scholarly journals Heavy Fuel Oil Combustion Characteristics Evaluation in Various Swirling Flow Conditions

2021 ◽  
Author(s):  
Xinyan Pei ◽  
Ayman.M Elhagrasy ◽  
Long Jiang ◽  
Kamal M. AlAhmadi ◽  
Saumitra Saxena ◽  
...  
Keyword(s):  
Swirling Flow ◽  
Flame Temperature ◽  
High Energy ◽  
Solid Particles ◽  
Fuel Oil ◽  
High Energy Density ◽  
Flow Conditions ◽  
Heavy Fuel Oil ◽  
Swirl Flows ◽  
Swirling Flame

Abstract Heavy fuel oil (HFO) is an economical fuel alternative for power generation as its low production cost and high energy density. However, its incomplete combustion induced by the presence of long-chain petroleum molecules in the fuel results in high levels of emissions. Here, we investigate the influence of the swirl flow on the combustion and emissions of a spray HFO swirling flame. To this end, HFO is sprayed into a hot swirling air, using an air-blast nozzle. The flame blowout limits are tested under different swirl flows. An investigation of the in-flame temperature fields, gaseous emissions including CO, CO2, O2, NOX, SOX, UHC (Unburned Hydrocarbon) and solid particles in the form of cenospheres are used to quantify the performance of the HFO combustion. The influence of the HFO swirling flame is tested under different conditions of global equivalence ratio, swirling number, and tangential and axial airflow rates. A comparison of two different flame regimes that fuel-jet dominate flame and air-driven vortex flows are investigated and compared in various swirling flow conditions. The results show that the tangent air is the primary factor for preheating and evaporating the fuel, thus defining the flame operating regimes.

scholarly journals Swirling Flame Combustion of Heavy Fuel Oil: Effect of Fuel Sulfur Content

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Xinyan Pei ◽  
Abdul Gani Abdul Jameel ◽  
Chaoqin Chen ◽  
Ibrahim A. AlGhamdi ◽  
Kamal AlAhmadi ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Sulfur Content ◽  
Flue Gas ◽  
Flame Temperature ◽  
Fuel Oil ◽  
Gaseous Emissions ◽  
So2 Emissions ◽  
Heavy Fuel Oil ◽  
Ultra Low Sulfur Diesel ◽  
Swirling Flame

Abstract In the present work, an experimental investigation on the effect of sulfur content in heavy fuel oil (HFO) on the gaseous emissions under swirling flame conditions was carried out. The sulfur content in HFO was varied by blending with ultra-low sulfur diesel and four fuel samples containing 3.15, 2.80, 1.97, and 0.52% sulfur (by mass) were prepared. Pure asphaltenes were added to the blends to ensure that the asphaltene content in the fuel remained the same. The fuels were then fired in a high-swirl stabilized, turbulent spray flame. The combustion performance of the fuels was evaluated by measuring flame temperature distribution, gaseous emissions (SOx, NOx, CO, CO2, and flue gas pH), and particulate matter (PM) emissions (morphology, composition, and pH). The results showed a significant reduction in the SO2 emissions and acidity of the flue gas when the sulfur content in the fuel was reduced, as expected. The reduction was more than would be expected based on sulfur content, however. For example, the flue gas SO2 concentration reduced from 620 ppm to 48 ppm when the sulfur content in the fuel was reduced from 3.15 to 0.52% (by mass). Sulfur balance calculations indicate that nearly 97.5% of the sulfur in the fuel translates into gaseous emissions and the remaining 2.5% appears in PM emissions. Ninety-five percent of the gaseous sulfur emissions are SO2, whereas the rest appears as SO3. Varying the sulfur content in the fuel did not have a major impact on the flame temperature distribution or NOx emissions. The morphologies and the size distribution of the PM also did not change significantly with the sulfur content as the asphaltenes content of the fuels remained the same.

