bluuebunny/crossref_metadata_2025 huggingface dataset:
E-consumer conformity and its impact on consumer attitude
Authors: Khandelwal Utkal , Yadav Seemant Kumar , Tripathi Vikas , Agrawal Vivek
Published: October 2018

Purpose

With the tremendous increase in the number of netizens, online consumer behavior has become an important issue nowadays. One of the important issues of online consumer behavior is e-consumer conformity. This paper aims to explore prominent factors of e-consumer conformity and its impact on consumer attitude, which helps marketers to understand this new business arena and involve this relationship to enhance their business.

Design/methodology/approach

For the purpose, convenience sampling was used with sample size of 510. Offline as well as online mode of survey was applied. The resultant hypotheses (based on the developed model depicting normative and informational consumer conformity effect on attitude) were examined by structured equation modeling.

Findings

The present study presents the different dimensions of e-consumer conformity and its difference in metro and non-metro cities on which marketers have to frame their strategies. The study revealed that the customer attitude is largely affected by others expectations (conformance with others expectations, NCC) rather others knowledge and expertise (ICC). Additionally, the comparison of virtual conformity behavior of metro and non-metro customers was made, and it was found that conformity behavior does not significantly differ in these two contexts.

Practical implications

Business saturation in metro cities, infrastructural growth and technological advancement in non-metro cities, companies are moving toward non-metro cities. Due to contextual differences existing between metro and non-metro market, it is difficult to trace the changes in the marketing policies and device the appropriate strategy accordingly for the marketers. In lieu of this, the present study presents the different dimensions of e-consumer conformity and its degree of difference in metro and non-metro cities on which marketers have to frame their strategies.

Originality/value

Good number of research has been conducted on consumer conformity in India; however, there is a scarcity of literature in virtual consumer conformity in India. This research is not only establishing the relationship between virtual consumer conformity and consumer attitude but also establishing the difference of virtual consumer conformity in metro and non-metro cities in India.
Error analysis of laser scanner for robust autonomous navigation of mobile robot in diverse illumination environment
Authors: Singh Ravinder , Nagla Kuldeep Singh
Published: October 2018

Purpose

Modern service robots are designed to work in a complex indoor environment, in which the robot has to interact with the objects in different ambient light intensities (day light, tube light, halogen light and dark ambiance). The variations in sudden ambient light intensities often cause an error in the sensory information of optical sensors like laser scanner, which reduce the reliability of the sensor in applications such as mapping, path planning and object detection of a mobile robot. Laser scanner is an optical sensor, so sensory information depends upon parameters like surface reflectivity, ambient light condition, texture of the targets, etc. The purposes of this research are to investigate and remove the effect of variation in ambient light conditions on the laser scanner to achieve robust autonomous mobile robot navigation.

Design/methodology/approach

The objective of this study is to analyze the effect of ambient light condition (dark ambiance, tube light and halogen bulb) on the accuracy of the laser scanner for the robust autonomous navigation of mobile robot in diverse illumination environments. A proposed AIFA (Adaptive Intensity Filter Algorithm) approach is designed in robot operating system (ROS) and implemented on a mobile robot fitted with laser scanner to reduce the effect of high-intensity ambiance illumination of the environment.

Findings

It has been experimentally found that the variation in the measured distance in dark is more consistent and accurate as compared to the sensory information taken in high-intensity tube light/halogen bulbs and in sunlight. The proposed AIFA approach is implement on a laser scanner fitted on a mobile robot which navigates in the high-intensity ambiance-illuminating complex environment. During autonomous navigation of mobile robot, while implementing the AIFA filter, the proportion of cession with the obstacles is reduce to 23 per cent lesser as compared to conventional approaches.

Originality/value

The proposed AIFA approach reduced the effect of the varying ambient light conditions in the sensory information of laser scanner for the applications such as autonomous navigation, path planning, mapping, etc. in diverse ambiance environment.
Performance evaluation of bearing degradation based on stationary wavelet decomposition and extra trees regression
Authors: Nistane Vinod , Harsha Suraj
Published: October 2018

Purpose

In rotary machines, the bearing failure is one of the major causes of the breakdown of machinery. The bearing degradation monitoring is a great anxiety for the prevention of bearing failures. This paper aims to present a combination of the stationary wavelet decomposition and extra-trees regression (ETR) for the evaluation of bearing degradation.

Design/methodology/approach

The higher order cumulants features are extracted from the bearing vibration signals by using the stationary wavelet decomposition (stationary wavelet transform [SWT]). The extracted features are then subjected to the ETR for obtaining normal and failure state. A dominance level curve build using the dissimilarity data of test object and retained as health degradation indicator for the evaluation of bearing health.

Findings

Experiment conducts to verify and assess the effectiveness of ETR for the evaluation of performance of bearing degradation. To justify the preeminence of recommended approach, it is compared with the performance of random forest regression and multi-layer perceptron regression.

