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Records with Type: Published Article
Showing records 1 to 25 of 649. [First] Page: 1 2 3 4 5 Last
Joint Estimation of the Electric Vehicle Power Battery State of Charge Based on the Least Squares Method and the Kalman Filter Algorithm
Xiangwei Guo, Longyun Kang, Yuan Yao, Zhizhen Huang, Wenbiao Li
November 16, 2018 (v1)
Keywords: AUKF, joint estimation, least square method with a forgetting factor
An estimation of the power battery state of charge (SOC) is related to the energy management, the battery cycle life and the use cost of electric vehicles. When a lithium-ion power battery is used in an electric vehicle, the SOC displays a very strong time-dependent nonlinearity under the influence of random factors, such as the working conditions and the environment. Hence, research on estimating the SOC of a power battery for an electric vehicle is of great theoretical significance and application value. In this paper, according to the dynamic response of the power battery terminal voltage during a discharging process, the second-order RC circuit is first used as the equivalent model of the power battery. Subsequently, on the basis of this model, the least squares method (LS) with a forgetting factor and the adaptive unscented Kalman filter (AUKF) algorithm are used jointly in the estimation of the power battery SOC. Simulation experiments show that the joint estimation... [more]
One-Dimensional Modeling of an Entrained Coal Gasification Process Using Kinetic Parameters
Moonkyeong Hwang, Eunhye Song, Juhun Song
November 16, 2018 (v1)
Keywords: coal gasification, entrained flow, equilibrium model, kinetic parameters, parameter studies, reactor model
A one-dimensional reactor model was developed to simulate the performance of an entrained flow gasifier under various operating conditions. The model combined the plug flow reactor (PFR) model with the well-stirred reactor (WSR) model. Reaction kinetics was considered together with gas diffusion for the solid-phase reactions in the PFR model, while equilibrium was considered for the gas-phase reactions in the WSR model. The differential and algebraic equations of mass balance and energy balance were solved by a robust ODE solver, i.e., an semi-implicit Runge⁻Kutta method, and by a nonlinear algebraic solver, respectively. The computed gasifier performance was validated against experimental data from the literature. The difference in product gas concentration from the equilibrium model, and the underlying mechanisms were discussed further. The optimal condition was found after parameter studies were made for various operating conditions.
Performance Evaluation of Palm Oil-Based Biodiesel Combustion in an Oil Burner
Abdolsaeid Ganjehkaviri, Mohammad Nazri Mohd Jaafar, Seyed Ehsan Hosseini, Anas Basri Musthafa
November 16, 2018 (v1)
Keywords: combustion, equivalence ratio, NOx, oil burner, palm oil
This paper presents an experimental investigation of the combustion characteristics of palm methyl ester (PME), also known as palm oil-based biodiesel, in an oil burner system. The performance of conventional diesel fuel (CDF) and various percentages of diesel blended with palm oil-based biodiesel is also studied to evaluate their performance. The performance of the various fuels is evaluated based on the temperature profile of the combustor’s wall and emissions, such as nitrogen oxides (NOx) and carbon monoxide (CO). The combustion experiments were conducted using three different oil burner nozzles (1.25, 1.50 and 1.75 USgal/h) under lean (equivalence ratio (Φ) = 0.8), stoichiometric (Φ = 1) and rich fuel (Φ = 1.2) ratio conditions. The results show that the rate of emission formation decreases as the volume percent of palm biodiesel in a blend increases. PME combustion tests present a lower temperature inside the chamber compared to CDF combustion. High rates of NOx formation occur u... [more]
Elimination of the Inrush Current Phenomenon Associated with Single-Phase Offline UPS Systems
Syed Sabir Hussain Bukhari, Shahid Atiq, Byung-il Kwon
November 16, 2018 (v1)
Subject: Other
Keywords: current regulation, inrush currents, offline, uninterruptible power supply
Critical load applications always rely on UPS systems to uphold continuous power during abnormal grid conditions. In case of any power disruption, an offline UPS system starts powering the load to avoid blackout. However, this process can root the momentous inrush current for the transformer installed before the load. The consequences of inrush current can be the reduction of output voltage and tripping of protective devices of the UPS system. Furthermore, it can also damage the sensitive load and decrease the transformer’s lifetime. To prevent the inrush current, and to avoid its disruptive effects, this research suggests an offline UPS system based on a current regulated inverter that eliminates the inrush current while powering the transformer coupled loads. A detailed comparative analysis of the conventional and proposed topologies is presented and the experiment was performed by using a small prototype to validate the performance, and operation of the proposed topology.
