In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days.
Amid the increasing demand for higher efficiency in combustion driven handheld tools, the recent developments in electric machine technology together with the already existing benefits of small combustion engines for these applications favor the investigation of potential advantages in hybrid powertrain tools. This concept-design study aims to use a fully parametric, system-level simulation model with exchangeable blocks, created with a power-loss approach in Matlab and Simulink, in order to examine the potential of different hybrid configurations for different tool load cycles. After the model introduction, the results of numerous simulations for 36 to 100 cc engine displacement will be presented and compared in terms of overall system efficiency and overall powertrain size. The different optimum hybrid configurations can show a reduction of up to 30 % in system’s brake specific fuel consumption compared to the baseline combustion engine driven model.
In industrial processes, combustion engines and co-generation plants, large amounts of waste heat are generated, which are often lost to the environment. The conversion of this thermal energy into mechanical work and ultimately into electrical power promises a significant improvement in energy utilization, the efficiency of the overall system and, consequently, cost-effectiveness. Therefore, the use of a Rankine Cycle is a well-established technical process. A recent research project investigates a novel expansion machine to be integrated into an RC-process to convert the heat energy into mechanical work. Primarily, the present work deals with the fluid dynamic simulation of this expander, which is based on the principle of a rotary piston engine. The aim is to develop, analyze and optimize the process and the corresponding components. Hence, a CFD model has to be built up, which should correspond as closely as possible to the requirements and geometries of the physical engine.
For improving the thermal efficiency and the reduction of hazardous gas emission from IC engines, it is crucial to model the heat transfer phenomenon starting from the intake system and predict the intake air’s mass and temperature as precise as possible. Previously the authors developed an empirical equation based on an experimental setup of an intake port model of an ICE in order to be implemented into the engine control unit and numerical simulation software for heat transfer calculations. The authors developed an empirical equation based on the conventional Colburn analogy with the addition of Graetz and Strouhal numbers. Introduced dimensionless numbers were used to characterize the entrance region, and intermittent flow effects, respectively.
Due to the increasing computational power, significant progress has been made over the past decades when it comes to CAD, multibody and simulation software. The application of this software allows to develop products from scratch, or to investigate the static and dynamic behavior of multibody models with remarkable precision. In order to keep the development costs low for highly sophisticated products, more precisely motorcycle rider assistance systems, it is necessary to focus extensively on the virtual prototyping using different software tools. In general, the interconnection of different tools is rather difficult, especially when considering the coupling of a detailed multibody model with a simulation software like MATLAB Simulink. The aim of this paper is to demonstrate the performance of a motorcycle rider assistance algorithm using a cosimulation approach between the free multibody software called FreeDyn and Simulink based on a sophisticated multibody motorcycle model.
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
As the complexity of products increases, traditional text-based systems engineering can no longer meet the needs. To solve the problem, Model-based Systems Engineering offers a unified communication platform among relevant staff by carrying out diagram-based unambiguous description, analysis and design for the demand, structure and behavior of complex systems in the form of a model. It, however, still remains a challenge to implement MBSE modeling and model-driven technology and application as well as its integration with the industry.
High temperature distribution in disc brake mounted within in-wheel motor driven vehicle has several negative effects on braking performance. This is mainly due to the enclosed nature of the braking system. This paper aims to determine the effect of contact geometry on temperature distribution and thermal buckling in such a brake. Numerical analysis is conducted to investigate the variation of temperature field on the brake disc at different cover angles of pads while maintaining the same moment of friction. The effect of different radial positions of the pads is a second consideration in the current work, using a transient modeling approach. To validate the simulation results, an approximate, analytical solution is derived according to energy conservation. The results show that, for the same work done by the pads, the maximum temperature on the disc increases with a decrease in the pad cover angle.
High speed on-off valve under the control of high frequency pulse width modulation (PWM) can make control linearly as proportional valve does. It is because its valve opening is adjusted linearly by duty ratio within a certain range. It is significant for high speed on-off valve to achieve precise linear control performance. In practice the performance is influenced not only by control strategy, but also the structural parameters of the valve, such as seat angle, spool diameter of valve and so on. In this paper, it is indicated that the effects of structural parameters on linear control performance of high speed on-off valve is exerted by flow force since different structural parameters bring about different valve opening-flow force characteristics. Accordingly, the relationship between the valve structural parameters and flow force is emphasized.