Records Added in February 2020
Records added in February 2020
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Showing records 1 to 25 of 144. [First] Page: 1 2 3 4 5 Last
Study of Ground Heat Exchangers in the Form of Parallel Horizontal Pipes Embedded in the Ground
Krzysztof Neupauer, Sebastian Pater, Krzysztof Kupiec
February 24, 2020 (v1)
Keywords: heat transfer, horizontal ground heat exchanger, linear heat source model, renewable energy sources
In order to predict long-term changes in the temperature of the ground in which a horizontal ground heat exchanger has been installed, it is beneficial to implement simplified mathematical models of heat transfer. The possibility of using a one-dimensional equation of heat conduction while modelling heat transfer in a ground heat exchanger with horizontal pipes has been demonstrated in the work. A theoretical analysis based on the linear heat source model as well as experimental research works have been carried out. It has been concluded that the temperature profiles of the ground in which parallel pipes of the heat exchanger are placed do not significantly differ from the profiles for the heat exchanger in the form of a plate; in particular, this refers to large distances from the level in which the pipes are positioned, small distances between pipes axes and the long duration of the process. Discrepancies between the calculated temperature increases for pipe and plate exchangers vari... [more]
Identification and Quantification of Volatile Compounds Found in Vinasses from Two Different Processes of Tequila Production
Elizabeth Rodríguez-Félix, Silvia Maribel Contreras-Ramos, Gustavo Davila-Vazquez, Jacobo Rodríguez-Campos, Erika Nahomy Marino-Marmolejo
February 24, 2020 (v1)
Subject: Materials
Keywords: dark fermentative, inhibitors, stillage, tequila, volatile compounds
Vinasses are the main byproducts of ethanol distillation and distilled beverages worldwide and are generated in substantial volumes. Tequila vinasses (TVs) could be used as a feedstock for biohydrogen production through a dark fermentative (DF) process due to their high content of organic matter. However, TV components have not been previously assayed in order to evaluate if they may dark ferment. This work aimed to identify and quantify volatile compounds (VC) in TV and determine if the VC profile depends upon the type of production process (whether the stems were initially cooked or not). TVs were sampled from 3 agave stems with a not-cooking (NC) process, and 3 agave stems with a cooking (C) process, and volatile compounds were determined by gas chromatography coupled with mass spectrometry (GC⁻MS). A total of 111 volatile compounds were identified, the TV from the cooking process (C) showed the higher presence of furanic compounds (furfural and 5-(hydroxymethyl) furfural) and organ... [more]
A Comparison of Thermal Models for Temperature Profiles in Gas-Lift Wells
Langfeng Mu, Qiushi Zhang, Qi Li, Fanhua Zeng
February 24, 2020 (v1)
Keywords: gas lift, governing equation, temperature profile, wellbore profile
Gas lift is a simple, reliable artificial lift method which is frequently used in offshore oil field developments. In order to enhance the efficiency of production by gas lift, it is vital to exactly predict the distribution of temperature-field for fluid within the wellbore. A new mechanistic model is developed for computing flowing fluid temperature profiles in both conduits simultaneously for a continuous-flow gas-lift operation. This model assumes steady heat transfer in the formation, as well as steady heat transfer in the conduits. A micro-units discrete from the wellbore, whose heat transfer process is analyzed and whose heat transfer equation is set up according to the law of conservation of energy. A simplified algebraic solution to our model is conducted to analyze the temperature profile. Sensitivity analysis was conducted with the new model. The results indicate that mass flow rate of oil and the tubing overall heat transfer coefficient are the main factors that influence t... [more]
Remote Power Control Injection of Grid-Connected Power Converters Based on Virtual Flux
Nurul Fazlin Roslan, Alvaro Luna, Joan Rocabert, Jose Ignacio Candela, Pedro Rodriguez
February 24, 2020 (v1)
Keywords: LCL-filter, proportional resonant current controller, remote point, virtual flux estimation, voltage sensorless, voltage source converter