Simulation of Wind Speed in the Ventilation Tunnel for Surge Tanks in Transient Processes
Jiandong Yang, Huang Wang, Wencheng Guo, Weijia Yang, Wei Zeng
November 16, 2018 (v1)
Keywords: hydroelectric power plants, numerical simulation, surge tank, transient process, ventilation tunnel, wave superposition, wind speed
Hydroelectric power plants’ open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this article adopts the one-dimensional numerical simulation method and establishes a mathematical model of a wind speed by assuming the boundary conditions of air discharge for a surge tank. Thereafter, the simulation of wind speed in a ventilation tunnel, for the case of a surge tank during transient processes, is successfully realized. Finally, the effective mechanism of water-level fluctuation in a surge tank and the shape of the ventilation tunnel (including length, sectional area and dip angle) for the... [more]
Overcoming the Fundamental Limit: Combustion of a Hydrogen-Oxygen Mixture in Micro- and Nano-Bubbles
Vitaly Svetovoy, Alexander Postnikov, Ilia Uvarov, Remco Sanders, Gijs Krijnen
November 16, 2018 (v1)
Keywords: combustion, microsystems, nanobubbles
Combustion reactions quench in small volumes due to fast heat escape via the volume boundary. Nevertheless, the reaction between hydrogen and oxygen was observed in nano- and micro-bubbles. The bubbles containing a mixture of gases were produced in microsystems using electrochemical decomposition of water with a fast switching of voltage polarity. In this paper, we review our experimental results on the reaction in micro- and nano-bubbles and provide their physical interpretation. Experiments were performed using microsystems of different designs. The process was observed with a stroboscope and with a vibrometer. The latter was used to measure the gas concentration in the electrolyte and to monitor pressure in a reaction chamber covered with a flexible membrane. Information on the temperature was extracted from the Faraday current in the electrolyte. Since the direct observation of the combustion is complicated by the small size and short time scale of the events, special attention is... [more]
Quantitative Model and Metrics of Electrical Grids’ Resilience Evaluated at a Power Distribution Level
Alexis Kwasinski
November 16, 2018 (v1)
Keywords: brittleness, dependence, fragility, power distribution, power grids, resilience, resistance
This paper presents a framework to systematically measure and assess power grids’ resilience with a focus on performance as perceived by customers at the power distribution level. The proposed framework considers an analogous measure of availability as a basic metric for resilience and defines other key resilience-related concepts and metrics, such as resistance and brittleness. This framework also provides a measurement for the degree of functional dependency of loads on power grids and demonstrates how the concepts of resilience and dependency are inherently related. It also discusses the implications of considering human-centered processes as fundamental constituting components of infrastructure systems. Thanks to its quantitative nature, the proposed resilience framework enables the creation of tools to evaluate power grids’ performance as a lifeline and to assess the effects of plans for optimal electrical power infrastructure deployment and operation. The discussion is supported... [more]
Potential Biogas Production from Artichoke Byproducts in Sardinia, Italy
Fabio De Menna, Remo Alessio Malagnino, Matteo Vittuari, Giovanni Molari, Giovanna Seddaiu, Paola A. Deligios, Stefania Solinas, Luigi Ledda
November 16, 2018 (v1)
Subject: Biosystems
Keywords: artichoke, biogas, byproducts, Sardinia
The paper aims at evaluating the potential biogas production, both in terms of CH₄ and theoretical energy potential, from globe artichoke agricultural byproducts in Sardinia. Field data about the productivity of byproducts were collected on five artichoke varieties cultivated in Sardinia, to assess the biomethane production of their aboveground non-food parts (excluding the head). Moreover, secondary data from previous studies and surveys at regional scale were collected to evaluate the potential biogas production of the different districts. Fresh globe artichoke residues yielded, on average, 292.2 Nm³·tDOM−1, with dissimilarities among cultivars. Fresh samples were analyzed in two series: (a) wet basis; and (b) wet basis with catalytic enzymes application. Enzymes proved to have some beneficial effects in terms of anticipated biomethane availability. At the regional level, ab. 20 × 10⁶ Nm³ CH₄ could be produced, corresponding to the 60% of current installed capacity. However, district... [more]
