Biogas Flow Rate Research Articles

Possibilities of Biogas Upgrading on a Bio-Waste Sorbent Derived from Anaerobic Sewage Sludge

The development of biogas upgrading technologies is now an essential issue in recovering fuel-grade methane. Nowadays, trends in biogas upgrading include investigations of low-cost and renewable materials as sorbents for biogas enrichment to produce biomethane. Therefore, in this work, wastewater anaerobic sludge stabilized with calcium oxide was used as the bio-waste sorbent to capture carbon dioxide from biogas, employing a fixed bed column. The biogas flow rate was the parameter considered for examining the breakthrough responses. It was observed that breakthrough time decreases with increasing biogas inflow rate from 570 ± 10 min at 5 mL/min to 120 ± 12 min at 35 mL/min. The maximum sorption capacity of 127.22 ± 1.5 mg CO2/g TS of sorbent was estimated at 15 mL/min. Biomethane concentration in biogas increased from 56.5 ± 1.7 v% in the raw biogas to 98.9 ± 0.2 v% with simultaneous low carbon dioxide content of 0.44 ± 0.2 v%. A strong positive correlation (R2 = 0.9919) between the sorption capacity and the biogas flow rate was found in the range of biogas inflow rates between 5 mL/min and 15 mL/min. Moreover, the correlation analysis showed a strong negative relationship (R2 = 0.9868) between breakthrough time and the mass of carbon dioxide removal, and the biogas flow rates ranged from 10 mL/min to 20 mL/min.

Identification of Sulphur Oxidizing Bacteria on Charcoal Made of Salak Fruit Seeds for Hydrogen Sulfide Removal in Biogas

Alternative energy sources to substitute fossil fuels have been developed, biogas being one of them. However, H2S needs to be removed in biogas because it promotes corrosion in the equipment using biogas. The H2S can be removed from biogas by biological processes. H2S was removed by biofiltration, in which H2S degrading bacteria immobilized on the packing material inside a column. This study aimed to determine the genera of microorganisms that degrade H2S in biogas. Moreover, this research aimed to investigate the ability of these microorganisms to degrade H2S. The novelty of this research is the use of charcoal from salak fruit seed as a packing material for immobilization the microorganisms in the biofilter; therefore, the packing material is more durable and does not rot. The isolated sludge taken from liquid wastewater treatment in the tofu industry was tested for sulfide degradation. Then, the best of bacteria to degrade sulfide was immobilized on the surface of charcoal made of salak fruit seeds and after acclimatization and the bacteria grew well. We tested their capability of forming biofilms on the surface of the charcoal of salak fruit seeds. Further identification showed that the isolate was Bacillus cereus with a similarity value of 98%. An experiment to remove H2S of biogas using a biofilter column with immobilized Bacillus cereus bacteria on the surface of the charcoal of salak fruit seeds showed that the Bacillus cereus bacteria could degrade H2S of biogas that flew in the biofilter through the surface of charcoal of salak fruit seeds. The highest removal efficiency was obtained for H2S (RE) at the packing height of 80 cm; 97.15% of which was achieved at a biogas flow rate of 30 L/hour, the H2S concentration was 142.48 ppm for 4 hours.

Performance Study of Two Serial Interconnected Chemostats with Mortality.

The present work considers the model of two chemostats in series when a biomass mortality is considered in each vessel. We study the performance of the serial configuration for two different criteria which are the output substrate concentration and the biogas flow rate production, at steady state. A comparison is made with a single chemostat with the same total volume. Our techniques apply for a large class of growth functions and allow us to retrieve known results obtained when the mortality is not included in the model and the results obtained for specific growth functions in both the mathematical literature and the biological literature. In particular, we provide a complete characterization of operating conditions under which the serial configuration is more efficient than the single chemostat, i.e., the output substrate concentration of the serial configuration is smaller than that of the single chemostat or, equivalently, the biogas flow rate of the serial configuration is larger than that of the single chemostat. The study shows that the maximum biogas flow rate, relative to the dilution rate, of the series device is higher than that of the single chemostat provided that the volume of the first tank is large enough. This non-intuitive property does not occur for the model without mortality.