Renewable Energy Source (RES)-based power plants need to control the active and reactive power at the Point of Common Connection (PCC) with the grid, in order to comply with the requirements of the Transmission System Operators (TSOs). This point is normally far away from the power converter station, and the cables and step-up transformers have a non-neglectable influence on the delivered power. In order to overcome this drawback, this paper presents a control algorithm that permits one to control remotely the power injected at the PCC, by adjusting the local controller of the Voltage Source Converters (VSCs). In this work, the synchronization with the grid is done based on the Virtual Flux (VF) concept. The results reveals that the VF estimation is able to produce a reliable estimation of the grid voltage in any point of the network, and makes it possible to calculate the necessary current reference for injecting a desired active and reactive power at a point that can be some kilometr... [more]
Review of Research Progress on the Electrical Properties and Modification of Mineral Insulating Oils Used in Power Transformers
Xiaobo Wang, Chao Tang, Bo Huang, Jian Hao, George Chen
February 24, 2020 (v1)
Subject: Materials
Keywords: electrical properties, mineral insulating oil, molecular dynamics simulation, power transformer
In November 2017, the first ±1100 kV high-voltage direct-current power transformer in the world, which was made by Siemens in Nurnberg, passed its type test. Meanwhile, in early 2017, a ±1000 kV ultra-high voltage (UHV) substation was officially put into operation in Tianjin, China. These examples illustrate that the era of UHV power transmission is coming. With the rapid increase in power transmission voltage, the performance requirements for the insulation of power transformers are getting higher and higher. The traditional mineral oils used inside power transformers as insulating and cooling agents are thus facing a serious challenge to meet these requirements. In this review, the basic properties of traditional mineral insulating oil are first introduced. Then, the variation of electrical properties such as breakdown strength, permittivity, and conductivity during transformer operation and aging is summarized. Next, the modification of mineral insulating oil is investigated with a... [more]
Robust Condition Assessment of Electrical Equipment with One Class Support Vector Machines Based on the Measurement of Partial Discharges
Emilio Parrado-Hernández, Guillermo Robles, Jorge Alfredo Ardila-Rey, Juan Manuel Martínez-Tarifa
February 24, 2020 (v1)
Keywords: early fault prevention, electrical asset monitoring, noise characterization, One Class Support Vector Machines (OCSVM), partial discharge discrimination
This paper presents a system for the detection of partial discharges (PD) in industrial applications based on One Class Support Vector Machines (OCSVM). The study stresses the detection of Partial Discharges (PD) as they represent a major source of information related to degradation in the equipment. PD measurement is a widely extended technique for condition monitoring of electrical machines and power cables to avoid catastrophic failures and the consequent blackouts. One of the most important keystones in the interpretation of partial discharges is their separation from other signals considered as not-PD especially in low SNR measurements. In this sense, the OCSVM is an interesting alternative to binary SVMs since it does not need a training set with examples of all the output classes correctly labelled. On the contrary, the OCSVM learns a model of the signals acquired when the equipment is in PD-free mode, defined as a state where no degradation mechanism is active, so one only need... [more]
Hypothesis Tests-Based Analysis for Anomaly Detection in Photovoltaic Systems in the Absence of Environmental Parameters
Silvano Vergura
February 24, 2020 (v1)
Keywords: ANOVA, Bartlett’s test, Hartigan’s dip test, Jarque-Bera’s test, Kruskal-Wallis’ test, Mood’s Median test, residential buildings, Tukey’s test, urban context
This paper deals with the monitoring of the performance of a photovoltaic plant, without using the environmental parameters such as the solar radiation and the temperature. The main idea is to statistically compare the energy performances of the arrays constituting the PV plant. In fact, the environmental conditions affect equally all the arrays of a small-medium-size PV plant, because the extension of the plant is limited, so any comparison between the energy distributions of identical arrays is independent of the solar radiation and the cell temperature, making the proposed methodology very effective for PV plants not equipped with a weather station, as it often happens for the PV plants located in urban contexts and having a nominal peak power in the 3÷50 kWp range, typically installed on the roof of a residential or industrial building. In this case, the costs of an advanced monitoring system based on the environmental data are not justified, consequently, the weather station is of... [more]
