Combustion Period Research Articles

Investigative research of diesel/ethanol advanced combustion strategies: A comparison of Premixed Charge Compression Ignition (PCCI) and Direct Dual Fuel Stratification (DDFS)

Direct Dual Fuel Stratification (DDFS) is a new low-temperature combustion (LTC) approach that employs dual fuel direct injection in the combustion chamber. In this method, a relatively small proportion of diesel fuel was pre-injected and utilized to activate the burning of the premixed charge followed by direct injection of a diesel/ethanol mixture (75% diesel, 25% ethanol by volume) into the combustion chamber near TDC. The DDFS approach generates a lower reactivity charge in the central sector of the combustion chamber and a stronger reactivity charge along the wall. For the examination of combustion vibrations and acoustic, a new technique dependent on the fast Fourier transform (FFT) of the cylinder vibration statistics was used. Whereas the PCCI combustion technique is more likely to cause knocking than the typical diesel CI, the results show that charge stratification in DDFS combustion does have a good effect in reducing vibration intensity. Owing to the improved controllability of the start of combustion and burning period, DDFS combustion attained a brake thermal efficiency (BTE) of 51%, which was larger than CI and PCCI. DDFS shows ultra-low nitrogen oxide (NOx) (below 1 g/kW-h), mild carbon monoxide (CO) (below 6 g/kW-h), and unburned hydrocarbons (UHC) emissions. Because of the higher thermal efficiency and a decreased carbon source due to presence of ethanol, DFFS combustion could produce lower CO levels by up to 34% when compared to PCCI.

Assessment of Air Pollution Levels during Sugarcane Stubble Burning Event in La Feria, South Texas, USA

Agricultural stubble burning is the third largest source of air pollution after vehicular and industrial emissions. Fine particulate matter (PM2.5), volatile organic compounds (VOCs), carbon monoxide (CO), nitrogen dioxide (NO2), and black carbon (BC) are some of the pollutants emitted during such burning events. The Lower Rio Grande Valley (RGV) region of South Texas is a major hub of agricultural activity, and sugarcane farming is one of them. Unfortunately, this activity results in episodic events of high air pollution in this low-resourced, Hispanic/Latino majority region of the U.S.–Mexico border. This study presents results from a sugarcane site in La Feria, South Texas, where the air quality was monitored before, during, and after the sugarcane stubble burning. Various parameters were monitored on an hourly basis from 24 February 2022 to 4 April 2022. Our results demonstrate high levels of all the monitored pollutants during the burning phase in contrast to the pre- and post-burning period. The black carbon levels went up to 6.43 µg m−3 on the day of burning activity. An increase of 10%, 11.6%, 25.29%, 55%, and 67.57% was recorded in the PM1, PM2.5, PM10, Black Carbon, and CO levels, respectively, during the burning period in comparison with the total study period. The absorption Ångström exponent value reached a maximum value of 2.03 during the burning activity. ThePM2.5/PM10 ratio was 0.87 during the burning activity. This study also highlights the importance for continuous monitoring of air quality levels due to stubble burning in the Lower Rio Grande Valley Region of South Texas.

CFD Numerical Simulation of Operation Optimization for Energy Saving during Combustion Period of Kalugin Top Combustion Hot Blast Stove

CFD Numerical Simulation of Operation Optimization for Energy Saving during Combustion Period of Kalugin Top Combustion Hot Blast Stove

An Experimental Study on SO2 Emission and Ash Deposition Characteristics of High Alkali Red Mud under Large Proportional Co-Combustion Conditions in Fluidized Bed

