices for metrics of gear rattle especially useful in order to conduct comparisons among different operative conditions. Some examples of application of the proposed technique are reported in the paper. The theoretical investigations regard comparative analysis with respect to the amplitude and to the frequency of speed fluctuations and to the gears lubrication regime.

On the road transportation sector, considering its deep involvement with many social expectations, assumed such proportions to become one of the major source of air pollution, mainly in urban highly congested areas. The use of reciprocating internal combustion engines (ICE) dominates the sector and the environmental dimension of the problem is under a strong attention of Governments. European Community, for instance, through sequences of regulations (EURO) reduced the emission allowed of primary pollutants; more recently, the Community added limits to climate-altering gases which directly refer to fuel consumption reduction. These limits today appear the new driver of the future engine and vehicle technological evolution. Similar efforts are under commitment by other developed countries (USA, Japan, etc,…) as well as also by the other Countries whose economic importance will dominate the markets in a very near future (BRICS Countries). The need to fulfill these issues and to keep the traditional engine expectations (torque, speed, fun to drive, etc..) triggered, especially in recent decades, a virtuous cycle whose result will be a new engine and vehicle era. The evolution till had today has been driven by the EURO limits and it demonstrated surprisingly that emission reduction and engine performances can be matched without compromises in both sides. Today, adding severe limits on equivalent CO 2 , emissions, it appears very difficult to predict how future engines (and vehicles) will be improved; new technologies are entering to further improve the traditional thermal powertrain but the way to a massive and more convinced electrification seems to be definitely opened. The two aspects will match in the sector of energy recovery which appears one of the most powerful tools for fuel consumption saving and CO 2 reduction. When the recovery is done on exhaust gases it has an additional interest, having a moderate cost per unit of CO 2 saved. The potentiality of this recovery is huge: 30%–35% of the chemical energy provided by the fuel is lost with the flue gases. For different reasons engines for passengers cars or goods transportation (light and heavy unit engines) as well those used for electricity generation (gen-set) are interested to this recovery: the first sector for the CO 2 reduction, the second for the increasing value of electrical energy on the market. This wide interest is increasing the probability to have in a near future a reliable technology, being different actors pushing in this direction. In recent years the literature focused the attention to this recovery through a working fluid (organic type) on which the thermal energy is recovered by increasing its enthalpy. Thanks to a sequence of thermodynamic transformations (Rankine or Hirn cycle), mechanical work is produced. Both concept (Organic working fluid used and Rankine Cycle) are addressed as ORC technology. This overall technology has an evident complexity and doesn’t match with the need to keep reduced costs: it needs an energy recovery system at the gas side, an expander, a condenser and a pump. The space required by these components represents a limiting aspect. The variation of the flow rate and temperature of the gas (typical in ICE), as well as that at the condenser, represents additional critical aspect and call for suitable control strategies not yet exploited. In this paper the Authors studied an energy recovery method integrated with the turbocharging system, which does not require a working fluid making the recovery directly on the gas leaving the cylinders. Considering that the enthalpy drop across the turbine is usually higher than that requested by the compressor to boost the intake air, the concept was to consider an additional turbine which operates in parallel to the existing one. Room for recovery is guaranteed if one considers that a correct matching between turbine and compressor is actually done bypassing part of the exhaust gas from the turbine (waste gate) or using a variable geometry turbine (VGT) which, in any case, represents an energy loss. An additional positive feature is that this recovery does not impact on engine performances and the main components which realizes the recovery (valves & turbine) are technologically proven. In order to evaluate the potentiality of such recovery, the Authors developed a theoretical activity which represents the matching between turbocharger and engine. Thanks to an experimental characterization done on an IVECO F1C 16v JTD engine, an overall virtual platform was set up. The result produced a very satisfactory representation of the cited engine in terms of mechanical engine performances, relevant engine flow rates, pressures and temperatures. The ECU functions were represented too, such as boost pressure, EGR rates, rack control of VGT, etc… Two new direct recovery configurations have been conceived and implemented in the engine virtual platform.