Probability Density Function Characterization for Aggregated Large-Scale Wind Power Based on Weibull Mixtures
Emilio Gómez-Lázaro, María C. Bueso, Mathieu Kessler, Sergio Martín-Martínez, Jie Zhang, Bri-Mathias Hodge, Angel Molina-García
November 16, 2018 (v1)
Keywords: Akaike information criterion (AIC), Bayesian information criterion (BIC), Weibull distributions, Weibull mixtures, wind power generation
The Weibull probability distribution has been widely applied to characterize wind speeds for wind energy resources. Wind power generation modeling is different, however, due in particular to power curve limitations, wind turbine control methods, and transmission system operation requirements. These differences are even greater for aggregated wind power generation in power systems with high wind penetration. Consequently, models based on one-Weibull component can provide poor characterizations for aggregated wind power generation. With this aim, the present paper focuses on discussing Weibull mixtures to characterize the probability density function (PDF) for aggregated wind power generation. PDFs of wind power data are firstly classified attending to hourly and seasonal patterns. The selection of the number of components in the mixture is analyzed through two well-known different criteria: the Akaike information criterion (AIC) and the Bayesian information criterion (BIC). Finally, the... [more]
Field Study on Humidification Performance of a Desiccant Air-Conditioning System Combined with a Heat Pump
Koichi Kawamoto, Wanghee Cho, Hitoshi Kohno, Makoto Koganei, Ryozo Ooka, Shinsuke Kato
November 16, 2018 (v1)
Keywords: dedicated outdoor air system (DOAS), desiccant, heat pump, humidification
A desiccant air-conditioning system was developed as a latent-load-processing air conditioner in a dedicated outdoor air system during the summer. This study investigated the application of this air-conditioning system to humidification during the winter without using make-up water, thereby eliminating the cause of microbial contamination in air-conditioning systems. The experiments were conducted with a system used for summer applications to determine the feasibility of adsorbing vapor from outdoor air and supplying it to an indoor space. The humidification performance, energy efficiency, and operating conditions were examined. Although the conditions were subpar because the experiments were performed with an actual dedicated outdoor air system, the results showed that it is possible to supply air with a minimum humidity ratio of 5.8 g/kg dry air (DA) when the humidity ratio of outdoor air ranges from 1.8 to 2.3 g/kg DA. The minimum humidification performance required for a dedicated... [more]
Field Experiments on 10 kV Switching Shunt Capacitor Banks Using Ordinary and Phase-Controlled Vacuum Circuit Breakers
Wenxia Sima, Mi Zou, Qing Yang, Ming Yang, Licheng Li
November 16, 2018 (v1)
Subject: Other
Keywords: field tests, phase selection, shunt capacitor banks, vacuum circuit breakers (VCBs)
During the switching on/off of shunt capacitor banks in substations, vacuum circuit breakers (VCBs) are required to switch off or to switch on the capacitive current. Therefore, the VCBs have to be operated under a harsh condition to ensure the reliability of the equipment. This study presents a complete comparison study of ordinary and phase-controlled VCBs on switching 10 kV shunt capacitor banks. An analytical analysis for switching 10 kV shunt capacitor banks is presented on the basis of a reduced circuit with an ungrounded neutral. A phase selection strategy for VCBs to switch 10 kV shunt capacitor banks is proposed. Switching on current waveforms and switching off overvoltage waveforms with, and without, phase selection were measured and discussed by field experiments in a 110 kV substation in Chongqing, China. Results show that the operation of phase-controlled VCBs for 10 kV switching shunt capacitor banks is stable, and phase-controlled VCBs can be used to implement the 10 kV... [more]
Influence of Fine Metal Particles on Surface Discharge Characteristics of Outdoor Insulators
Yong Liu, Bowen Xia, Boxue Du, Masoud Farzaneh
November 16, 2018 (v1)
Subject: Materials
