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A thermal fluid flow analysis for multiflow channel(MFC) condenser for automotive air-conditioning system using HFC-134a refrigerant has been carried out. The present study has been done as a part of the work intended to develop a design tool of HFC-134a refrigerant air conditioning system for passenger vehicle by applying a steady state simulation scheme to obtain the performance optimization. Thermodynamic and flow properties of HFC-134a refrigerant and temperature profile of the air flow over the surface of MFC condenser are predicted as a function of flow channel distance using a model of finite difference method. Variations of the heat transfer rate and pressure distribution are predicted under consideration of the actual multiflow channel constructions. The results of the predicted analysis obtained from the simulation analytical model were found to be conform with the known actual operation conditions of HFC-134a condenser in passenger vehicle air conditioning system.

The effect of local fuel concentration on cyclic variability in combustion and engine performance in a lean burn stratified charge engine has been investigated. The fuel concentration in a plane close to the spark plug was measured for a large number of cycles using laser-induced fluorescence (LIF) and simultaneous measurement of in-cylinder pressure in an one-cylinder optical research engine. It could be shown quantitatively that the fuel concentration in a small region close to the spark plug has a dominating effect on the subsequent pressure development for lean mixtures. Variations in the mixture concentration in the vicinity of the spark plug contribute significantly to cyclic variation in combustion. Measurement of the flame area in the same plane 20 °CA after ignition revealed that the direction of growth of the established flame is not significantly influenced by the stoichiometry.

We present a planar laser-induced fluorescence (PLIF) study of the effect of fuel volatility on the unburned hydrocarbons (UHC) outgassing from a simulated crevice in a single cylinder 1992 GM quad-4 engine. The crevice consists of a small volume in the cylinder wall which is connected to the cylinder by a small orifice. The crevice volume and orifice are intended to simulate the piston ring-pack region and the top ring gap. A fuel that consists of 90% by volume iso-octane and 10% of a ketone is used in these experiments. The ketone serves both to represent a particular fuel distillation fraction and as the fluorescent marker. A range of ketones are used to represent fuel distillation fractions between 56°C and 173°C. For each fuel, in-cylinder single-shot and multi-cycle averaged two-dimensional fluorescence images are obtained from a region near the simulated crevice.

A computer program has been developed to optimize the performance of finned tube evaporators. The developed program is used to predict the thermal and hydrodynamic performance of finned tube evaporators. The model is based on a steady-state finite difference model. The correlations for predicting the heat transfer and pressure drop are used from the literature. Experimental data is used to validate the developed model for a finned tube evaporator with R-12 as the working fluid. The simulated performance for heat transfer rate is within ±8 %; and refrigerant pressure drop is within ±10 % of the experimental data. The simulated data shows that 66 % of the heat transfer area is occupied by flow boiling; 23 % by the dryout region; and remaining 11 % is controlled by single-phase vapor flow. Work is continuing on predicting the performance of serpentine and laminate type evaporators with R-134a as the working fluid.

Mixture formation analysis in the combustion chamber of a slightly modified mass-production SI engine with port-fuel injection using nonintrusive laser measurement techniques is presented. Laser Raman scattering and planar laser-induced tracer fluorescence are employed to measure air-fuel ratio and residual gas content of the charge with and without spatial resolution. Single-cycle measurements as well as cycle-averaged measurements are performed. Engine operation parameters like load, speed, injection timing, spark timing, coolant temperature, and mean air-fuel ratio are changed to study whether the effects on mixture formation and engine performance can be resolved by the applied laser spectroscopic techniques. Mixture formation is also analyzed by measurement of the charge composition as a function of crank angle. Clear correlations of the charge composition data and engine operating conditions are seen.

A computer program has been developed to optimize the performance of finned tube condensers. The developed program is used to predict the thermal and hydrodynamic performance of finned tube condensers. The model is based on a steady-state finite difference model. The correlations for predicting the heat transfer and pressure drop are used from the literature. Experimental test data is used to validate the developed model for a finned tube condenser with R-134a as the working fluid. The simulated performance for the condenser heat transfer is within ±7%; and refrigerant pressure drop is within 10% of the experimental data. The simulated data for the condenser coil shows that 16% of the total heat transfer area is occupied by single-phase vapor flow where the superheated vapor are cooled to the saturated conditions; 72% by condensation; and the remaining 12% is controlled by the single-phase liquid flow which results in subcooling.

