Effects of membrane electrode assembly fabrication parameters on the proton exchange membrane fuel cell performance

In this paper, experimental investigation focuses on analysing the simultaneous influences of four different fabrication parameters, including carbon loading in GDL, Nafion content in CL, drying temperature of CL and hot pressing temperature. Active area of the MEAs was 25?cm² and characterisation of them was carried out by a 700?W fuel cell test station. Results show that the existence of MPL in GDL can improve performance of the PEMFC because of creating an even and steady surface which decreases ohmic resistance. The results confirm that the robustness of the optimum fabrication parameters influence performance of the cell. Optimum values of the parameters are: carbon loading in GDL, 3?mg?cm^?2; catalyst drying temperature, 60°C and Nafion content, 45%; but hot pressing temperature effect was lower than the other parameters. The expected performance of the fuel cell at optimum condition is 184.447?mW?cm^?2.     

Optimization of electro-oxidation and electro-Fenton techniques for the treatment of oilfield produced water

Electrochemical advanced oxidation processes are the most promising methods for destroying and degrading organic and inorganic pollutants present in produced water effluents. This study presents the electro-oxidation process using graphite electrodes and electro-Fenton process using iron electrodes for the treatment of real produced water. The effect of operating parameters such as current density on chemical oxygen demand (COD) removal efficiency was addressed. The result showed that electro-Fenton process was more efficient than electro-oxidation process where it gave 98% as maximum COD removal efficiency with energy consumption of 1.9 kWh/dm³ at H₂O₂ concentration of 12 mM, current density of 10 mA/cm², temperature of 25°C, pH of 3, and treatment time of 80 min compared with 96.9% as maximum COD removal efficiency with energy consumption of 3 kWh/dm³ at pH of 6, current density of 10 mA/cm², temperature of 40°C, and reaction time of 80 min when using electro-oxidation process. These results demonstrated that electrochemical technologies are very promising methods for the treatment of produced water from oil/gas industry, so it can be safely disposed of or effectively reused for injection and irrigation.     

A combined current density technique for the electrochemical oxidation of perfluorooctanoic acid (PFOA) with boron‐doped diamond

Perfluoroalkyl substances (PFAS) have unique properties that limit their degradability in the environment. One of these PFAS is an acid (PFOA). Electrochemical oxidation is a promising method for remediation, but energy costs are high. To limit the energy consumption, this study used a boron‐doped diamond (BDD) electrode stack and a combined current density technique that employed 50 mA/cm² for the first 0.25 hours then lowered the current density to 1, 5, or 10 mA/cm². This technique is similar to one developed previously; however, that method was only developed for compounds comprising of carbon, oxygen and nitrogen, whereas PFAS have the addition of fluorine. For the degradation of PFOA, the combined current density of 50 and 5 mA/cm² (50&5) allowed for a 37% reduction in energy usage to obtain 75% defluorination compared to using 50 mA/cm² alone. Further investigation into remediating an ion‐exchange regeneration solution shows great promise.     

Production and characterisation of bio-ethanol from various Nigerian feedstocks

Bio-ethanol fuel was synthesised from various Nigerian feedstocks (palm (Elaeis guineensis) wine, raffia (Raphia vinifera) trunk and sugarcane (Saccharum L.)) to serve as alternative fuels for internal combustion engines. Bio-ethanol was obtained through fermentation and distillation from these selected Nigerian crops and was then purified. Physical properties of the bio-ethanol such as vapour pressure, octane number, flash point, heating values, auto ignition temperature and density were evaluated using the American Society for Testing and Materials methods. Sugarcane gave the highest yield of alcohol, 72.7 cl/L of juice produced while palm wine and sap from raffia trunk gave 4.0?cl/L and 2.03?cl/L, respectively. The calorific value, research octane number and the flash point of the produced ethanol (E₁₀₀) are 29.78?MJ/kg, 114 and 12.5?°C, respectively. The results of the characterisation showed that the produced fuels are alternative fuels that can be used on modern petrol engines with little or no engine modifications.     