The identification of the water cavitation regime is an important issue in a wide range of machines, as hydraulic machines and internal combustion engine. In the present work several experiments on a water cavitating flow were conducted in order to investigate the influence of pressures and temperature on flow regime transition. In some cases, as the injection of hot fluid or the cryogenic cavitation, the thermal effects could be important. The cavitating flow pattern was analyzed by the images acquired by the high-speed camera and by the pressure signals. Four water cavitation regimes were individuated by the visualizations: no-cavitation, developing, super and jet cavitation. As by image analysis, also by the frequency analysis of the pressure signals, different flow behaviours were identified at the different operating conditions. A useful approach to predict and on-line monitoring the cavitating flow and to investigate the influence of the different parameters on the phenomenon is the application of Artificial Neural Network (ANN). In the present study a three-layer Elman neural network was designed, using as inputs the power spectral density distributions of dynamic differential pressure fluctuations, recorded downstream and upstream the restricted area of the orifice. Results show that the designed neural networks predict the cavitation patterns successfully comparing with the cavitation pattern by visual observation. The Artificial Neural Network underlines also the impact that each input has in the training process, so it is possible to identify the frequency ranges that more influence the different cavitation regimes and the impact of the temperature. A theoretical analysis has been also performed to justify the results of the experimental observations. In this approach the nonlinear dynamics of the bubbles growth have been used on an homogenous vapor-liquid mixture model, so to couple the effects of the internal dynamic bubble with the other flow parameters.

A new technique for simulating engine pressure waves consisting of linking pressure response and mass flow rate excitation in the frequency domain has been presented. This is achieved on the so-called “dynamic flow bench”. With this new approach, precise, fast and robust results can be obtained while taking into account all the phenomena inherent to compressible unsteady flows. The method exhibited promising results when it was incorporated in a GT-Power/Simulink coupled simulation of a naturally aspirated engine. However, today’s downsized turbocharged engines come with more stringent simulation necessities, where discontinuities such as the charge air cooler (CAC) must be correctly modeled. Simulating such engines with the transfer function methodology is quite difficult because it requires mounting the entire intake line on the bench. Modeling wave action for these engines requires an understanding in the frequency domain of the flow’s characteristics through the different elements that make up the intake line. This leads us to study the acoustic transfer matrices. In order to split the intake line into separate elements, a straight duct of 185mm length is chosen as a first reference. It is mounted on the dynamic flow bench and pressure response is measured after an impulse mass flow excitation. Transfer functions of relative pressure and mass flow rate are then identified at given points upstream and downstream of this reference tube. These functions produce the desired transfer matrix poles. The resulting matrix is validated by inserting the tube in the intake lines of two four-cylinder engines which are modeled in GT-Power. Pressure and mass flow are registered at the measurement points of the tube from the simulation. The time series data upstream of the tube is treated in the frequency domain and the transfer matrix is used to calculate the corresponding downstream values. Measured values from the native simulation and those calculated using the transfer matrix propagation are then compared. Finally, the experimental technique for identifying transfer matrices of more complex elements using two versions of the previous tube is presented.

An experimental and numerical study is carried out to evaluate the significance of gas leakage for a non-lube optically accessible internal combustion engine and to obtain estimation for the gas flow out of the combustion chamber at each engine cycle and its effect on the in-cylinder component states during optical engine’s operation. Attention is paid to blow-by and circumferential flow through the gaps between the piston rings and the liner. Optical engines are typically operated without lubrication to avoid window fouling and generation of fluorescence by oil particles that interfere with laser diagnostic signals, in view of this circumstance significant blow-by is expected in optical engines due to lack of “wet-seal” on the cylinder walls which permits circumferential flow of gases through the piston ring pack region resulting in increased blow-by. Semi analytical model estimating the mass loss rate is incorporated into zero dimensional thermodynamic IC engine model which simulates in-cylinder processes. Predicted results are compared for leaking and non-leaking engine simulations.