Keywords: discharge luminesce, fine metal particles, flashover voltage, micrometer-level size, outdoor insulator, particle amount, surface discharge characteristic
Focusing on the influence of fine metal particles on the insulation characteristics of outdoor insulators, spherical micrometer-level iron powders were used to represent fine metal particles of different parameters on a polymer insulator specimen surface. Dynamic movement and lift-off behavior of fine particles, as well as the triggered surface discharges under AC voltage were investigated in a uniform electric field under different experimental conditions. The results reveal that the inception, propagation and intensity of surface discharges are significantly affected by the particle parameters, including particle size, amount and distributing characteristic. Based on the measurement of light emission during the flashover process using a high-speed camera, the process of surface discharge to flashover triggered by the fine metal particles were investigated to obtain a relationship between flashover voltage, discharge light intensity and particle parameters. It is suggested that partic... [more]
Environmental Analysis of Petrol, Diesel and Electric Passenger Cars in a Belgian Urban Setting
Nils Hooftman, Luis Oliveira, Maarten Messagie, Thierry Coosemans, Joeri Van Mierlo
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: electric vehicle, emissions, life cycle assessment, non-exhaust, urban
The combustion of fossil fuels in the transport sector leads to an aggravation of the air quality along city roads and highways. Urban air quality is a serious problem nowadays as the number of vehicles increases on a yearly basis. With stricter Euro emission regulations, vehicle manufacturers are not meeting the imposed limits and are also disregarding the non-exhaust emissions. This paper highlights the relevance of non-exhaust emissions of passenger vehicles, both conventional (diesel and petrol) or electric vehicles (EV), on air quality levels in an urban environment in Belgium. An environmental life cycle assessment was carried out based on a real-world emission model for passenger cars and fuel refinery data. A cut-off was applied to the models to highlight what emissions, both from the refinery to the exhaust and electricity production for EV, do actually occur within Belgium’s borders. Results show that not much progress has been made from Euro 4 to 6 for conventional vehicles.... [more]
Implementing a Novel Hybrid Maximum Power Point Tracking Technique in DSP via Simulink/MATLAB under Partially Shaded Conditions
Shahrooz Hajighorbani, Mohd Amran Mohd Radzi, Mohd Zainal Abidin Ab Kadir, Suhaidi Shafie, Muhammad Ammirrul Atiqi Mohd Zainuri
November 16, 2018 (v1)
Keywords: digital signal processing (DSP), global maximum power point (GMPP), O), partial shadow (PS), perturb and observation (P&, photovoltaic (PV), Simulink/MATLAB
This paper presents a hybrid maximum power point tracking (MPPT) method to detect the global maximum power point (GMPP) under partially shaded conditions (PSCs), which have more complex characteristics with multiple peak power points. The hybrid method can track the GMPP when a partial shadow occurs either before or after acquiring the MPP under uniform conditions. When PS occurs after obtaining the MPP during uniform conditions, the new operating point should be specified by the modified linear function, which reduces the searching zone of the GMPP and has a significant effect on reducing the reaching time of the GMPP. Simultaneously, the possible MPPs are scanned and stored when shifting the operating point to a new reference voltage. Finally, after determining the possible location of the GMPP, the GMPP is obtained using the modified P&O. Conversely, when PS occurs before obtaining the MPP, the referenced MPP should be specified. Thus, after recognizing the possible location of... [more]
Electric Vehicles in Logistics and Transportation: A Survey on Emerging Environmental, Strategic, and Operational Challenges
Angel Alejandro Juan, Carlos Alberto Mendez, Javier Faulin, Jesica de Armas, Scott Erwin Grasman
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: electric vehicles, green vehicle routing problems, logistics and transportation