As an industrial solid waste, the discharge of a large amount of red mud (RM) causes serious environmental problems; thus, a large proportion of RM co-combustion has been proposed to solve the consumption problem. In this paper, an experiment with various proportions of RM co-combustion was conducted on a 0.2 t/h circulating fluidized bed (CFB) boiler. Desulfurization performance, combustion characteristics, and ash deposition characteristics were analyzed, especially under the large proportional co-combustion conditions. As the study results showed, the desulfurization efficiency was positively correlated with the RM co-combustion proportion. When the RM co-combustion proportion reached 50%, the desulfurization efficiency was over 94%. After a period of cyclic combustion, the highest desulfurization efficiency exceeded 99.5%. The smaller size of RM was beneficial to improve the combustion efficiency and the combustion stability. However, a large area of sintering formed on the top of the heating surface in the furnace, which was lighter than the sintering of high alkali fuels such as Zhundong coal. Meanwhile, the content of sulfates, such as Na2SO4 and CaSO4, in the ash increased, which clearly proves that RM has the desulfurization effect. Therefore, a large proportion of co-combustion could meet the requirements of in-situ desulfurization and realize the resource utilization of RM.

The Dynamic Functions of Euphemism: The Martyrdom of the Jordanian Air Force Pilot Moath Al-Kasasbeh at the Hands of ISIS

The present paper explores death euphemistic alternatives used by media during the period of kidnapping and later burning the Jordanian air force pilot Moath Al-Kasasbeh at the hands of ISIS[i]. The internet-based data serving as a research tool for the present study explained the dynamic functions of death-related euphemisms, showing that what had been avoided before burning because of its dysphemistic sense (assassination and murder) was used as a euphemism and as a gentler substitute for the unexpected burning. Conceptual metaphor was also used as a euphemistic substitute for the ugly burning of the pilot, and not as doublespeak aimed at hiding the reality. The use of the word sacrifice in place of burning, the conceptualization of death and burning as journey and facing or cuddling fate or angles were found to be euphemistic alternatives used to report the act of burning the Jordanian Air Force Pilot Moath Al-Kasasbeh. Examining euphemisms in conjunction with face wants and politeness, it was found that burning euphemisms which are based on lexical substitutions are aimed at saving the public self-image of the pilot’s bereaved family and protecting their self-esteem. Keywords: Euphemism; Dysphemism; Pragmatic, Politeness, Burning, Metaphor.

Effects of carbonization on the combustion of rice husks briquettes in a fixed bed

Carbonization of raw materials for making briquettes has been identified as a possible way of improving calorific values and fixed carbon contents of briquettes. In spite of these benefits, the main challenges of carbonization are increased percentage of ash content and energy required to process the fuel. In this study, fuels with mixtures of carbonized and raw rice husks were combusted in a fixed bed to examine the effect of carbonization on their combustion properties with an aim of establishing an optimum ratio. Bed temperature distribution, ignition, flame propagation speed, combustion rates and reaction zone thickness were investigated. All experiments were performed in a fixed bed operated in a reverse counter-current flame propagation mode. Four mixtures consisting of different ratios of carbonized rice husks were used to process briquettes; namely, 25 wt%, 50 wt%, 75 wt% and 100 wt% biochar. Air-mass flux for combustion of each mixture was varied between 0.02 and 0.6 kg/m2s. It was established that carbonization increases ignition time and peak bed temperature but lowers flame propagation speed, reaction zone thickness, and combustion rates. Briquettes with lower percentage of biochar had higher volatiles and higher devolatilization rate that shortened combustion period. Briquettes with carbonized rice husk of between 50 wt% and 75 wt% were found to have optimum combustion properties. Processing of briquettes should be done within these carbonization ratios in order to achieve desirable combustion properties.