Modelling and simulation of single- and triple-junction solar cells using MATLAB/SIMULINK

The main objective of this paper is to determine the single- and triple-junction solar cells’ I–V and P–V curves, define maximum voltage, current, and power. The paper demonstrates and analyses different environmental conditions that affect the solar cells, such as temperature and irradiance. The performance of single- and triple-junction solar cells is evaluated by analysing the fill factor. In this work, the analysis of single- and triple-junction solar cells is carried out through software simulation. Different conditions demonstrated to observe the results of this variation in both single- and triple-junction cells, such as observing the solar cell behaviour under variation of temperature between 15°C (288.315?K) and 45°C (318.15?K) for the single-junction cell and between 268.15?K (?5°C) and 348.15?K (75°C) for the triple-junction cell to observe the effect of temperature on open circuit voltage, the variation of different levels of irradiance to observe its effect on open circuit voltage and current density on both cell types, and cell performance evaluation using the fill factor concept. Practical results used in this paper are obtained from Clyde Space’s laboratories. Tests of Clyde Space were done using halide lamps to simulate the irradiation conditions with irradiance of half sun which is equivalent to 0.05?W?cm^?2. The operation was done under temperature of 40°C which is equivalent to 313.15?K.     

Modelling study of an upflow microbial fuel cell catalysed with anaerobic aged sludge

An electrochemical model for an upflow dual-chambered microbial fuel cell (MFC) process is proposed in this study. The model was set up on the basis of the experimental results and the analysis of biochemical and electrochemical processes in the MFC biocatalysed with anaerobic aged sludge and alternatively fuelled with a synthetic acetate-based and actual domestic wastewaters. Simulation of the process shows that the model describes the process reasonably well with correlation coefficients higher than 0.97. The analysis of model simulation illustrates how the current output depends mainly on the substrate concentration as well as other main variables. The relationship between the current output and over-voltage is revealed by the modelling study. For acetate-based wastewaters with initial chemical oxygen demand (COD) concentrations of 350, 700, 1050, and 1400 mg/L, maximum observed power densities were 290, 405, 448, and 525 mW/m² associated with maximum COD removals of 84%, 88%, 83%, and 82%, respectively.     

Synthesis and characterisation of biodiesel from Nigerian physic nut,castor bean,dika nut and sandbox seed oils

Biodiesel fuels were synthesised from Nigerian physic nut seed (Jatropha curcas), castor bean seed (Ricinus communis), dika nut (Irvingia gabonensis) and sandbox seed (Hura crepitans) oil. The direct base-catalysed transestetification process was employed in the biodiesel production using methanol and sodium hydroxide (NaOH) as alcohol and catalyst, respectively. The transesterification process involved 500 ml of J. curcas, castor bean seed, dika nut and sandbox seed oils, 100 ml of methanol and 1.0% of NaOH by weight for each oil. The process was carried out at different reaction temperatures in order to examine the effect of temperature on biodiesel yield of the oils. An average maximum biodiesel yield of 89.00% at 50 °C, 61.50% at 45 °C, 74.33% at 50 °C and 88.50% at 55 °C were obtained for Jatropha, castor, dika nut and sandbox oils, respectively. The calorific values of diesel decreased from 42.7 to 42.475, 41.48, 42.330 and 42.13 MJ/kg with a blend of 10% of physic nut, castor bean, dika nut and sandbox seed biodiesel, respectively. The calorific values of the produced biodiesel from physic nut, castor bean, dika nut and sandbox seed oils are 40.45, 30.50, 39.00 and 37.00 MJ/kg, respectively. The cetane number, kinematic viscosity at 40 °C and pour point of the produced biodiesel are 59.4, 4.20 mm²/s and?1°C for physic nut biodiesel; 50, 10.75 mm²/s and?45°C for castor biodiesel; 52, 3.20 mm²/s and?6°C for dika nut biodiesel and 50, 4.20 mm²/s and 6 °C for sandbox seed biodiesel, respectively. The results showed that the addition of biodiesel to diesel generally increases the density, kinematic viscosity, flash point and pour point but, on the other hand, reduces the calorific value of the produced blend.     

