直喷式柴油机燃用生物柴油燃烧特性的研究

研究了柴油机燃用0#柴油和生物柴油的燃烧放热规律。通过对燃烧特征参数的计算分析,发现生物柴油的燃烧始点有所提前,滞燃期缩短;燃烧初期放热尖峰出现时刻对应的曲轴转角有所提前,瞬时放热率峰值下降;燃烧持续期延长。同时还比较了柴油机燃用生物柴油和0#柴油的经济性和排放特性,发现燃油消耗率上升12％左右,而各种排放污染物除NOx略有上升外,CO、HC和颗粒物(PM)均显著下降。     

Emissions of a diesel engine using B20 and effects of hydrogen addition

The blended biodiesel with up to 20% biodiesel in petroleum diesel (B20) is considered nowadays as available in production. Previous studies investigating the effect of B20 on engine emissions led to some contradictory results. The present study continued the investigation on B20, 20% biodiesel (rapeseed methyl esters) blend effects and was also extended on B20 enriched with hydrogen. It was conducted on a conventional tractor diesel engine running alternatively with B20 and petroleum diesel at various speeds and full load and then, with the same fuels enriched with hydrogen, at 60% load and two speeds.     

A review of the effects of catalyst and additive on biodiesel production, performance, combustion and emission characteristics

This article is a literature review of the effect of different catalysts and additives on biodiesel production, performance, combustion and emission characteristics. This study is based on the reports of about 60 scientists who published their findings between 1998 and 2010. It was reported that base catalyst produced more biodiesel compared to acid type catalysts. There was not much variation in engine performance with the use of catalyst. Combustion characteristics were improved with the use of additives. It was found that ignition delay was reduced and premixed combustion duration was increased with the addition of catalyst. HC emission and PM emission were reduced with the use of catalysts.     

A numerical study on combustion and emission characteristics of premixed hydrogen air flames

Main challenges for micro power generators that utilize combustion process for energy production are inadequate residence time, destructive radical wall interactions and intensified heat loss which are mainly rooted from size limitation of such devices. To achieve high and uniform energy output, and bring in a solution to these challenges in an environment friendly manner without any kind of fundamental modification, effect of equivalence ratio on combustion and emission behavior of premixed hydrogen/air flames is numerically investigated in this study. For this purpose, an experimentally tested micro cylindrical combustor model is constructed and premixed hydrogen/air combustion in this model is simulated by varying equivalence ratio between 0.5 and 1.2 to find an optimal equivalence ratio with respect to drawbacks of micro power generators. Combustion and turbulence models implemented in this study are Eddy Dissipation Concept and Standard k-ε models, respectively. A detailed hydrogen/air reaction mechanism which consists of 9 species and 19 steps is employed to accurately gain insight into combustion process. Simulation results show that as the equivalence ratio decreases; centerline temperature distribution gets a lower value and the place where chemical reactions take place moves downstream. The most uniform temperature distribution is achieved between 0.8 and 1.0 equivalence ratios. The highest NO_x formation is at 0.9 equivalence ratio and its mass fraction decreases sharply when the equivalence ratio reduces from 0.9 to 0.5.     

发动机燃用生物柴油的性能研究

通过对比研究了柴油机燃用餐饮废弃油炼制的生物柴油、柴油及B50时在高原地区的动力性、经济性及排放特性。研究结果表明：在柴油机不进行任何调整的情况下,全负荷时,燃用生物柴油的发动机动力性降低6.8%,B50降低3%;燃用生物柴油有效燃油消耗率升高了13.8%;燃用B50在高速高负荷时柴油机热效率提高2.5%;无论在全负荷还是在部分负荷工况下,燃用生物柴油均能大幅度降低柴油机烟度、CO和HC排放,但会引起NOx排放量的上升。     

An insight on hydrogen fuel injection techniques with SCR system for NOX reduction in a hydrogen–diesel dual fuel engine