Fire reaction and post-fire impact properties of flax fibre reinforced composites containing intumescent flame retardants

The current research aims at investigating the fire reaction and post-fire impact characteristics of flax fibre reinforced composites based on different polymer matrices, such as epoxy resin and polypropylene (PP). The effects of stacking sequences of polymer sheets and flax fabrics within the composites are explored by a cone calorimeter. Heat release and smoke production results indicate that a top surface and number of flame-retardant polymer layers played significant roles in determining the fire reaction properties. Furthermore, post-fire impact properties of flax-epoxy and flax-PP composites depending on burning periods are analysed in this study at the first time. A fully instrumented drop-weight impact testing demonstrates that an increase in heat exposure time led a gradual decrease in impact properties of the composites due to fire-induced damages on fibres and polymers. However, pre-melting and re-consolidation of PP are beneficial to have higher impact energy and force of the flax-PP composite over those of the flax-epoxy counterpart. In addition, the char formation of composites due to intumescent flame retardant enhances the fire reaction properties of composites, whereas there is no significant influence on the post-fire impact characteristics due to highly brittle nature of carbonaceous char.

Computational assessment of the effects of pre-chamber and piston geometries on the combustion characteristics of an optical pre-chamber engine

Pre-chamber combustion (PCC) has the potential to extend the lean-burn limit in spark-ignition engines, which can promote engine efficiency and relieve the concern of emissions of nitrogen oxides. This work assessed the effects of pre-chamber (PC) and piston geometries on the combustion characteristics of an optical methane PCC engine with both experimental and computational approaches. Five active-type PCs with different volumes and nozzle diameters (12 nozzles distributed evenly in two layers) and two pistons (bowl and flat) were tested under lean-burn conditions. Multi-cycle pressure and heat release profiles, natural flame luminosity images, and OH* chemiluminescence images were measured and employed for CFD modeling validations. The PCs with the smaller nozzle diameter yielded more intensely-reacting jets from the upper layer of nozzles compared to the other PCs, attributed to the stronger gas choke there, which dramatically affected the flow fields. A larger PC volume allowed more air–fuel mixture to be trapped within the PC whose combustion then resulted in faster pressure buildup, which, however, led to higher heat transfer loss. Compared to the bowl piston, the flat piston generated a higher heat release rate during the late combustion period owing to the relatively longer jet propagation within the squish region.

An Investigation of the Impact of Combustion Chamber Geometry on Turbulent Burning Speeds in a Thermodynamic Model

Abstract Combustion is the main parameter that affects efficiency and exhaust gas emissions. Recently, different studies have been carried out to increase the combustion rates due to the increasing use of the alternative fuels and lean mixtures in spark ignition engines. In general, in the absence of systems such as an optical access engine or ionization probes, combustion process evaluation is done based on cylinder pressure. In this study, the effect of different combustion chamber geometries on the turbulent burning speeds was investigated experimentally and theoretically. A three-zone, quasi-dimensional thermodynamic model for a spark ignition engine was constructed. Measured cylinder pressure data were used to establish the transition between the zones of the model and determine turbulent burning speeds. Two different turbulent speeds were calculated in the model, these are flame propagation and consumption speeds. It was seen that combustion chamber geometry significantly affected turbulent burning speeds. In MAN-Ricardo shapes and cylindrical shapes, the turbulent burning speeds decreased after it reached a maximum value in the combustion period. In flat geometry, without any bowl, speed continuously decreased different from other two designs. By means of a quasi-dimensional thermodynamic model, mean values of the turbulent burning and the flame propagation speeds can be calculated without having any optical observation.

Enhanced aerosols over the southeastern Tibetan Plateau induced by open biomass burning in spring 2020