Originality/value

The experimental results indicated that the presently adopted method shows better performance for detecting the degradation more accurately at early stage. Furthermore, the diagnostics and prognostics have been getting much attention in the field of vibration, and it plays a significant role to avoid accidents.
A three-dimensional active zero state PWM for common-mode voltage reduction of a three-phase four-leg voltage-source inverter
Authors: Hasanzad Fardin , Rastegar Hasan , Pichan Mohammad
Published: October 2018

Purpose

This paper aims to investigate the common-mode voltage (CMV) issue of a three-phase four-leg voltage-source inverter. A new space vector modulation method, named as three-dimensional active zero state Pulse-width modulation (PWM) (3-D AZSPWM), is proposed to reduce the CMV level.

Design/methodology/approach

PWM is a general method to generate the switching signals of the power converters in order to obtain high-quality output voltages. However, the CMV produced by PWM methods has become a serious problem. 3-D AZSPWM is proposed to solve this issue. In 3-D AZSPWM, instead of using zero voltage vectors with high CMV level, appropriate complementary non-zero vectors are introduced to synthesize reference vector. The proposed method is classified into four types of AZSPWM1(a), AZSPWM1(b), AZSPWM2(a) and AZSPWM2(b) based on different complementary vectors chosen for each type. An extend software simulation using MATLAB/Simulink is performed to verify the superior performance of the proposed methods.

Findings

Compared to other reduced CMV methods, the proposed method not only reduces the CMV but also retains the positive characteristics of the three-dimensional classical space vector PWM (3-D CSVPWM).

Originality/value

The proposed method does not suffer from linear modulation region limitation and also does not impose additional switching loss. Furthermore, calculated output voltage harmonic distortion factor illuminates acceptable quality of output voltage produced by the proposed method.
A Dynamic Model Incorporating the Effects of the Ion Diffusion and Side Reactions for the Vanadium/Air Redox Flow Battery
Authors: Shi Yu , Zhao Jiyun
Published: October 2018

The vanadium/air redox flow battery working performance will be affected by many factors, including the quality of the membrane used and the working conditions. The crossover rate of vanadium ions for the membrane can determine the capacity due to the ion diffusion and the side reactions. The high reaction temperature for the VARFB also influence the diffusion coefficient. Based on Fick’s Law, by using Arrhenius Equation to predict the temperature effect, and take into consider that the mass balance for each reacting ions and reaction temperature, the dynamic modelling on capacity decay can be developed. Then by using Nernst Equation, the voltage change of VARFB can also be calculated. This dynamic model will predict the concentration change of the battery as a function of time, after benchmarking with the experimental data, this model can compare the performance of the battery with a different order of diffusion coefficient membranes in different working condition. This model can also predict the contacting V2+ concentration to the electrode and catalyst to monitor the working efficiency.
A Stand-Alone Hybrid Photovoltaic, Fuel Cell and Battery System
Authors: Qandil Mohammad D. , Amano Ryoichi S. , Abbas Ahmad I.
Published: October 2018

The main purpose of this study is to investigate the feasibility of using a hybrid photovoltaic (PV), fuel cell (FC) and battery system to power different load cases, which are intended to be used at Al-Zarqa governorate in Jordan. All aspects related to the potentials of solar energy in Al-Hashemeya area were studied. The irradiation levels were carefully identified and analyzed, and found to range between 4.1–7.6 kWh/m2/day; these values represented an excellent opportunity for the photovoltaic solar system. Various renewable and non-renewable energy sources, energy storage methods and their applicability regarding cost and performance are discussed, in which HOMER (Hybrid Optimization for Electric Renewable) software is used as a sizing and optimization tool. Different scenarios with Photovoltaic slope, diesel price, and fuel cell cost were done. A remote residential building, school and factory having an energy consumption of 31 kWh/day with a peak of 5.3 kW, 529 kWh/day with a maximum of 123 kW and 608 kWh/day with a maximum of 67 kW respectively, were considered as the case studies’ loads. It was found that the PV-diesel generator system with battery is the most suitable solution at present for the residential building case, while the PV-FC-diesel generator-electrolyzer hybrid system with battery suites best both the school and factory cases.

The load profile for each case was found to have a substantial effect on how the system’s power produced a scheme. For the residential building, PV panels contributed by about 75% of the total power production, the contribution increased for the school case study to 96% and dropped for the factory case to almost 50%.
Experimental Investigation of a Flat Plate Photovoltaic/Thermal Collector
Authors: Modrek Mohamad , Al-Alili Ali
Published: October 2018

