Combustion properties of Bromus tectorum L.: influence of ecotype and growth under four CO2 concentrations

2006 ◽  
Vol 15 (2) ◽  
pp. 227 ◽  
Author(s):  
Robert R. Blank ◽  
Robert H. White ◽  
Lewis H. Ziska
Keyword(s):  
Bromus Tectorum ◽  
Combustion Process ◽  
Co2 Concentration ◽  
High Elevation ◽  
Total Heat ◽  
Tissue Concentrations ◽  
Complete Combustion ◽  
Co2 Concentrations ◽  
Combustion Properties ◽  
Heat Released

We grew from seed the exotic invasive annual grass Bromus tectorum L., collected from three elevation ecotypes in northern Nevada, USA. Plants were exposed to four CO2 atmosphere concentrations: 270, 320, 370, and 420 μmol mol–1. After harvest on day 87, above-ground tissue was milled, conditioned to 30% relative humidity, and combustion properties were measured using a cone calorimeter. Plants exposed to 270 μmol mol–1 CO2 had significantly less total heat released than plants exposed to higher CO2 concentrations. Total heat released was least for the low-elevation ecotype, statistically similar for the mid-elevation ecotype, and significantly increased for the high-elevation ecotype. Plant attributes that significantly correlated with heat release included tissue concentrations of lignin, glucan, xylan, potassium, calcium, and manganese. The data suggest that a decline in tissue concentrations of lignin, xylan, and mineral constituents, as CO2 concentration increases from 270 μmol mol–1 to higher levels, affects the combustion process. We suspect that as tissue concentrations of lignin and inorganics decline, char formation decreases, thereby allowing more complete combustion. Changes in combustion parameters of B. tectorum induced by different CO2 concentrations and elevation ecotype may be a strong consideration to understanding fire behaviors of the past, present, and future.

scholarly journals Direct demonstration of complete combustion of gas-suspended powder metal fuel combustion using bomb calorimetry

2022 ◽  
Author(s):  
Quan Tran ◽  
Igor Altman ◽  
Pascal Dube ◽  
Mark Malkoun ◽  
R. Sadangi ◽  
...  
Keyword(s):  
Heat Release ◽  
Combustion Process ◽  
Heat Of Combustion ◽  
Additional Parameter ◽  
Metal Powders ◽  
Metal Combustion ◽  
Complete Combustion ◽  
Direct Demonstration ◽  
Metal Fuel ◽  
Heat Released

Abstract Off-the-shelf calorimeters are typically used for hydrocarbon-based fuels and not designed for simulating metal powder oxidation in gaseous environments. We have developed a method allowing a typical bomb calorimeter to accurately measure heat released during combustion and achieve nearly 100% of the reference heat of combustion from powder fuels such as aluminum. The modification uses a combustible organic dispersant to suspend the fuel particles and promote more complete combustion. The dispersant is a highly porous organic starch-based material (i.e., packing peanut) and allows the powder to burn as discrete particles thereby simulating dust-type combustion environments. The demonstrated closeness of measured Al heat of combustion to its reference value is evidence of complete metal combustion achieved in our experiment. Beyond calorific output under conditions simulating real reactive systems, we demonstrate that the calorimeter also allows characterization of the temporal heat release from the reacting material and this data can be extracted from the instrument. The rate of heat release is an important additional parameter characterizing the combustion process. The experimental approach described will impact future measurements of heat released during combustion from solid fuel powders and enable scientists to quantify the energetic performance of metal fuel more accurately as well as the transient thermal behavior from combusting metal powders.

scholarly journals Effects of Climatic Conditions, Season and Environmental Factors on CO2 Concentrations in Naturally Ventilated Primary Schools in Chile

2021 ◽  
Vol 13 (8) ◽  
pp. 4139
Author(s):  
Muriel Diaz ◽  
Mario Cools ◽  
Maureen Trebilcock ◽  
Beatriz Piderit-Moreno ◽  
Shady Attia
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Primary Schools ◽  
Co2 Concentration ◽  
Building Design ◽  
Climatic Conditions ◽  
Indoor Environmental Quality ◽  
Co2 Concentrations ◽  
The Impact

