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Fuel efficiency for tractor/trailer combinations continues to be a key area of focus for manufacturers and suppliers in the commercial vehicle industry. Improved fuel economy of vehicles in transit can be achieved through reductions in aerodynamic drag, tire rolling resistance, and driveline losses. Fuel economy can also be increased by improving the efficiency of the thermal to mechanical energy conversion of the engine. One specific approach to improving the thermal efficiency of the engine is to implement a waste heat recovery (WHR) system that captures engine exhaust heat and converts this heat into useful mechanical power through use of a power fluid turbine expander. Several heat exchangers are required for this Rankine-based WHR system to collect and reject the waste heat before and after the turbine expander. The WHR condenser, which is the heat rejection component of this system, can be an additional part of the front-end cooling module.

High-voltage battery system plays a critical role in eco-friendly vehicles due to its effect on the cost and the electric driving range of eco-friendly vehicles. In order to secure the customer pool and the competitiveness of eco-vehicle technology, vehicle electrification requires lowering the battery cost and satisfying the customer needs when driving the vehicles in the real roads, for example, maximizing powers for fun drive, increasing battery capacities for achieving appropriate trip distances, etc. Because these vehicle specifications have a critical effect on the high-voltage battery specification, the key technology of the vehicle electrification is the appropriate decision on the specification of the high-voltage battery system, such as battery capacity and power. These factors affect the size of battery system and vehicle under floor design and also the profitability of the eco-friendly vehicles.

A piston in a diesel engine is subject to the high pressure and the high thermal load. The high structural reliability is required to the piston in the automotive diesel engine and it is important to confirm the design parameters of piston in initial design stage. There are lots of research works proposing new geometries, materials and manufacturing techniques for engine pistons. But, the failures of piston occur frequently in development stage. Failure mechanisms are mainly fatigue related. This paper presents failure mechanisms of the high cycle fatigue and low cycle thermal fatigue cracks which occur on the piston during durability test using engine dynamometer. In this study, FE analysis was carried out to investigate the root cause of piston failure. The analysis includes the FE model of the piston moving system, temperature dependent material properties, mechanical and thermal loadings.

Various polymer-based coatings are applied on piston skirt to reduce friction loss between the piston skirt and cylinder bore which is one of main factors of energy loss in an automotive engine system. These coatings generally consist of polymer binder (PAI) and solid lubricants (graphite or MoS₂) for low friction property. On the other hand, the present study found that PTFE as a solid lubricant and nano diamond as hard particles can be used to improve the low friction and wear resistance simultaneously. In the process of producing coating material, diamond particles pulverized to a nano size tend to agglomerate. To prevent this, silane (silicon coupling agent) treatment was applied. The inorganic functional groups of silane are attached to the nano diamond surface, which keep the diamond particles are apart.

A validation study was performed comparing the simulation results of the Lattice-Boltzmann Equation (LBE) based flow solver, PowerFLOW®, to cooling cell measurements conducted at Volvo Trucks North America (VTNA). The experimental conditions were reproduced in the simulations including dynamometer cell geometry, fully detailed under-hood, and external tractor geometry. Interactions between the air flow and heat exchangers were modeled through a coupled simulation with the 1D-tool, PowerCOOL™, to solve for engine coolant and charge air temperatures. Predicted temperatures at the entry and exit plane of the radiator and charge-air-cooler were compared to thermocouple measurements. In addition, a detailed flow analysis was performed to highlight regions of fan shroud loss and cooling airflow recirculation. This information was then used to improve cooling performance in a knowledge-based incremental design process.

In order to understand the automotive PEM fuel cell system, mathematical system modeling is conducted and the model is implemented and simulated by using the Matlab®/Simulink®. The components such as fuel cell stack, air supplier, and radiator are modeled individually and integrated into a system level. The PEM fuel cell system operation control includes thermal management, air supply control, hydrogen supply control, fuel cell stack protection control, and load following control. In the thermal management, the inlet and outlet temperature of coolant are controlled to operate the fuel cell stack in desired temperature range and to prevent flooding inside the fuel cell stack. In air supply control and hydrogen supply control, the flow rates of air and hydrogen are controlled not to starve the fuel cell stack according to the output current. A control structure for the system is developed and confirmed by using the developed simulation model.

