Engine power

Abstract: As a renewable, sustainable and alternative fuel for compression ignition engines, biodiesel instead of diesel has been increasingly fueled to study its effects on engine performances and emissions in the recent 10 years. But these studies have been rarely reviewed to favor understanding and popularization for biodiesel so far. In this work, reports about biodiesel engine performances and emissions, published by highly rated journals in scientific indexes, were cited preferentially since 2000 year. From these reports, the effect of biodiesel on engine power, economy, durability and emissions including regulated and non-regulated emissions, and the corresponding effect factors are surveyed and analyzed in detail. The use of biodiesel leads to the substantial reduction in PM, HC and CO emissions accompanying with the imperceptible power loss, the increase in fuel consumption and the increase in NOx emission on conventional diesel engines with no or fewer modification. And it favors to reduce carbon deposit and wear of the key engine parts. Therefore, the blends of biodiesel with small content in place of petroleum diesel can help in controlling air pollution and easing the pressure on scarce resources without significantly sacrificing engine power and economy. However, many further researches about optimization and modification on engine, low temperature performances of engine, new instrumentation and methodology for measurements, etc., should be performed when petroleum diesel is substituted completely by biodiesel.

Abstract: Toyota hybrid system (THS) is used in the current best selling hybrid vehicle on the market-the Toyota Prius. This hybrid system contains a power-split planetary gear system which combines the benefits of series and parallel hybrid vehicles. In this paper, we developed a dynamic model of the THS powertrain and then apply it for model-based control development. Two control algorithms are introduced: one based on the stochastic dynamic programming method, and the other based on the equivalent consumption minimization strategy. Both approaches determine the engine power based on the overall vehicle efficiency and apply the electrical machines to optimize the engine operation. The performance of these two algorithms is assessed by comparing against the dynamic programming results, which are non-causal but provide theoretical benchmarks for other implementable control algorithms.

Abstract: The influence of cetane number improver on heat release rate and emissions of a high-speed diesel engine fueled with ethanol-diesel blend fuel was investigated.Different percentages of cetane number enhancer(0~0_0,0.2~0_0,0.4~0_0) were added to blends,and the engine tests were performed on a high speed diesel engine.The results show that the engine power decreases slightly; the thermal efficiency improves remarkably,and the NO_x and smoke emissions decrease simultaneously when diesel engine is fueled with blends.Besides, the engine power can be recovered,NO_x and smoke emissions are further reduced when cetane number improver is added to blends.By the combustion analysis,it can be found that the ignition delay prolongs;the total combustion duration shortens,and the maximum heat release rate increases for ethanol-diesel blend fuel when compared to diesel fuel; in addition,the combustion characteristics of ethanol-diesel blend fuel at large load may be recovered to diesel fuel by cetane number improver. However a large difference still exists at lower load.