Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 6 Articles
CO2 emissions from fossil fuel combustion have been considered as the most important driving factor of global climate change. A\ncomplete understanding of the rules of CO2 emissions is warranted inmodifying the climate change mitigation policy. The current\npaper advanced a new algorithm of parameter estimation for the logistic equation, which was used to simulate the trend of CO2\nemissions from fossil fuel combustion. The differential equation of the transformed logistic equation was used as the beginning\nof the parameter estimation. A discretization method was then designed to input the observed samples. After minimizing the\nresidual sum of squares and letting the summation of the residual be equal to 0, the estimated parameters were obtained. Finally,\nthis parameter estimation algorithm was applied to the carbon emissions in China to examine the simulation precision. The\nerror analysis indicators mean absolute percentage error (MAPE), median absolute percentage error (MdAPE), maximal absolute\npercentage error (MaxAPE), and geometric mean relative absolute error (GMRAE) all showed that the new algorithm was better\nthan the previous ones....
A novel thermodynamic system is proposed to recover the waste heat of an internal combustion engine (ICE) by integrating the\ntrans critical carbon dioxide (CO2) refrigeration cycle with the super criticalCO2 power cycle, and eight kinds of integration schemes\nare developed. The key parameters of the system are optimized through a genetic algorithm to achieve optimum matching with\ndifferent variables and schemes, as well as the maximum net power output (????net). The results indicate that replacing a single turbine\nscheme with a double-turbine scheme can significantly enhance the net power output (????net) and lower the inlet pressure\nof the power turbine (????4). With the same exhaust parameters of ICE, the maximum ????net of the double-turbines scheme is 40%ââ?¬â??\n50% higher than that of the single-turbine scheme. Replacing a single-stage compression scheme with a double-stage compression\nscheme can also lower the value of ????4, while it could not always significantly enhance the value of ????net. Except for the power\nconsumption of air conditioning, the net power output of this thermodynamic system can reach up to 13%ââ?¬â??35% of the engine\npower when it is used to recover the exhaust heat of internal combustion engines....
Some previous research results have shown that EGR (exhaust gas recirculation) rate, pilot fuel quantity, and main injection timing\nclosely associated with engine emissions and fuel consumption. In order to understand the combined effect of EGR rate, pilot fuel\nquantity, and main injection timing on the NO???? (oxides of nitrogen), soot, and ISFC (indicated specific fuel consumption), in this\nstudy, CFD (computational fluid dynamics) simulation together with the Taguchi method and the ANOVA (analysis of variance)\ntechnique was applied as an effective research tool. At first, simulation model on combustion and emissions of a light duty diesel\nengine at original baseline condition was developed and the model was validated by test. At last, a confirmation experiment with\nthe best combination of factors and levels was implemented. The study results indicated that EGR is the most influencing factor\non NO????. In case of soot emission and ISFC, the greatest influence parameter is main injection timing. For all objectives, pilot fuel\nquantity is an insignificant factor. Furthermore, the engine with optimized combination reduces by at least 70% for NO????, 20% in\nsoot formation, and 1% for ISFC, in contrast to original baseline engine....
Small scale experimentation using particle image velocimetry investigated the effect of the diffusive injection of methane, air, and\ncarbon dioxide on the coherent structures in a swirling flame. The interaction between the high momentum flow region (HMFR)\nand central recirculation zone (CRZ) of the flame is a potential cause of combustion induced vortex breakdown (CIVB) and occurs\nwhen the HMFR squeezes the CRZ, resulting in upstream propagation. The diffusive introduction of methane or carbon dioxide\nthrough a central injector increased the size and velocity of the CRZ relative to the HMFR whilst maintaining flame stability,\nreducing the likelihood of CIVB occurring.The diffusive injection of air had an opposing effect, reducing the size and velocity of\nthe CRZ prior to eradicating it completely. This would also prevent combustion induced vortex breakdown CIVB occurring as a\nCRZ is fundamental to the process; however, without recirculation it would create an inherently unstable flame...
The effort ofmanymanufacturers of heat sources is to achieve themaximum efficiency of energy transformation chemically bound\nin the fuel to heat. Therefore, it is necessary to streamline the combustion process and minimize the formation of emission during\ncombustion.The paper presents an analysis of the combustion air temperature to the heat performance and emission parameters of\nburning biomass. In the second part of the paper the impact of different dendromass on formation of emissions in small heat source\nis evaluated.The measured results show that the regulation of the temperature of the combustion air has an effect on concentration\nof emissions from the combustion of biomass....
An experimental study of turbulent combustion of hydrogen sulfide (H2S) and natural gas was performed to provide reference\ndata for verification of CFD codes and direct comparison. Hydrogen sulfide is present in most crude oil sources, and the explosion\nbehaviour of pureH2S and mixtures with natural gas is important to address. The explosion behaviour was studied in a four-meterlong\nsquare pipe.The first two meters of the pipe had obstacles while the rest was smooth. Pressure trans ducerswere used to measure\nthe combustion in the pipe.The pure H2S gave slightly lower explosion pressure than pure natural gas for lean-to-stoichiometric\nmixtures. The richH2S gave higher pressure than natural gas.Mixtures ofH2S and natural gas were also studied and pressure spikes\nwere observed when 5% and 10% H2S were added to natural gas and also when 5% and 10% natural gas were added to H2S. The\naddition of 5% H2S to natural gas resulted in higher pressure than pure H2S and pure natural gas. The 5% mixture gave much faster\ncombustion than pure natural gas under fuel rich conditions....
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