Adopting the Spray-guided Gasoline Direct Injection (SGDI) concept, a new multi-cylinder engine has designed. The engine has piezo injectors at the central position of its combustion chamber, while sparkplugs are also at the center. The sparkplug location is designed so that the spark location is at the outer boundary of the fuel spray where the appropriate air-fuel mixture is formed. A few important operating parameters are chosen to investigate their effects on the combustion stability and fuel consumption. The final experimental results show a good potential of the SGDI engine; the fuel consumption rate was much less than that of the base Multi Port Injection (MPI) engine at various engine operating conditions.

As the current and future emission regulations become stringent, the research on exhaust manifold with CCC (Close Coupled Catalyst) has been the interesting and remarkable subject. To design of exhaust manifold with CCC is a difficult task due to the complexity of the flow distribution caused by the pulsating flows that are emitted at the exhaust ports. This study is concerned with the theoretical and experimental approach to improve catalyst flow uniformity through the basic understanding of exhaust flow characteristics. Computational and experimental approach to the flow for exhaust manifold of conventional cast type, stainless steel bending type with 900 cell CCC system in a 4-cylinder gasoline engine was performed to investigate the flow distribution of exhaust gases.

The primary purpose of using a plastic material instead of conventional aluminum cast for intake manifold is to reduce its weight and cost. Moreover, the use of plastic for intake manifold is regarded as a key for further development of so called an “intake modular system”. As a secondary effect, the engine power can be increased with the help of improved interior surface roughness and lowered air temperature. With regard to NVH, however, plastic intake manifold is considered somewhat negative since it is less rigid and less dense than aluminum one. In this paper, the mechanism that plastic intake manifold affects the performance and NVH of in-line 4 cylinder gasoline engine is presented. In connection with engine performance, air flow efficiency of not only intake manifold itself but also other components of intake system and also cylinder head is evaluated.

During the design process for a vehicle, the CAD surface geometry becomes available at an early stage so that numerical assessment of aerodynamic performance may accompany the design of the vehicle's shape. Accurate prediction requires open grille models with detailed underhood and underbody geometry with a high level of detail on the upper body surface, such as moldings, trim and parting lines. These details are also needed for aeroacoustics simulations to compute wall-pressure fluctuations, and for thermal management simulations to compute underhood cooling, surface temperatures and heat exchanger effectiveness. This paper presents the results of a significant effort to capitalize on the investment required to build a detailed virtual model of a pickup truck in order to simultaneously assess performance factors for aerodynamics, aeroacoustics and thermal management.

Most of car makers nowadays produce Cylinder Head Cover with Thermoplastic to get the benefit of weight and cost reduction. The production of Cylinder Head Cover with Thermoplastic brings a number of benefits such as enhancement in productivity, design freedom, integration with other parts and reduction in weight. However, NVH characteristics, sealing performance issues possibly caused by design of cover and gasket and loss of properties of materials when used for long-term period still remain as critical tasks to be solved. Especially in case of car OEMs strongly insist that we have to meet their severe specifications requirements so as to satisfy their customers' growing demand. Sealing performance is one of the core factors, which require continuous effort and studies to meet the OEM's specifications.

The purpose of this paper is to investigate the air/fuel mixture formation and combustion characteristics in a spray-guided GDI engine using a commercial code, STAR-CD. This engine adopted the outwardly opening injector located in the center of cylinder head, which forms a hollow cone spray. The spray injection was modeled arranging multiple points using random function along the ring-shaped nozzle exit. To predict the breakup of spray, Reitz-Diwakar's breakup model was used, and the model constants were calibrated against published experimental data in a constant volume chamber. The validated spray models were applied to the analysis of spray behavior and mixture formation process inside the engine combustion chamber under operating condition of ultra-lean mixture (λ ≈ 4). To predict the combustion process, the modified eddy breakup combustion model was applied.

The characteristics of diesel spray injected into the cylinder provide crucial clues to the perception of the combustion performance in a compression ignition engine. In this study, five different diesel common rail injectors were examined which have different hole numbers, orifice sizes, jet cone angles, and hydraulic flow rates. Both the macroscopic and microscopic characteristics of diesel sprays were compared through Mie-scattered light imaging and PDA (Phase-Doppler anemometry) measurements. Seven hole injector with smaller hole was found to give better air/fuel mixing and favorable droplet size compared with other injectors. To evaluate the feasibility of achieving lower emission level with the different diesel sprays, the combustion and emission characteristics in case of 6 and 7 hole injectors were investigated under the same fuel flow rate condition in a light duty DI diesel engine.