Internal combustion engines continue to dominate in many fields like transportation, agriculture and power generation. Among the various alternative fuels, hydrogen is a long-term renewable and less polluting fuel (Produced from renewable energy sources). In the present experimental investigation, the performance and emission characteristics were studied on a direct injection diesel engine in dual fuel mode with hydrogen inducted along with air adopting carburetion, timed port and manifold injection techniques. Results showed that in timed port injection, the specific energy consumption reduces by 15% and smoke level by 18%. The brake thermal efficiency and NO_X increases by 17% and 34% respectively compared to baseline diesel. The variation in performance between port and manifold injection is not significant. The unburnt hydrocarbons and carbon monoxide emissions are lesser in port injection. The oxides of nitrogen are higher in hydrogen operation (both port and manifold injection) compared to diesel engine. In order to reduce the NO_X emissions, a selective catalytic converter was used in hydrogen port fuel injection. The NO_X emission reduced upto a maximum of 74% for ANR (ratio of flow rate of ammonia to the flow rate of NO) of 1.1 with a marginal reduction in efficiency. Selective catalytic reduction technique has been found to be effective in reducing the NO_X emission from hydrogen fueled diesel engines.     

Hydrogen enriched waste oil biodiesel usage in compression ignition engine

In the present study, hydrogen enrichment for biodiesel-diesel blends was evaluated to investigate the performance and emission characteristics of a compression ignition engine. Biodiesel was obtained from waste oil and blended to pure diesel fuel by volume fraction of 0%, 10% and 20%. After that, pure hydrogen was introduced through the intake air at different flow rates. Effects of pure hydrogen on performance and emission characteristics were investigated by evaluating power, torque, specific fuel consumption, CO, CO₂ and NO_x emissions. Experimental study revealed that waste oil biodiesel usage deteriorated performance and emission parameters except CO emissions. However, the enrichment test fuels with hydrogen fuel can improve performance characteristics and emission parameters, whereas it increased NO_x emissions. Brake thermal efficiency and specific fuel consumption were improved when the test fuels enriched with hydrogen gas. Because of absence of carbon atoms in the chemical structure of the hydrogen fuel, hydrogen addition dropped CO and CO₂ emissions but increment in cylinder temperature caused rising in NO_x emissions.     

Effect of injection parameters on the combustion and emission characteristics in a common-rail direct injection diesel engine fueled with waste cooking oil biodiesel

The objective of this paper was to study the effects of the injection pressure and injection timing on the combustion and emission characteristics in a single-cylinder common-rail direct injection (CRDI) diesel engine fueled with waste cooking oil (WCO) biodiesel and commercial diesel fuel. The fuel property including fatty acid composition for the biodiesel were measured and compared with those of the conventional diesel fuel. The engine tests were conducted at two injection pressures (80 and 160 MPa) and different injection timings from −25 to 0 crank angle degree (CAD) after top dead center (aTDC) under two different engine loads. The results showed that the indicated specific fuel consumption (ISFC) with respect to the injection timings of the biodiesel was higher than that of the diesel fuel under all experimental conditions. The peak cylinder pressure and the peak heat release rate of the biodiesel were slightly lower, while the ignition delay was slightly longer under all operating conditions. In terms of emissions, the biodiesel had benefits in reduction of smoke, carbon monoxide (CO), hydrocarbon (HC) emissions especially with high fuel injection pressure. The nitrogen oxide (NO_x) emissions of the biodiesel were relatively higher than those of the diesel under all experimental conditions.     

Study on combustion and emissions of a turbocharged compression ignition engine fueled with dimethyl ether and biodiesel blends

In this study, combustion and emissions characteristics of a turbocharged compression ignition engine fueled with dimethyl ether (DME) and biodiesel blends are experimentally investigated. The effects of nozzle parameter on combustion and emissions are evaluated. The result shows that with the increase of DME proportion, ignition delay, the peak in-cylinder pressure, peak heat-release rate, peak in-cylinder temperature decrease, and their phases retard. Compared to the nozzle 6 × 0.40 mm, the peak cylinder pressure and peak heat-release rate are higher with nozzle 6 × 0.35 mm, and their phases are advanced. Increased DME proportion in fuel blends causes greater differences. Compared to biodiesel, NO_x emissions of blends significantly decrease; HC emissions and CO emissions increase slightly. DME–biodiesel blends can be used as an alternative in a turbocharged CI engine. To obtain low NO_x emissions and a soft engine operation, for high DME proportion blended fuels, nozzle of 6 × 0.40 mm adopted.     

