Abstract: Fuel injection systems in modern diesel engines are designed and built to comply with very stringent environmental standards. They should also meet the highest level of fuel economy. Drivability, rapid response and easy and accurate control are a common demand. Changing the fuel characteristics could affect the performance of the fuel injection system. This study focuses on the evaluation of fuel spray characteristics of straight used cooking oil (SUCO) and its blends with petroleum diesel (PD) as a surrogate for pure PD. Used cooking oil blends have quite different physical properties from those of pure PD. Data for the lower heating value (LHV), density and viscosity were obtained from laboratory analysis. These data were merged with the physical and thermodynamic conditions of the diesel engine of interest to evaluate the dynamic behaviour of the fuel jet in 360° of crank rotation namely, the compression stroke, and the power stroke including the injection process. Engine operational conditions were calculated using a diesel dual thermodynamic cycle taking into account fuel injection adjustment at three different speeds, namely, idle speed, maximum torque speed and rated power speed. The results showed that fuel jet characteristics vary with SUCO content in the fuel blend. Two ranges of SUCO content in the blends were distinguished, 0 – 80% SUCO content and 80 – 100% SUCO content. Both showed a constant rate of change of jet characters per 10% increase in SUCO content in the fuel blend. Lower rates of change of fuel characters were observed at 0-80% SUCO content. The higher the temperature, the lower the rate of change of fuel jet characteristics.
Abstract: The purpose of this paper is to analyze the influence of passenger load on diesel bus emissions based on the real-world on-road emission data collected by the Portable Emission Measurement System (PEMS). It is also analyzed whether passenger load affect the accuracy of emission models based on VSP. The results indicate that the influence of passenger load on emission rates of CO2, CO, NOX and HC is various with different speed and acceleration ranges. As for the distance-based emission factors of CO2, CO, NOX and HC, per-passenger emission factors decrease with the rise of passenger load. In addition, it is found that the influence of passenger load can be omitted properly in the emission models of low and middle speed bins. But that can lead to an error reaching up to 49% if the influence of passenger load is neglected in the models of high speed bins.
Abstract: Tourist traffic plays a crucial role in the development of tourist attractions. A complete transportation system is a prerequisite to support and guarantee the implementation of all tourist functions. In the special planning of tourist area, predicting and analyzing tourist traffic demand lays the important foundation for other content. Due to the lack of historical data in the newly-developed tourist areas, selection of scenic transportation modes, determination of the size of transportation facilities and traffic management methods should be made on the basis of accurate forecast of future traffic demand. Considering the characteristics of the newly-developed tourist area, this article proposed a tourist traffic prediction model based on the gray model and the environmental capacity limited model. With the example of the tourist area of Nishan, Qufu, this paper predicted the total annual tourist reception capacity as well as tourist numbers by the prediction model. The model results show that the joint prediction model have positive significance in improving reasonableness and accuracy of predicting tourist traffic demand.
Abstract: The basic principle of matter element analysis theory was applied to establish the multi-level extensible evaluation model of advanced public transportation system. First, evaluation index system was established from three aspects, the transit technology level, economic benefit, social benefit and environmental impact. Then, according to the characteristics of evaluation indexes on different levels, entropy method and AHP was respectively used to determine the index weight value. Grade of evaluation was given by calculating relational degrees by layers. Finally, APTS in a city was studied as an example, and improvement measures were put forward. The method is proved to be reasonable and valid.
Abstract: Database design methodology as the core of system design is brought forward combining the application environment and business processes of parking toll collection. Then the four stages of the parking toll collection system design are analyzed. They are the requirement analysis, conception framework design, logic framework design and physical framework design respectively. Through scheming out an optimum database mode applied to all kinds of parking toll collection system, the proposed system is able to collect parking fees based on PDA and manage the real-time information of parking lots.
Abstract: A calculation method on pollutant emission inventory is established based on the standard LTO cycle of the International Civil Aviation Organization (ICAO) by analyzing the factors influencing aircraft engine emissions at civil aviation airports. For a certain airport in China, the emissions of HC, CO, NOx and SO2 per hour for a whole day from the aircraft engines are calculated, and the variations of various pollutant emissions with time are analyzed based on the air traffic data, the civil aviation fleet composition, the flight detailed take-off and landing information at the airport, and ICAO engine emission data bank. It’s found that the variations of the pollutant emissions with time are different, in which, the emissions of HC and CO are significantly influenced by the frequency of flight arrival at airport, however, the emission of NOx is influenced by the frequency of flight departure from airport greatly, and the emission of SO2 is influenced by the total frequency of flight arrival at and departure from airport comprehensively. For solving the problem of local high-emission time, some solutions are suggested, such as equipping aircrafts with low-emission engines or optimizing the flight schedule.
Abstract: In this paper, a 4 cylinder SI engine was fuelled with gasoline, M10, M30 and M85 methanol-gasoline blends, and the cold start transient performances were investigated under the ambient temperature of 15°C, -7°C, -15°C and-25°C, respectively. The engine speed curves indicate the existence of misfire and incomplete combustion, which are proved by the measured temperatures and the indicated mean effective pressure (IMEP) obtained from the cylinder pressure analyses. The addition of methanol increases the starting time at low temperature, but improves the combustion. The peak speed and the transient period increase with the increase of methanol fraction, while the speed fluctuation decreases.
Abstract: A twin annular premixing swirler (TAPS) combustor model of low emissions was developed in this study. And computational studies on combustion process in the combustor model were carried out. Standard k-ε Turbulence Model, PDF non-premixed combustion model, Zeldovich thermal NOx formation model and DPM two-phase model were employed. The distributions of some key performance parameters such as gas temperature, flow velocity, concentrations of NOx and CO emissions were obtained and analyzed. At the same time, combustion mechanics inside the TAPS combustor model were investigated. The computational results indicated that the TAPS combustor employed in this study does a better job of improving key combustion performances such as combustion efficiency, total pressure recovery and outlet temperature distribution factor, and reducing NOx and CO emissions at the same time.
Abstract: Thermodynamic simulation of a two-stage expansion air-powered engine was established and working process simulation was conducted based on this model. The effects of inlet pressure (0.8Mpa-3.0Mpa), intake duration angle of second-stage (100°CA-160°CA) and cylinder diameter of second-stage (120mm-200mm) on the gas temperature, pressure and output torque were analyzed. The results show that effective power and output torque both increase with the increase of above three parameters, meanwhile effective gas consumption rate decreases.