The Tibetan Plateau is the third pole of the world, with an essential role in regulating Northern Hemisphere climate. Previous studies showed that atmospheric aerosols over the Tibetan Plateau are influenced by biomass burning (BB) products from South and Southeast Asia. In fact, open biomass burning (OBB) is also an important form of BB in Southeast Asian countries, causing serious springtime air pollution yearly. However, there are still scientific gaps in the contribution of OBB to surrounding regional aerosols, especially on the Tibetan Plateau. In order to quantify this contribution, we collected samples of fine particulate matter and derived the concentrations of major water soluble ion, water soluble organic carbon (WSOC), and total carbon (TC) and total nitrogen (TN) as well as the dual isotopic compositions of carbon and nitrogen (δ13C and δ15N) during March–June on the southeastern Tibetan Plateau. δ13C and δ15N showed no significant difference (p > 0.05) between the OBB and non-OBB periods. Furthermore, both δ13C and δ15N (−25.7 ± 0.7 ‰ and 8.0 ± 3.6 ‰) values calculated during the whole sampling period were similar to the BB value, indicating that the primary source of TC and TN in aerosols was BB, whether OBB or non-OBB burning periods. TC and TN concentrations during the OBB period (6.5 ± 2.9 μg m−3 and 1.2 ± 0.4 μg m−3, respectively) were significantly higher than during the non-OBB period (4.1 ± 1.7 μg m−3, with p = 0.014, and 0.7 ± 0.3 μg m−3, with p = 0.013, respectively). Active fire data and surface smoke concentrations further indicated that BB emissions from Southeast Asia were higher during the OBB period. This suggests that OBB-related high BB emissions significantly enhanced atmospheric aerosols concentrations on the southeastern Tibetan Plateau.

Heat energy accumulation construction for bioethanol burner

Commonly sold bioethanol fireplaces can represent significant heat source, however due to their intermittent operation the heat energy output is strongly uneven. The aim of this study was to determine the possibilities of heat energy accumulation by individually built ethanol fireplace intended for commonly sold ethanol burner installation. For the measurements of heat energy output, long term tests of the individually built ethanol fireplace with 1, 2 and 3 consecutive combustion periods in a unique calorific room were performed. Accumulation ethanol fireplace has proven high ratio between accumulated heat energy after the ethanol burner last burn-out reaching from 21.4 to 48.4% according to the number of consecutive fuel doses. By usage of the described ethanol fireplace the time of heat energy releasing was increased from approximately 1.15, 2.35 and 3.55 h in case of ethanol burner usage in a non-accumulation fireplace for 1, 2 and 3 fuel doses to 6.5, 11 and 15 h in case of accumulation ethanol fireplace usage. This was also strongly connected with average heat output ranging between 2.54 to 2.47 kW in the case of ethanol burner usage in a non-accumulation ethanol fireplace and 0.38 to 0.59 kW in the case of accumulation ethanol fireplace usage.

Assessing over decadal biomass burning influence on particulate matter composition in subequatorial Amazon: literature review, remote sensing, chemical speciation and machine learning application.

A study on aerosols in the Brazilian subequatorial Amazon region, Tangará da Serra (TS) and Alta Floresta (AF) was conducted and compared to findings in an additional site with background characteristics (Manaus, AM). TS and AF counties suffer from intense biomass burning periods in the dry season, and it accounts for high levels of particles in the atmosphere. Chemical characterization of fine and coarse particulate matter (PM) was performed to quantify water-soluble ions (WSI) and black carbon (BC). The importance of explanatory variables was assessed using three machine learning techniques. Average concentrations of PM in AF and TS were similar (PM2.0, 17±10 µg m-3 (AF) and 16±11 µg m-3 (TS) and PM10-2.0, 13±5 µg m-3 (AF) and 11±7 µg m-3 (TS)), but higher than the background site. BC and SO4 2- were the prevalent components as they represented 27%-68% of particulates chemical composition. The combination of the machine learning techniques provided a further understanding of the pathways for PM concentration variability, and the results highlighted the influence of biomass burning for key sample groups and periods. PM2.0, BC, and most WSI presented higher concentrations in the dry season, providing further support for the influence of biomass burning.