Solid-State Anaerobic Digestion of Dairy Manure from a Sawdust-Bedded Pack Barn: Moisture Responses
Eunjong Kim, Seunghun Lee, Hyeonsoo Jo, Jihyeon Jeong, Walter Mulbry, Shafiqur Rhaman, Heekwon Ahn
February 24, 2020 (v1)
Subject: Other
Keywords: biogas, dairy manure, methane, moisture content, solid-state anaerobic digestion
Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD) provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs) of 70, 76, and 83% and digested at 37 °C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS) reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL (gVS)−1. These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to thr... [more]
A Review of Electric Vehicle Lifecycle Emissions and Policy Recommendations to Increase EV Penetration in India
Rachana Vidhi, Prasanna Shrivastava
February 24, 2020 (v1)
Subject: Energy Policy
Keywords: electric vehicle, emissions, India, policy, pollution, transportation electrification, vehicle to grid (V2G)
Electric vehicles reduce pollution only if a high percentage of the electricity mix comes from renewable sources and if the battery manufacturing takes place at a site far from the vehicle use region. Industries developed due to increased electric vehicle adoption may also cause additional air pollution. The Indian government has committed to solving New Delhi’s air pollution issues through an ambitious policy of switching 100% of the light duty consumer vehicles to electric vehicles by 2030. This policy is based on vehicle grid interaction and relies on shared mobility through the electric vehicle fleet. There are several human behavioral changes necessary to achieve 100% adoption of electric vehicles. This paper reviews different steps in the lifecycle of an electric vehicle (EV), their impact on environmental emissions, and recommends policies suitable for different socio-economic group that are relevant to the Indian market. To reduce air pollution through adoption of electric vehi... [more]
An Improved Interval Fuzzy Modeling Method: Applications to the Estimation of Photovoltaic/Wind/Battery Power in Renewable Energy Systems
Nguyen Gia Minh Thao, Kenko Uchida
February 24, 2020 (v1)
Keywords: automatic-tuning scheme, boundary points, interval fuzzy modeling, linear programming, lower bound, min-max optimization, photovoltaic/wind/battery power system., upper bound
This paper proposes an improved interval fuzzy modeling (imIFML) technique based on modified linear programming and actual boundary points of data. The imIFML technique comprises four design stages. The first stage is based on conventional interval fuzzy modeling (coIFML) with first-order model and linear programming. The second stage defines reference lower and upper bounds of data using MATLAB. The third stage initially adjusts scaling parameters in the modified linear programming. The last stage automatically fine-tunes parameters in the modified linear programming to realize the best possible model. Lower and upper bounds approximated by the imIFML technique are closely fitted to the reference lower and upper bounds, respectively. The proposed imIFML is thus significantly less conservative in cases of large variation in data, while robustness is inherited from the coIFML. Design flowcharts, equations, and sample MATLAB code are presented for reference in future experiments. Perform... [more]
A Tale of Two Chinese Transit Metropolises and the Implementation of Their Policies: Shenyang and Dalian (Liaoning Province, China)
Rui Mu, Martin de Jong
February 24, 2020 (v1)
Subject: Energy Policy
Keywords: China, Dalian, policy implementation, Shenyang, transit metropolis, transport policy
To promote sustainable urbanization and combat the economic, environmental, energy and safety issues that go with rapid motorization, the Ministry of Transport in China has introduced the “Transit Metropolis” program with a substantive amount of funds devoted to the implementation of the program in local governments. This represents the largest ever central government-led effort addressing transit metropolis development in the world. How has the program been implemented locally? Have the selected demonstration cities followed the same principle or taken comparable measures to implement their version of the transit metropolis? What is their performance? These questions remain unknown in the current literature. This article answers the above questions through a literature review, interviews and comparative case studies in Shenyang and Dalian, two large cities in Liaoning Province. It shows that both cities have successfully achieved the target levels for building a transit metropolis. Si... [more]