In-situ identification of iron electrocoagulation speciation and application for natural organic matter (NOM) removal

In this work, iron speciation in electrocoagulation (EC) was studied to determine the impact of operating parameters on natural organic matter (NOM) removal from natural water. Two electrochemical EC parameters, current density (i) and charge loading rate (CLR), were investigated. Variation of these parameters led to a near unity current efficiency (φ = 0.957 ± 0.03), at any combination of i in a range of 1–25 mA/cm² and CLR in a range of 12–300 C/L/min. Higher i and CLR led to a higher bulk pH and limited the amount of dissolved oxygen (DO) reduced at the cathode surface due to mass transfer limitations. A low i (1 mA/cm²) and intermediate CLR (60 C/L/min) resulted in low bulk DO (<2.5 mg/L), where green rust (GR) was identified by in-situ Raman spectroscopy as the primary crystalline electrochemical product. Longer electrolysis times at higher i led to magnetite (Fe₃O₄) formation. Both higher (300 C/L/min) and lower (12 C/L/min) CLR values led to increased DO and/or increased pH, with lepidocrocite (γ-FeOOH) as the only crystalline species observed. The NOM removal of the three identified species was compared, with conditions leading to GR formation showing the greatest dissolved organic carbon removal, and highest removal of the low apparent molecular weight (<550 Da) chromophoric NOM fraction, determined by high performance size exclusion chromatography.     

Efficient recovery of nano-sized iron oxide particles from synthetic acid-mine drainage (AMD) water using fuel cell technologies

Acid mine drainage (AMD) is an important contributor to surface water pollution due to the release of acid and metals. Fe(II) in AMD reacts with dissolved oxygen to produce iron oxide precipitates, resulting in further acidification, discoloration of stream beds, and sludge deposits in receiving waters. It has recently been shown that new fuel cell technologies, based on microbial fuel cells, can be used to treat AMD and generate electricity. Here we show that this approach can also be used as a technique to generate spherical nano-particles of iron oxide that, upon drying, are transformed to goethite (α-FeOOH). This approach therefore provides a relatively straightforward way to generate a product that has commercial value. Particle diameters ranged from 120 to 700 nm, with sizes that could be controlled by varying the conditions in the fuel cell, especially current density (0.04-0.12 mA/cm²), pH (4-7.5), and initial Fe(II) concentration (50-1000 mg/L). The most efficient production of goethite and power occurred with pH = 6.3 and Fe(II) concentrations above 200 mg/L. These results show that fuel cell technologies can not only be used for simultaneous AMD treatment and power generation, but that they can generate useful products such as iron oxide particles having sizes appropriate for used as pigments and other applications.     

Electrochemical treatment of chemical oxygen demand in produced water using flow‐by porous graphite electrode

Produced water is the largest wastewater stream generated in the oil and gas industries. In this study, experiments were carried out using a bench‐scale electrochemical cell using flow‐by porous graphite electrode, for oxidation of organic matter in produced water which was collected from natural gas processing field (real sample). The effect of anodic current density and influent feed flow rate on chemical oxygen demand (COD) removal efficiency, and energy consumption were investigated. The maximum removal efficiency of 66.52% was obtained for a flow rate of 50 mL/min, current density of 1.41 mA/cm² and pH of 7.3 for an influent COD of 2845 mg O₂/L. The energy consumption at these conditions was 2.12 kWh/kg_COD.     

Flammability limits of iso-butanol/iso-octane/n-heptane blends

A set of experiments was carried out to determine the flammability limits (FL) of blends of iso-butanol and a surrogate fuel for gasoline at 154±11 °C and ≈91.4 kPa. The surrogate gasoline was a binary PRF mixture of 87% iso-octane and 13% n-heptane (PRF 87). The volumetric fraction of iso-butanol in the liquid fuel was varied from 0 to 0.25 at a step of 0.05. Flammability tests with pure fuels were also performed to confirm the reliability of the applied experimental procedure. The homogeneous air/fuel mixtures were defined as flammable when formed a self-sustained flame able to travel upward a 0.3 m long open combustion tube. The lower FL of the blends of iso-butanol and PRF 87 (0.80−0.98%) were estimated correctly with the mixing rule of Le Chatelier, but the same simplified model failed to reproduce the measured upper flammability limits (5.10−5.61%).     

