Performance Study Of The Compressed-Air Power Car Based On Gas Ejector

Air-powered car with source of compressed air, as a ‘zero pollution’ new energyvehicle，has raised great concern in many countries. As a vehicle-mounted powerproducer, whether energy of the gas cylinders can be used effectively will be thebiggest restriction factor in the car development. The way of reducing high gaspressure is a key technological issue for the future success of air-powered cartechnologies. Although there has been much research and improvement in the engineof the car both at home and abroad, technologies on how to reduce the energy losswhen pressure reducing, especially study of how to control the quality energycompensation is still very weak.In view of the current situation of the huge energy consumption in the process ofpressure reducing, a new kind of high-pressure reducing system, using a ejector toeject the low-pressure gas as the throttling valve, is proposed in this paper. Firstly theprinciple and classification of injector was introduced. The ejecting coefficient whichrepresents the working performance of the ejector was researched, Especially theinfluence of different pressure and temperature of working fluid and ejector fluid onejector coefficient. Then the size of the ejector was calculated in the given conditionsand the law was summarized. The results show that it had good result to use highworking fluid pressure, high working fluid temperature, high ejecting fluid pressure,low ejecting fluid temperature and high mixing fluid temperature for improving theejection coefficient.Through establishing the mathematical model of power system, the loss andefficiency comparison of ejector and throttling in reducing pressure in the sameworking conditions was studied. Based on the analysis of the affecting factors ofinjection coefficients, a new decompression scheme, ejecting the exhaust gas whichhad low temperature and high pressure instead of ejecting the atmosphere wasproposed, which greatly improved the injection coefficient and output power. Theresults show that the exhaust ejector has the best effect, then ejector atmospheric,reflecting the superiority of exhaust ejector in the reduced pressure application.Appling the ejector to the mathematical model of two-stage and three-stagesystem and different design schemes are raised, With reference to the inflation exhaustejector before the thought, we gave four kinds of schemes (A, B, C, D) and analyzed the superiority and practical applicability of these schemes. Pass the contrast ofcoefficient and output power, and considering the possibility of actual operation, wechoose the scheme of ejecting gas from intermediate stage before the first expansion.In actual work pressure range, the output power can be improved from6%to17%.This topic research lays the foundation for the further study of the energyefficiency of air-powered car. It also provides the basis data and design basis for thedesign and distribution between stages of multi-level engines.