A Comparative Study on Controllers for Improving Transient Stability of DFIG Wind Turbines During Large Disturbances
Minh Quan Duong, Sonia Leva, Marco Mussetta, Kim Hung Le
February 24, 2020 (v1)
Keywords: crowbar protection, Doubly-Fed Induction Generator (DFIG), squirrel-cage induction generator (SCIG), transient stability, wind turbine
Under power system short-circuits, the Doubly-Fed Induction Generator (DFIG) Wind Turbines (WT) are required to be equipped with crowbar protections to preserve the lifetime of power electronics devices. When the crowbar is switched on, the rotor windings are short-circuited. In this case, the DFIG behaves like a squirrel-cage induction generator (SCIG) and can adsorb reactive power, which can affect the power system. A DFIG based-fault-ride through (FRT) scheme with crowbar, rotor-side and grid-side converters has recently been proposed for improving the transient stability: in particular, a hybrid cascade Fuzzy-PI-based controlling technique has been demonstrated to be able to control the Insulated Gate Bipolar Transistor (IGBT) based frequency converter in order to enhance the transient stability. The performance of this hybrid control scheme is analyzed here and compared to other techniques, under a three-phase fault condition on a single machine connected to the grid. In particula... [more]
Design of Peak Efficiency of 85.3% WPC/PMA Wireless Power Receiver Using Synchronous Active Rectifier and Multi Feedback Low-Dropout Regulator
Zaffar Hayat Nawaz Khan, Young-Jun Park, Seong Jin Oh, Byeong Gi Jang, Seong-Mun Park, Hamed Abbasizadeh, Young Gun Pu, Keum Cheol Hwang, Youngoo Yang, Minjae Lee, Kang-Yoon Lee
February 24, 2020 (v1)
Keywords: active rectifier, multi-feedback low-dropout regulator, power conversion efficiency (PCE), wireless power receiver
An efficient synchronous active rectifier and Multi Feedback low drop out (LDO) Regulator coupled with a wireless power receiver (WPR) is proposed in this study. An active rectifier with maximum power conversion efficiency (PCE) of 94.2% is proposed to mitigate the reverse leakage current using zero current sensing. Output voltage and current are regulated by multi-feedback LDO regulator, sharing the single path transistor. The proposed chip is fabricated in the 0.18 μm BCD technology having die area of 16.0 mm². A 94.2% power conversion efficiency with the load current of 800 mA is measured for the proposed active rectifier.
Integrated Optimization of Speed Profiles and Power Split for a Tram with Hybrid Energy Storage Systems on a Signalized Route
Zhuang Xiao, Pengfei Sun, Qingyuan Wang, Yuqing Zhu, Xiaoyun Feng
February 24, 2020 (v1)
Keywords: hp-adaptive pseudospectral method, hybrid tram, multiple phases integrated optimization, signal control strategy
A tram with on-board hybrid energy storage systems based on batteries and supercapacitors is a new option for the urban traffic system. This configuration enables the tram to operate in both catenary zones and catenary-free zones, and the storage of regenerative braking energy for later usage. This paper presents a multiple phases integrated optimization (MPIO) method for the coordination of speed profiles and power split considering the signal control strategy. The objective is to minimize the equivalent total energy consumption of all the power sources, which includes both the energy from the traction substation and energy storage systems. The constraints contain running time, variable gradients and curves, speed limits, power balance and signal time at some intersections. The integrated optimization problem is formulated as a multiple phases model based on the characters of the signalized route. An integrated calculation framework, using hp-adaptive pseudospectral method, is propose... [more]
Mitigation Conducted Emission Strategy Based on Transfer Function from a DC-Fed Wireless Charging System for Electric Vehicles
Li Zhai, Yu Cao, Liwen Lin, Tao Zhang, Steven Kavuma
February 24, 2020 (v1)
Keywords: conducted emission, electric vehicle, mitigation strategy, wireless charging system