Photovoltaic thermal collectors (PVT) combines technologies of photovoltaic panels and solar thermal collectors into a hybrid system by attaching an absorber to the back surface of a PV panel. PVT collectors have gained a lot of attention recently due to the high energy output per unit area compared to a standalone system of PV panels and solar thermal collectors. In this study, performance of a liquid cooled flat PVT collector under the climatic conditions of Abu Dhabi, United Arab Emirates was experimentally investigated. The electrical performances of the PVT collector was compared to that of a standalone PV panel. Moreover, effect of sand accumulation on performance of PVT collectors was examined. Additionally, effect of mass flow rate on thermal and electrical output of PVT collector was studied. Electrical power output is slightly affected by changes in mass flow rate. However, thermal energy increased by 22% with increasing flow rate. Electrical power output of a PV panel was found to be 38% lower compared to electrical output of PVT collectors. Dust accumulation on PVT surface reduced electrical power output up to 7% compared with a reference PVT collector.
EnergyPlus Integration Into Co-Simulation Environment to Improve Home Energy Saving Through Cyber-Physical Systems Development
Authors: Singer Joe , Roth Thomas , Wang Chenli , Nguyen Cuong , Lee Hohyun
Published: October 2018

This paper presents a co-simulation platform which combines a building simulation tool with a Cyber-Physical Systems (CPS) approach. Residential buildings have a great potential of energy reduction by controlling home equipment based on usage information. A CPS can eliminate unnecessary energy usage on a small, local scale by autonomously optimizing equipment activity, based on sensor measurements from the home. It can also allow peak shaving from the grid if a collection of homes are connected. However, lack of verification tools limits effective development of CPS products. The present work integrates EnergyPlus, which is a widely adopted building simulation tool, into an open-source development environment for CPS released by the National Institute of Standards and Technology (NIST). The NIST environment utilizes the IEEE High Level Architecture (HLA) standard for data exchange and logical timing control to integrate a suite of simulators into a common platform. A simple CPS model, which controls local HVAC temperature set-point based on environmental conditions, was tested with the developed co-simulation platform. The proposed platform can be expanded to integrate various simulation tools and various home simulations, thereby allowing for co-simulation of more intricate building energy systems.
Modeling, Development and Preliminary Testing of a 2 MW PEM Fuel Cell Plant Fueled With Hydrogen From a Chlor-Alkali Industry
Authors: Campanari Stefano , Guandalini Giulio , Coolegem Jorg , ten Have Jan , Hayes Patrick , Pichel A. H.
Published: October 2018

The chlor-alkali industry produces significant amounts of hydrogen as byproduct and an interesting benefit can be obtained by feeding hydrogen to a PEM fuel cell unit, whose electricity and heat production can cover part of the chemical plant consumptions. The estimated potential of such application is up to 1100 MWel installed in the sole China, a country featuring a large presence of chlor-alkali plants.

This work presents the modeling, development and first experimental results from field tests of a 2 MW PEM fuel cell power plant, built within the European project DEMCOPEM-2MW and installed in Yingkou, China as the current world’s largest PEM fuel cell installation. After a preliminary introduction to the market potential of PEM Fuel cells in the chlor-alkali industry, it is first discussed an overview of project’s MEA and fuel cell development for long life stationary applications, focusing on the design-for-manufacture process and the high-volume manufacturing route developed for the 2MW plant.

The work then discusses the modeling of the power plant, including a specific lumped model predicting FC stack behavior as a function of inlet streams conditions and power set point, according to regressed polarization curves. Cells performance decay vs. lifetime reflects long-term stack test data, aiming to evidence the impact on overall energy balances and efficiency of the progression of lifetime. BOP is modeled to simulate auxiliaries consumption, pressure drops and components operating conditions. The model allows studying different operational strategies that maintain the power production during lifetime, minimizing efficiency losses; as well as to investigate the optimized operating setpoint of the plant at full load and during part-load operation.

The last section of the paper discusses the experimental results, through a complete analysis of the plant performance after plant startup, including energy and mass balances and allowing to validate the model. Cumulated indicators over the first nine months of operations regarding energy production, hydrogen consumption and efficiency are also discussed.
A Simple EAM Potential for Hydrogen-Selective Palladium Based Membranes for Biomass Derived Syngas Processing
Authors: Hijazi Iyad , Zhang Yang , Fuller Robert
Published: October 2018

Biomass offers the potential to economically produce hydrogen via gasification from an abundant and renewable feedstock. When hydrogen is produced from a biomass gasifier, it is necessary to purify it from syngas streams containing components such as CO, CO2, N2, CH4, and other products. Therefore, a challenge related to hydrogen purification is the development of hydrogen-selective membranes that can operate at elevated temperatures and pressures, provide high fluxes, long operational lifetime, and resistance to poisoning while still maintaining reasonable cost. Palladium based membranes have been shown to be well suited for these types of high-temperature applications and have been widely utilized for hydrogen separation. Palladium’s unique ability to absorb a large quantity of hydrogen can also be applied in various clean energy technologies, like hydrogen fuel cells. In this paper, a fully analytical interatomic Embedded Atom Potential (EAM) for the Pd-H system has been developed, that is easily extendable to ternary Palladium based hydride systems such as Pd-Cu-H and Pd-Ag-H. The new potential has fewer fitting parameters than previously developed EAM Pd-H potentials and is able to accurately predict the cohesive energy, lattice constant, bulk modulus, elastic constants, melting temperature, and the stable Pd-H structures in molecular dynamics (MD) simulations with various hydrogen concentrations. The EAM potential also well predicts the miscibility gap, the segregation of the palladium hydride system into dilute (α) and concentrated (β) phases.
Comprehensive Parametric Analysis and Sensitivity Study of Latent Heat Thermal Energy Storage System in Concentrated Solar Power Plants
Authors: Chirino Hermes , Xu Ben
Published: October 2018