Most recent implementations of the Atkinson cycle are not optimal from the point of view of Thermal Conversion Efficiency ( TCE ). For example, Toyota has put in its Prius II a gasoline engine which should achieve high efficiency by using a modified Atkinson cycle based on variable intake valve timing management. Firstly, this implementation of the Atkinson cycle is not the optimal solution because some of the air is first sucked from the intake manifold into the cylinder and subsequently returned back there. As a consequence, the oscillating air stream considerably reduces the thermal conversion efficiency of this cycle. Secondly, this implementation of the Atkinson cycle reaches only low levels of Indicated Mean Pressure ( IMEP ) and, thirdly, it is not suitable for part load Engine Operating Points ( EOP ) because of the lower TCE. For these reasons, this implementation of the Atkinson cycle is suitable only for hybrid vehicles, where the engine — because it is not directly linked mechanically to the wheels — works only in its best EOP. In this paper the losses in TCE of Internal Combustion Engine ( ICE ), especially for the Atkinson cycles, are analyzed in detail and a proposal is made for their reduction for aspirated and especially for high pressure supercharged engines.

The European Union recently established an ambitious target by 2020 that consists of increasing the utilization of renewable energy up to 20%, reducing its overall pollutant emissions to at least 20%, and achieving a primary energy saving of 20% compared to reported 1990 levels. This aim could be reached only with strong effort in different sectors, such as residential, commercial, industry, tertiary, transportation, .... In particular in the European Union a remarkable contribution to energy consumption and CO 2 emissions is concentrated in residential and commercial sector. The introduction of more efficient technologies in these sectors could help in achieving the results expected by 2020. An option is given by cogeneration, defined as the combined “production” of electric and/or mechanical and thermal energy starting from single energy source, that could be considered one of the first elements to save primary energy, to avoid network losses and to reduce the greenhouse gas emissions. In particular, our interest will be focused on the microcogeneration (electric power ≤ 15 kW), which represents a valid and interesting application for residential and light commercial users. The energetic, economic and environmental implications due to the use of small scale cogeneration systems were reported, starting by an experimental research activity performed by the authors and other researchers.

For complex equipments, the phenomena of system declining such as wear and fatigue often takes place and spreads after a period of running. So it is important to identify the interior structural change of system during maintenance to avoid the system to be broken abruptly. Traditionally there are two methods to analyze and predict the structural change of system. One is from the monitoring data of equipments. Another is from the mechanism of structural changing and the interior working process of equipments. In this paper a combining method, which combining the advantages of the above two methods, is used to identify the structural change of internal combustion engines. The principle of the method is to firstly build an analytical system model, in which the system parameters stand for the structural parameters or constraints. Then the current value of system parameters in the model can be identified by comparing the calculating responding results and the detected responding data. From the varying of system parameters the structural change of system can be deduced. For internal combustion engines (ICEs), the most important CPSR (combustion Chamber-Piston-cylinder Sleeve-piston Rings) system is taken as the research object. A multidisciplinary model is built to simulate the interior working processes, especially the combustion process, the structural dynamics process, the tribology process and the coupling processes among them. Then the seeking-roots method (SRM) is used to identify the value of system parameters. A case study on a low power gasoline engine verifies the above method. In the case study, the blow by gap, which stands for the wear of piston rings and cylinder sleeve, is identified with the detected combustion pressure. The case study shows that the method of this paper can identify the structural change of complex equipments. It can provide accurate information for equipments maintenance as well as the residual life prediction.