Current logistics and transportation (L&T) systems include heterogeneous fleets consisting of common internal combustion engine vehicles as well as other types of vehicles using “green” technologies, e.g., plug-in hybrid electric vehicles and electric vehicles (EVs). However, the incorporation of EVs in L&T activities also raise some additional challenges from the strategic, planning, and operational perspectives. For instance, smart cities are required to provide recharge stations for electric-based vehicles, meaning that investment decisions need to be made about the number, location, and capacity of these stations. Similarly, the limited driving-range capabilities of EVs, which are restricted by the amount of electricity stored in their batteries, impose non-trivial additional constraints when designing efficient distribution routes. Accordingly, this paper identifies and reviews several open research challenges related to the introduction of EVs in L&T activities, inclu... [more]
Numerical Investigation of a Tuned Heave Plate Energy-Harvesting System of a Semi-Submersible Platform
Kun Liu, Haizhi Liang, Jinping Ou
November 16, 2018 (v1)
Keywords: heave plate, semi-submersible, tuned mass damper (TMD), Wave Energy, wave energy converter
A novel tuned heave plate energy-harvesting system (THPEH) is presented for the motion suppressing and energy harvesting of a semi-submersible platform. This THPEH system is designed based on the principle of a tuned mass damper (TMD) and is composed of spring supports, a power take-off system (PTO) and four movable heave plates. The permanent magnet linear generators (PMLG) are used as the PTO system in this design. A semi-submersible platform operating in the South China Sea is selected as the research subject for investigating the effects of the THPEH system on motion reduction and harvesting energy through numerical simulations. The numerical model of the platform and the THPEH system, which was established based on hydrodynamic analysis, is modified and validated by the results of the flume test of a 1:70 scale model. The effects of the parameters, including the size, the frequency ratio and the damping ratio of the THPEH system, are systematically investigated. The results show t... [more]
The Chaotic-Based Control of Three-Port Isolated Bidirectional DC/DC Converters for Electric and Hybrid Vehicles
Zheng Wang, Bochen Liu, Yue Zhang, Ming Cheng, Kai Chu, Liang Xu
November 16, 2018 (v1)
Keywords: bidirectional DC/DC converter, chaotic modulation, electric and hybrid vehicles, Energy Conversion, shifted-phase angle based control
Three-port isolated (TPI) bidirectional DC/DC converters have three energy ports and offer advantages of large voltage gain, galvanic isolation ability and high power density. For this reason this kind of converters are suitable to connect different energy sources and loads in electric and hybrid vehicles. The purpose of this paper is to propose chaotic modulation and the related control scheme for TPI bidirectional DC/DC converters, in such a way that the switching harmonic peaks can be suppressed in spectrum and the conducted electromagnetic interference (EMI) is reduced. Two chaotic modulation strategies, namely the continuously chaotic modulation and the discretely chaotic modulation are presented. These two chaotic modulation strategies are applied for TPI bidirectional DC/DC converters with shifted-phase angle based control and phase-shifted PWM control. Both simulation and experiments are given to verify the validity of the proposed chaotic modulation-based control schemes.
The Health Costs of Revised Coal Mining Limits in Northern Bohemia
Vojtěch Máca, Jan Melichar
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: airborne pollution, coal mining, coal-fired power plant, external costs, impact-pathway approach
Brown coal has been the major source of energy for more than 150 years for the Czech economy, but its role in the coming decades is nowadays the source of heated debate. Many of the recurring discussions address the coal reserves that were set aside in 1991 in order to halt the massive destruction of the landscape and the unprecedented deterioration of the human environment in Northern Bohemia. We study the proposed variants of the revised mining limits using the impact-pathway approach in order to quantify and monetize the health effects of airborne emissions from coal mining and the use of extracted coal for the production of electricity and heat. We find that the dominant health impacts associated with the revision of the limits, estimated to be up to 7 billion euros over the 2015⁻2050 period, will stem from the use of coal for the production of electricity and heat and that a large part of the impact will be borne by populations outside the Czech Republic.
