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首页> 外文会议>EAEC European automotive congress >PREDICTION OF THE WALL FILM FORMATION AND PERFORMANCE OF AN ENGINE OPERATED WITH THE ETHANOL BLEND E85
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PREDICTION OF THE WALL FILM FORMATION AND PERFORMANCE OF AN ENGINE OPERATED WITH THE ETHANOL BLEND E85

机译：用乙醇混合E85预测壁膜形成和发动机的性能

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Efforts will have to be made to reduce the CO_2-emission of future vehicles. For example, a fleet emission limit of 120 g/km will be introduced in Europe by 2012. In addition a steadily growing number of vehicles faces limited oil resources. Therefore, low carbon fuels and fuels from biomass with an improved CO_2-balance like ethanol are considered as an important alternative to conventional fuels for SI engines. However, ethanol has a different stoichiometric air/fuel-ratio, a lower heating value and a higher heat of vaporization than conventional fuels. This has a high impact on the engine process. Therefore, detailed investigations on the engine process are necessary to predict the differences of the gas exchange, the engine efficiency and the full load performance when switching to ethanol. A turbocharged SI engine with port fuel injection was investigated at the Institute for Powertrains and Automotive Technology of the Vienna University of Technology in order to show the potentials when being operated with the ethanol blend E85. Numerical studies with the code GT-Power and measurements at the engine test bench have been carried out to explain the mixture preparation with conventional fuel and E85. It could be shown with the help of detailed CFD-simulations that an extensive wall film formation takes place in the inlet port during the fuel injection. Therefore, the heat of vaporization is rather taken from the material than from the aspirated air. This effect decreases the evaporative cooling of the mixture and, as a result, a higher boost pressure than predicted by simulation is required to reach a defined torque. There is a significantly higher impact observable for E85 compared to conventional fuel because of its higher heat of vaporization and lower stoichiometric air/fuel-ratio. Therefore, the mixture formation for E85 must be considered in more detail when analysing the engine process. In the following, a predictive model of the wall film formation in the inlet ports and thermal models of the port walls were used for the numerical studies. With the improved model the gas exchange and necessary boost pressure were in good agreement with measurements from the engine test bench for both fuels. The investigations have shown that particularly for alternative fuels with fluid properties that differ from those of conventional fuel the standard simulation models do not remain valid and an analysis of the whole process, employing measurements and numerical methods, is necessary.
机译：努力将不得不作出减少未来汽车的CO_2排放。例如，为120g / km的船队排放极限将被在欧洲2012年另外稳步增长数量的车辆面对有限的石油资源引入。因此，与像乙醇的改进的CO_2平衡低碳燃料和燃料从生物质被认为是一种用于SI发动机的传统燃料的重要替代品。然而，乙醇具有不同的化学计量的空气/燃料比，较低的热值和汽化比常规燃料的较高的热量。这对发动机的过程有很大影响。因此，在发动机过程详细的调查是必要切换到乙醇时预测的气体交换，发动机效率和全负载性能的差异。与燃油喷射涡轮增压汽油机在研究所动力系统和维也纳技术大学汽车技术，以展现潜力与乙醇混合E85被操作时调查。与代码GT-电源和测量在发动机试验台数值研究已经进行了解释与传统的燃料和E85的混合物制备。它可以与详述CFD-模拟的帮助，广泛的壁膜形成在燃料喷射期间发生在入口端口中显示。因此，汽化的热量而从材料取自吸入的空气比。这个效果降低了蒸发冷却的混合物，并且，作为结果，比模拟预测的更高的增压压力达到规定的转矩所需。有一个显著更高的冲击观测到E85相比由于其较高的蒸发热，降低化学计量的空气/燃料比的常规的燃料。因此，对于E85的混合物形成必须进行更详细的分析引擎进程时考虑。在下文中，在入口端口和端口壁的热模型的壁膜形成的预测模型被用于数值研究。随着改良型气体交换和必要的增压压力是与从发动机试验台两种燃料测量吻合。的研究已显示，特别是用于与从那些常规燃料的不同流体特性的替代燃料的标准模拟模型不保持有效和全过程的分析，采用测量和数值方法，是必要的。

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