Tests have been carried out over a wide range of operating conditions on a single circuit plate-finned tube type of refrigerant evaporator, exchanging heat between ambient air and refrigerant R134a. Uniform and non-uniform air flow distributions were applied with the objective of studying the effects of non-uniformity on heat transfer. The experimental results revealed that, for a given total volume flow of air, heat transfer performances could be up to 15% better with a non-uniform flow where turbulence levels were also high. Extensive comparisons were also made between these measurements and predictions from a computer model. This was designed to simulate the thermal behavior of cross-flow heat exchangers on a tube segment-by-segment basis, allowing for flow non-uniformity. Predictions were found to match measurements satisfactorily for test cases involving uniform air flows and a relatively large temperature difference between fluids.

High Velocity Oxygen Fuel sprayed face coatings have shown great promise for piston rings used for High Power Density Diesel Engines. Various coatings have been tested on both wear test rigs and in engines. A highly dense HVOF cermet coating was developed with reasonable crack resistance during service. The HVOF coated piston rings wore three to six times lower than chrome plating. Cylinder liner (counter face) wear was found to be one to three times higher than chrome. However, engine oil consumption and blow by were within normal values. The HVOF coating is considered to be an excellent replacement for chrome plating. The coating process is more environmentally friendly than the chrome plating process. Also, the coating has potentially lower or equivalent production cost when compared to chrome.

This paper presents an optimization methodology for the design of fin louvers of compact heat exchangers based on 2-D CFD calculations. The mesh generation and its automatization is described. The validation of the methodology and the results of this validation are presented. Finally, an example of application is given.

Hino has developed new J-series medium-duty diesel engines for trucks and buses. The new J-series comprises four, five and six-cylinder engines with the same cylinder bore and stroke and with both naturally aspirated and charge air cooled. Both output and torque have been enhanced along with fuel efficiency in an engine that is lighter and more compact than ever and reaches new heights of durability and reliability. J-series engine features a 4-valve system and OHC valve train design, which achieved an uniform combustion by a centered nozzle and combustion chamber design. This decreases the maximum combustion temperature and hence improved the NOx,smoke and PM emissions. And a reduced pumping loss results in improving the fuel consumption. J-series engines thus meet the Japanese 1994 emission regulations. Another feature is a fully electronically controlled common-rail fuel injection system, which is equipped in a specified engine of naturally aspirated 6 cylinder.

Continental Automotive Systems started development of an electromechanical brake-by-wire system (EMB) 2 years ago. A major part of the development deals with the control of the brake actuator. For the development of control algorithms a special test stand was built. It consists of the seat capsule, the actuator and the PC-based electronic control unit. As the electronic unit also performs a real time vehicle and actuator simulation a complete Hardware-in- the-Loop system supports simultaneous engineering within this project. This paper describes the Hardware-in-the-Loop development system and shows first results obtained in an early state of the development process.

A Hazard and Operability Study (HAZOP) is a method of system examination that was developed by the chemical processing industry for hazard identification in the design of chemical processing plants. The HAZOP method has been applied to portions of an antilock braking control strategy and was found to be effective for identifying the potential for unintended operation of software control logic. This paper presents an overview of the HAZOP method as it has been adapted to the examination of software control strategies. The paper also provides an example HAZOP examination of a simplified ABS logic element that is representative of part of an ABS control strategy.

Planar laser induced fluorescence (PLIF) has been used to observe the in-cylinder transport of unburned fuel that, while trapped in the ring-land and ring-groove crevices, survives combustion in the propagating flame. Away from the top-ring gap, we detect a wall-jet comprised of unburned charge exiting the top ring-land crevice opening. At the location of the top-ring gap, we observe unburned fuel lying in the cool boundary layer along the cylinder wall during the later stages of the expansion stroke. This layer is scraped into the roll-up vortex during the exhaust stroke. These data lead us to conclude that away from the end gap, unburned, high pressure charge, trapped between the two compression rings escapes as a wall jet after ring-reversal near bottom center. Conversely, at the ring gap, when the cylinder pressure drops below the pressure between the compression rings, the trapped charge escapes through the gap and forms a thin layer on the cylinder wall.

