Photochlorination of toluene – the thin line between intensification and selectivity. Part 1: intensification and effect of operation conditions

2021 ◽  
Vol 6 (1) ◽  
pp. 82-89 ◽  
Author(s):  
Ümit Taştan ◽  
Dirk Ziegenbalg
Keyword(s):  
Energy Efficiency ◽  
Side Reactions ◽  
Thin Line ◽  
Operation Conditions ◽  
Microstructured Reactors

Intensification of photochlorination of toluene in microstructured reactors by up to a factor of 10 was achieved, but also caused an unexpected decrease of selectivity. Dynamic irradiation suppressed side reactions and increased energy efficiency.

Reactions in Activated Peroxide Systems and their Influences on Bleaching Performance

2020 ◽  
Vol 17 ◽  
Author(s):  
Xiaoyan Wang ◽  
Jinmei Du ◽  
Changhai Xu
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Energy Efficiency ◽  
Textile Industry ◽  
High Energy ◽  
Side Reactions ◽  
Competitive Reactions ◽  
High Energy Efficiency ◽  
Hydrolysis Of ◽  
Bleach Activators

Abstract:: Activated peroxide systems are formed by adding so-called bleach activators to aqueous solution of hydrogen peroxide, developed in the seventies of the last century for use in domestic laundry for their high energy efficiency and introduced at the beginning of the 21st century to the textile industry as an approach toward overcoming the extensive energy consumption in bleaching. In activated peroxide systems, bleach activators undergo perhydrolysis to generate more kinetically active peracids that enable bleaching under milder conditions while hydrolysis of bleach activators and decomposition of peracids may occur as side reactions to weaken the bleaching efficiency. This mini-review aims to summarize these competitive reactions in activated peroxide systems and their influence on bleaching performance.

scholarly journals Degradation Investigation of Electrocatalyst in Proton Exchange Membrane Fuel Cell at a High Energy Efficiency

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3932
Author(s):  
Jie Song ◽  
Qing Ye ◽  
Kun Wang ◽  
Zhiyuan Guo ◽  
Meiling Dou
Keyword(s):  
Energy Efficiency ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
High Energy ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Operation Conditions ◽  
High Efficient ◽  
Exchange Membrane

The development of high efficient stacks is critical for the wide spread application of proton exchange membrane fuel cells (PEMFCs) in transportation and stationary power plant. Currently, the favorable operation conditions of PEMFCs are with single cell voltage between 0.65 and 0.7 V, corresponding to energy efficiency lower than 57%. For the long term, PEMFCs need to be operated at higher voltage to increase the energy efficiency and thus promote the fuel economy for transportation and stationary applications. Herein, PEMFC single cell was investigated to demonstrate its capability to working with voltage and energy efficiency higher than 0.8 V and 65%, respectively. It was demonstrated that the PEMFC encountered a significant performance degradation after the 64 h operation. The cell voltage declined by more than 13% at the current density of 1000 mA cm−2, due to the electrode de-activation. The high operation potential of the cathode leads to the corrosion of carbon support and then causes the detachment of Pt nanoparticles, resulting in significant Pt agglomeration. The catalytic surface area of cathode Pt is thus reduced for oxygen reduction and the cell performance decreased. Therefore, electrochemically stable Pt catalyst is highly desirable for efficient PEMFCs operated under cell voltage higher than 0.8 V.

Powder Spheroidization Using Induction Plasma Technology

2000 ◽  
Author(s):  
N.M. Dignard ◽  
M.I. Boulos
Keyword(s):  
Energy Efficiency ◽  
Maximum Energy ◽  
Operating Conditions ◽  
Side Reactions ◽  
Induction Plasma ◽  
Silica Alumina ◽  
Change In The Mean ◽  
The Individual ◽  
Semi Empirical ◽  
Objective Being

Abstract An experimental study of the spheroidization efficiency of induction plasma processes was completed. The main objective being to obtain models which could be subsequently used for the prediction of the spheroidization efficiency for various powders and plasma operating conditions. Silica, alumina, chromium oxide and zirconia powders were treated during the experimentation. For the plasma treatment of the powders the installation used had a maximum available power of 50 kW with an operating frequency of 3 MHz. Operating conditions were varied such to minimize side reactions and the evaporation of powders. The resulting powders did show the presence of cavities and a slight change in the mean diameters. The maximum energy efficiency based semi-empirical model did predict the spheroidization efficiency of the particles beyond a defined critical point known as the maximum energy efficiency point. For the model, the maximum energy efficiency is distinct for the individual powders but remain within a defined range which is reflected in the small variations in the Z constant.

scholarly journals Technological Innovation in the Aspect of Safety in the Process of Heat Supply

2019 ◽  
Vol 1 (1) ◽  
pp. 412-418
Author(s):  
Aleksandra Wrzalik ◽  
Matevž Obrecht
Keyword(s):  
Energy Efficiency ◽  
Heat Supply ◽  
Renewable Energy Sources ◽  
District Heating ◽  
High Energy ◽  
The European Union ◽  
Heating Systems ◽  
Operation Conditions ◽  
Network Operation ◽  
The Impact

AbstractIn recent years heating in Poland has been transformed as a result of the priorities of the country's energy policy implemented within the European Union. The increase in energy security, the development of renewable energy sources and the fulfilment of legal and environmental requirements are very important. Exploitation of district heating systems should ensure reliable and safe heat supplies for industrial and municipal customers with high energy efficiency and reduction of environmental impact. The article discusses the conditions and directions of centralized heating systems development as well as technical and economic issues, which are important for the security of heat supply. The Author describes selected technological innovations used in the technical infrastructure for heat transfer and modern IT systems which are improving the management of heating systems. The article includes the results of simulation research with use of IT tools showing the impact of selected innovations on the improvement of network operation conditions. Directions of modernization of heating systems in the aspect of increasing energy efficiency and security of heat supply have also been indicted here.