Between the ages of 6 and 18, children spend between 30 and 42 h a week at school, mostly indoors, where indoor environmental quality is usually deficient and does not favor learning. The difficulty of delivering indoor air quality (IAQ) in learning facilities is related to high occupancy rates and low interaction levels with windows. In non-industrialized countries, as in the cases presented, most classrooms have no mechanical ventilation, due to energy poverty and lack of normative requirements. This fact heavily impacts the indoor air quality and students’ learning outcomes. The aim of the paper is to identify the factors that determine acceptable CO2 concentrations. Therefore, it studies air quality in free-running and naturally ventilated primary schools in Chile, aiming to identify the impact of contextual, occupant, and building design factors, using CO2 concentration as a proxy for IAQ. The monitoring of CO2, temperature, and humidity revealed that indoor air CO2 concentration is above 1400 ppm most of the time, with peaks of 5000 ppm during the day, especially in winter. The statistical analysis indicates that CO2 is dependent on climate, seasonality, and indoor temperature, while it is independent of outside temperature in heated classrooms. The odds of having acceptable concentrations of CO2 are bigger when indoor temperatures are high, and there is a need to ventilate for cooling.

scholarly journals The Synergy of Two Biofuel Additives on Combustion Process to Simultaneously Reduce NOx and PM Emissions

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2784
Author(s):  
Jerzy Cisek ◽  
Szymon Lesniak ◽  
Winicjusz Stanik ◽  
Włodzimierz Przybylski
Keyword(s):  
Heat Release ◽  
Combustion Rate ◽  
Combustion Process ◽  
The Other ◽  
Fuel Additive ◽  
Exhaust Gas ◽  
Synergy Effect ◽  
Engine Exhaust ◽  
Other Hand ◽  
Heat Released

The article presents the results of research on the influence of two fuel additives that selectively affect the combustion process in a diesel engine cylinder. The addition of NitrON® reduces the concentration of nitrogen oxides (NOx), due to a reduction in the kinetic combustion rate, at the cost of a slight increase in the concentration of particulate matter (PM) in the engine exhaust gas. The Reduxco® additive reduces PM emissions by increasing the diffusion combustion rate, while slightly increasing the NOx concentration in the engine exhaust gas. Research conducted by the authors confirmed that the simultaneous use of both of these additives in the fuel not only reduced both NOx and PM emissions in the exhaust gas but additionally the reduction of NOx and PM emissions was greater than the sum of the effects of these additives—the synergy effect. Findings indicated that the waveforms of the heat release rate (dQ/dα) responsible for the emission of NOx and PM in the exhaust gas differed for the four tested fuels in relation to the maximum value (selectively and independently in the kinetic and diffusion stage), and they were also phase shifted. Due to this, the heat release process Q(α) was characterized by a lower amount of heat released in the kinetic phase compared to fuel with NitrON® only and a greater amount of heat released in the diffusion phase compared to fuel with Reduxco® alone, which explained the lowest NOx and PM emissions in the exhaust gas at that time. For example for the NOx concentration in the engine exhaust: the Nitrocet® fuel additive (in the used amount of 1500 ppm) reduces the NOx concentration in the exhaust gas by 18% compared to the base fuel. The addition of a Reduxco® catalyst to the fuel (1500 ppm) unfortunately increases the NOx concentration by up to 20%. On the other hand, the combustion of the complete tested fuel, containing both additives simultaneously, is characterized, thanks to the synergy effect, by the lowest NOx concentration (reduction by 22% in relation to the base). For example for PM emissions: the Nitrocet® fuel additive does not significantly affect the PM emissions in the engine exhaust (up to a few per cent compared to the base fuel). The addition of a Reduxco® catalyst to the fuel greatly reduces PM emissions in the engine exhaust, up to 35% compared to the base fuel. On the other hand, the combustion of the complete tested fuel containing both additives simultaneously is characterized by the synergy effect with the lowest PM emission (reduction of 39% compared to the base fuel).

scholarly journals Energy Treatment of Solid Municipal Waste in Combination with Biomass by Decentralized Method with the Respect to the Negative Effects on the Environment

2021 ◽  
Vol 13 (8) ◽  
pp. 4405
Author(s):  
Miroslav Rimar ◽  
Olha Kulikova ◽  
Andrii Kulikov ◽  
Marcel Fedak
Keyword(s):  
Heavy Metals ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Process Analysis ◽  
Combustion Process ◽  
Municipal Waste ◽  
Negative Effects ◽  
Combustion Properties ◽  
Polycyclic Aromatic ◽  
Fuel Mixtures

Waste is a product of society and one of the biggest challenges for future generations is to understand how to sustainably dispose of large amounts of waste. The main objective of this study was to determine the possibility and conditions of the decentralized combustion of non-hazardous municipal waste. The analysis of the combustion properties of a mixture of wood chips and 20–30% of municipal solid waste showed an improvement in the operating parameters of the combustion process. Analysis also confirmed that the co-combustion of dirty fuels and biomass reduced the risk of releasing minerals and heavy metals from fuel into the natural environment. Approximately 55% of the heavy metals passed into the ash. The analysis of municipal solid waste and fuel mixtures containing municipal solid waste for polycyclic aromatic hydrocarbons showed the risk of increasing polycyclic aromatic hydrocarbon concentrations in flue gases.