Quantitative 1-D spatially-resolved NO LIF measurements in the combustion chamber of a mass-production SI engine with port-fuel injection using a tunable KrF excimer laser are presented. One of the main advantages of this approach is that KrF laser radiation at 248 nm is only slightly absorbed by the in-cylinder gases during engine combustion and therefore it allows measurements at all crank angles. Multispecies detection turned out to be crucial for this approach since it is possible to calculate the in-cylinder temperature from the detected Rayleigh scattering and the simultaneously acquired pressure traces. Additionally, it allows the monitoring of interfering emissions and spectroscopic effects like fluorescence trapping which turned out to take place. Excitation with 248 nm yields LIF emissions at shorter wavelengths than the laser wavelength (at 237 and 226 nm).

A laboratory method has been developed to rank the scuff resistance of piston ring coatings. This method employs a standard wear test apparatus with a specially designed sample holder. Scuff resistance of electrolytic chrome, thermal spray and physical vapor deposition (PVD) face coatings have been examined. Based on this method, examined PVD coatings produced the highest scuff resistance of all the tested face coatings.

The latest developments of material surface engineering to reduce the friction and wear of the piston ring in recent decade have been summarized. This paper analyzes the severe operating conditions of the piston ring in engine in detail. Based on the theoretical analysis, the essential technique requirements for piston ring wear resistant coatings are proposed. The state of research and application, the process features and furture development tendency of main material surface engineerings such as plasma spray, neckel-based plating and vapor deposition are investigated. The results show that material surface engineering will play more and more important role in the piston ring and other components in high performance engine in the near furture. Particularly the nickel-based plating and physical vapor deposition are more powerful and flexible in pratical application for the piston ring.

The chief aim of the work concerns the optimisation of a forced convection air cooling system and particularly of the external heat exchange surfaces, applied on a small internal combustion two-stroke engine. At the present time in the industrial practice, the design of cooling system and of fin arrays is developed by means of simple technical criteria, starting fiom the assumption to consider the thermal loading of engine about 30% of the power furnished by fuel. This paper describes an approach that combines theoretical and simulation techniques with experimental methods. Attention is primarily focused on the most important input data of this kind of optimisation represented by the thermal load of the engine. Then attempts are made to establish some general criteria for the optimum design. The proposed calculation methods have carried out the creation of a PC software, useful instrument for the design phase of a new engine or for the improvement of an old one.

The U.S. Department of Energy, through Argonne National Laboratory, and in cooperation with Natural Resources-Canada and Chrysler Canada, sponsored and organized the 1996 Propane Vehicle Challenge (PVC). For this competition, 13 university teams from North America each received a stock Chrysler minivan to be converted to dedicated propane operation while maintaining maximum production feasibility. The converted vehicles were tested for performance (driveability, cold- and hot-start, acceleration, range, and fuel economy) and exhaust emissions. Of the 13 entries for the 1996 PVC, 10 completed all of the events scheduled, including the emissions test. The schools used a variety of fuel-management, fuel-phase and engine-control strategies, but their strategies can be summarized as three main types: liquid fuel-injection, gaseous fuel-injection, and gaseous carburetor. The converted vehicles performed similarly to the gasoline minivan.

The effectiveness of using catalytic aftertreatment to control excessive hydrocarbon and carbon monoxide emissions is well known. However, a thorough understanding of how the catalyst and vehicle work together as an integrated system is still in developmental stages. A major goal of the investigation was to examine catalyst performance under the dynamic conditions existing during normal vehicle operation. The impact of applying catalytic aftertreatment, with and without the addition of secondary air, to three small 2-stroke motorcycles is examined. It is found that catalysts respond well to the varied conditions encountered with 2-stroke engine powered vehicles. While the addition of secondary air is beneficial to increased hydrocarbon reductions, its impact on carbon monoxide can be variable and a function of vehicle operation.

A combined one-dimensional, multi-dimensional computational fluid dynamic modelling technique has been developed for analysis of unsteady gas dynamic flow through automotive mufflers. The technique facilitates assessment of complex designs in terms of back-pressure and noise attenuation. The methodology has been validated on a number of common exhaust muffler arrangements over a wide range of test conditions. Comparison between measured and simulated data has been conducted on a Single-Pulse (SP) rig for detailed unsteady gas dynamic analysis and a Rotary-Valve (RV) rig in conjunction with an anechoic chamber for noise attenuation analysis. Results obtained on both experimental arrangements exhibit excellent gas dynamic and acoustic correlation. The technique should allow optimisation of a wide variety of potential muffler designs prior to prototype manufacture.