The manufacturers are competing against each other based on their development ability. A manufacturer who wants to do better than others must emphasize its ability of product development. The resources that product development relies on are more distributed than ever along with the varying of the global design environment. So more and more resources outside of enterprises are needed during the product design process. The platform supporting the product modern design under the circumstance of distributed resources will meet the requirement of the enterprise’s product design and development under such conditions. The platform will also simplify the implementation on the integral of the IT support system for design resources outside of enterprises. In this paper the characteristics and supporting technologies of product design platform, which supporting the distributed design resource circumstance and centering on the enterprise, are studied. The building method of the platform is presented and a prototype of the product design platform is developed. Three subsystems are included in the platform. They are the product requirements analysis system, the product design planning system and the knowledge management system. Many design tasks can be supported on the platform, such as product requirement analysis, concept design, detail design, experiment, and maintenance knowledge acquirement. The distributing, implementing, tracking and managing of product lifecycle tasks can also be supported on the platform. The distributed design resources could be sealed as application components to provide design services. Design work flow model and knowledge flow model are built and controlled through the FIPER software. The design knowledge is managed based on the ontology theory. The virtual prototype of a complex product can be built and run more easily with the design platform. The process of building a virtual prototype could be described simply as following. Firstly the distributed models are sealed as application components. Then the components are published in the FIPER environment. Finally, the virtual prototype is built in the form of design work flow model in which the distributed components are integrated. To simulate the coupling of multi-discipline behaviors in a complex product design, the coupling formula is proposed to express the relations of different discipline behaviors. Based on the coupling formula, the coupling simulation can be run on the platform. Finally, a lifecycle performance prototype of an internal combustion engine is developed through the platform to verify the platform’s functions.

This paper presents a methodology for the inspection of geometric features on an internal combustion engine valve seat. Inspection of valve seat geometry using a high-precision non-contact range sensor is investigated. A method that can extract the cone angle, the valve seat length and the roundness of the cone surface has been presented. In-line implementation requires a methodology to analyze data from a minimum number of parallel cross sectional profiles of the valve seat. An in-line valve seat inspection prototype machine with two axes of motion that utilizes the method presented in this paper is presented. Validation of the method on several valve seat samples shows a high degree of repeatability, and the results are comparable to coordinate measurement machine measurements of the same samples.

The objective of this work is to do an energetic, exergetic and thermoeconomic analysis of a cogeneration system. This system is composed of an internal combustion engine, a heat recovery steam generator (HRSG), an absorption refrigeration system (ARS) and a cooling tower (CT). With the use of the mass and energy balances, several parameters of efficiency based in the First Law of Thermodynamics were calculated for the cogeneration system. With the use of the exergy balance, the exergetic efficiencies for the engine, HRSG, ARS, CT and the total system were calculated. Also, the irreversibility contribution of each system component was shown. An optimization was done, having as functional objective the maximization of the difference of the operational incomes and expenses. An exergetic cost analysis was made using the Theory of the Cost Exergetic (TCE). The system in study gets to save up to 28,5% of fuel in comparison with the divided production of heat and electric energy. The largest irreversibility that happened in the cycle is due to the engine, which participates in the average with 78% of the total. The analysis with the TCE showed that the product of the ARS is more expensive in comparison with the process heat and electricity.

Over the last few decades a tremendous effort has been made to reduce road vehicles engines contribution to air pollution and fuel consumption. Due to the more stringent limits imposed by governments, various manufactures started working in the incorporation of alternative powertrain configurations, such as pure electric vehicles (EV), hybrid electric vehicles (HEV) and fuel cell vehicles (FCV), in the automotive consumer market. In order to appreciate the advantages and disadvantages of these new vehicles over conventional vehicles a comparison must be performed in terms of efficiency and pollutant emissions. However, hybrid vehicles comprise many components with at least two different energy conversion devices (i.e. internal combustion engine and electric machine) drawing energy from at least two different energy storage devices (i.e. fuel tank and battery). In recent times, many hybrid propulsion system configurations have emerged and many others can be imagined comprising multiple reversible and irreversible energy paths. Therefore, considering that in a hybrid vehicle at least two different forms of energy (i.e. fuel chemical energy and electricity) are consumed, fuel consumption alone is no more sufficient to give a measure of the effectiveness of a hybrid propulsion system. This paper presents a first attempt to give a general mathematical form of the traction energy, the global efficiency and the specific fuel consumption of a hybrid electric vehicle that recovers as particular cases the thermal vehicle and the series hybrid electric vehicle. To evaluate the efficiency of the generic propulsion system the complete process from fuel energy and electricity to power available at the wheels is considered. The introduced concept of equivalent fuel consumption can be the basis for the comparison between road vehicles whatever the powertrain is pure thermal or hybrid. In order to get a better understanding of the mathematical analysis and its potential effectiveness some numerical simulations of hybrid vehicles virtual prototypes are performed through a suitable simulation model. The aim of the present analysis is to provide an instrument that allow a quick evaluation of the performances of hybrid electric vehicles.