Real-time capable simulation of diesel combustion processes for HiL applications

2017 ◽  
Vol 19 (2) ◽  
pp. 214-229 ◽  
Author(s):  
Daniel Neumann ◽  
Christian Jörg ◽  
Nils Peschke ◽  
Joschka Schaub ◽  
Thorsten Schnorbus
Keyword(s):  
Heat Release ◽  
Real Time ◽  
Fuel Injection ◽  
Combustion Process ◽  
Boost Pressure ◽  
Diesel Combustion ◽  
Main Challenge ◽  
Combustion Properties ◽  
Input Variables ◽  
Improved Model

The complexity of the development processes for advanced diesel engines has significantly increased during the last decades. A further increase is to be expected, due to more restrictive emission legislations and new certification cycles. This trend leads to a higher time exposure at engine test benches, thus resulting in higher costs. To counter this problem, virtual engine development strategies are being increasingly used. To calibrate the complete powertrain and various driving situations, model in the loop and hardware in the loop concepts have become more important. The main effort in this context is the development of very accurate but also real-time capable engine models. Besides the correct modeling of ambient condition and driver behavior, the simulation of the combustion process is a major objective. The main challenge of modeling a diesel combustion process is the description of mixture formation, self-ignition and combustion as precisely as possible. For this purpose, this article introduces a novel combustion simulation approach that is capable of predicting various combustion properties of a diesel process. This includes the calculation of crank angle resolved combustion traces, such as heat release and other thermodynamic in-cylinder states. Furthermore, various combustion characteristics, such as combustion phasing, maximum gradients and engine-out temperature, are available as simulation output. All calculations are based on a physical zero-dimensional heat release model. The resulting reduction of the calibration effort and the improved model robustness are the major benefits in comparison to conventional data-driven combustion models. The calibration parameters directly refer to geometric and thermodynamic properties of a given engine configuration. Main input variables to the model are the fuel injection profile and air path–related states such as exhaust gas recirculation rate and boost pressure. Thus, multiple injection event strategies or novel air path control structures for future engine control concepts can be analyzed.

scholarly journals Elevated CO2 Concentrations and Water Stress Affect the Ability of Italian Ryegrass to Remediate Herbicides and Enhance its Allelopathic Effect

2019 ◽  
Vol 37 ◽  
Author(s):  
L.P. SILVEIRA ◽  
A.R. FEIJÓ ◽  
C. BENETTI ◽  
J.P. REFATTI ◽  
M.V. FIPKE ◽  
...  
Keyword(s):  
Water Stress ◽  
Elevated Co2 ◽  
Co2 Concentration ◽  
Italian Ryegrass ◽  
Allelopathic Effect ◽  
Irrigated Rice ◽  
Allelopathic Potential ◽  
Co2 Concentrations ◽  
Temporal Persistence ◽  
The Impact

ABSTRACT: The long temporal persistence of select herbicides negatively impacts crops sown in succession to irrigated rice. One way to reduce these compounds in the soil over time is through phytoremediation. However, elevated CO2 concentrations may interfere with the phytoremediation process. Another consequence of climate change is the production of allelopathic compounds by forage species used as remedial agents. This study aimed to evaluate the impact of elevated CO2 concentration and drought stress on the remediation of soil samples contaminated with imazapyr + imazapic herbicides by Italian ryegrass and any subsequential affect on the allelopathic effect of this species. We report that the increasing CO2 decreased the phytoremediation potential of ryegrass. Water stress combined with a CO2 concentration of 700 µmol mol-1 caused increased allelopathy. Overall, these are the first data to indicate a significant effect of higher CO2 levels with respect to both phytoremediation efficacy and allelopathic potential of the plant species used in phytoremediation.

scholarly journals Effect of elevated carbon dioxide on biology and morphometric parameters of yellow stem borer, Scirpophaga incertulas infesting rice (Oryza sativa)