Trends and Variability of PM2.5 at Different Time Scales over Delhi: Long-term Analysis 2007–2021

The present study investigated the long-term inter-annual, seasonal, and monthly trend analysis and variability of PM2.5 at different time scales over the national capital, Delhi, India using high-resolution surface observations from six stations during 2007-2021. The non-parametric Mann-Kendall and Theil-Sen slope estimator were used to study the temporal variations. The long-term PM2.5 concentration showed an overall small but statistically significant decreasing trend with an average decrease of -1.35 (95 % CI: -2.3, -0.47) μg m-3 year-1. Seasonal trends revealed a significant decreasing value of -3.05 μg m-3 year-1 (p < 0.1) for summer, insignificant declining trend of -1.95 μg m-3 year-1 for monsoon and no significant trend was found for the post-monsoon and winter season. Except for December and January, all months displayed a decreasing trend for PM2.5 concentration. These findings indicate that particle pollution over the city is declining at a very slow rate. A rising trend was found for relative humidity and surface pressure, whereas a declining trend for wind speed and PBLH noted. No trend was observed for temperature and rainfall. The Pearson linear correlation between PM2.5 and meteorological variables was studied using monthly mean data. Rainfall, air temperature, PBLH, and wind speed showed a negative correlation with PM2.5, whereas surface pressure had a positive correlation and relative humidity displayed an inverted U-shape relationship. The average concentration of PM2.5 in the study period of 15 years remained 125 ± 86 μg m-3 (ranging between 20 to 985 μg m-3) and during winter, summer, monsoon, and post-monsoon seasons it was 174 ± 75, 101 ± 48, 66 ± 50, and 192 ± 93 μg m-3 respectively. The monthly average PM2.5 concentration observed minimum in August and maximum in November. Satellite data of fire events showed that the crop residue burning over the Punjab region had a significant contribution to the peak PM2.5 levels in Delhi during the crop burning period. Government agencies need more strict action plans, especially during winter, to comply with air quality standards.

Modeling Method of Engine Zero-dimensional Combustion Model Based on PSO Algorithm Optimization

To improve the low accuracy of the zero-dimensional combustion model established by BP-NN, a particle swarm-neural network (PSO-NN) algorithm was proposed. The PSO optimize weights and thresholds of NN, and the operating and combustion parameters are constructed, and then compared with NN algorithm. The results show that comparing with NN algorithm, the zero-dimensional combustion model constructed by PSO-NN algorithm has higher prediction accuracy, and the mean square error of the main combustion period m is 0.0034, which is 78.21% lower than that before optimization. The particle swarm algorithm has quicker convergence and stronger versatility, which is suitable for the study of diesel engine 0-D model.

Combined Experimental and Numerical Investigation into Combustion Characteristics of Crude Oil under Different Permeability Ranges: Thermal EOR Implication

In situ combustion (ISC) has drawn much attention in the exploitation of heavy oil reservoirs because of its small surface footprint and high recovery efficiency relative to steam injection. As for now, the combustion characteristics of heavy crude oil under different permeability ranges have not been well-understood, particularly in low-permeability conditions. In this work, we systematically conducted the combustion tube (CT) experiments under permeabilities of roughly 650 and 480 mD. Following that, a reaction kinetics model that could simulate the CT results well was established. Finally, the corrected reservoir simulation approach was used to study the ISC characteristics of one heavy oil in the permeability range of 50–1000 mD. The combustion characteristics under different permeability ranges could be classified into four main types on the basis of the experimental studies and numerical predictions. (1) The consecutive combustion front failed to be formed from 50 to 180 mD. (2) The consecutive combustion front was formed and the coking zone appeared from 180 to 250 mD, which was accompanied by weak heat release and serious plugging effect of the oil bank and coking zone. (3) The stable combustion front was formed with obvious heat release from 250 to 500 mD, and there was a weak plugging effect of the oil bank and coking zone at the initial stage of combustion. (4) In the permeability range of 500–1000 mD, the stable combustion front featured with a peak temperature higher than 500 °C was formed with a negligible plugging effect of the oil bank and coking zone. For heavy oil reservoirs with permeabilities lower than 250 mD, much attention should be put on the variations into combustion front temperature and displacement pressure difference at the initial period of combustion. If the temperature continued to decrease and/or the displacement pressure difference continued to rise, some measures should be actively adjusted to increase heat release yielded by combustion, including the increase of the air injection rate and ignition temperature, the injection of catalysts, and so forth. This work could add new insights into the differences and connections of combustion characteristics of heavy oil under different permeability ranges, which should be of great significance for thermal enhanced oil recovery.

