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This study shows the measurement and calculation of exhaust heat exchange coefficient in a pipe of internal combustion engine. A specific exhaust-air heat exchanger has been installed on the exhaust line of engine. The Nusselt-Reynolds correlation has been developed and compared to the steady state conditions. The Convective Augmentation Factor (CAF) is approximately 2 at low Reynolds number and 1 at high Reynolds number. The EGR cooler and the exhaust-coolant heat exchanger for improving the passenger compartment heating have been shown.

Euro4 and EPA/02 emission regulations for the European and North American Heavy Duty truck market will require development of high efficiency, low pollution diesel engines. Informations received from main engine, truck manufacturers and literature surveys performed during the past two years shows that several technical solutions are being evaluated in order to reach the required emission levels. These technical solutions can be divided into 3 main groups: 1 Further optimization of fuel combustion including: increase of air to fuel ratio, further retardation of fuel injection timing. 2 Cooled EGR including: high recycled exhaust gas ratios, short EGR loop, compressed and aftercooled EGR. 3 Exhaust gas aftertreatment including: de-NOx catalysts, particle traps, particle afterburning. Different technical solutions will have different impacts on the heat rejection requirements and consequently on the layout and costs of the future cooling systems.

In this paper, a parameter to quantify the cyclic variability in first stages of combustion is presented, as an evolution of the parameter proposed by Hill and Kapil. This parameter relates the mean time necessary for the initial flame to reach the periphery of a turbulence eddy structure moving from the flame kernel position. This parameter is used in combination with quasi-dimensional models in order to predict and analyze small-scale turbulence contribution to cyclic variations. The cyclic dispersion parameter could be introduced in the predictive models as a delay in the combustion beginning. The parameter is compared with the experimental standard deviations in mass burned fraction at spark time obtained from others researchers works and own experimental data. A satisfying agreement between predictions and measurements is achieved.

Sound propagation within high temperature hydrocarbon combustion product was considered. Different methods for calculating sound speed within chemically reacting gas mixture were reviewed. One dimensional sound propagation was assumed. Results obtained using all these methods were presented. The results were compared and it was shown how error could be generated if inappropriate model is used for acoustic analysis in a chemically reactive gas mixture.

A one-dimensional model has been developed for the species and energy transfer over a thin (0.1-0.5 mm) layer of liquid fuel present on the wall of a spark-ignition engine. Time-varying boundary conditions during compression and flame passage were used to determine the rate of methanol vaporization and oxidation over a mid-speed, mid-load cycle, as a function of wall temperature. The heat of vaporization and the boiling point of the fuel were varied about a baseline to determine the effect of these characteristics, at a fixed operating point and lean conditions (ϕ = 0.9). The calculations show that the evaporation of fuels from layers on cold walls starts during flame passage, peaking a few milliseconds later, and continuing through the exhaust phase.

In spark ignition engines, the mechanism of transferring electrical energy from an ignition system into the mixture in the spark gap is controlled by many aspects. The major parameters of these aspects are inputs of electrical energy, combustion energy release, and heat transfers. Heat caused by combustion energy is transferred to the spark plug, cylinder head, unburned mixture, and others. This study presents the development and validation of a flame kernel initiation and propagation model in SI engines, and most of the aspects described above are considered during the course of the model development. Furthermore, the model also takes into account the strain rate of the initial kernel and residual gas fraction. The model is validated by the engine experiments, which are conducted in a constant volume combustion chamber.

Understanding lubrication failures at the shoe/swashplate contact of automotive swashplate compressors will greatly enhance the reliability of the air conditioning system. Maintaining proper lubrication is not always possible during transient conditions. Therefore, a method for detection of lubricant loss is of great interest to the automotive industry. Three methods for detecting lubrication loss were examined: contact resistance, acoustic emission, and dynamic pressure oscillations. A mobile air conditioning test stand capable of recording many system parameters was used. Oil return to the compressor was monitored using an oil separator and a refrigerant/oil concentration sensor. Data were taken during steady oil return rates and after oil shut off. The electrical contact resistance between the shoe and swashplate was used to indicate changes in the lubrication conditions at this critical interface. Measurements were taken at two oil return rates during steady oil return tests.