Experimental and modeling analyzing the biogas upgrading in the microchannel: Carbon dioxide capture by seawater enriched with low-cost waste materials

There are multiple techniques to enhance the calorific value of biogas by removing impurities, especially carbon dioxide (CO 2 ). This study used a T-shaped microchannel to purify biogas by seawater containing 0.1 wt% of Iranian modified clinoptilolite zeolite and several precipitates (i.e., water distillation, phosphogypsum, power plant clarifier unit). These additives increase the alkalinity and CO 2 absorption ability of seawater. Effects of temperature, liquid flow rate, and biogas flow rate on the CO 2 removal efficiency have been investigated. The response surface methodology is also employed to construct a quadratic model to predict the CO 2 removal efficiency as a function of these variables. The P -value for all variables was less than 0.05, indicating that all four models were significant. Moreover, according to R 2 values ranging from 0.9920 to 0.9997, the experimental CO 2 absorption values have acceptable agreement with the model predictions. The maximum CO 2 capture by seawater solutions containing zeolite and precipitates of phosphogypsum waste, plant clarifier, and water distillation at 30 ° C, in a liquid flow rate of 150 ml/h and a gas flow rate of 50 ml/min was 96.85, 96.01, 92.99, and 90.23%, respectively. The results achieved in this study are essential for the appropriate design of a micro-reactor for biogas upgrading and understanding the effect of operating conditions on its CO 2 removal efficiency. • Biogas upgrading (CO 2 removal) by low-cost materials is studied in micro-reactor. • Seawater is used as an absorption solution in the micro-reactor for the CO 2 capture. • The applied materials show high efficiency in a broad range of operating conditions. • All studied absorbents completely remove CO 2 under the optimum conditions. • The suggested method reduces cost and energy required for the biogas upgrading.

The effect of seasonal biomass availability and energy demand on the operation of an on-farm biomethane plant

Globally, 10% of milk production occurs in countries whereby dairy livestock have pasture access for the majority of the year, leading to the seasonal collection and availability of dairy slurry. This can pose challenges if dairy slurry is used as a feedstock in on-farm biogas plants. On-farm biogas plants may also have limited gas grid access and have to facilitate seasonal gas demands of consumers in their locality. The effects of seasonal gas demand coupled with seasonal slurry availability have yet to be addressed in literature. This work aims to analyse the effects of such seasonal factors, and whether optimised digestate recirculation may alleviate some of these challenges. Countries which employ pasture-based dairy farming require such evidence to successfully develop on-farm biogas plants, reduce fugitive emissions resultant from current manure management practices, and furthermore, produce alternatives to fossil fuels. Ireland is used as a case study in this work and the effects of seasonal or constant slurry availability and seasonal or constant gas demand is investigated. The sustainability of such systems is also evaluated in terms of emissions reductions as per EU regulations. For a farm with slurry production from 100 dairy cows and 10 ha of grass dedicated for anaerobic digestion, the seasonal availability of slurry leads to a 21% reduction in total biomethane production; over 12 times the required digestate recirculation; smaller digester sizes; and increased variation in the organic loading rate throughout the year. Facilitating a seasonal gas demand leads to larger digester sizes due to periods of increased mass flow rates, and large peaks and troughs in biogas flow rates. Seasonal slurry availability increases greenhouse gas emissions by ca. 11 g of CO2 per megajoule of biomethane produced. Pasture-based AD systems may successfully manage the seasonal availability of slurry by optimising digestate recirculation to lower the solids content of the plant.

