Abdellatif M. Sadiq

Bio: Abdellatif M. Sadiq is an academic researcher from Qatar University. The author has contributed to research in topics: Combustion & Diesel engine. The author has an hindex of 2, co-authored 3 publications receiving 17 citations.

Turbulent Flames in Enclosed Combustion Chambers: Characteristics and Visualization—A Review

Abstract: Remarkable progress has been achieved in measuring the flame propagation rate accurately under laminar conditions, which can be used to predict turbulent flame propagation rates using some correlations fitted to experimental data. However, such propagation rates, unlike the laminar case, cannot be unambiguously determined. Nevertheless, the advancement of laser imaging techniques has led to several definitions of turbulent burning rates (Roshan et al., 2010, “Simulation of Global Warming Effect on Outdoor Thermal Comfort Conditions,” Int. J. Environ. Sci. Technol., 7(3), pp. 571–580). Recently, a unified scaling factor has been successfully demonstrated using data gathered from several fan-stirred bombs. Such results are promising in compiling a comprehensive database of turbulent propagation rates for potential and common fuels of interest to internal combustion engines (ICEs) and gas turbines alike. The strict worldwide legislation to reduce emissions has forced many industries to look into alternative fuels with less emissions. One such alternative fuel that has gained much interest recently is the gas-to-liquid (GTL) fuel, which is being used in blended forms in several combustion applications. However, detailed combustion characteristic investigations are required before using this new alternative fuel widely in engines (Business, 2018, “Qatar’s Exporters Directory 2018”). In this study, the significant issues associated with the use of fan-stirred bombs are investigated. First, the effect of varying fan speed and geometry is reviewed, and then, the measurement techniques that are commonly used to track flame propagation are discussed. This is followed by the study of the effect of using different types of fuels on combustion characteristics. Furthermore, the use of diesel and gasoline optical engine setups as advanced flame visualization tools have been reviewed extensively.

Investigating the Effect of Utilizing New Induction Manifold Designs on the Combustion Characteristics and Emissions of a Direct Injection Diesel Engine

Abstract: New induction manifold designs have been developed in this work to enhance the turbulence intensity and improve the mixing quality inside diesel engine cylinders. These new designs employ a spiral-helical shape with three different helical diameters (1D, 2D, 3D; where D is the inner diameter of the manifold) and three port outlet angles: 0 deg, 30 deg, and 60 deg. The new manifolds have been manufactured using three-dimensional printing technique. Computational fluid dynamics simulations have been conducted to estimate the turbulent kinetic energy (TKE) and the induction swirl generated by these new designs. The combustion characteristics that include the maximum pressure raise rate (dP/dθ) and the peak pressure inside the cylinder have been measured for a direct injection (DI) diesel engine utilizing these new manifold designs. In addition, engine performance and emissions have also been evaluated and compared with those of the normal manifold of the engine. It was found that the new manifolds with 1D helical diameter produce a high TKE and a reasonably strong induction swirl, while the ones with 2D and 3D generate lower TKEs and higher induction swirls than those of 1D. Therefore, dP/dθ and peak pressure were the highest with manifolds 1D, in particular manifold m (D, 30). Moreover, this manifold has provided the lowest fuel consumption with the engine load by about 28% reduction in comparison with the normal manifold. For engine emissions, m (D, 30) manifold has generated the lowest CO, SO2, and smoke emissions compared with the normal and other new manifolds as well, while the NO emission was the highest with this manifold.

Combustion Characteristics and Emissions of a Direct-Injection Diesel Engine Fueled with GTL Fuel Blends

Abstract: I. IntroductionGas to Liquids (GTL) is one of clean alternative fuels which loosely defined terms that is generally used to describe the chemical conversion of natural gas to some type of liquid products. As such, it excludes the production of liquefied natural gas (LNG), but includes the conversion of gas to methanol, liquid fuels, and petrochemicals, being the most common applications. In other words, Gas to liquids (GTL) technology is used to convert a carbon containing feedstock such as natural gas, to synthetic diesel fuels and further developed by oil companies. Fewer studies investigated the use of GTL diesel with the existing diesel engines to study the effect of using this new alternative fuel on the efficiency and emissions in these engines. Hence, the objectives of this study are to investigate the behavior of the GTL – diesel fuel blends in context of different combustion characteristics, engine performance and emissions. It is expected that the outcomes of this study will shed further light o...