The large dv/dt and di/dt outputs of power devices in wireless charging system (WCS) in electric vehicles (EVs) always introduce conducted electromagnetic interference (EMI) emissions. This paper proposes a mitigation conducted emission strategy based on transfer function from a direct current fed (DC-fed) WCS for EVs. A complete test for the DC-fed WCS is set up to measure the conducted emission of DC power cables in a frequency range of 150 kHz⁻108 MHz. An equivalent circuit with high-frequency parasitic parameters for WCS for EV is built based on measurement results to obtain the characteristics of conducted emission from WCS. The transfer functions of differential mode (DM) interference and common mode (CM) interference were established. A judgment method of using transfer functions to determine the dominated interference mode responsible for EMI is proposed. From the comparison of simulation results between CM or DM and CM+DM interference, it can be seen that the CM interference i... [more]
Towards Optimal Power Management of Hybrid Electric Vehicles in Real-Time: A Review on Methods, Challenges, and State-Of-The-Art Solutions
Ahmed M. Ali, Dirk Söffker
February 24, 2020 (v1)
Keywords: hybrid electric vehicles, intelligent transportation systems, pattern recognition, real-time optimal power management
In light of increasing alerts about limited energy sources and environment degradation, it has become essential to search for alternatives to thermal engine-based vehicles which are a major source of air pollution and fossil fuel depletion. Hybrid electric vehicles (HEVs), encompassing multiple energy sources, are a short-term solution that meets the performance requirements and contributes to fuel saving and emission reduction aims. Power management methods such as regulating efficient energy flow to the vehicle propulsion, are core technologies of HEVs. Intelligent power management methods, capable of acquiring optimal power handling, accommodating system inaccuracies, and suiting real-time applications can significantly improve the powertrain efficiency at different operating conditions. Rule-based methods are simply structured and easily implementable in real-time; however, a limited optimality in power handling decisions can be achieved. Optimization-based methods are more capable... [more]
Optimal Control Algorithms with Adaptive Time-Mesh Refinement for Kite Power Systems
Luís Tiago Paiva, Fernando A. C. C. Fontes
February 24, 2020 (v1)
Keywords: adaptive algorithms, airborne wind energy, continuous-time systems, kite power systems, nonlinear systems, optimal control, real-time optimization, time-mesh refinement
This article addresses the problem of optimizing electrical power generation using kite power systems (KPSs). KPSs are airborne wind energy systems that aim to harvest the power of strong and steady high-altitude winds. With the aim of maximizing the total energy produced in a given time interval, we numerically solve an optimal control problem and thereby obtain trajectories and controls for kites. Efficiently solving these optimal control problems is crucial when the results are used in real-time control schemes, such as model predictive control. For this highly nonlinear problem, we derive continuous-time models—in 2D and 3D—and implement an adaptive time-mesh refinement algorithm. By solving the optimal control problem with such an adaptive refinement strategy, we generate a block-structured adapted mesh which gives results as accurate as those computed using fine mesh, yet with much less computing effort and high savings in memory and computing time.
A Voltage and Frequency Control Strategy for Stand-Alone Full Converter Wind Energy Conversion Systems
Andrés Peña Asensio, Santiago Arnaltes Gómez, Jose Luis Rodriguez-Amenedo, Manuel García Plaza, Joaquín Eloy-García Carrasco, Jaime Manuel Alonso-Martínez de las Morenas
February 24, 2020 (v1)
Keywords: frequency regulation, full converter (FC), isolated operation, permanent magnet synchronous generators (PMSGs), voltage-sourced converter, wind energy