Improving combustion and emission characteristics of a biogas/biodiesel-powered dual-fuel diesel engine through trade-off analysis of operation parameters using response surface methodology

The present study focused on using dual-fuel such as Mahua oil biodiesel and biogas in a diesel engine to analyze performance and emission by varying compression ratio (CR) and engine loads. Following the experimental step, the response surface approach was used to model-predict, and optimize. The variance analysis was used to create relationship functions between the independent control variables (engine loads and CR) and their dependent response variables (performance and emission indices). A robust model is indicated by a high coefficient of determination value for all outputs (0.8673 – 0.9917). The optimization yielded 15.25% brake thermal efficiency, 326 °C exhaust gas temperature, 2.85 kg/h biogas flow rate, 68.9% liquid fuel replacement, and 44 bar peak cylinder pressure. A trade-off study of engine performance vs. emission at optimal operating settings produced 4.45 vol% CO2, 39 ppm NOx, 90 ppm HC, and 90.17 ppm CO. The validation test in the lab revealed that all of the predicted output was within a 6% error range. This research indicated that dual-fuel might be an excellent choice for improving waste-to-energy prospects, performance, and emissions.

Development of Inexpensive, Automatic, Real-Time Measurement System for On-Line Methane Content and Biogas Flowrate

Development of Inexpensive, Automatic, Real-Time Measurement System for On-Line Methane Content and Biogas Flowrate

Analysis of the Influence of Temperature on the Anaerobic Digestion Process in a Plug Flow Reactor

The production of biogas by means of the anaerobic digestion process is becoming increasingly attractive in the green economy context. When municipal organic waste is used to produce biogas, a further positive effect on urban waste disposal is obtained. Starting from the anaerobic digestion model n.1, an accurate analysis of the temperature effects on the anaerobic digestion process in a plug flow reactor is performed. This paper aims at presenting a comprehensive and integrated one-dimensional biological and thermal model for a plug flow reactor. Partial differential equations with respect to time and space are considered to model the heat transfer between the reactor and the internal heat exchanger and between the reactor and the environment. In this scope, a suitable simulation code was developed in MATLAB and validated using the data available in literature. The results of the calculations show that temperature plays a crucial role in the anaerobic digestion process, since it strongly affects the kinetic rates of the microbial species and the methane production. The results obtained in terms of temperature fields and biogas production are compared with the ones available in literature, dealing with a continuously stirred tank reactor. The comparison is conducted considering that both reactors process a volumetric waste flow rate of 20 m3/d and have the same structural characteristics. The plug flow reactor resulted better performance with a produced biogas flow rate equal to 2300 Nm3/year.

Equilibrium Behavior of CO2 Adsorption from Biogas onto Zeolites

Biogas is one of the types of renewable energy that has a major gas content of CH4 and CO2. One of the methods for upgrading biogas is adsorption. The principle of adsorption’s work is to deliver biogas into a column with containing adsorbent, so that a CO2 gas is bound to zeolite, causing the CH4 to increase in the result product. The biogas used in research came from a cow feces that was dumped into a 10bar pressure vessel. Adsorbent used zeolite 13X that was activated. The biogas tube has a height 0.3 m and diameter 3 cm. It was made of stainless steel and there was a cartridge heater inside. Biogas was channeled into adsorbent column with pressure variations 0.8, 1.2, 1.6 and 2 bars and temperature variations 30, 50 and 100°C. The flow rate of biogas used 4 L/minute with a 4-minute data retrieval. Data retrieval was continuous, so that the composition of CO2 gas from beginning to end recorded on the Gas analyzer. The research aims to identify the balance of adsorption with variations in pressure and temperature by Langmuir equation which has been developed. The results show if the higher the pressure, then CO2 that was absorbed is inversely proportional to the temperature where the higher the temperature, the less CO2 was adsorbed. This research succeeded in getting the Langmuir constant, maximum amount adsorbed of CO2, and heat of adsorption.

