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Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "L: Energy Sources".

Deadline for manuscript submissions: closed (30 September 2019) | Viewed by 20345

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Guest Editor
Department of Fire Protection Engineering, University of Maryland, College Park, MD, USA
Interests: combustion and fire research; soot formation and oxidation; microgravity combustion; refrigerant flammability; hydrogen flames; laminar diffusion flames; sodium fires; battery fires; vehicle fires and diagnostics development

Special Issue Information

Dear Colleagues,

This Special Issue of Energies gathers research on combustion as related to energy production and the associated fire and explosion safety. Both fundamental and applied research is welcome. Articles may be original research or reviews. Submissions must include state-of-the-art experiments, computations, and/or theory.

Combustion provides an estimated 85% of the world’s energy consumption. Advances in combustion research can benefit society in three main ways. Improving energy efficiency can reduce fuel consumption. Improving emissions can reduce climate change and adverse health effects. Improving fire and explosion safety can protect people, property, and the environment.

The topical areas covered by this Special Issue are broad. It is hoped that this breadth will lead to a better understanding of combustion and improved diagnostic and numerical tools. This, in turn, may result in improved combustors, a cleaner environment, novel fuels, and improved safety and energy security.

Dr. Peter B. Sunderland
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • alternative fuels
  • chemical kinetics
  • clean energy
  • computational combustion
  • diagnostics
  • engines
  • fires and explosions
  • flames
  • pollutants
  • power generation

Published Papers (5 papers)

