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research-article  
Aldo Márquez-Nolasco, Roberto Conde-Gutiérrez, J. Alfredo Hernandez, Armando Huicochea, Javier Siqueiros and Ociel Rodriguez
J. Energy Resour. Technol   doi: 10.1115/1.4036544
The most critical component of an absorption heat transformer is the absorber, by the exothermic reaction which is carried out, resulting a useful thermal energy. This article proposed a model based on improving the performance of energy for an absorber with disks of graphite during the exothermic reaction, through of an optimal strategy. Two models of artificial neural networks (ANN) were developed to predict the thermal energy, through two important factors: internal heat in the absorber (QAB) and the temperature of the working solution of the absorber outlet (TAB). Confronting the simulated and real data, a satisfactory agreement was appreciated, obtaining a mean absolute percentage error value of 0.24 % to calculate QAB and of 0.17 % to calculate TAB. Furthermore, from these ANN models, the inverse neural network (ANNi) allowed improves the thermal efficiency of the absorber (QAB and TAB). To achieve find the optimal values was necessary to propose an objective function, where the genetic algorithms were indicated. Finally, by applying the ANNi-GAs model, the optimized network configuration was to find an optimal value of concentrated solution of LiBr-H2O and the vapor inlet temperature to the absorber. The results obtained from the optimization allowed to reach a value of QAB from 1.72 kW to 2.44 kW, when a concentrated solution of LiBr-H2O at 59 % was used and increased the value of TAB from 104.73ºC to 109.2°C, when was used a vapor inlet temperature of 73ºC.
TOPICS: Thermal energy, Optimization, Disks, Artificial neural networks, Graphite, Temperature, Vapors, Water, Heat, Thermal efficiency, Absorption, Gases, Errors, Genetic algorithms
research-article  
Bahri Kutlu, Evren M. Ozbayoglu, Stefan Z. Miska, Nicholas Takach, Mengjiao Yu and Clara Mata
J. Energy Resour. Technol   doi: 10.1115/1.4036540
This study concentrates on the use of materials known as hollow glass spheres, also known as glass bubbles, to reduce the drilling fluid density below the base fluid density without introducing a compressible phase to the wellbore. Four types of lightweight glass spheres with different physical properties were tested for their impact on rheological behavior, density reduction effect, survival ratio at elevated pressures and hydraulic drag reduction effect when mixed with water based fluids. A Fann75 HPHT viscometer and a flow loop were used for the experiments. Results show that glass spheres successfully reduce the density of the base drilling fluid while maintaining an average of 0.93 survival ratio, the rheological behavior of the tested fluids at elevated concentrations of glass bubbles is similar to the rheological behavior of conventional drilling fluids and hydraulic drag reduction is present up to certain concentrations. All results were integrated into hydraulics calculations for a wellbore scenario that accounts for the effect of temperature and pressure on rheological properties, as well as the effect of glass bubble concentration on mud temperature distribution along the wellbore. The effect of drag reduction was also considered in the calculations.
TOPICS: Density, Glass, Drag reduction, Rheology, Fluids, Drilling, Bubbles, Fluid density, Hydraulics, Pressure, Flow (Dynamics), Temperature, Temperature distribution, Water
research-article  
Yuta Uemura, Yasutada Tanabe, Hiroya Mamori, Naoya Fukushima and Makoto Yamamoto
J. Energy Resour. Technol   doi: 10.1115/1.4036541
Since it is important to prevent the wake produced by upstream wind turbines from interfering with downstream wind turbines, a method of deflecting such wakes is desired. In this paper, we present the coupled analysis results of a CFD simulation involving a three-bladed wind turbine with a yaw control system that utilizes rFlow3D CFD code, which was developed by JAXA, primarily for rotorcraft use. Herein, 3D, compressible, and unsteady Reynolds averaged Navier Stokes equation with a Spalart-Allmaras turbulence model is adopted as the governing equation. In the present study, we begin by carrying out wind turbine computations using various yaw angles while focusing on the resulting wake velocity distribution and aerodynamic loads, after which we discuss the influence of the yaw angle. Next, based on the wake velocity distribution results for each yaw angle, we move on to a wake interference avoidance simulation for downstream turbines that utilizes two prepared turbines. Through the present study, the following characteristics were confirmed. The results show wake deflection produced by adding yaw angle can provide a sufficient wake skew angle even in far-wake events. Furthermore, the yaw angle introduction accelerates the progression of vortex dissipation and brings about early velocity recovery in the wake region. Simultaneously, the introduction decreases the power generation amount of the yawed upstream turbine and increases the fatigue load of flapwise moment added to the blade root. In this paper, the details of flow field, fluctuation, and the yawed turbine performance characteristics will also be described.
TOPICS: Wakes, Deflection, Wind turbines, Yaw, Turbines, Computational fluid dynamics, Simulation, Stress, Energy dissipation, Energy generation, Flow (Dynamics), Fatigue, Control systems, Turbulence, Vortices, Blades, Computation, Performance characterization, Reynolds-averaged Navier–Stokes equations
research-article  
Ali Al Sam, Robert Szasz and Johan Revstedt
J. Energy Resour. Technol   doi: 10.1115/1.4036542
In the current study, the effects of the non-locally generated long sea surface wave’s (swells) on the power production of a 2 by 2 wind farm are investigated by using Large Eddy Simulations (LES) and Actuator-Line Method (ALM). The short sea waves are modeled as a roughness height, while the wave induced stress accounting for swell effects is added as an external source term to the momentum equations. The results show that the Marine Atmospheric Boundary Layers (MABL) obtained in this study have similar characteristics as the MABLs observed during the swell conditions by many other studies. The current results indicate also that swells have significant impacts on the MABL. As a consequence of these changes in the MABL, swells moving faster than the wind and aligned with the local wind direction increase the power extraction rate.