Application of machine learning and Box-Behnken design in optimizing engine characteristics operated with a dual-fuel mode of algal biodiesel and waste-derived biogas

Waste-derived biogas and third-generation algal biodiesel are attractive alternative fuels to substitute fossil diesel in a diesel engine. However, using biodiesel as a pilot liquid fuel and biogas as the main fuel in a diesel engine is a complicated and highly non-linear process. The current study seeks to predict and optimize the combustion and exhaust emission characteristics of a variable compression dual-fuel combustion engine. Data from experiments were obtained at a variety of engine loads, compression ratios, pilot fuel injection pressures, and timings. A multi-layer perceptron network was employed to develop an Artificial Neural Network (ANN) based prognostic model using the experimental data. The developed prognostic model was used to estimate brake thermal efficiency, biogas flow rates, peak in-cylinder pressure, carbon dioxide, unburned hydrocarbons, oxides of nitrogen, and carbon monoxide. The predictive model's robustness is demonstrated by statistical metrics such as R (0.9723–0.988) and R2 (0.9453–0.9761), Nash-Sutcliffe model efficiency (94–97%), and mean absolute percentage error (0.013–0.128%), Kling-Gupta efficiency (0.9548–0.9836), and Theil's U2 model uncertainty (0.162–0.368). To optimize the parameters of dual-fuel combustion, the Multi-Output Response Surface Methodology (RSM) was employed. The trade-off assessment between emission and efficiency using the desirability approach revealed that 84% engine load, 244 bar of fuel injection pressure, 28 °BTDC of injection timing, and 17.5 compression ratio are the best-operating conditions for the test engine. An experimental investigation was used to corroborate the RSM research findings, and errors were less than 9%. It was revealed that ANN-linked RSM is a good hybrid technique for modeling, prediction, and optimization of the performance of a dual-fuel engine.

Consideration of biological and inorganic additives in upgraded anaerobic digestion BioModel

This paper deals with the numerical simulation of biogas production in the anaerobic digestion process of organic waste. Special attention is focused on the modeling of the activities of biological and inorganic additives, which are used to enhance the process and reduce H2S content in the biogas. For this purpose, an existing BioModel is upgraded with the modified Michaelis-Menten kinetics in order to model the enzymatic hydrolysis and with adequate modeling of physicochemical processes. The upgraded BioModel was calibrated with experimental data obtained from a full-scale biogas plant, used in combination with an active set optimization procedure; the relative agreement indices were 0.9376, 0.9419, 0.7957, and 0.7663 for biogas, CH4, H2, and H2S flow rates, respectively. Statistical efficiency criteria differ up to 5% in model calibration and validation. The obtained results confirm the importance of additives modeling and the usefulness of the proposed model for industrial biogas plants’ performance improvement.

Techno-economic and sustainability analysis of siloxane removal from landfill gas used for electricity generation

A technoeconomic analysis (TEA) and life cycle assessment (LCA) was conducted on the use of landfill gas (LFG) for electricity generation using an internal combustion engine. This study provides insights that can guide LFG waste to energy (WTE) operators on decisions concerning installation of contaminant removal from LFG for electricity generation. Four scenarios were analyzed; the first (Scenario 1) was a facility with a single siloxane removal unit (SREU) sized for 6 months of continuous use, the second (Scenario 2) was a facility with parallel SREUs sized for one month of use, the third (Scenario 3) was a facility with no SREU, and the fourth was a facility that flared all LFG captured. The TEA revealed that the chiller cost was over 50% the total purchase cost of the LFG pre-treatment system. When the complete LFG to electricity process was analyzed, the internal combustion engine had the highest percentage of total capital investment and the total annual cost. For the base case, it became economically beneficial to install a SREU at facilities with LFG flowrates greater than ∼2000 m3/h. Sensitivity analysis showed that at a base case of 1700 m3/h, LFG (50% CH4), and 50 mg/m3 D4, the net income of facilities in Scenarios 1 to 3 became positive at an electricity sales price greater than 5.5 cents/kWh. LCA revealed that Scenario 2 had the greatest CO2 emission reduction. Scenario 3 is observed to save less CO2 emissions as biogas flowrate increases due to frequent engine shutdowns. Although there are differences in the global warming potential (GWP 100) for Scenarios 1 to 3, with Scenario 2 being the best and Scenario 3 being the worst, the differences are very small. For this reason, economics alone are sufficient in decision making.

