ORCID Profile
0000-0001-5672-9448
Current Organisation
Edith Cowan University
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Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 04-2016
Publisher: Elsevier BV
Date: 11-2027
Publisher: Informa UK Limited
Date: 04-11-2003
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 02-2018
Publisher: SAGE Publications
Date: 15-07-2023
DOI: 10.1177/09576509221115505
Abstract: Stationary and mobile power generation systems, as well as those for aero propulsion, continue to rely heavily on gas turbines. Operational envelopes which critically depends on (flame) jet stabilisation mechanisms, such as swirl, are also affected by considerations for emissions control. In this context, the evolving swirling flow domains feature injection of side (peripheral) dilution air. Despite this, the role of side dilution jets on modifying the flow, turbulence, and mixing fields of turbulent bluff-body (BB) stabilised (swirling) annular flows has not been investigated. This study uses three-dimensional simulations, supported with experimental data to establish boundary conditions, to investigate the interaction of side dilution jets (Re d = 18,000) with both non-swirling (S = 0) and swirling (S = 0.3) turbulent BB stabilised annular flows (Re s = 35,500). Constant Temperature Anemometry (CTA) measurements are conducted to resolve inlet boundary conditions. The Reynolds Stress Model (RSM) and species transport model (isothermal) are used with validations against benchmark datasets. Results show that the introduction of side dilution jets into a confined domain, whether swirling or not, induces (asymmetrical) Peripheral Recirculation Zones (PRZ). However, the strength, length, and location of PRZ varies with swirl and the downstream positioning of side dilution jets (H = 2.6D, 6.6D). Additionally, side dilution jets increase centreline velocity decay for both, non-swirling and swirling BB flows. In terms of turbulence characteristics, addition of side dilution jets leads to significant gains in shear layer turbulence with an increase of 72% and 35% in turbulent kinetic energy for non-swirling and swirling BB flows, respectively. Analysis of the mixing characteristics shows negligible impact of side dilution jets in the upstream region, however, from x/D 3 considerable improvement in central jet (fuel) mixing is observed.
Publisher: Informa UK Limited
Date: 20-04-2021
Publisher: Elsevier BV
Date: 12-2017
Publisher: Elsevier BV
Date: 09-2014
Publisher: Elsevier BV
Date: 07-2006
Publisher: Informa UK Limited
Date: 18-09-2007
Publisher: Informa UK Limited
Date: 2007
Publisher: Elsevier BV
Date: 2024
Publisher: Elsevier BV
Date: 09-2015
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 2022
Publisher: SAGE Publications
Date: 28-04-2023
DOI: 10.1177/09576509231173010
Abstract: Air staging features widely in biomass combustion from small space heaters to industrial-scale moving grate systems. Whilst studies have been conducted into the impact of air staging on emissions and combustion performance, there is little or no insight into the exact flow dynamic and physical mechanisms that are induced by secondary air under such conditions. This paper uses experimental data to validate numerical predictions before investigating the flow field structures and mixing characteristics in a fixed bed air staged combustor. The study utilizes Constant Temperature Anemometry (CTA) experiments to establish boundary conditions for a lab-scale fixed bed combustor. Results from numerical simulations obtained using [Formula: see text] l- 𝜔 model were in good agreement with experimental data. Conditions tested cover five different secondary to total air ratios (Q s /Q t ) and two different locations of secondary air injection. Results show that at Q s /Q t = 0.50, 0.25 and 0.18 one strong recirculation zone is induced upstream of the secondary air injection and one downstream. Varying the point of injection of secondary air from h/D = 0.64 to h/D = 0.40 also had an effect on the size of the upstream recirculation zone. Q s /Q t = 0.50 had the highest values of mixing index among all spatially located planes at the upstream of secondary air injection. The overall findings shed light on the possible flow interactions between secondary air and the top layers of fuel bed. They also highlight the significance of secondary air on inducing both upstream and downstream flow structures.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2023
DOI: 10.1007/S12155-023-10572-Z
Abstract: Non-conventional torrefaction under partially oxidative conditions is an emerging cost-effective thermochemical pre-treatment method to improve the quality of biomass for energy applications. The literature lacks data on the combustion of biomass torrefied under oxygen-deficient atmosphere with actual reactor conditions (inevitable non-uniformities in the thermal environment). In this work, a dual mode fixed-bed biomass (torrefaction) reactor and combustor was operated on Australian biomass pellets, to torrefy the fuels at 275 °C for 30 min using partially oxidative atmosphere (O 2 : 5 vol%, balance N 2 ) and then to combust them. Combustion behaviour with a particular focus on gaseous emissions of raw, blended (25% torrefied), and torrefied (100%) pellet fuels in a batch-type combustor was investigated. The decomposition behaviour was analysed in a thermogravimetric analyser to understand the impact of biomass constituents on the direct combustion of the tested s les. Results indicate that unlike the combustion of raw biomass, the fuels torrefied under partially oxidative conditions burned 45% faster, attained high packed-bed temperatures (1382 °C) and exhaust gas temperatures (657 °C) then latter (bed: 1128 °C, exhaust: 574 °C) at similar airflow. Additionally, 100% torrefied pellets emitted 38% less NOx compared to raw biomass pellets. However, low CO values for torrefied biomass were attained at higher primary airflows compared to raw. The combustion of 100% torrefied biomass in a fixed-bed was dominated by both flaming and smouldering phases with a modified combustion efficiency (MCE) value of 91%, whereas raw biomass combustion occurred in flaming phase with an MCE value of 98% at same airflow (0.35 kg·m −2 ·s −1 ). The outcomes of this work provide useful insights into the viability of using biomass fuels torrefied under partially oxidative conditions alongside other industrial processes generating (waste) heat and flue gases.