Compared to Solar Photovoltaics (PV), Concentrated Solar Power (CSP) can store the excess solar thermal energy, extend the power generation at night and cloudy days, and levelize the mismatch between energy demand and supply. To make CSP competitive, Thermal Energy Storage (TES) system filled with phase change material (PCM) is a promising indirect energy storage technique, compared to the TES system using concrete or river rocks. It is of great interests to solar thermal community to apply the latent heat thermal energy storage (LHTES) system for large scale CSP application, because PCMs can store more thermal energy due to the latent heat during the melting/freezing process. Therefore, a comprehensive parametric analysis of LHTES system is necessary in order to improve its systematic performance, since LHTES system has a relatively low energy storage efficiency compared to TES systems using sensible materials.

In this study, an 11-dimensionless-parameter space of LHTES system was developed, by considering only the technical constraints (materials properties and operation parameters), instead of economic constraints. Then the parametric analysis was performed based on a 1D enthalpy-based transient model, and the energy storage efficiency was used as the objective function to minimize the number of variables in the parameter space. It was found that Stanton number (St), PCM radius (r), and void fraction (ε) are the three most important ones. The sensitivity study was conducted then based on the three dimensionless-parameter space which will significantly influence the system performance. The results of this study make LHTES system competitive with TES system using sensible materials in terms of energy storage efficiency.
Modeling a New Design for Heat Transfer System and Electrical Generator
Authors: Homadi Abdulrahman , Hall Tony
Published: October 2018

Traditional heat transfer techniques have become inadequate for many applications today and innovation of new technologies has become an urgent necessity. From another angle, securing electrical power remote areas in unconventional ways is receiving widespread attention. In this study, we present a new technique to dissipate heat, which is suitable in narrow and slanted places, as well as, generate electricity. The system consists of a permanent magnet (PM) and a spring where they act as opposing forces on a ferromagnetic disk moving in a specific space. Above the Curie temperature (Tc) of the ferromagnet, spring force (Fspring) overcomes the strength of the PM due to loss the magnetic susceptibility of the ferromagnet. PM’s force is gradually increasing and overcomes the Fspring due to the cooling of the ferromagnetic. Thermally, the system consists of high and low temperature zones and the ferromagnetic works as an active heat carrier. The opposing forces of the PM and the spring make the ferromagnetic moves in two opposite directions. COMSOL Multiphysics 5.2a software is used to get the simulation results in this study. This technique is suitable for many applications especially when heat transfer is required in the horizontal or oblique direction. This technique provides clean energy using only a waste heat from anywhere as a source.
Investigation of Parasitic Absorption in Back Contact of CdTe Solar Cells
Authors: Smay Joshua , Rashwan Ola , Then James , Perez Darien
Published: October 2018

Thin film solar cells (TFSC) differ from the conventional wafer solar cell panels in that they are a fraction of the thickness, hence they boast reduced material costs, lighter weight, and possible flexibility. To improve their light-trapping and absorption efficiency, manufacturers currently use nanometer scale texturing. When manufacturing nano textured thin film solar cells in the substrate configuration, the back reflector is also textured. It has been observed that a textured back reflector leads to parasitic light absorption in silicon solar cells. This occurrence reduces the back reflector effectiveness, and thus reduces absorption in the absorber layer and overall efficiency. However, there is little to no similar research done for thin film (CdTe/CdS) solar cells devices. In this work, wave optical analyses of thin film CdTe/CdS solar cells with and without nano texturing on the metal back reflectors were simulated using ANSYS ANSOFT High Frequency Structural Simulator (HFSS). The optical analyses yielded percentage absorptions for unit cells with four absorber thicknesses range between 250- to 1000 nm, with and without a textured back reflector over six wavelengths range from 360nm to 860 nm, and with 3 different back contact metals (Au, Ag, and Al). It was noted that the textured back contacts show a substantial increase in the absorption in the active CdTe layer in the infrared range. Additionally, back reflector texturing increases the parasitic absorption in the metal back reflector layer as well, especially with ultrathin absorber layer. It was also found that additional parasitic absorption due to a textured back reflector has less of an impact on absorption as the active absorber thickness increases to 500 nm, 750 nm, or 1000 nm. Finally, silver (Ag) as back contact outperforms both aluminum (Al) and gold (Au). This finding might be crucial to solar cell manufacturers because it could possibly be an overlooked factor in achieving higher efficiencies for relatively thin cells.
Additive Manufacturing of Spent Fuel Storage Rack Model by Selective Laser Melting
Authors: He Xiaoming , Zhu Ziqiang , Shao Changlei , Huang Ran
Published: October 2018