Performance assessment of biogas-fed solid oxide fuel cell system for municipal solid waste treatment

An enormous amount of municipal waste is produced globally and a large proportion of this waste is dumped into the landfill that is now about to reach the maximum capacity and makes it obligatory to investigate alternative methods for waste treatment. This study proposes a novel design to treat the organic fraction municipal solid waste (OFMSW) to generate electricity using solid oxide fuel cells (SOFC). The detailed process simulation is conducted using the standard chemical process simulator Aspen Plus which predicts the electricity that is generated using the OFMSW as feedstock. The biogas from the system is employed to the reformer that produces syngas and this mixture of hydrogen and carbon monoxide is fed to the SOFC with air to generate electricity. The detailed characterization of the proposed system is conducted and numerous sensitivity analyses are performed to investigate the system performance. The study also employs a detailed technical and economic feasibility of the biogas-fed SOFC system for municipal solid waste treatment. The proposed design employs 1,000 Nm3/hr of biogas flow rate that produces 3,633 kW of DC power using SOFC. The thermal management of the designed system is also performed to recover the additional heat within the designed system. A detailed techno-economic feasibility study is conducted for the proposed system and the capital and operating expenditures, income and depreciation costs are also evaluated. The economic and cash flow analyses show that the plant is suitable for a long-term scenario. It has been predicted that if the electricity price increase to 130 $/MWh, it will take 5 years as a payback period for the long-term scenario. Furthermore, the results obtained from the sensitivity studies and techno-economic analysis are presented and discussed.

Intensified biogas upgrading via various wastewater using microchannel

In this article, several ideas have been proposed for CO2 separation and biogas upgrading using industrial wastewater. Synthetic gas (60% CH4, 40% CO2) has been upgrading in atmospheric pressure in a T-shaped microchannel using municipal, meat processing, water distillation, dairy, caustic, and fish pond wastewater. The municipal, fish pond, and meat processing wastewater contain ammonia, while dairy, and water distillation wastewater contains Ca2+, and Mg2+. Also, the caustic refinery wastewater contains NaOH, with higher alkalinity for CO2 separation. The effect of temperature, gas, and liquid flow rate were investigated. RSM analysis provided a function of three dependent variables of quadratic model for prediction of responses (CO2 removal efficiency and total mass transfer in gas phase) by each absorbent, and all models were meaningful. In addition, given that all R2 values were greater than 0.94, it was indicated that experimental values for removal of CO2 and mass transfer coefficient are favorably consistent with the values of the model. Maximum CO2 absorption was obtained at 30°C, liquid flow rate of 150 mL/hr, and biogas flow rate of 50 mL/min. According to the results obtained for mass transfer coefficient, these coefficients are at least 5 to 22 times greater than mass transfer coefficient in chemical absorption in normal absorption towers, such as packed towers.

Modeling and optimization of an upflow anaerobic sludge blanket (UASB) system treating blackwaters

In the present work, a novel mathematical dynamic model describing the upflow anaerobic sludge blanket (UASB) has been developed. The model incorporates both the biological processes and the transport of sludge particles specifically related to the UASB treatment of blackwater. The processes occurring in the reactor are modeled as a sequence of two completely-mixed reactive tanks, one representing the sludge bed where most solids concentrate and the other representing a less solid-concentrated liquid volume. Solids from the sludge bed are assumed to be dragged to the upper zone of the reactor by the methane gas produced. The time variation of the sludge bed volume is included by assuming a constant sludge density. The model is calibrated against published data obtained from a stable operation of a lab-scale UASB system treating at different organic loading rates blackwater collected from real vacuum toilets. Good model prediction compatibility with the measurements of emitted biogas and methane gas flow rates, effluent COD, volatile fatty acids, pH and sludge bed volume was revealed. Furthermore, the model was successfully validated against another independent set of data from a UASB reactor treating a more diluted type of blackwater collected from conventional toilets. A scenario analysis performed using such a validated model reveals higher methane production yield but also higher effluent COD concentration at increasing organic loading rates and sludge bed volumes. It is found that longer HRTs can improve COD removal efficiency and methane production in blackwater treatment processes.

