Advanced Materials Research Vols. 516-517

Abstract: Through researching and comparing the combustion characteristics of various gaseous fuels, this paper, based on the characteristics of gaseous fuels, proposes a LPG+H2 composite fuel scheme with liquefied petroleum gas (LPG) as a clean alternative fuel and hydrogen (H2) as an additive fuel on LPG engine, and completes an initial experiment on the gaseous LPG+H2 composite fuel used on engine. It also explores how the air-fuel ratio, ignition timing and ignition energy of the gaseous fuel with three different levels of H2 content influence the dynamic properties and emission characteristics of the engine.

Abstract: An experimental study was carried out on a prototype of a scroll expander used as the air-powered vehicle engine. The speed characteristic was tested based on the test system at the constant suction temperature and pressure. The results show that the air mass consumption rate and the output power both increase with the rotating speed. The maximum air mass consumption rate is 800kg/h and the maximum power achieves 8.112 kW. The effective efficiency increases with the rotating speed but the increment decreases. The maximum efficiency is only 0.26 due to the low manufacturing and assembly accuracy of the expander.

Abstract: Fouling is an important performance degradation factor of axial flow compressor. In order to reveal fouling mechanism, flow simulation of four cases of NASA rotor37 has been performed, such as clean compressor, compressor with roughness of 50μm, 100μm and 150μm. Thermodynamics performance parameters of compressor at different rotational speed with different roughness are discussed. And then fouling sources and its influence factor are analyzed. Research finds that gas contaminants can deposit in blade surface existed with internal oil and water. Simultaneously, humidity, temperature, flow velocity and contact area are the main factors for the formation of compressor fouling. Finally, research finds that fouling can easily formed in suction surface and fouling level of leading edge is more critical than other locations.

Abstract: Multi-dimensional simulation was applied for the investigation of the combustion system of a heavy-duty diesel engine. Firstly, the matching of combustion chamber and injection pressure has been determined by simulation. Then through intermediate characteristic parameters which could quantitatively describe the properties of the mixing and combustion, the influence of the matching of chamber caliber ratios and injection pressure on each sub-process in compression and power stroke was analyzed comprehensively. The results showed that, for the model studied in this article, increasing the combustion chamber caliber ratio and injection pressure could help expanding the distribution range of the mixture in cylinder, making the mixture more uniform, increasing the proportion of the dilute mixture, thus effectively improved the power performance.

Abstract: The performance of internal combustion engine can be improved by using variable valve timing technology. but how to get the optimal inlet/export valve open or close angles under various operating conditions still relies mainly on testing calibration method. By means of one-dimensional working process simulation method, the performance of a four cylinder diesel engine was simulated, and the influences of diffrent inlet/export valve timing on engine performances were compared. Optimum valve timing values and engine performances under thirty kinds of working conditions were gotton. After that, the engine performances compared with that without variable valve timing. Simulation results show that the engine performance, especially the emission performance, can be improved at all simulation working conditions. The method used in this paper may be a new way for calibration of optimal valve timing.

Abstract: In addition to the aerodynamic effects, turbulence and cavitation play an important role on the primary atomization. Different spray breakup models were analysized and evaluated though simulation of spray with them and then a new model of coupling the nozzle cavitating and turbulence flow to the spray primary breakup was put forward. The numerical simulation results with all these different spray primary breakup models were comparied with the experimental data and then the new model were proved to be much better. The study may effectively help establish the accurate spray breakup model.

Abstract: Parallel-series is a kind of hybrid configuration which is used in excavator. This configuration can give full contribution to the energy saving potential of hybrid excavator. In the paper, based on the cycle power of excavator, the hybrid power-train’s parameters are matched. Then we analysis the matching results on the software simulation model we have built. The simulation results show that using this method the system can meet the power demand of excavator, and the efficiency of the excavator was improved.

Abstract: This article presents the steady-state modeling and analysis of a grid-connected six-phase induction generator for renewable energy generation powered by hydro turbine. The basis of the analysis is nodal admittance method as applied to the equivalent circuit, and used to analyze the behavior of the machine for the operating mode such as (i) when only one three-phase winding set is connected to grid, (ii) when one three-phase winding set is connected to grid and other three-phase winding set is subjected to load, and (iii) when both the three-phase winding sets are connected to grid through an interconnecting Y-/Y six-phase to three-phase transformer. Nodal admittance based matrix equations are easier to modify in order to account for mutual leakage coupling between two three-phase winding sets, core loss component, and make the analysis very easy, fast and accurate. Through analytical and practical studies, it is shown that machine can feed direct, reliable, and low cost power to grid without interface network. The analytical results are found to be in good agreement with experimental results.

Abstract: The development of ultra-supercritical units is feasible choice of energy utilization ratio in China, its stability and economy rely on control system of turbine mightily. The control system of 600MW turbine is widely used currently, according to the non-linear time-varying excitation control system of turbine speed, the speed of turbine is employed as the feedback variable, a controller combined with a PID feedback loop control system is designed, analyzed and studied respectively from theory and emulation. The simulation results shows that PID feedback control has good effects in inhibiting interference andstabilizing system. Put forward strategy that can control the speed of turbine on this basis in order to achieve the goal of turbine’s fast tracking and stability control.

Abstract: In recent years, the main research focus for vehicle transmission systems has been the development of the Continuously Variable Transmission (CVT). CVTs can provide passengers with greater comfort, reduce energy consumption, and offer better transmission efficiency. CVT systems achieve the desired gear ratio by adjusting the hydraulic pressure on the rear and front pulleys using a solenoid valve. Our study aims to increase the efficiency of an existing CVT system, without reducing its performance. In this study have modified the CVT so that we can independently control the external and internal axes electronically. The speed of the hydraulic pump in the gearbox is not affected by the engine speed. In this way, In this study can achieve the lowest possible hydraulic pressure. In our study, In this study use the visual programming language LabVIEW as the human-machine interface for the monitoring program. In addition, a data acquisition system is used to collect experimental parameters, record data in real time, and perform data consolidation. Our system uses varying loads in order to evaluate the improvement in transmission efficiency over many operating conditions. Through the use of solenoids valves acting together, the pipeline hydraulic pressure can be varied. The widths of the front and rear pulleys are thus changed to achieve the goal of continuous variation. Under different loads, the relationships between the measured efficiency and the hydraulic pressure on the rear and front pulleys are used to verify and confirm the increase in efficiency achieved by controlling the hydraulic pressure.