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Research

17 pages, 2967 KiB  
Article
Identification and Quantification of Uncertainty Components in Gaseous and Particle Emission Measurements of a Moped
by Barouch Giechaskiel, Alessandro A. Zardini, Tero Lähde, Michael Clairotte, Fabrizio Forloni and Yannis Drossinos
Energies 2019, 12(22), 4343; https://doi.org/10.3390/en12224343 - 14 Nov 2019
Cited by 9 | Viewed by 1962
Abstract
The recent Euro 4 and 5 environmental steps for L-category vehicles (e.g., mopeds, motorcycles) were mainly designed to reduce the emissions of particulate matter and ozone precursors, such as nitrogen oxides and hydrocarbons. However, the corresponding engine, combustion, and aftertreatment improvements will not [...] Read more.
The recent Euro 4 and 5 environmental steps for L-category vehicles (e.g., mopeds, motorcycles) were mainly designed to reduce the emissions of particulate matter and ozone precursors, such as nitrogen oxides and hydrocarbons. However, the corresponding engine, combustion, and aftertreatment improvements will not necessarily reduce the solid particle number (SPN) emissions, suggesting that a SPN regulation may be necessary in the future. At the same time, there are concerns whether the current SPN regulations of passenger cars can be transferred to L-category vehicles. In this study we quantified the errors and uncertainties in emission measurements, focusing on SPN. We summarized the sources of uncertainty related to emission measurements and experimentally quantified the contribution of each uncertainty component to the final results. For this reason, gas analyzers and SPN instruments with lower cut-off sizes of 4 nm, 10 nm, and 23 nm were sampling both from the tailpipe, and from the dilution tunnel having the transfer tube in closed or open configuration (i.e., open at the tailpipe side). The results showed that extracting from the tailpipe 23–28% of the mean total exhaust flow (bleed off) resulted in a 24–31% (for CO2) and 19–73% (for SPN) underestimation of the emissions measured at the dilution tunnel. Erroneous determination of the exhaust flow rate, especially at cold start, resulted in 2% (for CO2) and 69–149% (for SPN) underestimation of the tailpipe emissions. Additionally, for SPN, particle losses in the transfer tube with the closed configuration decreased the SPN concentrations around 30%, mainly due to agglomeration at cold start. The main conclusion of this study is that the open configuration (or mixing tee) without any instruments measuring from the tailpipe is associated with better accuracy for mopeds, especially related to SPN measurements. In addition, we demonstrated that for this moped the particle emissions below 23 nm, the lower size currently prescribed in the passenger cars regulation, were as high as those above 23 nm; thus, a lower cut-off size is more appropriate. Full article
(This article belongs to the Special Issue Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass)
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16 pages, 3074 KiB  
Article
Impact of Water Content on Energy Potential and Combustion Characteristics of Methanol and Ethanol Fuels
by Jozef Martinka, Peter Rantuch and Igor Wachter
Energies 2019, 12(18), 3491; https://doi.org/10.3390/en12183491 - 10 Sep 2019
Cited by 10 | Viewed by 7030
Abstract
Methanol and ethanol are among the most important biofuels and raw materials used to produce biorenewable fuels. These fuels are used with varying water contents. Nevertheless, the exact impact of the water content of these fuels on the energy potential and combustion characteristics [...] Read more.
Methanol and ethanol are among the most important biofuels and raw materials used to produce biorenewable fuels. These fuels are used with varying water contents. Nevertheless, the exact impact of the water content of these fuels on the energy potential and combustion characteristics is still unknown. Besides that, there are two noticeable risks (environmental impact of combustion and fire risk) associated with their production, processing, and utilization. Likewise, impact of the water content of these fuels on fire risk and the impact of their combustion on the environment is also unknown. The best indicator of energy potential is the effective heat of combustion, and the best combustion characteristic and indicator of the impact of the combustion of alcohols on the environment is the carbon monoxide (CO) yield, whereas the fire risk of liquid fuels is quantified by the flash point and maximum heat release rate (mHRR). The dependency of flash point on the water content was determined via the Pensky-Martens apparatus and the dependencies of the effective heat of combustion, CO yield, and mHRR on the water content were determined via the cone calorimeter. With increased water content, the flash points of both methanol and ethanol exponentially increased and the both effective heat of combustion and mHRR almost linearly decreased. In the range of water content from 0 to 60%, the CO yield of both methanol and ethanol was practically independent of the water content. Full article
(This article belongs to the Special Issue Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass)
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20 pages, 9720 KiB  
Article
Optimization of Air Distribution to Reduce NOx Emission and Unburned Carbon for the Retrofit of a 500 MWe Tangential-Firing Coal Boiler
by Hyunbin Jo, Kiseop Kang, Jongkeun Park, Changkook Ryu, Hyunsoo Ahn and Younggun Go
Energies 2019, 12(17), 3281; https://doi.org/10.3390/en12173281 - 26 Aug 2019
Cited by 15 | Viewed by 3478
Abstract
The use of separated overfire air (SOFA) has become a standard technique of air staging for NOx reduction in the coal-fired boiler and can also be applied to existing boilers by retrofit. This study was to optimize the air distribution for the proposed [...] Read more.