2022 ◽  
Vol 24 (1) ◽  
Author(s):  
GOURI SHANKAR GIRI ◽  
S. V. S. RAJU ◽  
S. D. MOHAPATRA ◽  
MUNMUN MOHAPATRA
Keyword(s):  
Carbon Dioxide ◽  
Larval Instar ◽  
Co2 Concentration ◽  
Elevated Carbon Dioxide ◽  
Stem Borer ◽  
Developmental Period ◽  
Morphometric Parameters ◽  
Scirpophaga Incertulas ◽  
Yellow Stem Borer ◽  
Co2 Concentrations

An experiment was conducted at Research Farm, National Rice Research Institute, Cuttack, Odisha, India to quantify the effect of elevated carbon dioxide (CO2) concentrations on the biology and morphometric parameters of yellow stem borer (Scirpophaga incertulas, Pyralidae, Lepidoptera). Yellow stem borer is one of the major pest of rice in the whole rice growing regions of South East Asia. The effect of three carbon dioxide concentrations i.e. 410 ppm (ambient), 550 ppm and 700 ppm on the duration of the developmental period as well as morphometric parameters of each stage of the lifecycle of the pest was analysed. It was found that, there was an increase in the duration of the developmental period of each stage of life cycle as the concentration of CO2 increases. However, the life span of the adult moth was significantly lower under the elevated CO2 concentrations when compared with ambient CO2 concentration. Morphometric parameters viz., mean length, width and weight of each larval instar, pupa and adult were found to be significantly higher in elevated concentrations of CO2 as compared to ambient concentration.

scholarly journals Konsentrasi Co2 Pada Ruang Kelas Dengan Sistem Ventilasi Alami, Tipe Jendela Gantung Atas

2018 ◽  
Vol 1 (1) ◽  
pp. 137-144
Author(s):  
Basaria Talarosha ◽  
Valencia Rosardy
Keyword(s):  
Natural Ventilation ◽  
Co2 Concentration ◽  
Learning Performance ◽  
Opening Angle ◽  
The Public ◽  
Public Elementary Schools ◽  
Co2 Concentrations ◽  
Size Number ◽  
Window Opening ◽  
The City

Proses pernafasan menghasilkan udara yang mengandung 4,4% volume CO2 sehingga konsentrasi CO2 di dalam ruang kelas dapat menjadi lebih tinggi dari ruang luar jika ventilasi tidak mencukupi. Konsentrasi CO2 > 1000 ppm akan mengganggu kesehatan dan konsentrasi belajar yang berdampak pada penurunan performa belajar siswa. Penelitian sebelumnya menunjukkan adanya hubungan antara konsentrasi CO2 di dalam ruang kelas dengan ukuran, jumlah, posisi dan tipe jendela pada ruang kelas yang menggunakan sistem ventilasi alami. Tipe jendela gantung atas disebutkan memiliki performa yang paling buruk dalam menetralkan konsentrasi CO2 di dalam ruang. Studi bermaksud mengukur kadar konsentrasi CO2 di dalam sebuah ruang kelas pada salah satu sekolah dasar negeri di kota Medan yang menggunakan tipe jendela gantung atas. Pengukuran konsentrasi CO2 dilakukan pada kondisi sudut bukaan jendela sisi koridor ruang kelas 10 dan 30 masing -masing selama tiga (3) hari. Hasil studi menunjukkan konsentrasi CO2 maksimum pada kondisi sudut bukaan jendela 10 lebih rendah dari pada kondisi sudut bukaan jendela 30LI, namun konsentrasi CO2 rata-rata pada kedua posisi jendela masih di bawah ambang batas konsentrasi CO2 yang diijinkan untuk kesehatan (<1000 ppm).   The breathing process produces air containing 4.4% of the volume of CO2 so that the concentration of CO2 in the classroom can be higher than the outside space if there is insufficient ventilation. CO2 concentration> 1000 ppm will interfere with the health and concentration of learning which has an impact on decreasing student learning performance. Previous research has shown a correlation between CO2 concentrations in classrooms with the size, number, position and type of windows in classrooms that use natural ventilation systems. The upper hanging window type is said to have the worst performance in neutralizing CO2 concentrations in space. The study intends to measure the level of CO2 concentration in a classroom in one of the public elementary schools in the city of Medan that uses a type of upper hanging window. Measurements of CO2 concentrations were carried out at the corridor opening angle of the class 10 and 30 for three (3) days, respectively. The results showed that the maximum CO2 concentration at the window opening angle 10 was lower than the 30LI window opening, but the average CO2 concentration in both window positions was still below the threshold of the permissible CO2 concentration for health (<1000 ppm).