Outdoor,indoor, and personal black carbon exposure from cookstoves burning solid fuels

Black carbon (BC) emissions from solid fuel combustion are associated with increased morbidity and mortality and are important drivers of climate change. We studied BC measurements, approximated by particulate matter (PM_2.5) absorbance, in rural Yunnan province, China, whose residents use a variety of solid fuels for cooking and heating including bituminous and anthracite coal, and wood. Measurements were taken over two consecutive 24‐h periods from 163 households in 30 villages. PM_2.5 absorbance (PM_abs) was measured using an EEL 043 Smoke Stain Reflectometer. PM_abs measurements were higher in wood burning households (16.3 × 10^?5/m) than bituminous and anthracite coal households (12 and 5.1 × 10^?5/m, respectively). Among bituminous coal users, measurements varied by a factor of two depending on the coal source. Portable stoves (which are lit outdoors and brought indoors for use) were associated with reduced PM_abs levels, but no other impact of stove design was observed. Outdoor measurements were positively correlated with and approximately half the level of indoor measurements (r = 0.49, P < 0.01). Measurements of BC (as approximated by PM_abs) in this population are modulated by fuel type and source. This provides valuable insight into potential morbidity, mortality, and climate change contributions of domestic usage of solid fuels.     

New Correlation Between Ignition Time and Moisture Content for Pine Needles Attacked by Firebrands

The capacity of firebrands for ignition is closely related to fuel conditions which include fuel type, moisture content (MC), fuel distribution and fuel bulk density, among which MC is the most important. In this paper, a new correlation between ignition time (t _ig) and MC of fuels is established by theoretical consideration of the heat transfer processes that occur when fuels are ignited by glowing firebrands that have settled on a fuel bed. The results suggest a linear relationship between t _ig ^1/2 and MC. This linear correlation is verified by data from six groups of firebrand ignition experiments in which pine needles were used as the fuel to be ignited, with MCs ranging from 12.9% to 65%. The wind speed during experimentation was maintained at 3 m/s (±0.2 m/s). The studies by Jolly et al. support the theoretical correlation.     

A study of hydrogen as an alternative fuel

ABSTRACT

As oil prices increase, the interest in alternative fuels increases. This is evidenced by demonstration programmes and commitments by states such as India. The concern of the air quality in many areas around the world makes ?nding solutions more urgent. As the price of oil increases, alternate fuels become more ruthless. Major questions remain to be answered on which fuel or fuels will emerge and to what extent alternative sources will replace gasoline as the main product of crude oil. A combination of available alternative fuels will evolve with the most likely choices affected by a number of technical, political and market factors. In order to allow a wider application of alternative fuels, a number of obstacles have to be overcome. These include economic, technological, and infrastructural issues. In the past, gasoline has been plentiful and has had a signi?cant price advantage compared to other fuels. This could change quickly and alternative fuels would need to become more commonplace. One of the alternatives involves the more widespread use of biomass-produced fuels. In this paper describes that hydrogen as an alternative fuel. Hydrogen powered fuel cells could have wide applications, replacing batteries in many portable application, vehicle and using hydrogen for home electrical needs.     

Effect of current density on accelerated corrosion of reinforcing steel bars in concrete

Abstract

Impressed anodic current techniques are used widely to accelerate corrosion of steel embedded in concrete in the laboratory. This paper investigates the relationship between applied current density, degree of corrosion, type of corrosion and ultimate strength of corroded beams. Twenty beams were divided into four groups with a 0.5, 1, 2.5 or 5% degree of corrosion. Current densities of 0.25, 0.5, 1.0 or 2.5 mA/cm² were applied to each group, respectively. The beams were flexurally tested and the reinforcing steel bars were retrieved, cleaned, weighed and the surface examined. The results demonstrated that higher current densities and degree of corrosion caused more localised corrosion. The applied current density has little effect on the degree of corrosion and on ultimate strength of the same degree of corroded beam. Based on this work, a current density of 1 mA/cm² is recommended for the artificial acceleration of corrosion for steel embedded in concrete.     