Additive Manufacturing (AM) can fabricate 3D complex functional parts, which can reduce material waste and increase manufacturing efficiency significantly. These benefits make AM technique suitable for some critical industry applications. Confident application of the AM technique requires whole understanding of AM parts’ properties. Safety and economics are essential to nuclear power plant. In this study, an innovative 316L stainless steel spent fuel storage rack with integrative structure was designed, and a small model of this rack was fabricated by selective laser melting (SLM), mechanical properties of the 316L stainless steel manufactured by SLM technique are studied and discussed. Key technical issues of application of AM to manufacturing nuclear parts are also discussed.
Analysis of the Thermal-Hydraulic and Mechanical Performance of Intermediate Heat Exchangers Used in Systems With Very High Temperature Nuclear Reactors
Authors: de la Torre Valdés Raciel , Francois Lacouture Juan Luis
Published: October 2018

Intermediate heat exchangers are one of the most critical devices in the safety of facilities with very high temperature nuclear reactors. In this application, the printed circuit heat exchanger (PCHE) design has been the one that has shown the greatest advantages in terms of heat transfer, compaction and structural strength. In this work, a thermal-hydraulic and mechanical model of the PCHE was developed using computational fluid dynamics (CFD) techniques and finite element methods, respectively. The CFD model was validated by comparison with experimental data and empirical correlations of Nusselt number and friction factor published by other authors. A methodology was proposed to evaluate the operation of the exchanger based on the analysis of capital and operating costs. As a relevant aspect of this methodology, the relationship between the maximum Von Misses stress in the structure and the time of operation was considered. In the structural calculations it was observed that increasing the temperature gradient between the channels caused by the increase of the mass flows of gases, causes the displacement of the solid region and the maximum stress increase. The Taguchi method was applied to identify the dimensions that have the greatest influence on the operation of the PCHE and to obtain an optimized design of the device.
Economic Modelling and Evaluation of a Repurposed Gas Turbine Engine
Authors: Rowlands David Olusina , Savill Mark
Published: October 2018

In this paper, an economic model is presented for the evaluation of gas turbine total productive life cost and profitability. The model utilizes input from gas turbine engine performance, emissions and lifing models to provide quantitative information on the economic implications of an investigated system or investment option.

In this study, the proposed model is used to conduct economic analysis on a turbojet engine, repurposed for alternative profitable use in electrical power generation. Results from the analysis are compared against competitor units to determine the models economic feasibility, benefits and limitations over competitors. Results obtained from the investigation reveal that the repurposed unit is economically feasible and favours profitability at minimal investment costs, with least burden on consumers. At a discount rate of 2.5%, investing in the repurposed engine model offers an investment base 13% lower, NPV 6% higher and an LCOE 24% higher in simple cycle than in combined cycle operation.
Micro-Tubular Flame-Assisted Fuel Cell Power Generation Running Propane and Butane
Authors: Milcarek Ryan J. , Ahn Jeongmin
Published: October 2018

Direct use of propane and butane in Solid Oxide Fuel Cells (SOFCs) is desirable due to the availability of the fuel source, but is challenging due to carbon coking, particularly on the commercially available Ni+YSZ anode. A novel dual chamber Flame-assisted Fuel Cell (FFC) configuration with micro-tubular SOFCs (mT-SOFCs) is proposed for direct use of higher hydrocarbon fuels. Combustion exhaust for propane and butane fuels is analyzed experimentally and compared with chemical equilibrium. mT-SOFC polarization and power density testing in the FFC configuration with propane and butane fuels is discussed. Peak power and electrical efficiency conditions are assessed by varying the fuel-rich combustion equivalence ratio and flow rate. Carbon deposition and soot formation on the Ni+YSZ anode is investigated with a scanning electron microscope. The results indicate that reasonable power density (∼289 mW.cm−2) can be achieved while limiting soot formation in the flame and carbon deposition on the anode. Electrical efficiency based on the higher heating value of the fuels is analyzed and future research is recommended. Possible applications of the technology include small scale power generation, cogeneration and combined cycle power plants.
Numerically Study on Combustion and NOx Emission Characteristics in Tangentially Fired Boiler Co-Firing Semi-Coke
Authors: Du Yongbo , Wang Chang'an , Wang Pengqian , Lv Qiang , Che Defu
Published: October 2018