A Sectoral Micro-Economic Approach to Scenario Selection and Development: The Case of the Greek Power Sector
Alexandros Flamos
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: actor-based modeling and analysis, generation capacity adequacy, policy assessment, power market, scenario development
Generating policy-relevant scenarios is instrumental for understanding and developing policy measures. These are especially relevant to the power sector. Practitioners have been working on policy-relevant scenarios for the ex-ante assessment of policy measures in a meaningful way for end-users related to climate change mitigation and adaptation strategies. This paper presents a method for generating such policy relevant scenarios by focusing on the actor-contingent elements of the scenarios, i.e., the developments that are within the control of system actors to change or bring about. Several scenario techniques focusing on systematic-formalized or quantitative approaches have been published on this front over the past few years. Here, we introduce a methodology that is best suited for the assessment of the expected effect of different policy measures on the involved stakeholders’ behavior as well as for the analysis of the interactions between different policy measures as reflected on... [more]
Multi-Objective Demand Response Model Considering the Probabilistic Characteristic of Price Elastic Load
Shengchun Yang, Dan Zeng, Hongfa Ding, Jianguo Yao, Ke Wang, Yaping Li
November 16, 2018 (v1)
Keywords: demand response, electricity consumption satisfaction (ECS), interaction benefit satisfaction (IBS), price elastic load (PEL), Stochastic Optimization, uncertainty
Demand response (DR) programs provide an effective approach for dealing with the challenge of wind power output fluctuations. Given that uncertain DR, such as price elastic load (PEL), plays an important role, the uncertainty of demand response behavior must be studied. In this paper, a multi-objective stochastic optimization problem of PEL is proposed on the basis of the analysis of the relationship between price elasticity and probabilistic characteristic, which is about stochastic demand models for consumer loads. The analysis aims to improve the capability of accommodating wind output uncertainty. In our approach, the relationship between the amount of demand response and interaction efficiency is developed by actively participating in power grid interaction. The probabilistic representation and uncertainty range of the PEL demand response amount are formulated differently compared with those of previous research. Based on the aforementioned findings, a stochastic optimization mode... [more]
Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 2: Numerical Modeling
Sona Kazemi, Melissa Barazandegan, Madjid Mohseni, Khalid Fatih
November 16, 2018 (v1)
Subject: Biosystems
Keywords: crossover, electrode spacing, flat-plate microbial fuel cell (FPMFC), mixed potential theory, numerical model, passive air-breathing, separator
The separator plays a key role on the performance of passive air-breathing flat-plate MFCs (FPMFC) as it isolates the anaerobic anode from the air-breathing cathode. The goal of the present work was to study the separator characteristics and its effect on the performance of passive air-breathing FPMFCs. This was performed partially through characterization of structure, properties, and performance correlations of eight separators presented in Part 1. Current work (Part 2) presents a numerical model developed based on the mixed potential theory to investigate the sensitivity of the electrode potentials and the power output to the separator characteristics. According to this numerical model, the decreased peak power results from an increase in the mass transfer coefficients of oxygen and ethanol, but mainly increasing mixed potentials at the anode by oxygen crossover. The model also indicates that the peak power is affected by the proton transport number of the separator, which affects t... [more]
A Systematic Study of Separators in Air-Breathing Flat-Plate Microbial Fuel Cells—Part 1: Structure, Properties, and Performance Correlations
Sona Kazemi, Madjid Mohseni, Khalid Fatih
November 16, 2018 (v1)
Subject: Biosystems
Keywords: crossover, electrode spacing, flat-plate microbial fuel cell, passive air-breathing, separator