Hydrogen-Enriched Biogas Premixed Charge Combustion and Emissions in Direct Injection and Indirect Injection Diesel Dual Fueled Engines: A Comparative Study

Abstract: This paper presents a comparative study on combustion and emissions of hydrogen-enriched biogas premixed charge direct injection dual-fuel (DIDF) engine and indirect injection dual-fuel (IDIDF) engine. The results show that the IDIDF engine outperforms the DIDF engine in terms of higher indicative engine cycle work (Wi) and lower emissions of CO, soot, and noise, but the disadvantage is higher NOx emission. Under the same fueling condition, the IDIDF engine’s Wi is on average 6% higher than that of the DIDF engine, but the NOx concentration in the combustion products of the IDIDF engine is 1.5 times higher than that of the DIDF engine. The IDIDF engine creates the stratified mixture distribution with higher O2 concentration in the auxiliary combustion chamber, which is favorable for auto-ignition and reduces the ignition delay. The biogas composition affects slightly CO and soot emissions, but significantly affects NOx emission. When the methane composition in biogas increases from 60% to 80%, the soot volume fraction is approximately 0.1 ppm in both types of combustion chambers, the CO concentration varies from 1.4% to 1.8%, and the NOx concentration varies from 3000 to 5000 ppm in the case of IDIDF engine and 2500–4500 ppm in the case of DIDF engine. For both types of dual-fuel engines, when engine speed increases, CO concentration and the soot volume fraction increase, while Wi and NOx concentration decrease.

A Review on the Performance, Combustion, and Emission Characteristics of Spark-Ignition Engine Fueled With 2,5-Dimethylfuran Compared to Ethanol and Gasoline

Abstract: Currently, the supply of diminishing fossil fuel reserves, and the rise in challenges in environmental, political and economic consequences have caused the great concerns in the development of modern society; these have forced the policy-makers and researchers to look for the renewable and green energy sources. Deemed as a promising renewable alternative to traditional fossil fuels, 2,5-dimethylfuran (DMF, chemical formula C6H8O)—a derivative of furan—has the potential to relieve the growing shortage of fossil fuels while satisfying the increase in global energy demand and minimizing the adverse effects of climate change. DMF can be used as a clean source of liquid transportation biofuel given the fact that it is directly obtained from biomass-derived carbohydrates. In reviewing current DMF production methods, this review paper analyzes and presents the comparison of catalytic performance in the conversion of biomass into DMF. In addition, the applicability of DMF in spark-ignition (SI) engines is thoroughly analyzed based on the spray and flame, combustion, performance, and emission characteristics of SI engines running on DMF compared with ethanol and gasoline. More interestingly, the knocking, lubrication, and wear characteristics in SI engines fueled with DMF are also evaluated and discussed. Nonetheless, further investigation on optimization strategies on DMF production process should be conducted prior to the initiation of large-scale commercialization as well as the application of DMF to real-world SI engines.

Experimental and Numerical Study on the Formation Mechanism of Flow Field in a Side-Ported Rotary Engine Considering Apex Seal Leakage

Abstract: The aim of this research is to investigate the influences of apex seal leakage on the formation mechanism of flow field in a side-ported rotary engine by particle image velocimetry (PIV) and computational fluid dynamics (CFD). In this study, a PIV was used to acquire the two-dimensional (2D) flow field on the rotor housing central plane at an engine speed of 700 rpm. A three-dimensional (3D) dynamic simulation model considering leakage through apex seals was established and verified by the 2D-PIV experiment results. Thereafter, CFD analysis was used to further understand the 3D flow field in combustion chamber under the action of apex seal leakage. The simulation results showed that for the three engine speeds (2000, 3500, and 5000 rpm), in the intake stroke, the vortex generated in the front end of combustion chamber under the condition with no leakage, was strengthened and destroyed by the effects of the small (0.02 mm) and the large (0.08 mm) apex seal leakage gaps, respectively. As the apex seal leakage gap increased, the volume efficiency and the peak pressure decreased continuously. The volume efficiency and the peak pressure caused by any fixed apex seal leakage gap decreased with the increase of the engine speed. Compared with the volumetric efficiency of the condition with no leakage at 2000 and 5000 rpm, the volumetric efficiency of apex seal leakage gap of 0.08 mm decreased only by 24.6% at 5000 rpm, but by 41.2% at 2000 rpm.

Prediction of Ultra-Lean Spark Ignition Engine Performances by Quasi-Dimensional Combustion Model with a Refined Laminar Flame Speed Correlation

Abstract: The turbulent combustion in gasoline engines is highly dependent on laminar flame speed SL. A major issue of the quasi-dimensional (QD) combustion model is an accurate prediction of the SL, which is unstable under low engine speeds and ultra-lean mixture. This work investigates the applicability of the combustion model with a refined SL correlation for evaluating the combustion characteristics of a high-tumble port gasoline engine operated under ultra-lean mixtures. The SL correlation is modified and validated for a five-component gasoline surrogate. Predicted SL values from the conventional and refined functions are compared with measurements taken from a constant-volume chamber under micro-gravity conditions. The SL data are measured at reference and elevated conditions. The results show that the conventional SL overpredicts the flame speeds under all conditions. Moreover, the conventional model predicts negative SL at equivalence ratio ϕ ≤ 0.3 and ϕ ≥ 1.9, while the revised SL is well validated against the measurements. The improved SL correlation is incorporated into the QD combustion model by a user-defined function. The engine data are measured at 1000–2000 rpm under engine load net indicated mean effective pressure (IMEPn) = 0.4–0.8 MPa and ϕ = 0.5. The predicted engine performances and combustions are well validated with the measured data, and the model sensitivity analysis also shows a good agreement with the engine experiments under cycle-by-cycle variations.