Semi-coke is a specific solid fuel, which is mainly produced by upgrading low-rank coal. The poor reactivity of semi-coke makes a difficulty to its practical utilization in utility boilers. Previous research was mainly focused on the combustion behavior of semi-coke, while the industrial application has to be understood. In this paper, the effect of co-firing semi-coke and bituminous coal on the operation performance of pulverized boiler was numerically studied. The work was conducted on a 300 MW tangentially fired boiler, and the temperature distribution, the char burnout and NOx production were mainly examined. The results indicate that the incomplete combustion heat loss drops with the increase in semi-coke blending ratio. The NOx concentration increases from 186 mg/Nm3 for only firing the bituminous coal to 200, 214, and 255 mg/Nm3, when the blending ratio was 17%, 33% and 50%, respectively. With enhancing excess air coefficient for the co-firing condition, the combustion efficiency got improved, while NOx production increased very slightly. In general, the boiler is well adapted to co-firing semi-coke, and the semi-coke blending ratio of 1/3 with an excess air coefficient of 1.235 is recommended.
Effect of Using Different Equations of State in the Analysis of Rotary Displacer Stirling Engine
Authors: Bagheri AmirHossein , Williams Pavlina J. I. , Foster Phillip R. , Bostanci Huseyin
Published: October 2018

The ideal gas equation of state is defined for a theoretical gas composed of molecules that have perfect elastic collisions and no intermolecular interchange forces. However, it has been widely reported that such an ideal model may not be a realistic representation under certain circumstances, in particular when the compressibility factor (Z) is not close to unity, and the consideration of other equations of state (real models) is imperative.

This study investigates the effect of using different equations of state, namely, the van der Waals, Redlich-Kwong, and Peng-Robinson equations, in the ideal isothermal analysis of a rotary displacer Stirling engine with the most commonly used gases, helium and air. The results are obtained numerically considering two major SE applications (cryocooling and distributed power generation) and two sets of operating conditions, and plotted in the form of Pressure-Volume diagrams. The amount of work per cycle based on the ideal gas model is taken as reference to compare the results from other models. The data show that at low pressure or high temperature conditions (corresponding to low density), the ideal gas equation is suitable for both gases, and using different models has no significant impact in the overall analysis. Additionally, while the use of ideal gas model is rather practical and fast, implementation of other models necessitate intensive computational processes.
Study of Surface Tension and Natural Evaporation of Aqueous Surfactant Solutions
Authors: Dikici Birce , Lehman Matthew J.
Published: October 2018

Surface tension and solution evaporation of aqueous solutions of sodium lauryl sulfate (SLS), ECOSURF™ EH-14, and ECOSURF™ SA-9 under natural convection is examined through experimental methods. SLS is an anionic surfactant while EH-14 and SA-9 are environmentally-friendly nonionic surfactants.

Surfactants are known to affect evaporation performance of solutions and are studied in relation to water loss prevention and heat dissipation. Surfactants could be useful under drought conditions which present challenges to water management on a yearly basis in arid areas of the world. Recent water scarcity in the greater Los Angeles area, south eastern Africa nations, eastern Australia and eastern Mediterranean countries has high cost of water loss by evaporation. Surfactants are studied as a potential method of suppressing evaporation in water reservoirs. Surfactants are also studied as performance enhancers for the working fluid of heat dissipation devices, such as pulsating heat pipes used for electronics cooling. Some surfactants have been shown to lower thermal resistances and friction pressure in such devices and thereby increase their efficiency.

The static surface tensions of the aqueous-surfactant solutions are measured with surface tensiometer using Wilhelmy plate method. The surfactants are shown to lower surface tension significantly from pure water. The surface tension values found at the Critical Micelle Concentration are 33.8 mN/m for SLS, 30.3 mN/m for EH-14, and 30.0 mN/m for SA-9. All three surfactants reduced natural convection water loss over 5 days with SLS showing the greatest effect on evaporation rates. The maximum evaporation reduction by each surfactant from distilled water with no surfactants after 5 days is 26.1% for SLS, 20.8% for EH-14, and 18.4% for SA-9.
Techno-Economic Analysis of a PV-Battery System for a Commercial Building Under Different Utility Rate Structures
Authors: Raj Anupam , Reddy T. Agami
Published: October 2018

The synergy between solar photovoltaic (PV) systems and behind-the-meter battery storage to reduce utility costs in buildings has drawn increasing attention. This paper presents results of a case study involving an economic analysis of battery-supported PV systems for an existing two-story commercial building in Albuquerque, New Mexico under different utility rate tariffs. The building, with 17,430 ft2 conditioned area, has been modeled in a detailed building energy simulation program, and hourly building electricity demand data and electricity demand generated using Typical Meteorological Year 2 (TMY2) weather file. The effect of strategies leading to demand leveling and demand limiting have also been discussed. Parametric analysis using System Advisor Model (SAM) software has been performed to determine the optimal sizing of the PV and battery systems for the given electric demand profiles under the assumed utility rate tariffs which will result in largest net present value (NPV). The results have been found to be highly sensitive to the costs of the PV systems and battery packs. Under the assumed realistic circumstances, we find that the inclusion of a battery pack in either a new or existing PV system does not improve the NPV even when the cost of battery storage is reduced from its current $250/kWh down to an unrealistic $50/kWh.
Maximizing Plant Efficiency While Minimizing Water Usage Through Use of a Phase Change Material-Based Cold Energy Storage System
Authors: Charles Joshua , Romero Carlos , Neti Sudhakar , Pan Chunjian , Wang Xingchao , Bonner Richard , Zheng Ying , Chen Chien-Hua , Hoenig Sean
Published: October 2018