Optimization of vehicle air conditioning performance at various drive cycles and ambient conditions can be achieved by regulating and distributing the refrigerant flow entering evaporators. Thermostatic expansion valve (TXV), as a flow control device, has been a key element in improving vehicle A/C system operating efficiency and maximizing cooling capacity. Three scenarios are addressed in this paper: (a) the selection of TXVs for a sports utility vehicle (SUV) climate control system, in which a front HVAC unit and an auxiliary HVAC unit are installed; (b) the methodology of developing a goal-oriented criterion for identifying the TXV combination to fulfill the optimization of A/C system performance; and (c) the analytical and experimental evaluation of vehicle cooling performance by varying TXV combinations in various vehicle operating modes.

A new mechanism DL-pulley has been developed to improve the riding quality by avoiding ON/OFF shock caused by turning on/off of the conventional magnetic clutch (MagCl) for the automotive air conditioner (A/C) compressor. DL-pulley was aimed for Dampening compressor torque fluctuation and Limiting torque transfer when the A/C compressor is seized. For its development, high performance sliding material was the key to realize the sliding mechanism of the torque limiting function. Specifically, the friction coefficient of sliding material must be stable in any environment that the automobile is used. This paper describes the development of new structure DL-pulley with sliding mechanism and new sliding material. In the development process, the relationship between stability of friction coefficient and adhesion has been experimentally clarified.

Vehicle acceleration induced pressure spike on the high side of an Air Conditioning (AC) system is causing considerable concerns, especially for systems with high efficiency compressors. Head pressure surge in the order of one to two hundred pounds per square inch can be observed within a time span of 10 seconds or less. As the industry moves to meet increased system durability standards and passenger comfort requirements, clear understanding of the underlying mechanisms is required so that the impact of the head pressure spike can be minimized or eliminated. The present investigation seeks to understand the mechanisms of the head pressure spike phenomenon through both experimental and mathematical analyses. Experimentally, extensive testing has been conducted in environmental wind tunnel. Our mathematical analysis is based on the mass conservation principle for the refrigerant flow through the high side of an AC system.

The objective of this paper is to present a methodology for the cooling system optimization based on experimental and numerical studies. Experimental measurements of fan performance for several truck fans have been carried out in order to determine the representative fan curves. These fan curves have been used to numerically simulate the performance of a truck cooling module consisting of heat exchangers and fan. The cooling module performance optimization has been carried out considering different fans, fan pumping power and fan overdrive ratios. The fan shroud has great influence on the cooling air flow distribution across the exchangers. The test bench has potentials to test a charge air cooler and a radiator at the same time simulating different truck operating conditions. In order to investigate the influence of different shrouds on the performance, experimental measurements and numerical study have been done for several module configurations.

Traditionally there have been two types of automotive fixed-displacement air-conditioning compressors on the market. One is the wobble plate (single sided) compressor, and the other is an opposed (double sided) swash plate compressor. Due to the increasing demand for high speed, high performance, quiet compressors, a single sided, swash plate compressor with a fixed displacement was developed. This compressor combines the positive attributes from both types of compressors into a new superior product designed to surpass market requirements.

In order to improve the Thermal System Management and fulfill the need of car Manufacturers, VALEO is developing new engine cooling « intelligent » Components and Strategies. The evolution of engine cooling strategies with the introduction of electronics in Fan System like FANTRONIC® is presented here. The use of such controlled actuators allows to reduce noise annoyances, pollutant emissions, fuel consumption and to improve comfort and engine cooling. The tests achieved on a Mercedes A Class allow to compare different kind of engine cooling strategies on a statistical driving car use on a whole year. This method uses three inputs: vehicle speed, air ambient temperature and air conditioning use. Outputs are electric / gas consumption and noise annoyances integrated with an equivalent noise level method.

In an effort to model a complete engine cooling module, Valeo has developed static and dynamic FEA models for its engine cooling fans. The static FEA analysis has led to a significant fan weight optimization for constant Van Mises stresses and ring deflection (a 15% reduction). Both experimental and numerical results have stressed the importance of the model of the interface between the motor and the fan in the dynamic FEA modal analysis. Moreover, the main engine cooling fan modes have been identified for the first time.