Investigations into the Combined Effect of Mahua Biodiesel Blends and Biogas in a Dual Fuel Engine

Rapid depletion of conventional fuel sources has led to the use of alternative fuels and implementation of variant engine technologies to reduce deleterious emissions being released and deliver thermal energy for numerous applications. This research aims to study the usage of mahua methyl ester in a single-cylinder 4-stroke CI engine, optimized to operate in the dual fuel mode. Performance, combustion and emission characteristics are recorded and compared with diesel with the sole aim of finding the blend that provides adequate performance and diminishing emissions. To this effect, the percentage of mahua biodiesel blend, load, biogas flow rate and methane fraction are varied. The experimentation is conducted using three mahua biodiesel blend variants namely B10, B20 and B30. Gaseous fuel comprising biogas (CH4 and CO2 in ratio of 3:2) and methane (CH4) are incorporated in the dual fuel condition at 8 litre per minute (lpm) and 12 lpm. B20 blend demonstrated better performance and emission characteristics. The addition of biodiesel (B20) showed more than 5% improvement in brake thermal efficiency. Additionally, comparing with normal diesel mode, B20 showed lower CO (0.061%) and NOx (615 ppm) emissions. In the dual fuel condition, methane and biogas are effective in reducing the NOx emissions, but with a negative repercussion of extortionately elevated HC and CO emissions. The best combination is deduced to be B20 mahua biodiesel at 8 lpm of biogas flow rate in the dual fuel mode due to better performance and emission characteristics.

An experimental assessment on dual fuel engine behavior powered by waste tire-derived pyrolysis oil – biogas blends

This paper is intended to investigate the usability of waste tire pyrolysis oil along with diesel and biogas dual fuel in the CI engines. In this framework, the waste tire chips are firstly pyrolyzed in the study, and then are volumetrically blended into the conventional diesel fuel (DF) at the ratio of 20%. The biogas flow rate changes as 0.5, 1, and 2 L/min when the engine is fuelled by P20 test fuel. Throughout the experiments, the engine runs at a fixed engine speed of 1500 rpm under 2.5, 5, 7.5 and 10 Nm. In the results, it is noticed that the unburnt emissions such as CO and HC considerably increases with the presence of pyrolysis oil and biogas in the cylinder due to the lack of oxygen and lower heating value of these fuels. However, the NOx firstly rises with the diesel-pyrolysis oil blends by 2.21% but then pulls back with the introduction of biogas to the combustion chamber. It drops by 2.29%, 4.93%, and 11.14% for P20 + 0.5 BG, P20 + 1 BG, and P20 + 2 BG test fuels, respectively in comparison to that of DF. On the other hand, the engine performance worsens with the pyrolysis oil due to the lower energy content. Accordingly, the increment on BSFC is found to be 9.28%, 25.15%, 42.51%, and 67.68%, and the reduction on BTE is found to be 8.47%, 17.72%, 25.52%, and 33.48% for P20, P20 + 0.5 BG, P20 + 1 BG, and P20 + 2 BG test fuels, respectively. It is concluded that even if they worsen the engine performance and exhaust emissions, the burning of waste products in the forms of pyrolysis oil and biogas as fuel substitutions in CI engines seems a very promising way in terms of waste management, disposal the huge volume of waste products from the nature, and protection of rapidly depletion fossil fuel reserves.