A supplemental main steam condenser cooling system is under development, which utilizes a phase change material (PCM). This PCM rejects heat to the cool atmosphere at night until it is fully frozen. The frozen PCM is available for condenser cooling during peak daytime electric demand. Three calcium chloride hexahydrate (CaCl2·6H2O)-based PCMs were selected for development after being characterized using differential scanning calorimetry (DSC). Additives to minimize supercooling and phase separation have demonstrated good performance after long and short-term thermal cycling. Corrosion testing under both isothermal and cycling conditions was conducted to determine long-term compatibility between several common metals and the selected PCMs. Several metals were demonstrated to have acceptably low corrosion rates for long-term operation, despite continual immersion in the selected hydrated salts. A system optimization model was developed, which utilizes a 3D modeling approach called the Layered Thermal Resistance (LTR) model. This model efficiently models the nonlinear, transient solidification process by applying analytic equations to layers of PCM. Good agreement was found between this model and more traditional computational fluid dynamics (CFD) modeling. Next phases of the work includes prototype testing and a techno-economic analysis of the technology.
Modeling of a New Crank-Less Rotary Heat Engine Concept for Solar Power Utilization
Authors: Rashad Muhammad I. , Faiad Hend A. , Elzouka Mahmoud
Published: October 2018

This paper presents the operating principle of a novel solar rotary crank-less heat engine. The proposed engine concept uses air as working fluid. The reciprocating motion is converted to a rotary motion by the mean of unbalanced mass and Coriolis effect, instead of a crank shaft. This facilitates the engine scaling and provides several degrees of freedom in terms of structure design and configuration. Unlike classical heat engines (i.e. Stirling), the proposed engine can be fixed to the ground which significantly reduce the generation unit cost.

Firstly, the engine’s configuration is illustrated. Then, order analysis for the engine is carried out. The combined dynamics and thermal model is developed using ordinary differential equations which are then numerically solved by Simulink™. The resulting engine thermodynamics cycle is described. It incorporates the common thermodynamics processes (isobaric, isothermal, isochoric processes). Finally, the system behavior and performance are analyzed along with studying the effect of various design parameters on operating conditions such as engine speed, output power and efficiency.
A Cost-Effective Active Single Axis Solar Tracking Mechanism Based on Weight Imbalance Principle
Authors: Kader A. M. , Rashad Muhammad I. , Elzouka Mahmoud , El-Souhily B. M.
Published: October 2018

Solar trackers are rising in popularity; they benefit a wide range of applications since distributed solar energy generation can reduce electricity costs and support energy independence. In this paper, a simple solar tracking system is introduced. The system is a package unit that can be mounted on any solar panel. The system consists of an electrical motor connected directly to a sliding mass on a linear bearing. The electrical motor is controlled to slide the weight along the shafts in controlled steps. As a result, the photovoltaic panels are rotated automatically under the effect of controlled weight unbalance in fine angle increments to track solar trajectory without the need for traditional complex or costly mechanisms. Two light dependent resistors (LDR) sensors, mounted onto the surface of the solar photovoltaic panel, are exposed to solar irradiance and used to feed signals to a controller. A model of the solar tracking system is developed using ordinary differential equations, and numerically solved by MATLAB/Simulink™. The power consumption and tracking strategy of the proposed tracking system are estimated under realistic operating conditions (e.g. wind and brakes), and the power consumption is compared to the power generated by the photovoltaic panels. Optimum values for the sliding mass are suggested. Two photovoltaic modules are used to calculate the output parameters of the proposed tracking mechanism.
Integration of Wave Energy Harnessing Technologies to the Needs of Coastal Societies in North Carolina
Authors: Subramanian Akshith , Raut Gagee , Goudarzi Navid
Published: October 2018

Wave Energy is a predictable and stable form of renewable energies. In this work, the wave energy potential along the North Carolina shore is calculated using six-year (2012–2017) National Buoy Database (NDBC). The wave data from two buoys (US 192 and US 430) were collected and the average significant wave height (HS) and corresponding time period (T) were determined. The Reference Model 3 (RM3) defined by Department of Energy (DOE) was used to explore the potential power generation from wave energy. Simulations were setup on WEC-Sim, an open-source code based on MATLAB developed by the DOE. A six-degree of freedom solver was used to obtain the results for heave and pitch forces for the float. Dynamic responses were calculated by solving equations of motion based on Cummins’ equation about the body center of gravity. Waves were modeled as irregular ocean waves using North Carolina shore wave data. The preliminary results obtained the heave and surge forces on RM3 and the body reaction forces. The results from this work can be used for determination of RM3 performance for NC shore.
Enhancing Prediction Accuracy in the Evaluation of Power Plant Uprates Utilizing a Novel ‘Big Data’ Approach
Authors: Pechtl Peter , Scheinecker Christian , Petek Josef
Published: October 2018

The evaluation of power plant uprates has traditionally been based on the definition of several ‘typical’ operating modes based on historical data and a — more or less detailed — model of the plant that is compared in current configuration against the same base model including the modifications under consideration. For the economic assessment of the uprate, annual operating hours are allocated to the operating points, and fuel savings and/or additional output predicted by the model due to the modifications are evaluated against the expected investment cost. In this study, the authors demonstrate that this classic approach contains risks in several aspects, in particular:

• the representativeness of the ‘typical’ operating modes,

• the accuracy of the model, and

• the correctness of the assumptions in the allocation of operating hours.

