scholarly journals Simulation of Polydisperse Gas-Droplet Mixture Flows with Chemical Transformations

2021 ◽  
pp. 29-41
Author(s):  
Н.Н. Смирнов ◽  
В.В. Тюренкова ◽  
Л.И. Стамов ◽  
Дж. Хадем
Keyword(s):  
Spark Ignition ◽  
Reaction Chamber ◽  
Experimental Investigations ◽  
Chemical Transformations ◽  
Jet Injection ◽  
Flame Acceleration ◽  
Fuel Droplets ◽  
Detonation Transition ◽  
Nonequilibrium Effects ◽  
Droplet Mixture

В статье представлен обзор результатов теоретических, численных и экспериментальных исследований процессов горения и инициирования детонации в гетерогенных полидисперсных смесях. Обсуждаются проблемы распыления, испарения и горения капель топлива, а также неравновесные эффекты при распылении капель и фазовых переходах. Влияние неоднородности размеров капель и неоднородности пространственного распределения на воспламенение смеси и ускорение пламени было исследовано для сильного и мягкого инициирования детонации: ударной волной и искровым зажиганием с последующим переходом от дефлаграции к детонации (ДДТ). Изучены особенности впрыска и зажигания струи в реакционной камере. The paper presents the results of theoretical, numerical and experimental investigations of combustion and detonation initiation in heterogeneous polydispersed mixtures. The problems of fuel droplets atomization, evaporation and combustion, and the nonequilibrium effects in droplets atomization and phase transitions are discussed. The effects of droplets size nonuniformity and spatial distribution nonuniformity on mixture ignition and flame acceleration were investigated for strong and mild initiation of detonation: by a shock wave and spark ignition followed by deflagration to detonation transition (DDT). The features of jet injection and ignition in a reaction chamber are studied.

Investigating anode off-gas under spark-ignition combustion for SOFC-ICE hybrid systems

2021 ◽  
pp. 146808742110169
Author(s):  
Zhongnan Ran ◽  
Jon Longtin ◽  
Dimitris Assanis
Keyword(s):  
Hybrid Systems ◽  
Conversion Efficiency ◽  
Combustion Engine ◽  
Spark Ignition ◽  
Combustion Efficiency ◽  
Experimental Investigations ◽  
Fuel Conversion ◽  
Generation Plant ◽  
Complementary Role ◽  
Power Generation Plant

Solid oxide fuel cell – internal combustion engine (SOFC-ICE) hybrid systems are an attractive solution for electricity generation. The system can achieve up to 70% theoretical electric power conversion efficiency through energy cascading enabled by utilizing the anode off-gas from the SOFC as the fuel source for the ICE. Experimental investigations were conducted with a single cylinder Cooperative Fuel Research (CFR) engine by altering fuel-air equivalence ratio (ϕ), and compression ratio (CR) to study the engine load, combustion characteristics, and emissions levels of dry SOFC anode off-gas consisting of 33.9% H2, 15.6% CO, and 50.5% CO2. The combustion efficiency of the anode off-gas was directly evaluated by measuring the engine-out CO emissions. The highest net-indicated fuel conversion efficiency of 31.3% occurred at ϕ  = 0.90 and CR = 13:1. These results demonstrate that the anode off-gas can be successfully oxidized using a spark ignition combustion mode. The fuel conversion efficiency of the anode tail gas is expected to further increase in a more modern engine architecture that can achieve increased burn rates in comparison to the CFR engine. NOx emissions from the combustion of anode off-gas were minimal as the cylinder peak temperatures never exceeded 1800 K. This experimental study ultimately demonstrates the viability of an ICE to operate using an anode off-gas, thus creating a complementary role for an ICE to be paired with a SOFC in a hybrid power generation plant.

scholarly journals Modelling combustion in spark ignition engines with special emphasis on near wall flame quenching

2020 ◽  
pp. 146808742097290
Author(s):  
CP Ranasinghe ◽  
W Malalasekera
Keyword(s):  
Combustion Rate ◽  
Fractal Theory ◽  
Pressure Rise ◽  
Spark Ignition ◽  
Spatial Inhomogeneity ◽  
Combustion Model ◽  
Spark Ignition Engines ◽  
Flame Acceleration ◽  
Flame Quenching ◽  
Near Wall

A flame front is quenched when approaching a cold wall due to excessive heat loss. Accurate computation of combustion rate in such situations requires accounting for near wall flame quenching. Combustion models, developed without considering wall effects, cannot be used for wall bounded combustion modelling, as it leads to wall flame acceleration problem. In this work, a new model was developed to estimate the near wall combustion rate, accommodating quenching effects. The developed correlation was then applied to predict the combustion in two spark ignition engines in combination with the famous Bray–Moss–Libby (BML) combustion model. BML model normally fails when applied to wall bounded combustion due to flame wall acceleration. Results show that the proposed quenching correlation has significantly improved the performance of BML model in wall bounded combustion. As a second step, in order to further enhance the performance, the BML model was modified with the use of Kolmogorov–Petrovski–Piskunov analysis and fractal theory. In which, a new dynamic formulation is proposed to evaluate the mean flame wrinkling scale, there by accounting for spatial inhomogeneity of turbulence. Results indicate that the combination of the quenching correlation and the modified BML model has been successful in eliminating wall flame acceleration problem, while accurately predicting in-cylinder pressure rise, mass burn rates and heat release rates.

Service Methane Number as a Means to Avoid Knock in Natural Gas Fuelled Spark Ignition Engines

2003 ◽  
Author(s):  
Guillaume Brecq ◽  
Camal Rahmouni ◽  
Abdellilah Taouri ◽  
Mohand Tazerout ◽  
Olivier Le Corre
Keyword(s):  
Good Accuracy ◽  
Spark Ignition ◽  
Experimental Investigations ◽  
Spark Ignition Engines ◽  
Mean Absolute Deviation ◽  
Si Engine ◽  
Absolute Deviation ◽  
Gaseous Fuels ◽  
Maximum Absolute Deviation ◽  
Methane Number

Experimental investigations on the knock rating of gaseous fuels were carried out on a single cylinder SI engine of Lister-Petter make. The Service Methane Number (SMN) of different gas compositions is measured and then compared to the standard Methane Number (MN), calculated by the AVL software. Effects of engine parameters, by mean of the Methane Number Requirement (MNR) are also highlighted. A linear correlation, between the SMN and the MN, has been obtained with a maximum absolute deviation lower than 2 MN units. A prediction correlation giving the MNR from engine parameters has finally been deduced from experimental data with a good accuracy (mean absolute deviation of 0.5 MNR unit).

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