This paper addresses the design and analysis of a voltage and frequency control (VFC) strategy for full converter (FC)-based wind energy conversion systems (WECSs) and its applicability for the supply of an isolated load. When supplying an isolated load, the role of the back-to-back converters in the FC must change with respect to a grid-connected application. Voltage and frequency are established by the FC line side converter (LSC), while the generator side converter (GSC) is responsible for maintaining constant voltage in the DC link. Thus, the roles of the converters in the WECS are inverted. Under such control strategies, the LSC will automatically supply the load power and hence, in order to maintain a stable operation of the WECS, the wind turbine (WT) power must also be controlled in a load-following strategy. The proposed VFC is fully modelled and a stability analysis is performed. Then, the operation of the WECS under the proposed VFC is simulated and tested on a real-time tes... [more]
Effect of Electrolyte Thickness on Electrochemical Reactions and Thermo-Fluidic Characteristics inside a SOFC Unit Cell
Jee Min Park, Dae Yun Kim, Jong Dae Baek, Yong-Jin Yoon, Pei-Chen Su, Seong Hyuk Lee
February 24, 2020 (v1)
Keywords: computational fluid dynamics (CFD), electrolyte thickness, heat and mass transfer, operating temperature, solid oxide fuel cell (SOFC)
We investigated the effect of electrolyte thickness and operating temperature on the heat and mass transfer characteristics of solid oxide fuel cells. We conducted extensive numerical simulations to analyze single cell performance of a planar solid oxide fuel cell (SOFC) with electrolyte thicknesses from 80 to 100 μm and operating temperatures between 700 °C and 800 °C. The commercial computational fluid dynamics (CFD) code was utilized to simulate the transport behavior and electrochemical reactions. As expected, the maximum power density increased with decreasing electrolyte thickness, and the difference became significant when the current density increased among different electrolyte thicknesses at a fixed temperature. Thinner electrolytes are beneficial for volumetric power density due to lower ohmic loss. Moreover, the SOFC performance enhanced with increasing operating temperature, which substantially changed the reaction rate along the channel direction. This study can be used t... [more]
Screening of Amino Acids and Surfactant as Hydrate Promoter for CO2 Capture from Flue Gas
Jyoti Shanker Pandey, Yousef Jouljamal Daas, Nicolas von Solms
February 12, 2020 (v1)
Keywords: amino acids, Carbon Dioxide Capture, flue gas hydrate, sodium dodecyl sulfate
In this study, the kinetics of flue gas hydrate formation in bulk water in the presence of selected amino acids and surfactants are investigated. Four amino acids (3000 ppm) are selected based on different hydropathy index. Constant-ramping and isothermal experiments at 120 bar pressure and 1 °C temperature are carried out to compare their hydrate promotion capabilities with surfactant sodium dodecyl sulfate (SDS) (500−3000 ppm) and water. Based on experimental results, we report the correlation between hydrate promotion capability of amino acids and their hydrophobicity. Hydrophobic amino acids show stronger flue gas hydrate promotion capability than water and hydrophilic amino acids. We discuss the controlling mechanisms to differentiate between promoters and inhibitors’ roles among the amino acids. Between 2000−3000 ppm concentrations, hydrophobic amino acids have near similar promotion capabilities as SDS. This research highlights the potential use of amino acids as promoters or in... [more]
Numerical Study on the Influence of Inlet Guide Vanes on the Internal Flow Characteristics of Centrifugal Pump
Peifeng Lin, Yongzheng Li, Wenbin Xu, Hui Chen, Zuchao Zhu
February 12, 2020 (v1)
Keywords: centrifugal pump, inlet guide vanes, offset angle, the pressure fluctuation frequency
In order to make the centrifugal pump run efficiently and stably under various working conditions, the influences of the incoming vortex flow in the inlet pipe on the main flow in the impeller is studied numerically, based on the k − ω SST turbulence model. Some guide vanes with different offset angle were added to change the statistical characteristic of the internal flow in the inlet pipe of the centrifugal pump. Both contour distributions of internal flow and statistical results of external performance are obtained and analyzed. The results show that the existence of vanes can divide the large vortex because of the reversed flow from the rotating impeller at low flow rate conditions into small vortices, which are easier to dissipate, make the velocity and pressure distribution more uniform, improve the stability of the flow in the impeller, reduce the hydraulic loss, and improve the hydraulic performance of the pump. The pump with vanes of offset angle 25° has a small pressu... [more]
Modeling and Exploiting Microbial Temperature Response
Philipp Noll, Lars Lilge, Rudolf Hausmann, Marius Henkel