scholarly journals The challenge of simulating warmth of the mid-Miocene Climate Optimum in CESM1

2013 ◽  
Vol 9 (3) ◽  
pp. 3489-3518 ◽  
Author(s):  
A. Goldner ◽  
N. Herold ◽  
M. Huber
Keyword(s):  
Temperature Gradient ◽  
Climate Models ◽  
Co2 Concentration ◽  
Mean Annual Temperature ◽  
Earth System ◽  
Equatorial Pacific Ocean ◽  
Proxy Records ◽  
Co2 Concentrations ◽  
Eastern Equatorial Pacific ◽  
Climatic Period

Abstract. The mid-Miocene Climatic Optimum (MMCO) is an intriguing climatic period due to its above-modern temperatures in mid-to-high latitudes in the presence of close-to-modern CO2 concentrations. We use the recently released Community Earth System Model (CESM1.0) with a slab ocean to simulate this warm period, incorporating recent Miocene CO2 reconstructions of 400 ppm. We simulate a global mean annual temperature (MAT) of 18 °C, ~4 °C above the pre-industrial value, but 4 °C colder than the global Miocene MAT we calculate from climate proxies. Sensitivity tests reveal that the inclusion of a reduced Antarctic ice sheet, eastern equatorial Pacific Ocean temperature anomalies, increased CO2 to 560 ppm, and variations in obliquity only marginally improve model-data agreement. All MMCO simulations have an equator to pole temperature gradient which is at least ~ 10 °C larger than the reconstruction from proxies. The MMCO simulation most comparable to the proxy records requires a CO2 concentration of 800 ppm. Our results illustrate that MMCO warmth is not reproducible using the CESM1.0 forced with CO2 concentrations reconstructed for the Miocene or including various proposed Earth system feedbacks; the remaining discrepancy in the MAT is comparable to that introduced by a CO2 doubling. The models tendency to underestimate proxy derived global MAT and overestimate the equator to pole temperature gradient suggests a major climate problem in the MMCO akin to those in the Eocene. Our results imply that this latest model, as with previous generations of climate models, is either not sensitive enough or additional forcings remain missing that explain half of the anomalous warmth and pronounced polar amplification of the MMCO.

scholarly journals Impact of Boundary Condition and Kinetic Parameter Uncertainties on NOx Predictions in Methane-Air Stagnation Flame Experiments

2021 ◽  
Author(s):  
Antoine Durocher ◽  
Jiayi Wang ◽  
Gilles Bourque ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Boundary Conditions ◽  
High Pressures ◽  
Laminar Flame ◽  
Combustion Process ◽  
Industrial Applications ◽  
Parameter Uncertainties ◽  
Nox Formation ◽  
Important Species ◽  
Spectral Expansions ◽  
Combustion Properties

Abstract A comprehensive understanding of uncertainty sources in experimental measurements is required to develop robust thermochemical models for use in industrial applications. Due to the complexity of the combustion process in gas turbine engines, simpler flames are generally used to study fundamental combustion properties and measure concentrations of important species to validate and improve modelling. Stable, laminar flames have increasingly been used to study nitrogen oxide (NOx) formation in lean-to-rich compositions in low-to-high pressures to assess model predictions and improve accuracy to help develop future low-emissions systems. They allow for non-intrusive diagnostics to measure sub-ppm concentrations of pollutant molecules, as well as important precursors, and provide well-defined boundary conditions to directly compare experiments with simulations. The uncertainties of experimentally-measured boundary conditions and the inherent kinetic uncertainties in the nitrogen chemistry are propagated through one-dimensional stagnation flame simulations to quantify the relative importance of the two sources and estimate their impact on predictions. Measurements in lean, stoichiometric, and rich methane-air flames are used to investigate the production pathways active in those conditions. Various spectral expansions are used to develop surrogate models with different levels of accuracy to perform the uncertainty analysis for 15 important reactions in the nitrogen chemistry and the 6 boundary conditions (ϕ, Tin, uin, du/dzin, Tsurf, P) simultaneously. After estimating the individual parametric contributions, the uncertainty of the boundary conditions are shown to have a relatively small impact on the prediction of NOx compared to kinetic uncertainties in these laboratory experiments. These results show that properly calibrated laminar flame experiments can, not only provide validation targets for modelling, but also accurate indirect measurements that can later be used to infer individual kinetic rates to improve thermochemical models.

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