Passive air-breathing microbial fuel cells (MFCs) are a promising technology for energy recovery from wastewater and their performance is highly dependent on characteristics of the separator that isolates the anaerobic anode from the air-breathing cathode. The goal of the present work is to systematically study the separator characteristics and its effect on the performance of passive air-breathing flat-plate MFCs (FPMFCs). This was performed through characterization of structure, properties, and performance correlations of eight separators in Part 1 of this work. Eight commercial separators were characterized, in non-inoculated and inoculated setups, and were examined in passive air-breathing FPMFCs with different electrode spacing. The results showed a decrease in the peak power density as the oxygen and ethanol mass transfer coefficients in the separators increased, due to the increase of mixed potentials especially at smaller electrode spacing. Increasing the electrode spacing was... [more]
Analysis of a Solar Cooling System for Climatic Conditions of Five Different Cities of Saudi Arabia
M. Mujahid Rafique, Shafiqur Rehman, Aref Lashin, Nassir Al Arifi
November 16, 2018 (v1)
Subject: Other
Keywords: clean technology, desiccant wheel, energy saving, evaporative cooling, Saudi Arabia, thermal cooling
Air high in humidity leads to uncomfortable conditions and promotes the growth of different fungi and bacteria, which may cause health problems. The control of moisture content in the air using traditional air conditioning techniques is not a suitable option due to large consumption of primary energy and hence emission of greenhouse gases. The evaporative cooling technology is a cost effective and eco-friendly alternative but can provide thermal comfort conditions only under low humidity conditions. However, the evaporative cooling method can be used effectively in conjunction with desiccant dehumidifiers for better control of humidity. Such systems can control the temperature and humidity of the air independently and can effectively utilize the low-grade thermal energy resources. In this paper, the theoretical analysis of desiccant based evaporative cooling systems is carried out for five cities in Saudi Arabia (Jeddah, Jazan, Riyadh, Hail, and Dhahran). It has been observed that the... [more]
Economic Viability Study of an On-Road Wireless Charging System with a Generic Driving Range Estimation Method
Aditya Shekhar, Venugopal Prasanth, Pavol Bauer, Mark Bolech
November 16, 2018 (v1)
Subject: Energy Policy
Keywords: analysis, charging, contactless, cost, driving range, dynamic, economic, electric vehicle (EV), emissions, extension, inductive power transfer (IPT), static, viability, wireless
The economic viability of on-road wireless charging of electric vehicles (EVs) strongly depends on the choice of the inductive power transfer (IPT) system configuration (static or dynamic charging), charging power level and the percentage of road coverage of dynamic charging. In this paper, a case study is carried out to determine the expected investment costs involved in installing the on-road charging infrastructure for an electric bus fleet. Firstly, a generic methodology is described to determine the driving range of any EV (including electric buses) with any gross mass and frontal area. A dynamic power consumption model is developed for the EV, taking into account the rolling friction, acceleration, deceleration, aerodynamic drag, regenerative braking and Li-ion battery behavior. Based on the simulation results, the linear dependence of the battery state of charge (SoC) on the distance traveled is proven. Further, the impact of different IPT system parameters on driving range is i... [more]
Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case
Chirag Trivedi, Michel J. Cervantes, Ole G. Dahlhaug
November 16, 2018 (v1)
Keywords: computational fluid dynamic (CFD), Francis turbine, hydropower, pressure, turbulence, uncertainty, velocity
Hydraulic turbines are widely used to meet real-time electricity demands. Computational fluid dynamic (CFD) techniques have played an important role in the design and development of such turbines. The simulation of a complete turbine requires substantial computational resources. A specific approach that is applied to investigate the flow field of one turbine may not work for another turbine. A series of Francis-99 workshops have been planned to discuss and explore the CFD techniques applied within the field of hydropower with application to high-head Francis turbines. The first workshop was held in December 2014 at the Norwegian University of Science and Technology, Norway. The steady-state measurements were conducted on a model Francis turbine. Three operating points, part load, best efficiency point, and high load, were investigated. The complete geometry, meshing, and experimental data concerning the hydraulic efficiency, pressure, and velocity were provided to the academic and indu... [more]
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