The engineering process in the development of commercial vehicles is facing more and more stringent emission regulations while at the same time the market demands for better performance but with lower fuel consumption and higher reliability. Respective targets require better utilization of existing or even higher engine cooling capacity and optimization of aerodynamic performance for reduced drag. In order to aid on achieving both goals, special attention should be paid on understanding both external and under hood flow structures. This paper describes an optimization study for reducing aerodynamic drag and increasing engine cooling performance conducted on a Light Truck at Jiangling Motors Corporation (JMC). The approach is using simulation based on a LBM solver coupled with a heat exchanger model. Such methodology was used to predict both aerodynamic and cooling characteristics and help highlighting potential areas for improvement.

The Representative Interactive Flamelet(RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of soot and NOx formation. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the Eulerian Particle Flamelet Model using the multiple flamelets has been employed. Special emphasis is given to the turbulent combustion model which properly accounts for vaporization effects on turbulence-chemistry interaction.

Recently, upon customer’s needs for noise-free brake, carmakers are increasingly widely installing damping kits in their braking systems. However, an installation of the damping kits may excessively increase softness in the brake system, by loosening stroke feeling of a brake pedal and increasing compressibility after durability. To find a solution to alleviate this problem, we first conducted experiments to measure compressibility of shims by varying parameters such as adhesive shims (e.g., bonding spec., steel and rubber thickness), piston’s shapes (e.g., different contact areas to the shims), and the numbers of durability. Next, we installed a brake feeling measurement system extended from a brake pedal to caliper. We then compared experimental parameters with brake feeling in a vehicle. Finally, we obtained an optimized level of brake feeling by utilizing the Design for Six Sigma (DFSS).

Charge boosting strategy plays an essential role in improving the power density of diesel engines while meeting stringent emissions regulations. In downsized two-stage turbocharged engines, turbocharger matching is critical to achieve desired boost pressure while maintaining sufficiently fast transient response. A numerical simulation model is developed to evaluate the effect of two-stage turbocharger configurations on the perceived vehicle acceleration. The simulation model developed in GT-SUITE consists of engine, drivetrain, and vehicle dynamics sub-models. A model-based turbocharger control logic is developed in MATLAB using an analytical compressor model and a mean-value engine model. The components of the two-stage turbocharging system evaluated in this study include a variable geometry turbine in the high-pressure stage, a compressor bypass valve in the low-pressure stage and an electrically assisted turbocharger in the low-pressure stage.

This paper presents two closed-loop control methods for monitoring and improving the combustion behavior and the combustion noise on two 4-cylinder diesel engines, in which an in-cylinder pressure and an accelerometer transducer are used to monitor and control them. Combustion processes are developed to satisfy the stricter and stricter regulations on emissions and fuel consumption. These combustion processes are influenced by the factors such as engine durability, driving conditions, environmental influences and fuel properties. Combustion noise could be increased by these factors and is detrimental to interior sound quality. Therefore, it is necessary to develop robust combustion behaviors and combustion noise. For this situation, we have developed two closed-loop control methods. Firstly, a method using in-cylinder pressure data was developed for monitoring and improving the combustion noise of a 1.7L engine. A new index using the values calculated from the data was proposed.

Thermal performance of a brake system is one of the key attributes in a new vehicle development process. Adequate brake cooling characteristics are part of the vehicle performance and safety requirements. The design of a new brake system, however, can be a complex task from a thermal engineering perspective, particularly because of complex interactions between the brake component and the rest of the vehicle. Frequently, the vehicle integration issues are the most serious challenges for brake engineers. There are considerations on how much heat should be dissipated from a single and/or consecutive braking events vs. how much cooling can be provided to the brake corner. Design issues such as where to direct the cooling air to how much flexibility is allowed while complying with other requirements from the studio and aero teams. For a brake engineer, the priority is to maximize cooling to the brake corner and prevent system failure.

The success of improved fuel economy is the proper integration of thermal management components which are appropriately performed to reduce friction and wasted energy. The thermal management systems of vehicle are able to balance the multiple needs such as heating, cooling, or appropriate operation within specified temperature ranges of propulsion systems. Since the propulsion systems of vehicle have changed from a single energy source based on conventional internal combustion engine to hybrid system including more electrical system such as full type of hybrid electric vehicle or plug-in hybrid electric vehicles, a new transition associated with vehicle thermal management arises. More efficient thermal management systems are required to improve the fuel economy in the hybrid electric vehicles because of the driving of electric traction motor and the increase of engine off time. The decrease of engine operation time may not sustain the proper temperature ranges of engine and gearbox.