Publisher: Informa UK Limited
Date: 05-12-2017
Publisher: Informa UK Limited
Date: 12-2022
Publisher: Elsevier BV
Date: 2015
Publisher: Springer Singapore
Date: 2017
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 31-08-2023
DOI: 10.1007/S12155-022-10504-3
Abstract: In staged fixed bed biomass combustion, primary air is supplied beneath the fuel bed with secondary air then provided above in the freeboard region. For fixed bed configurations, the freeboard is further ided into a primary freeboard length (LI), which is upstream of the secondary air and a secondary freeboard length (LII), measured from the secondary air all the way to the exhaust port. Despite extensive research into fixed bed configurations, no work has been successfully completed that resolves the effects of changing LI on fuel conversion, both in the fuel bed and within the freeboard of batch-type biomass combustors. In this study, experiments on a 202 mm diameter and 1500 mm long batch-type combustor have been conducted to determine the effects of changing primary freeboard length over three secondary to total air ratios (Q s /Q t ) and two total air flow rates (Q t ). The impact of these conditions has been studied on (i) intra-bed fuel conversion, measured through burning rate (kg/m −2 s −1 ), fuel bed temperature (°C) and ignition front velocity (mm-s −1 ), as well as (ii) post-bed fuel conversion in the freeboard, expressed through freeboard temperatures and emissions (NO x ppm, CO 2 %, CO ppm, O 2 %). The fuel used throughout the above experiments was Australian hardwood pelletised biomass. Results show that changes to primary freeboard length over LI = 200 mm, 300 mm and 550 mm, or LI/D = 1.00, 1.48 and 2.72, respectively, affect both intra-bed and freeboard (post-bed) performance indicators. The highest values of burning rate, ignition front velocity and fuel bed temperature were observed for interim values of LI/D = 1.48 at Q s /Q t = 0.25 and Q t = 0.358 kg/m −2 s −1 . Primary freeboard lengths of LI/D = 1.00 and 1.48 were found to have higher freeboard temperatures, NO x and CO 2 as well as lower CO and O 2 values as compared to LI/D = 2.72 at Q s /Q t = 0.50 and 0.75. Increasing Q s /Q t from 0.25 to 0.50 for LI/D = 1.00 and 1.48 initially increased freeboard temperatures, with an accompanying increase in NO x and CO 2 as well as decrease in CO values. However, further increase in Q s /Q t to 0.75 lead to lower freeboard temperatures for all primary freeboard lengths.
Publisher: Informa UK Limited
Date: 21-01-2016
Publisher: Springer Science and Business Media LLC
Date: 26-07-2020
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 11-2015
Publisher: Elsevier BV
Date: 10-2019
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 05-2003
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 06-2016
Publisher: Elsevier BV
Date: 08-2015
Publisher: Elsevier BV
Date: 05-2016
Publisher: Springer Science and Business Media LLC
Date: 15-08-2022
Publisher: Elsevier BV
Date: 09-2021
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 11-2019
Publisher: Springer Science and Business Media LLC
Date: 21-01-2023
Publisher: Elsevier BV
Date: 12-2019
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 02-2019
Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 2002
Publisher: Springer Science and Business Media LLC
Date: 12-08-2023
DOI: 10.1007/S11630-023-1869-9
Abstract: Staged combustion of biomass is the most suitable thermo-chemical conversion for achieving lower gaseous emissions and higher fuel conversion rates. In a staged fixed bed combustion of biomass, combustion air is supplied in two stages. In the first stage, primary air is provided below the fuel, whereas in the later stage, secondary air is supplied in the freeboard region. The available literature on the effects of air staging (secondary air location) at a constant primary air flow rate on combustion characteristics in a batch-type fixed bed combustor is limited and hence warrants further investigations. This study resolves the effect of air staging, by varying the location of secondary air in the freeboard at five secondary to total air ratios in a batch-type fixed bed combustor. Results are reported for the effects of these controlled parameters on fuel conversion rate, overall gaseous emissions (CO 2 , CO and NO x ) and temperature distributions. The fuel used throughout was densified hardwood pellets. Results show that a primary freeboard length (distance between fuel bed top and secondary air injection) of 200 mm has higher fuel conversion rates and temperatures as well as lower CO emissions, at a secondary to total air ratio of 0.75 as compared to primary freeboard length of 300 mm. However, NO x emissions were found to be lower for a primary freeboard length of 300 mm as compared to 200 mm. An increase in secondary to total air ratio from 0.33 to 0.75 resulted in higher freeboard temperatures and lower CO as well as NO x emissions. The outcomes of this study will be helpful in the effective design of commercial scale biomass combustors for more efficient and environmentally friendly combustion.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 08-2015
No related grants have been discovered for Yasir Al-Abdeli.