TOPICS: Energy generation, Wind farms, Wind waves, Wind, Large eddy simulation, Accounting, Seas, Ocean waves, Momentum, Surface roughness, Stress, Waves, Actuators, Boundary layers
research-article  
Sumita Debbarma and Rahul Dev Misra
J. Energy Resour. Technol   doi: 10.1115/1.4036543
The technology for use of biodiesels (upto 20%) as alternative fuel in diesel engines has already been established. In this regard, some suitable modification of biodiesel with appropriate additives may help in increasing the biodiesel component in the biodiesel fuel blends. In order to evaluate the effects of iron nanoparticles blended palm biodiesel on the performance and emission characteristics of diesel engine, an experimental investigation is carried out in a single cylinder diesel engine. Methodically biodiesel prepared from palm oil and commercially available nano-sized iron nanoparticles (INP) are used in this study. Iron nanoparticles is suspended in the biodiesel in proportions 40 ppm and 120 ppm using an Ultrasonicator. The intact study is conducted in the diesel engine using the four fuel samples, namely: diesel, PB20, INP50PB30, and INP75PB30, consecutively. The addition of nano additive has resulted higher BTE by 3% and BSEC by 3.3%, compared to diesel fuel. The emission levels of carbon monoxide (~56%) and NOx (~4%) are appreciably reduced with the addition of INP. Increase in concentration of INP from 50 ppm to 75 ppm, BTE and BSEC tend to reduce, but CO and NOx emissions are reduced.
TOPICS: Nanoparticles, Diesel engines, Iron, Emissions, Biodiesel, Fuels, Diesel, Nitrogen oxides, Carbon, Cylinders
research-article  
Ronald W. Breault, Justin Weber and Sam Bayham
J. Energy Resour. Technol   doi: 10.1115/1.4036324
NETL has explored chemical looping in its 50 kW facility using a number oxygen carriers. In this work, the results for methane conversion in the fuel reactor with a hematite iron ore as the oxygen carrier are analyzed. The experimental results are compared to predictions using CFPD's Barracuda CFD code with kinetics derived from the analysis of fixed bed data. It has been found through analytical techniques from TGA data as well as the same fixed bed data that the kinetics for the methane-hematite reaction follow a nucleation and growth or Johnson-Mehl-Avrami (JMA) reaction mechanism. Barracuda does not accept nucleation and growth kinetics, however, there is enough sufficient variability of the solids dependence within the software such that the nucleation and growth behavior can be mimicked. This paper presents the method to develop the pseudo-JMA kinetics for Barracuda for the fixed bed data and then applies these values to the fuel reactor data for the 50 kW unit for validation. Finally, a fuel reactor design for near complete conversion is proposed.
TOPICS: Fuels, Computational fluid dynamics, Modeling, Nucleation (Physics), Methane, Oxygen, Computer software, Iron, Design, Solids
research-article  
Arild Saasen, Songxiong Ding, Per Amund Amundsen and Kristoffer Tellefsen
J. Energy Resour. Technol   doi: 10.1115/1.4033304
Materials such as added clays, weight materials, drill solids and metalic wear products in the drilling fluid are known to distort the geomagnetic field at the location of the Measurement While Drilling (MWD) tool magnetometers that are used to measure the direction of well path. This distortion contributes to substantial errors in determination of azimuth while drilling deviated wells. These errors may result in missing the target of a long deviated 12 ¼” section in the range of 1-200m; representing a significant cost to be mitigated. The error becomes even more pronounced if drilling occurs in arctic regions close to the magnetic North Pole ( or South Pole). The effect on the magnetometer readings is obviously linked to the kinds and amounts of magnetic materials in the drilling fluid. The problem has recently been studied by laboratory experiments and analyses of downhole survey data. A series of experiments has been carried out to understand how some drilling fluid additives relate to the magnetic distortion. Experiments with free iron ions show that presence of iron ions does not contribute to magnetic distortion; while experiments with bentonite-based fluids show a strong effect of bentonite on magnetic shielding. Albeit earlier measurements showing a strong dependency of the content of organophilic clay, clean laboratory prepared oil-based drilling fluids show no increased shielding when adding organophilic hectorite clays. The anticipated difference between these two cases is outlined in the paper. When eroded steel from an offshore drilling site is added into the oil-based drilling fluid, it is found that these swarf and steel fines significantly increase the magnetic shielding of the drilling fluid. The paper outlines how the drilling direction may be distorted by the presence of these additives and contaminants and how this relates to the rheological properties of the drilling fluid.
TOPICS: Fluids, Drilling, Rheology, Errors, Iron, Magnetic shielding, Steel, Ions, Magnetometers, Poles (Building), Drills (Tools), Solids, Wells, Weight (Mass), Wear, Scrap metals, Underwater drilling, Magnetic materials, Arctic region

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