Showing papers in "Journal of Energy Resources Technology-transactions of The Asme in 2018"

Review of Experimental and Computational Studies on Spray, Combustion, Performance, and Emission Characteristics of Biodiesel Fueled Engines

Abstract: Biodiesel has emerged as a suitable alternative to mineral diesel in compression ignition (CI) engines in order to ensure global energy security and to reduce engine out emissions in near future. Biodiesel derived from various feedstocks available worldwide fits well in the current fuel supply arrangement for transport sector. However, biodiesel as an alternative transportation fuel has been extensively investigated because of differences in its important fuel properties compared with baseline mineral diesel. Since fuel properties greatly influence spray development, combustion, and emission formation in internal combustion (IC) engines, a number of experimental and computational studies on biodiesel usage in CI engines have been performed to determine its brake thermal efficiency (BTE), gaseous emissions, durability, etc., by various researchers using variety of engines and feedstocks. In the present paper, a critical review of the effect of biodiesel's fuel properties on engine performance, emissions, and combustion characteristics in existing diesel engines vis-a-vis conventional diesel has been undertaken. In addition, the progress and advances of numerical modeling involving biodiesel are also reviewed to determine the effect of fuel properties on spray evolution and development of reaction mechanisms for biodiesel combustion simulations. Fuel properties are discussed in two categories: physical and chemical properties, which are key parameters affecting spray and combustion processes. Subsequent sections review spray, combustion, emissions, and performance characteristics of biodiesels under various engine operation conditions. In the last section of this review paper, numerical modeling of biodiesel covering recent numerical models and schemes to understand the behavior of biodiesel combustion and pollutants formation is included. This review paper comprehensively summarizes biodiesel fuel's (BDFs) spray, combustion, and emission characteristics using experimental and numerical approaches. Limitations and scope for future studies are discussed in each section.

Artificial Neural Network Based Prediction of Performances-Exhaust Emissions of Diesohol Piloted Dual Fuel Diesel Engine under Varying CNG Flowrates.

Abstract: The present study surveys the effects on performance and emission parameters of a partially modified single cylinder direct injection (DI) diesel engine fueled with diesohol blends under varying compressed natural gas (CNG) flowrates in dual fuel mode. Based on experimental data, an artificial intelligence (AI) specialized artificial neural network (ANN) model have been developed for predicting the output parameters, viz. brake thermal efficiency (Bth), brake-specific energy consumption (BSEC) along with emission characteristics such as oxides of nitrogen (NOx), unburned hydrocarbon (UBHC), carbon dioxide (CO2), and carbon monoxide (CO) emissions. Engine load, Ethanol share, and CNG strategies have been used as input parameters for the model. Among the tested models, the Levenberg–Marquardt feed-forward back propagation with three input neurons or nodes, two hidden layers with ten neurons in each layer and six output neurons, and tansig-purelin activation function have been found to the optimal model topology for the diesohol–CNG platforms. The statistical results acquired from the optimal network topology such as correlation coefficient (0.992–0.999), mean square error (MSE) (0.0001–0.0009), and mean absolute percentage error (MAPE) (0.09–2.41%) along with Nash–Sutcliffe coefficient of efficiency (NSE), Kling–Gupta efficiency (KGE), mean square relative error, and model uncertainty established itself as a real-time robust type machine learning tool under diesohol–CNG paradigms. The study also incorporated a special type of measure, namely Pearson's Chi-square test or goodness of fit, which brings up the model validation to a higher level.

Microwave-assisted Pyrolysis of Biomass for Bio-oil Production: A Review of the Operation Parameters

Abstract: Microwave‐assisted pyrolysis (MAP) is a new thermochemical process that converts bio‐ mass to bio‐oil. Compared with the conventional electrical heating pyrolysis, MAP is more rapid, eicient, selective, controllable, and lexible. This chapter provides an up‐to‐ date knowledge of bio‐oil production from microwave‐assisted pyrolysis of biomass. The chemical, physical, and energy properties of bio‐oils obtained from microwave‐assisted pyrolysis of biomass are described in comparison with those from conventional pyroly‐ sis, the characteristics of microwave‐assisted pyrolysis as afected by biomass feedstock properties, microwave heating operations, use of exogenous microwave absorbents, and catalysts are discussed. With the advantages it ofers and the further research and devel‐ opment recommended, microwave‐assisted pyrolysis has a bright future in production of bio‐oils that can efectively narrow the energy gap and reduce negative environmental impacts of our energy production and application practice.