Abundance and variation of gaseous NH3 in relation with inorganic fertilizers and soil moisture during Kharif and Rabi season.

In an agricultural country like India, inorganic fertilizers are the major contributors of atmospheric NH3 in rural areas affecting soil, vegetation and water bodies. In this study, day-night and seasonal variation of ammonia emissions were measured from July 2017 to June 2018 during Kharif and Rabi crop seasons at a rural agricultural site in Jhajjar district of Haryana. Also, NH3 emission inventory is prepared for the amount of fertilizers applied during its basal and top dressing. NH3 concentrations were noticed significantly lower after basal dressing of DAP fertilizers as compared to the concentrations after top dressing of urea. NH3 concentration in air increased with decrease in water saturation of the soil. NH3 emission was recorded as 1.4 to 45.2, 63.1 to 190.9, and 98.9 to 187.5μgm-3 during sowing, fertilizer addition, and grain filling stages, respectively, in Kharif season. Apart from these crop stages, NH3 was measured as 56.8 to 249.5μgm-3 during crop residue burning period. On the other hand, NH3 emissions ranged from 22.9 to 68.4, 59.4 to 104.71, 26.3 to 56.0, 48.2 to 147.2, and 21.5 to 80.4μgm-3 during sowing, crown root initiation (CRI), panicle initiation, grain filling, and maturity crop, respectively, in Rabi season. The average NH3 concentrations during Kharif season (125.3μgm-3) were significantly greater than the concentrations during Rabi season (51.8μgm-3). However, a reduction in the NH3 values was observed in the period between Kharif and Rabi seasons, which could be attributed to the wet deposition during monsoon and gas to particle conversion due to less temperature conditions during the periods.

Combustion, performance, and emission behavior of a CI engine fueled with different biodiesels: A modelling, forecasting and experimental study

The current automobile industry is greatly dependent upon petroleum supplies and is moving toward its terminating phases very soon. The depletion of petrol fuel reserves is therefore driving research in the field of alternative fuels. Several biofuels are produced from plants and natural waste, thus having the potential to reduce the level of CO2 in the atmosphere. Therefore, it is renewable and relatively cheaper than conventional fossil fuels since it is abundant and easier to produce. In this present experimental work, four types of biodiesels were investigated: SME (soybean methyl ester 100% by volume), RME (rapeseed methyl ester 100% by volume), B55 (SME 50%, RME 50%), B82 (SME 80%, RME 20%), and diesel fuel. The heat release rate diagram showed combustion period and ignition delay in the Blend 82 at elevated compression ratio compared to diesel fuel. Brake thermal efficiency was on average 4% to 7% lesser than diesel fuel for B82 blend; the value of cylinder pressure was higher in upper-level compression ratio but without knocking, thus ensuring safe combustion. Lower compression ratios gave lower values with maximum reduction of approximately 35% due to reduced temperature and lower brake mean effective pressure. The oxides of nitrogen emissions from the Blend 82 were higher around 20% than that of diesel. Also, the hydrocarbon emissions of the Blend 82 were lower between 7% and 62% than conventional diesel fuel. In addition to optimization and various results connectivity, Response surface analysis (RSM) and then ANN (Artificial neural network) modeling is performed for all the engine characteristics at the end of study.