EGR率对M15甲醇柴油燃烧与排放的影响

在不同工况下研究了不同EGR率对增压中冷柴油机燃用M15甲醇柴油混合燃料的燃烧和污染物排放的影响。实验结果表明：随着EGR的增加,最高缸压、最大放热率和缸内温度逐渐降低,所对应的曲轴转角后移,NOx排放大幅度降低,烟度、HC、CO等排放有不同程度的恶化。选择合适的EGR率可以消除柴油机NOx排放和烟度之间的Trade-off关系。     

Theoretical investigation of the combustion performance of ammonia/hydrogen mixtures on a marine diesel engine

Ammonia is a good hydrogen carrier and can be well combined with hydrogen for combustion. The combustion performance of the mixtures of ammonia and hydrogen in a medium-speed marine diesel engine was investigated theoretically. The HCCI combustion mode was selected for reducing thermal-NO_x production. The start fire characteristic of the NH₃–H₂ mixtures was studied under different equivalence ratio, hydrogen-doped ratio, and intake air temperature and pressure. Then, the combustion performance of the NH₃–H₂ mixtures (doping 30% hydrogen) was analyzed at a typical operation condition of engine. The addition hydrogen improved the laminar flame velocity of ammonia, and affected the NO_x emission. For the medium-speed marine engine fueled with NH₃–H₂, reducing combustion temperature, introducing EGR and combining with post-treatment technology would be a feasible scheme to reduce NO_x emission.     

Effects of turbulator angle and hydrogen addition on a biogas turbulent diffusion flame

This study is concerned with combustion characteristics of a biogas under varying turbulator angle conditions and hydrogen addition in a combustor. Turbulator angles have been changed 15°–45° at intervals of 15°. Investigations have been performed by using a CFD code. PDF/Mixture Fraction combustion and k-? standard turbulence models were used during predictions. The predicted temperature and emission profiles of the biogas are compared with the existing experimental measurements under turbulator angle of 15°. These predictions are in good agreement with the measurements in terms of distributions and values. It has been determined that percentage differences between the measured and the predicted values vary from about 0% to 12%. Then, predictions have been performed under 30° and 45° of turbulator angle cases and compared with each other. The effect of the hydrogen addition to the biogas fuel on combustion performances of the biogas has also been studied in the present study. Findings show that changes in turbulator angles highly affect the temperature and emission profiles of the biogas throughout the combustion chamber. Especially, the flame temperature zones move to the downstream of the burner. It may be also said that the flame temperatures of the biogas increase as the turbulator angle is changed due to better fuel–air mixture. In addition to these findings, it is demonstrated that the axial temperature levels increase as the hydrogen is added into the biogas.     

Performance and emission characteristics of a turpentine–diesel dual fuel engine

This paper describes an experimental study concerning the feasibility of using bio-oil namely turpentine obtained from the resin of pine tree. The emission and performance characteristics of a D.I. diesel engine were studied through dual fuel (DF) mode. Turpentine was inducted as a primary fuel through induction manifold and diesel was admitted into the engine through conventional fueling device as an igniter. The result showed that except volumetric efficiency, all other performance and emission parameters are better than those of diesel fuel with in 75% load. The toxic gases like CO, UBHC are slightly higher than that of the diesel baseline (DBL). Around 40–45% smoke reduction is obtained with DF mode. The pollutant No_x is found to be equal to that of DBL except at full load. This study has proved that approximately 75% diesel replacement with turpentine is possible by DF mode with little engine modification.     

Simulation of a hydrogen/natural gas engine and modelling of engine operating parameters

At the present work for improving the engine performance and decrease of emissions, a port injection gasoline engine is converted into direct injection. Engine performance behavior was investigated by AVL Fire software with adding hydrogen to natural gas from 0% up to 30%. Validation of the simulated model and experimental results show good confirmation. To determine the relationship between independent variables engine speed, ignition timing, injection timing and H₂% versus the dependent variables including engine performance parameters, specific fuel consumption, CO and statistical analysis models were used. Comparison between different errors models shows that Radial basis function model with training algorithm Bayesian regularization back propagation can estimate better engine performance variables. The results showed that adding hydrogen to natural gas cause the output power, torque, fuel consumption efficiency increase and specific fuel consumption drop. Also, CO decreases when ignition and injection timing be advanced and engine speed reaches to its largest.