Results from numerical computations performed to represent the transient behavior of vaporizing sprays injected into a constant volume chamber and into a High Speed Direct Injection combustion chamber are presented. In order to describe the liquid phase, a new model has been developed from ideas brought forward by recent experimental results (Siebers, 1999) and numerical considerations (Abraham, 1999). The liquid penetration length is given by a 1D model which has been validated on a large number of experiments. In the 3D calculation, break-up, vaporization, drag, collision and coalescence are not modeled. The mass, momentum and energy transfers from the liquid to the gas phase are imposed from the nozzle exit surface to the liquid penetration length. This model enables us to reach time step and grid-independent results. The gas penetrations obtained with the model are checked against experimental results in a constant volume chamber (Verhoeven et al., 1998).

A KIVA-based CFD tool has been utilized to simulate the effect of a Common-Rail injection system applied to a large, uniflow-scavenged, two-stroke diesel engine. In particular, predictions for variations of injection pressure and injection duration have been validated with experimental data. The computational models have been evaluated according to their predictive capabilities of the combustion behavior reflected by the pressure and heat release rate history and the effects on nitric oxide formation and wall temperature trends. In general, the predicted trends are in good agreement with the experimental observations, thus demonstrating the potential of CFD as a design tool for the development of large diesel engines equipped with Common-Rail injection. Existing deficiencies are identified and can be explained in terms of model limitations, specifically with respect to the description of turbulence and combustion chemistry.

An ultrahigh injection pressure, common rail fuel injection system was designed, fabricated, and evaluated. The result was a system suitable for high-power density diesel engine applications. The main advantages of the concept are a very short injection duration capability, high injection pressure independent of engine speed, a simplified electronic control valve, and good packaging flexibility. Two prototype injectors were developed. Tests were performed on an injector flow bench and in a single cylinder research engine. The first prototype delivered 320 mm3 within 2.5 milliseconds with a 2600 bar peak injection pressure. A conventional minisac nozzle was used. The second prototype employed a specially designed pintle nozzle producing a near-zero cone angle liquid jet impinging on a 9-mm cylindrical target centered on the piston bowl crown (OSKA-S system). The second prototype had the capability to deliver 316mm3 in 0.97ms.

Reductions in fuel consumption and pollutant emissions from direct injection diesel engines are important issues in engine research. To achieve these reductions, rapid and better fuel air mixing is the most important requirement. The mixing quality of diesel spray with air is generally improved by selecting the best injection parameters and improving the characteristics of air movement in the combustion chamber. The shape of the combustion chamber can also help to form better mixtures. In this study, improvement in mixture formation was attempted by changing the combustion chamber geometry. The fuel spray development was visualized from two directions in an actual engine with a transparent cylinder and piston arrangement. The place where spray impinges, the distance from impinging wall to nozzle tip, and the shape of the chamber entrance and bottom were varied to determine their effects on the fuel spray development in the combustion chamber.

The improvement of DI diesel engines for passenger cars to fulfil pollutant emission limits and lower fuel consumption and noise is closely linked to continued development of the injection system. Today's injection systems demonstrate varying potential in terms of the flexibility of injection parameters for improving mixture formation and combustion. DaimlerChrysler evaluated the potential of different injection systems, looking particularly at the distributor pump, unit injection system and Common Rail system. Based on the results of these investigations, the Common Rail system was selected. The tests presented in this paper were performed on a single-cylinder engine with Common Rail system. They focused on increased rail pressure in combination with different nozzle geometries. The results show significant benefits in NOx/smoke trade off at part load conditions with high EGR rate.

The introduction of the LDCR common rail injection system has opened up new possibilities in controlling the details of the injection rate and the spray characteristics. In particular, there is potential to optimize engine performance across the speed and load range, if a nozzle can be developed which has the facility to vary the final orifice area over the operating range of the engine. There are a number of different geometries which may achieve the required effects. Two possible methods are to throttle either the entrance or the exit of the nozzle holes to a greater or lesser extent, according to the engine running condition. The paper describes an investigation of the spray characteristics of entry and exit throttled orifices, and how they are affected by pressure levels and degrees of opening. In previous studies, large scale transparent models have accurately reproduced the different spray characteristics observed with actual nozzles.