The use of separated overfire air (SOFA) has become a standard technique of air staging for NOx reduction in the coal-fired boiler and can also be applied to existing boilers by retrofit. This study was to optimize the air distribution for the proposed SOFA installation in a 500 MWe tangential-firing boiler that has 20 identical units in Korea. Using computational fluid dynamics (CFD) incorporating advanced coal combustion submodels, the reference case was established in good agreement with the design data, and different flow ratios of burner secondary air, close-coupled OFA (CCOFA), and SOFA were evaluated. Increasing the total OFA ratio effectively suppressed NO formation within the burner zone but had a negative impact on the boiler performance. With moderate air staging, NO reduction became active between the CCOFA and SOFA levels and, therefore, the OFA distribution could be optimized for the overall boiler performance. For total OFA ratios of 25% and 30% with respective burner zone stoichiometric ratios of 0.847 and 0.791, increasing the SOFA ratio to 15% and 20%, respectively, was ideal for decreasing the unburned carbon release and ash slagging as well as NO emission. Too high or low SOFA ratios rapidly increased the unburned carbon because of inefficient mixing between the strong air jets and char particles. Based on these ideal cases, the actual air distribution can be adjusted depending on the coal properties such as the ash slagging propensity. Full article
(This article belongs to the Special Issue Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass)
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22 pages, 1478 KiB  
Article
Comparative Thermogravimetric Assessment on the Combustion of Coal, Microalgae Biomass and Their Blend
by Ricardo N. Coimbra, Carla Escapa and Marta Otero
Energies 2019, 12(15), 2962; https://doi.org/10.3390/en12152962 - 1 Aug 2019
Cited by 19 | Viewed by 3900
Abstract
In this work, thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and differential scanning calorimetric (DSC) were used to assess the combustion of microalgae biomass, a bituminous coal, and their blend. Furthermore, different correlations were tested for estimating the high heating value of microalgae biomass [...] Read more.
In this work, thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and differential scanning calorimetric (DSC) were used to assess the combustion of microalgae biomass, a bituminous coal, and their blend. Furthermore, different correlations were tested for estimating the high heating value of microalgae biomass and coal, with both materials possessing similar values. TGA evidenced differences between the combustion of the studied fuels, but no relevant interaction occurred during their co-combustion, as shown by the DTG and DSC curves. These curves also indicated that the combustion of the blend mostly resembled that of coal in terms of weight loss and heat release. Moreover, non-isothermal kinetic analysis revealed that the apparent activation energies corresponding to the combustion of the blend and coal were quite close. Overall, the obtained results indicated that co-combustion with coal might be a feasible waste to energy management option for the valorization of microalgae biomass resulting from wastewater treatment. Full article
(This article belongs to the Special Issue Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass)
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17 pages, 3796 KiB  
Article
Experimental Investigation of Ash Deposit Behavior during Co-Combustion of Bituminous Coal with Wood Pellets and Empty Fruit Bunches
by Tae-Yong Jeong, Lkhagvadorj Sh, Jong-Ho Kim, Byoung-Hwa Lee and Chung-Hwan Jeon
Energies 2019, 12(11), 2087; https://doi.org/10.3390/en12112087 - 31 May 2019
Cited by 24 | Viewed by 3483
Abstract
In Korea, oil-palm empty fruit bunches (EFBs), which are byproducts of the crude palm-oil milling process, are among the most promising potential energy sources for power plants. However, the slagging and fouling characteristics of EFBs during combustion have not yet been fully studied. [...] Read more.
In Korea, oil-palm empty fruit bunches (EFBs), which are byproducts of the crude palm-oil milling process, are among the most promising potential energy sources for power plants. However, the slagging and fouling characteristics of EFBs during combustion have not yet been fully studied. Accordingly, in this study, we investigated the fundamental ash behavior of EFBs in comparison to that of wood pellets (WPs) using a thermomechanical analyzer (TMA) and a drop-tube furnace (DTF). Ash melting and the deposition of ash particles were investigated with traditional prediction indices at several biomass blending ratios. The results demonstrated that, as the ratio of WPs to EFBs increases, the melting temperature decreases and the slagging propensity increases because of the increased biomass alkali content. Moreover, the penetration derived using the TMA shows a higher melting peak at which rapid melting occurs, and the melting temperature distribution is decreased with increased biomass blending. Conversely, the DTF results show different phenomena for ash deposition under the same blending conditions. Blend ratios approaching 10% WP and 15% EFB result in gradual decreases in ash deposition tendencies because of the lower ash contents of the co-combusted mass compared to that of the single coal ash. Further biomass addition increases ash deposition, which is attributable to ash agglomeration from the biomass. Thus, this study demonstrates that blending ratios of 10% WP and 15% EFB provide optimal conditions for co-combustion with the selected bituminous coal. In addition, it is shown that the slagging propensity of EFB is higher than that of WP owing to its ash content and simultaneous agglomeration. Full article
(This article belongs to the Special Issue Advances in Combustion of Gases, Liquid Fuels, Coal and Biomass)
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