Cenosphere formation of heavy fuel oil/water emulsion combustion in a swirling flame

2021 ◽  
Vol 216 ◽  
pp. 106800
Author(s):  
Xinyan Pei ◽  
Paolo Guida ◽  
K.M. AlAhmadi ◽  
Ibrahim A. Al Ghamdi ◽  
Saumitra Saxena ◽  
...  
Keyword(s):  
Fuel Oil ◽  
Heavy Fuel Oil ◽  
Water Emulsion ◽  
Swirling Flame ◽  
Oil Water

scholarly journals Metals and Alloys Additives as Enhancer for Rocket Propulsion: A Review

2021 ◽  
Vol 90 (1) ◽  
pp. 1-9
Author(s):  
Izham Izzat Ismail ◽  
Norhuda Hidayah Nordin ◽  
Muhammad Hanafi Azami ◽  
Nur Azam Abdullah
Keyword(s):  
Specific Impulse ◽  
Flame Temperature ◽  
High Energy ◽  
Combustion Efficiency ◽  
High Energy Density ◽  
Regression Rate ◽  
High Entropy ◽  
Rocket Propulsion ◽  
Wide Range ◽  
Metal Additives

A rocket's engine usually uses fuel and oxygen as propellants to increase the rocket's projection during launch. Nowadays, metallic ingredients are commonly used in the rocket’s operation to increase its performance. Metallic ingredients have a high energy density, flame temperature, and regression rate that are important factors in the propulsion process. There is a wide range of additives have been reported so far as catalysts for rocket propulsion. The studies show that the presence of metal additives improves the regression rate, specific impulse and combustion efficiency. Herein, the common energetic additives for rocket propulsion such as metal and light metals are reviewed. Besides the effect of these energetic particles on the regression behaviors of base (hybrid) fuel has been exclusively discussed. This paper also proposed a new alloy namely high entropy alloys (HEAs) as a new energetic additive that can potentially increase the performance of the rocket propellant system.

scholarly journals Large-eddy simulation of a reacting swirling flow in a model combustion chamber

2021 ◽  
Vol 2119 (1) ◽  
pp. 012031
Author(s):  
M Yu Hrebtov ◽  
E V Palkin ◽  
D A Slastnaya ◽  
R I Mullyadzhanov ◽  
S V Alekseenko
Keyword(s):  
Combustion Chamber ◽  
Swirling Flow ◽  
Low Velocity ◽  
Vortical Structures ◽  
Eddy Simulation ◽  
Precessing Vortex Core ◽  
Flamelet Generated Manifold ◽  
Swirl Flows ◽  
Large Eddy ◽  
Swirling Flame

Abstract We perform Large-eddy simulations of a non-premixed swirling flame in a model of a combustion chamber with a swirling air bulk flow at Re = 15000 and a central pilot low-velocity jet with methane using the Flamelet-generated manifold model. The unsteady behaviour of this regime is well reproduced based on the flame dynamics. The distribution of turbulent kinetic energy suggests the presence of intensive vortical structures typical of high-swirl flows similar to the precessing vortex core.

scholarly journals Preparation of spherical LiNi0.5Mn1.5O4 with core-multilayer shells structure by co-precipitation method and long cycle performance

2020 ◽  
Vol 213 ◽  
pp. 01011
Author(s):  
Guo-Jiang Zhou ◽  
Tao Yu ◽  
Yang Zhou ◽  
Li-Guo Wei
Keyword(s):  
Specific Capacity ◽  
Lithium Ion ◽  
High Energy ◽  
Solid Particles ◽  
High Energy Density ◽  
Cycle Performance ◽  
Precipitation Method ◽  
Xps Spectra ◽  
Long Cycle ◽  
Co Precipitation

As a promising cathode material for lithium ion battemensionalry of high voltage, spinel LiNi0.5Mn1.5O4 has attracted interest due to its high discharging voltage at 4.7 V and high energy density of 610 Wh kg-1. In this work, LiNi0.5Mn1.5O4 with a new core-multilayer shells structure (LNMO-900) is synthesized successfully by co-precipitation method and shows a better electrochemical performance. The formation of the core-multilayer shells structure is related to the kirkendall effect, the shell maintains structural stability, and improves long cycle performance. Core-multilayer shells structure is also beneficial for transmission of lithium ion, increasing rate performance. The effects of sintering temperature on the performance of LNMO were further investigated. Core-multilayer shells LiNi0.5Mn1.5O4 is synthesized successfully at 900 °C for 12 h uniquely. From the integral calculation of XPS spectra, a higher content of Mn4+ is observed in the outer shell of LNMO-900 compared with other homogeneous solid particles. The discharge specific capacity of LNMO-900 is 129.3 mAh g-1 at 1 C which is superior to others, and after 1000 cycles, LNMO-900 shows capacity retention of 87.9%. The initial capacity of LNMO-900 is 104.9 mAh g-1 at 5 C.