A natural gas-fired micro-cogenerator (MCHP) based on a reciprocating internal combustion engine that drives an electric heat pump (EHP), MCHP/EHP, has been analyzed. It allows a high degree of flexibility in terms of operating conditions, due to the possibility to use the two devices separately supplying electric and thermal (heating and cooling) energy (CCHT, Combined Cooling Heating and Power). The MCHP/EHP is a gas cooling technology that can contribute to optimize the natural gas and electricity consumptions in those countries where the HVAC systems are widespread. In particular, our interest was focused on micro-cogenerators (electric power ≤ 15 kW) at the moment available on the market, based on reciprocating internal combustion engine, that could have a great diffusion in the near future for domestic and light commercial applications. Starting by the results of an intense experimental activity an exergetic, economic and environmental analysis has been carried out to compare the proposed MCHP/EHP system to the conventional one based on separate “production”.

Thermo mechanical fatigue problem is treated to define an analysis methodology permitting the strength evaluation by reliability viewpoint. The main difficulty is the lack of both theoretical and experimental information; consequently the problem is treated verifying continually the validity and the limits of the developing solution method. The chosen application was the exhaust manifold of an IC engine; FE analyses were executed following the standard methodology consolidated by this time in CRF. In particular a time transient thermal analysis was performed taking into account the exhaust gas fluid dynamics inside the manifold; the thermo structural analysis took into account both geometrical and material non linearities; the contact between the manifold and the cylinder head was simulated and the bolts pre load was applied. The evaluation of the thermal fatigue damage is executed adapting methods developed to face isothermal fatigue, analysing also energetic criteria. A preliminary reliability evaluation was executed, on the base of numerical results and of experimental information. The results permitted the individuation of critical areas of the manifold and a preliminary evaluation of the number of cycles allowable before the rupture. Since the several criteria furnished different durations, a more accurate evaluation may be deferred to the execution of experimental tests.

During most of the operating conditions occurring on a vehicle driving cycle, a reciprocating IC engine works at low load and low speed, with poor fuel efficiency. In this regard downsizing appears as a major way of improving fuel consumption of Spark Ignition Engines. In fact, downsized engines have smaller friction surfaces and can work on the same vehicle and on the same driving cycle with higher mean effective pressure and higher efficiency. In this paper the main technical trends and problems related to SI engine downsizing are reviewed and discussed. Assuming a stoichiometric boosting, a simulation code is used to outline a strategy to improve low end torque of a downsized DISI engine. In the numerical experiments volumetric efficiency is enhanced by an optimal configuration of the inlet system. For the same objective, assuming a Variable Valve Timing, a proper selection of maximum lift and opening duration of the inlet valve allows a reduction of the reverse flow of fresh mixture. The optimization of the exhaust system and of the lift diagram of the exhaust valve leads both to the enhancement of volumetric efficiency and to the reduction of residual exhaust gas, with beneficial effects on knock phenomenon. An evaluation of fuel consumption gains resulting from downsizing is made as well, with reference to a New European Driving Cycle.

The high-speed pulsating flow is found in the exhaust system of the reciprocating internal combustion engine, the piping system connected to reciprocating compressor, etc., and has various features which never exist in the steady flow. This work is concerned with an experimental study of the high-speed pulsating flow in a straight pipe and the jet discharged by the pipe. In order to express quantitatively the intensity of compression wave in the pipe, the “intensity of compression wave” is defined and discussed. The shock formed in vortex ring in the issuing jet from the pipe is found to be due to Laval nozzle effect. The schlieren pictures taken with optical path inclined to the jet axis shows that the decay of vortex ring depends on the speed of the rotary valve.