Nano-structured manganese oxide as a cathodic catalyst for enhanced oxygen reduction in a microbial fuel cell fed with a synthetic wastewater

Microbial fuel cells (MFCs) provide new opportunities for the simultaneous wastewater treatment and electricity generation. Enhanced oxygen reduction capacity of cost-effective metal-based catalysts in an air cathode is essential for the scale-up and commercialization of MFCs in the field of wastewater treatment. We demonstrated that a nano-structured MnO_x material, prepared by an electrochemically deposition method, could be an effective catalyst for oxygen reduction in an MFC to generate electricity with the maximum power density of 772.8 mW/m³ and remove organics when the MFC was fed with an acetate-laden synthetic wastewater. The nano-structured MnO_x with the controllable size and morphology could be readily obtained with the electrochemical deposition method. Both morphology and manganese oxidation state of the nano-scale catalyst were largely dependent on the electrochemical preparation process, and they governed its catalytic activity and the cathodic oxygen reduction performance of the MFC accordingly. Furthermore, cyclic voltammetry (CV) performed on each nano-structured material suggests that the MnO_x nanorods had an electrochemical activity towards oxygen reduction reaction via a four-electron pathway in a neutral pH solution. This work provides useful information on the facile preparation of cost-effective cathodic catalysts in a controllable way for the single-chamber air-cathode MFC for wastewater treatment.     

Thermo-environmental performance analysis of irreversible solid oxide fuel cell – Stirling heat engine

A hybrid, irreversible solid oxide fuel cell – Stirling heat engine system is taken into account. Thermoenvironmental criterion approach, which enables to evaluate environmental impact of any thermal cycle, is applied to the considered system for the first time. Power density, exergy density, thermoenvironmental function density, energy and exergy efficiencies are considered. Results are presented and discussed to determine optimum operating conditions. Some important results for the hybrid system are ordered: maximum power density is 7489.92 (A?m^?2), maximum energy and exergy efficiencies are 0.800 and 0.887, respectively, and finally, thermoenvironmental function density is 0.0276 (W?mpts^?1?m^?2).     

Fuel loads in U.S. Cities

Sources of burnable material within U.S. cities are analyzed. Based on a detailed evaluation of construction practices, storage of burnable contents, building function and layout, and density of buildings in city districts, we derive urban fuel load densities in terms of land use type and geographic location. Residential building fuel loads vary regionally from 123 to 150 kg m^–2; non-residential building classes have loads from 39 to 273 kg m^–2. The results indicate that average U.S. urban area fuel loads range from 14 to 21 kg m^–2.     

Spot Fire Ignition of Natural Fuels by Hot Aluminum Particles

The ignition of combustible material by contact with hot metal particles is an important pathway by which wildland and urban spot fires are started. This work examines how fuel characteristics such as density, morphology and chemical composition effect the ability of the fuel to be ignited by a hot metal particle. Fuels were prepared out of three materials: alpha-cellulose, a barley/wheat/oat grass blend, and pine needles. Each material was prepared as a powder and as larger, long pieces: strips of cellulose paper, loose grass, and pine needles. These fuels are representative of thermal insulation (cellulose strips), dry grasses (grass blend), forest litter (pine needles) and duff (powders). Aluminum particles ranging from 2 mm to 8 mm in diameter heated to temperatures between 575°C and 1100°C were dropped onto these fuels. The particle temperature required for ignition becomes higher as the particle size decreased. The results show that the required temperatures for ignition of powders were lower, with this trend particularly pronounced for the alpha-cellulose fuels. The biomass fuels required higher temperature particles to ignite, indicating that the presence of other ligno-cellulosic materials make ignition more difficult.     

Influence of injection timing on cerium oxide nanoparticle doped in waste cooking palm oil bio-diesel and diesel blends fuelled in diesel engine

ABSTRACT

Injection timing (IT) is a vital factor among different injection parameters which governs the emissions and performance factors of the engine. This work portrays the effect of IT on cerium oxide nanoparticle doped Waste Cooking Palm Oil biodiesel and diesel blends. The doping is made at 30, 60 and 90?ppm. The modified fuels are introduced in reducing IT of 19°, 21° and 23°bTDC. 1500?rpm engine is made use in this study. Results revealed a significant reduction in emissions (CO, NO_X, HC and Smoke) at IT?=?23°bTDC. Furthermore, performance (BSFC, BTE) is improved for fuel blends at IT?=?23°bTDC.