Effect of Holes Array on Effusion Cooling Characteristics of a Three-Nozzle Model Combustor Liner

2017 ◽  
Author(s):  
Yongbin Ji ◽  
Bing Ge ◽  
Shusheng Zang ◽  
Jianhua Xin ◽  
Chun Ye ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Swirling Flow ◽  
Reacting Flow ◽  
Flow Conditions ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Annular Combustor ◽  
Swirling Flame ◽  
Cooling Behavior

Effusion cooling performance for a simulated three-nozzle annular combustor under both non-reacting and reacting flow conditions is experimentally investigated. Under this realistic swirling flow, cooling behavior shows the remarkable difference with that under uniform flow case. Mainstream air is electrically heated to a certain temperature level (180 °C) under non-reacting conditions, while methane-air premixed combustion is performed under reacting conditions at the equivalence ratio of 0.7. Especially, the effect of effusion holes array is discussed for the in-line and staggered layouts. Infrared thermography is used to record the temperature distribution on the two bent cooling test panels equipped with the outer and inner liners respectively after individual in-situ calibration process. Local and average overall cooling effectiveness results are then analyzed as a vital parameter to weigh the cooling performance. Results show that no matter under non-reacting or reacting flow conditions, the temperature distribution is skewed, which is closely related to the multi-nozzle swirling flow structure inside the combustor. In addition, an elliptic region area of relatively low cooling effectiveness appears at the downstream the injector outlet due to swirling jets impingement effect when the reaction is activated, however, this is not observed under cold flow cases. The impinging swirling flame on the combustor wall also leads to the local blowing ratio declining, so the effusion film will be not easy to issue through the holes. Influence of holes layout on the cooling characteristics are also different on the outer and inner liners. It is assumed to be caused by the interaction of effusion jets and main swirling flow. This reminds us that in the annular combustor, effusion cooling optimization should be considered according to the curvature. Generally, staggered effusion cooling holes arrangement presents better cooling performance than the in-line arrangement.

scholarly journals Product formation during discharge: a combined modelling and experimental study for Li–O$$_2$$ cathodes in LiTFSI/DMSO and LiTFSI/TEGDME electrolytes

2021 ◽  
Author(s):  
Michael T. Rauter ◽  
Matthias Augustin ◽  
Lena Spitthoff ◽  
Ann Mari Svensson
Keyword(s):  
Dynamic Change ◽  
Porous Electrode ◽  
High Energy ◽  
Product Formation ◽  
Solid Particles ◽  
High Energy Density ◽  
Model Parameters ◽  
Discharge Process ◽  
Continuous Change ◽  
Solution Mechanism

AbstractLi–air or Li–$$\text{O}_2$$ O 2 batteries are a promising energy storage technology due to the potentially high energy density. However, significant challenges related to reversible charge/discharge of these cells need to be solved. The discharge reaction is generally agreed to proceed via two main routes, which may occur simultaneously. These are the surface mechanism, leading to $$\text{Li}_2\text{O}_2$$ Li 2 O 2 product formation as surface films, or the solution mechanism, with solid particles formed in the pore structure of the cathode. A detailed understanding of the reaction mechanisms and the dynamic performance of the electrodes is key to further improvements. Here, we present a mathematical model for the discharge process, based on porous electrode theory, including effects of reactant transport and kinetic limitations, as well as the continuous change of properties due to the formation of reaction products via the solution mechanism and the surface mechanism. The model describes the dynamic change in the ratio of the surface and solution mechanism as a function of growth of film thickness, in line with recent findings. The model is able to predict the differences in experimentally obtained discharge curves between dimethyl sulfoxide and tetra ethylene glycol dimethyl ether solvents with 1M LiTFSI, with a minimum of free parameters. The model parameters are based on physical characterization of the materials and the electrodes, or determined by fitting to impedance spectra recorded during the discharge. The developed model and the methodology will provide a powerful tool for optimization of such electrodes. Graphic abstract

Numerical Analysis of the Swirl Intensity Decay Rate for Internal Turbulent Swirling Flow