Understanding the influence of summer biomass burning on air quality in North India: Eight cities field campaign study

Near real-time monitoring of major air pollutants, i.e., particulate matter (PM10, PM2.5, PM1), trace gases (O3, CO, NO, NO2, NOx, NH3, CO2, SO2) and Volatile Organic Compounds (VOCs: benzene, ethylbenzene, m-, p-xylene, o-xylene and toluene) along with climatological parameters was done in eight-cities field campaigns during the rabi (wheat) crop residue burning period in the northwest of Indo-Gangetic Plain (IGP) region. The phase-wise monitoring was done at eight locations representing rural, semi-urban and urban backgrounds. During the whole campaign, the semi-urban site (Sirsa) observed the highest average concentration of PM10 (226 ± 111 μg m−3) and PM2.5 (91 ± 67 μg m−3). The urban site (Chandigarh) reported the minimum concentrations of all the three size fractions of particulate matter with PM10 as 89 ± 54 μg m−3, PM2.5 as 42 ± 22 μg m−3 and PM1 as 20 ± 13 μg m−3 where the monitoring was done in the early phase of the campaign. The highest VOC concentration was recorded at the semi-urban (Sirsa) site, whereas the lowest was at a rural location (Fatehgarh Sahib). NH3 concentration was observed highest in rural sites (31.7 ± 29.8 ppbv), which can be due to the application of fertilizers in agricultural activities. Visible Infrared Imaging Radiometer Suite (VIIRS) based fire and thermal anomalies, along with HYSPLIT back trajectory analysis, show that major air masses over monitoring sites (22 %–70 %) were from the rabi crop residue burning regions. The characteristic ratios and Principal component analysis (PCA) results show that diverse sources, i.e., emissions from crop residue burning, solid biomass fuels, vehicles and industries, majorly degrade the regional air quality. This multi-city study observed that semi-urban regions have the most compromised air quality during the rabi crop residue burning and need attention to address the air quality issues in the IGP region.

Influence of Strategies in Injection on Shrinking Greenhouse Gas Emission in DiCI Engine with Tamarindus indica Biodiesel.

Transportation cost is stepping the world into bio-feedstocks to power the Direct Injection Compression Ignition (DiCI) engines. Biodiesel makes a better alternative to diesel. In this research, tamarind seed biodiesel (TSB), is mixed 20% with diesel, with the injection pressure (IP) and timings (IT) modifications examining the engine’s performance, combustion, and emission aspects. The experimented IPs were 180 bar and 240 bar. The ITs were experimented with at 19° bTDC and 27° bTDC respectively. Modifying the IT to 27° bTDC, elongates the combustion period as well as the heat release rate (HRR) of the experiments which increases the emission of NOx in both the IPs (180 and 240 bar) compared with the diesel. Increase in NOx emissions parallelly projected the unburnt hydrocarbon emissions. Although, injecting the fuel 19° bTDC, shrank NOx emission owing to reduced HRR and peak in-cylinder pressures. However, increase in the IP to 240 bar is the predominant factor for the decrease in the emission of NOx and unburnt hydrocarbons, because of the increased fuel viscosity for the TSB. Increased atomization enhances the chemical delay which on other hand decreases the carbon monoxide. Hence fuel injected, 19° bTDC performed better with the reduced GHG emissions.

Prediction of incubation period for spontaneous combustion of long-flame coal based on specific heat capacity and caloricity

A key index for assessing the risk of coal spontaneous combustion (CSC) is the incubation period of spontaneous combustion (IPSC). Long-flame coal samples were obtained from the Liushicun coal mine in Shaanxi, China. On the basis of the Kalenkin model and the thermal effect, thermophysical properties, and characterization parameters of CSC, an IPSC calculation model was established. The model assumes that surface oxidation and adsorption heat are combined to produce a heat effect, evaporate the water contained in coal, and desorb adsorbed gas. The time required for the temperature of coal to increase from room to ignition temperature can be calculated to obtain the IPSC of long-flame coal. In this study, the IPSC of long-flame coal was calculated to be approximately 45 days. This finding can provide a basis on which coal mines can formulate effective fire-fighting measures.