Experimental assessment of the influences of liquid-solid-gas fuel blends on DI-CI engine behaviors

This study aims to deeply investigate the effects of the boron nanoparticles reinforced diesel fuel along with various biogas (BG) flow rates (0.5, 1, and 2 L/min) on the engine performance and emission characteristics of a diesel engine. The tests were carried out using a single-cylinder, four-stroke, direct injection, compression-ignition engine at a constant engine speed of 1500 rpm and under the varying engine loads from 2.5 to 10 Nm with gaps of 2.5 Nm. In the results, it is seen that EGT started to decrease in both the addition of boron nanoparticles and the addition of biogas compared to that of conventional diesel fuel (DF). EGT reduced by 8.6% for DF+Boron test fuel, 14.4% for DF+Boron+ 0.5 BG, 21% for DF+Boron+ 1 BG, and 23.4% for DF+Boron+ 2 BG. Compared to diesel fuel, CO, NOx, and HC emissions decreased with the addition of nanoparticles at all loads. However, as the amount of biogas increased, CO and HC emissions increased, but NOx emissions decreased. CO emission dropped by 22.2% for DF+Boron test fuel, however, increased to be 5.6%, 16.7%, and 36.1% for DF+Boron+ 0.5 BG, DF+Boron+ 1 BG, and DF+Boron+ 2 BG respectively. NOx emission reduced by 4.9%, 8.6%, 10.7%, and 14.8% for DF+Boron, DF+Boron+ 0.5 BG, DF+Boron+ 1 BG, and DF+Boron+ 2 BG respectively. In comparison to that of conventional DF, the brake specific fuel consumption (BSFC) value decreased by 8.42% for DF+Boron test fuel due to high energy content of nanoparticles, but it increased by 10.94% for DF+Boron+ 0.5 BG, 28.01% for DF+Boron+ 1 BG, and 60.2% for DF+Boron+ 2 BG. In addition, brake thermal efficiency BTE value increased by 8.04% for boron-added test fuel, but it declined by 9.41% for DF+Boron+ 0.5 BG, 19.38% for DF+Boron+ 1 BG, and 32.2% for DF+Boron+ 2 BG as compared to that of DF. In the conclusion, it is noticed that the engine characteristics have worsened by the introduction of biogas into the cylinder, but these worsened characteristics can be improved with the presence of boron nitride nanoparticles.

Investigation of the Performance and Emission Characteristics of Diesel Engine Fueled with Biogas-Diesel Dual Fuel

Due to the popularity of diesel engines, utilization of fossil fuel has increased. However, fossil fuel resources are depleting and their prices are increasing day by day. Additionally, the emissions from the burning of petroleum-derived fuel is harming the global environment. This work covers the performance and emission parameters of a biogas-diesel dual-fuel mode diesel engine and compared them to baseline diesel. The experiment was conducted on a single-cylinder and four-stroke DI diesel engine with a maximum power output of 2.2 kW by varying engine load at a constant speed of 1500 RPM. The diesel was injected as factory setup, whereas biogas mixes with air and then delivered to the combustion chamber through intake manifold at various flow rates of 2, 4, and 6 L/min. At 2 L/min flow rate of biogas, the results were found to have better performance and lower emission, than that of the other flow; with an average reduction in BTE, HC, and NOx by 11.19, 0.52, and 19.91%, respectively, and an average increment in BSFC, CO, and CO2 by 11.81, 1.05, and 12.8%, respectively, as compared to diesel. The diesel replacement ratio was varied from 19.56 to 7.61% at zero engine load and 80% engine load with biogas energy share of 39.6 and 16.59%, respectively.

Some non-intuitive properties of serial chemostats with and without mortality

This paper discusses a model of two interconnected chemostats in series, characterized by biomass mortality. A comparison is established with a single chemostat of the same total volume in two different cases, that are with or without mortality rate. The outlet substrate concentration and the biogas flow rate are the main criteria for comparison. According to conditions depending on the operating parameters and the distribution of the total volume, our results show which structure, the series of the two chemostats or the single chemostat, performs better in terms of minimizing the outlet substrate concentration or maximizing the biogas flow rate, and this with or without account of mortality. Moreover, the differences and similarities in the results corresponding to the case with mortality and the one without mortality, are highlighted.