Utilizing the example of an actual uprate of a heat recovery steam generator (HRSG) in a large utility plant of an Austrian steel company, a new approach for an evaluation based on ‘big data’ is presented that uses a full year of operational data in hourly granularity for both, the verification of the accuracy of the plant model, and the evaluation of the effect of the uprate. The authors also provide details of the underlying technologies that allow for both, excellent match of operational data with a fully-fledged heat balance software and fast evaluation of tens of thousands of calculation cases.
Kansas City Power and Light (KCP&L): Hawthorn Station, Unit #5 Modular Titanium Tubed Condenser Project — A Case Study
Authors: Grogan Kim , Pearce Richard , Nightingale Darren M.
Published: October 2018

Kansas City Power & Light’s (KCP&L) Hawthorn Unit #5 is a coal fired power plant that was originally built in 1969. In 2000, the condenser had new condenser tube bundles installed with Admiralty tubes during the Hawthorn rebuild project. An evaluation of the unit in 2014 identified the potential for the conversion from open to closed cycle cooling. At the same time of the evaluation, multiple failures, causing high silica (derates), required action again in 2016. With improvements in condenser technology, and after evaluation of all the options available — including investment payback — it was decided to rebundle the condenser once again to improve the heat transfer surface area, and to anticipate the (future) requirement for the unit to operate at a higher design pressure on the circulating water side.

The current 1″ OD Admiralty Brass tubes and Muntz metal tube sheets were replaced with 7/8″ OD Titanium tubes and solid Titanium tube sheets. The waterboxes were also replaced with new carbon steel boxes, internally coated with a high solids epoxy lining, together with sacrificial anodes for cathodic protection. The new tube bundles and waterboxes were both designed for a higher design pressure. This was due to the possibility of a future cooling tower installation that would require an increased design pressure for the circulating water system. This Case Study Paper reviews the background to the requirement for new condenser tube bundles and waterboxes, compares the existing and replacement designs, reviews the installation process, and provides a summary of the project lessons learned. It is also intended to be of use to Plants that are considering changing from open to closed cooling cycle.
Functional response of Amblyseius largoensis to Raoiella indica eggs is mediated by previous feeding experience
Authors: Mendes Jairo A , Lima Debora B , Sousa Neto Eduardo P , Gondim Jr Manoel G C , Melo Jose Wagner S
Published: October 2018

The mechanisms involved in the acceptance and choice of prey by predatory mites are still poorly understood. The present study was designed to determine whether previous feeding experience of Amblyseius largoensis (Muma) (Acari: Phytoseiidae) on Raoiella indica Hirst (Acari: Tenuipalpidae) eggs could influence the predator’s functional response and related parameters. The consumption of R. indica eggs by experienced and naïve female A. largoensis was evaluated under increasing densities of eggs. Regardless of the predators’ previous experience, a gradual increase in the number of eggs consumed and a tendency to stabilize at higher densities were observed. Proportionally, egg consumption decreased with increasing egg densities, indicating a type II functional response for both experienced and naïve predators. Experienced and naïve predators also had the same attack rate. However, naïve predators had a handling time almost 50% longer than experienced predators and showed lower variation in egg consumption and lower peak egg consumption. The results of the present study demonstrate that previous feeding experience may alter parameters of the functional response of A. largoensis to R. indica eggs but not the type of response. Possibly, longer associations between native populations of A. largoensis and R. indica results in more aggressive predator populations.
Rapid change of superconductivity and electron-phonon coupling through critical doping in Bi-2212
Authors: He Y. , Hashimoto M. , Song D. , Chen S.-D. , He J. , Vishik I. M. , Moritz B. , Lee D.-H. , Nagaosa N. , Zaanen J. , Devereaux T. P. , Yoshida Y. , Eisaki H. , Lu D. H. , Shen Z.-X.
Published: October 2018

Conspiring interactions in a cuprate

More than 30 years after the discovery of high-temperature superconductivity in copper oxides, its mechanism remains a mystery. Electron pairing mediated solely by lattice vibrations—phonons—is thought to be insufficient to account for the high transition temperatures. He
et al.
found a rapid and correlated increase of the superconducting gap and electron-phonon interactions as the chemical composition of their bismuth-based cuprate samples was varied across a critical doping concentration. The interplay of electron-phonon with electron-electron interactions may lead to enhanced transition temperatures.

Science
, this issue p.
62