February 12, 2020 (v1)
Keywords: bioprocess engineering, calorimetry, monitoring and control, temperature modeling, thermal growth curve, thermoregulation
Temperature is an important parameter in bioprocesses, influencing the structure and functionality of almost every biomolecule, as well as affecting metabolic reaction rates. In industrial biotechnology, the temperature is usually tightly controlled at an optimum value. Smart variation of the temperature to optimize the performance of a bioprocess brings about multiple complex and interconnected metabolic changes and is so far only rarely applied. Mathematical descriptions and models facilitate a reduction in complexity, as well as an understanding, of these interconnections. Starting in the 19th century with the “primal” temperature model of Svante Arrhenius, a variety of models have evolved over time to describe growth and enzymatic reaction rates as functions of temperature. Data-driven empirical approaches, as well as complex mechanistic models based on thermodynamic knowledge of biomolecular behavior at different temperatures, have been developed. Even though underlying biological... [more]
Characteristics of Low-Temperature Polyvinyl Chloride Carbonization by Catalytic CuAl Layered Double Hydroxide
Erwei Pang, Weijun Liu, Shuhua Zhang, Nengshuo Fu, Zhongxun Tian
February 12, 2020 (v1)
Keywords: catalytic PVC pyrolysis, CuAl layered double hydroxide (CuAl-LDH), PVC carbonization
A good way to make carbon materials was presented in low-temperature polyvinyl chloride (PVC) carbonization by catalysis. The process of low-temperature PVC carbonization by CuAl-layered double hydroxide (CuAl-LDH) was investigated by thermogravimetric analysis (TGA) and tubular furnace. The results show that CuAl-LDH accounting for 5% of PVC mass enabled acceleration of the dehydrochlorination in PVC as soon as possible and maximized the yield of the PVC carbonized product. The vacuum with 0.08 MPa, 20 °C/min heating rate and 90 min carbonized maintenance time were optimal for PVC carbonization. Moreover, the best morphology and yield of the carbonized product was provided at a carbonization temperature of 300 °C.
Energy and Material Flows and Carbon Footprint Assessment Concerning the Production of HMF and Furfural from a Cellulosic Biomass
Hannes Schöppe, Peter Kleine-Möllhoff, Rolf Epple
February 12, 2020 (v1)
Subject: Energy Policy
Keywords: 5-hydroxymethylfurfural, bio-based chemical production, carbon footprint, furfural, HMF, material and energy flows
5-hydroxymethyl-furfural (HMF) and furfural are interesting as potential platform chemicals for a bio-based chemical production economy. Within the scope of this work, the process routes under technical development for the production of these platform chemicals were investigated. For two selected processes, the material and energy flows, as well as the carbon footprint, were examined in detail. The possible production process optimizations, further development potentials, and the research demand against the background of the reduction of the primary energy expenditure were worked out.
Polyetherimide-Montmorillonite Nano-Hybrid Composite Membranes: CO2 Permeance Study via Theoretical Models
Asif Jamil, Oh Pei Ching, Muhammad Naqvi, Hafiza Aroosa Aslam Khan, Salman Raza Naqvi
February 12, 2020 (v1)
Subject: Materials
Keywords: bharadwaj, CO2 permeation, composite membranes, hollow fibre, montmorillonite, polyetherimide
The incorporation of aminolauric acid modified montmorillonite (f-MMT) in polyetherimide (PEI) has been implemented to develop hollow fibre nano-hybrid composite membranes (NHCMs) with improved gas separation characteristics. The aforementioned characteristics are caused by enhanced f-MMT spatial dispersion and interfacial interactions with PEI matrix. In this study, existing gas permeation models such as, Nielsen, Cussler, Yang−Cussler, Lape−Cussler and Bharadwaj were adopted to estimate the dispersion state of f-MMT and to predict the CO2 permeance in developed NHCMs. It was found out that the average aspect ratio estimated was 53, with 3 numbers of stacks per unit tactoid, which showed that the intercalation f-MMT morphology is the dominating dispersion state of filler in PEI matrix. Moreover, it was observed that Bharadwaj model showed the least average absolute relative error (RE) values till 3 wt. % f-MMT loading in the range of ±10 for a pressure range of 2 to 10 bar. Hence, Bha... [more]
Showing records 1 to 25 of 144. [First] Page: 1 2 3 4 5 Last
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