Geopolymers as an alternative for oil well cementing applications: a review of advantages and concerns

Abstract: Geopolymers, being inorganic polymers created from rock sources, were evaluated as an alternative to Portland cement. To evaluate their usability, some properties of a selected geopolymer were measured and compared with those from a neat class G Portland cement. The geopolymeric slurries showed a non-Newtonian viscosity behavior with a measurable, albeit low, yield stress. The pumpability measurements using atmospheric and pressurized consistometer showed an adequate set profile for both the geopolymer and cement sample. Static fluid loss test shows that the geopolymeric slurries experienced a lower fluid loss compared to that of the Portland cement. The shrinkage factor for the geopolymers was reduced (expanded) as the downhole temperature was ramped up. The shrinkage of the Portland cement sample proceeded only with a lower rate. Tensile strength of the geopolymers was approximately 5% of their compressive strength; however, this value for Portland cement was approximately 10% of its compressive strength. Finally, shear bond strength of geopolymers would benefit from improvement.

Simulation of Cogeneration-Combined Cycle Plant Flexibilization by Thermochemical Energy Storage

Abstract: In the course of the “Energiewende,” the German electricity market is undergoing major changes. The state-aided priority of renewable generation has led to a significant decline in electricity prices. This reduces the profit margin of cogeneration units and increases the necessity of flexible operation to avoid electricity production when spot prices drop below marginal costs. In this work, a 100 MWel combined-cycle (CC) power plant supplying heat and power to a paper mill is investigated. Currently, the plant is operated heat-controlled and is therefore unable to react to changing electricity spot prices. With the integration of heat storage, the plant is enabled to switch to power-controlled mode. To evaluate the technical impact of the storage, the plant and a thermochemical MgO/ Mg(OH)2 storage are modeled using the stationary process simulation tool EBSILON PROFESSIONAL. Different operation modes are investigated and results are used to derive a mixed integer linear programming (MILP) model to optimize the operation of the plant/ storage system. Using this method, the overall economic impact of the storage on the plant operation is quantified.

Evaluation of Fuel Injection Strategies for Biodiesel Fueled CRDI Engine Development and Particulate Studies

Abstract: In this study, a state-of-the-art single cylinder research engine was used to investigate the effects of fuel injection parameters on combustion, performance, emission characteristics, and particulates and their morphology. The experiments were carried out at three FIPs (400, 700 and 1000 bar) and four SoMI timings (4°, 6°, 8° and 10° bTDC) for biodiesel blends [B20 (20% v/v biodiesel blend) and B40 (40% v/v biodiesel blend)] compared to baseline biodiesel at a constant engine speed (1500 rpm), without pilot injection and exhaust gas recirculation (EGR). The experimental results showed that FIP and SoMI timings affected the in-cylinder pressure and the heat release rate (HRR), significantly. At higher FIPs, the biodiesel blends resulted in slightly higher rate of pressure rise (RoPR) and combustion noise compared to baseline mineral diesel. All the test fuels showed relatively shorter combustion duration at higher FIPs and advanced SoMI timings. The biodiesel blends showed slightly higher NOx and smoke opacity compared to baseline mineral diesel. Lower particulate number concentration at higher FIPs was observed for all the test fuels. However, the biodiesel blends showed relatively higher particulate numbers compared to baseline mineral diesel. Significantly lower trace metals in the particulates emitted from biodiesel blend fueled engine was an important finding of this study. The particulate morphology showed relatively smaller number of primary particles in particulate clusters from biodiesel exhaust, which resulted in relatively lower toxicity, thus rendering biodiesel more environmentally benign.

Engine Characteristic Studies by Application of Antioxidants and Nanoparticles as Additives in Biodiesel Diesel Blends

Abstract: This study evaluates the effect of antioxidants and nanoparticles as additives with biodiesel and biodiesel diesel blends on the engine working characteristics, conducted on a single cylinder direct injection diesel engine at constant engine speed of 1500 rpm, constant injection timing of 26 °bTDC with constant injection pressure of 216 bar, under five different load conditions (0.08, 0.15, 0.23, 0.30, 0.45 and 0.53 MPa engine load). The antioxidants and nanoparticles blended test fuels are used as fuels in this experimental investigation. The antioxidant as additive in fuel, found to be more effective in suppressing the NO emission by disrupting the chain propagating reactions, trapping free radicals and decomposing peroxides. The high surface area to volume ratio of the nanoparticles acts as fuel borne catalyst by ameliorating the engine working characteristics and downplays the NO emission by buffering the oxygen molecule. The obtained experimental results indicates that B20SNAlCe test fuel enhances engine brake thermal efficiency by 13 % and reduces level of pollutants such as unburned hydrocarbon by 39 %, nitric oxide by 32 %, smoke opacity by 21 % and carbon monoxide by 60 % in compared with B100.