2007 ◽  
Author(s):  
A. F. Najafi ◽  
S. M. Mousavian ◽  
M. H. Saidi
Keyword(s):  
Decay Rate ◽  
Swirling Flow ◽  
Flow Conditions ◽  
Solid Body Rotation ◽  
Swirl Generator ◽  
Swirl Flows ◽  
Swirl Intensity ◽  
Pipe Inlet ◽  
Mathematical Relations ◽  
Intensity Decay

In this research the trend of swirl decay and factors influencing the turbulent swirl flows have been investigated in a fixed pipe. In this regard, turbulent swirling decay flow with solid body rotation has been numerically surveyed using different flow conditions at the pipe inlet. The numerical results have been validated and compared with the existing mathematical relations having satisfactory agreement. Results show that the swirl intensity decay rate has strong dependency on the Reynolds number. On this basis, correlations have been proposed which improves predictions of swirl intensity decay rate at upstream regions and those with high swirl intensity. In addition, analyses have been made to demonstrate that the previously developed correlations for predicting swirl intensity decay rate, agree with those provided in this study only for regions far enough down stream having the low swirl intensity. This implies that the swirl intensity decay rate should be a function of the type of swirl generator at the inlet.

Numerical Study of Composite Electrode's Particle Size Effect on the Electrochemical and Heat Generation of a Li-Ion Battery

2015 ◽  
Vol 6 (4) ◽  
Author(s):  
A. H. N. Shirazi ◽  
M. R. Azadi Kakavand ◽  
T. Rabczuk
Keyword(s):  
Heat Generation ◽  
Numerical Study ◽  
Lithium Ion ◽  
High Energy ◽  
Solid Particles ◽  
High Energy Density ◽  
Design Parameters ◽  
Operating Voltage ◽  
Battery Cell ◽  
Battery Capacity

Rechargeable lithium-ion batteries (LIBs) are now playing crucial roles in power supply and energy storage systems. Among all types of rechargeable batteries available nowadays, LIBs are one of the most important ways to store energy because of their high energy density, high operating voltage, and low rate of self-discharge. Nonetheless, the performance of LIBs could be improved by different design parameters, such as the size of solid particles in the battery composite electrodes. Therefore, this study aims to investigate the effect of the composite electrode particles size on the electrochemical and heat generation of an LIB. A Newman's electrochemical pseudo two-dimenisonal model was used to model the LIB cell. Reversible heat produced through electrochemical reactions was calculated as well as irreversible heat originating from internal resistances in the battery cell. Our results show that smaller sizes of electrode solid particles improve the thermal characteristics of the battery, especially in higher charge and discharge currents (C-rate). Furthermore, as the solid particle sizes decrease, the battery capacity increases for various C-rates in charge and discharge cycles.

Pilot-scale combustion studies with kraft lignin in a powder burner and a CFB boiler

TAPPI Journal ◽  
2010 ◽  
Vol 9 (6) ◽  
pp. 24-30 ◽  
Author(s):  
NIKLAS BERGLIN ◽  
PER TOMANI ◽  
HASSAN SALMAN ◽  
SOLVIE HERSTAD SVÄRD ◽  
LARS-ERIK ÅMAND
Keyword(s):  
Circulating Fluidized Bed ◽  
Black Liquor ◽  
Chloride Content ◽  
Pilot Scale ◽  
High Energy ◽  
Kraft Lignin ◽  
High Energy Density ◽  
Alkali Chloride ◽  
Cfb Boiler ◽  
Solid Biofuel

Processes have been developed to produce a solid biofuel with high energy density and low ash content from kraft lignin precipitated from black liquor. Pilot-scale tests of the lignin biofuel were carried out with a 150 kW powder burner and a 12 MW circulating fluidized bed (CFB) boiler. Lignin powder could be fired in a powder burner with good combustion performance after some trimming of the air flows to reduce swirl. Lignin dried to 10% moisture content was easy to feed smoothly and had less bridging tendencies in the feeding system than did wood/bark powder. In the CFB boiler, lignin was easily handled and cofired together with bark. Although the filter cake was broken into smaller pieces and fines, the combustion was not disturbed. When cofiring lignin with bark, the sulfur emission increased compared with bark firing only, but most of the sulfur was captured by calcium in the bark ash. Conventional sulfur capture also occurred with addition of limestone to the bed. The sulfur content in the lignin had a significantly positive effect on reducing the alkali chloride content in the deposits, thus reducing the high temperature corrosion risk.

Sign in / Sign up

Export Citation Format

Share Document