Fast fabrication of self-supported porous nickel phosphide foam for efficient, durable oxygen evolution and overall water splitting

2016 ◽  
Vol 4 (15) ◽  
pp. 5639-5646 ◽  
Author(s):  
Xiaoguang Wang ◽  
Wei Li ◽  
Dehua Xiong ◽  
Lifeng Liu
Keyword(s):  
Energy Efficiency ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Nickel Phosphide ◽  
Porous Nickel ◽  
Step Method ◽  
Overall Water Splitting ◽  
Operation Conditions ◽  
One Step

Self-supported porous Ni–P foam is fabricated by a convenient one-step method, and exhibits excellent electrocatalytic performance towards oxygen evolution reaction. An alkaline electrolyzer constructed using two self-supported porous Ni–P foams shows superior energy efficiency of 90.2% at 10 mA cm−2, and can sustain 1000 h under operation conditions without obvious degradation.

scholarly journals LabView-based Simulator for PV Modules Energy Efficiency Optimization

1970 ◽  
Vol 4 (1.) ◽  
Author(s):  
Csaba Szász
Keyword(s):  
Energy Efficiency ◽  
Virtual Instrument ◽  
Research Effort ◽  
Energy Conversion Efficiency ◽  
High Quality Research ◽  
Point Tracking ◽  
Operation Conditions ◽  
Conversion Rates ◽  
Wide Range ◽  
Efficiency Conversion

Due to the rapid depletion of traditional fossil energy resources the optimal utilization of renewable resources such as the solar energy becomes a leading task in power engineering. In recent years photovoltaic energy-linked technologies has reached major advances in order to achieve improved energy efficiency conversion rates. In this endeavor, a huge amount of high quality research effort is dedicated worldwide. This paper is focused to present the design and implementation steps of a LabView -based toolkit aimed to modeling and simulates solar photovoltaic (PV) cells in a wide range of operation conditions. By using its well known mathematical model, it has been conceived a versatile and user-friendly simulator well suitable to study and evaluate energy efficiency conversion processes. In order to maximize the energy conversion efficiency the maximum power point tracking (MPPT) algorithm has been implemented. The virtual instrument (VI) developed in the graphical programming language allows fast and convenient monitoring of PV cell output magnitudes and plots the I-U and P-U diagrams under different operation conditions. These curves have been compared then with the diagrams provided by the PV module manufacturer. The obtained results are in good agreement with the manufacturer’s catalogue data.

Energy Conversion Efficiency of Synthetic Jets

2011 ◽  
Author(s):  
Ri Li ◽  
Rajdeep Sharma ◽  
Mehmet Arik
Keyword(s):  
Energy Efficiency ◽  
Energy Conversion ◽  
Electric Power ◽  
Piezoelectric Actuators ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Signal Frequency ◽  
Laser Vibrometer ◽  
Zero Bias ◽  
Operation Conditions

Synthetic jets are driven by a periodic electrical signal to generate pulsated airflow that can provide cooling to a hot surface. The working principle of synthetic jets involves conversion of electrical energy into mechanical and fluid energy. Piezoelectric actuators, comprising of a thin metal substrate bonded to a piezoelectric disk are induced to undergo vibration motion in bending mode by an AC sine-wave voltage with zero bias. Synthetic jets, which consist of two piezoelectric actuators separated by a compliant ring at the outer periphery of the actuators, undergo a bellow-like action due to the periodic motion of the actuators, thereby ingesting air and pushing air at high velocities through the orifice. In this paper, we seek to understand and quantify the efficiency of synthetic jets with a view towards optimizing their design. In this study, energy efficiency of synthetic jet is defined based on thermodynamics principles. Analytical equations for calculating consumed electric power and airflow power are derived. Using the derived equations, energy efficiency of synthetic jets is experimentally investigated. Air velocity at the jet orifice is measured using constant temperature hotwire anemometry. Voltage signal and resultant current waveform are recorded to calculate electric power. In order to understand the structural behavior, laser vibrometer is used to measure the center out-of-plane deflection of the piezoelectric synthetic jet. Electrical power input is varied by changing signal frequency and voltage amplitude. Synthetic jets with two different orifice sizes are tested, and the efficiency of energy conversion is determined. The effects of jet design and operation conditions on energy efficiency are discussed.

Thermal Performances of a High Temperature Air Solar Absorber Based on Compact Heat Exchange Technology

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
B. Grange ◽  
A. Ferrière ◽  
D. Bellard ◽  
M. Vrinat ◽  
R. Couturier ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Wall Temperature ◽  
Solar Irradiation ◽  
Metallic Surface ◽  
Small Scale ◽  
Maximum Pressure ◽  
Outlet Temperature ◽  
Solar Absorber ◽  
Operation Conditions ◽  
Solar Receiver

In the framework of the French PEGASE project (Production of Electricity by GAs turbine and Solar Energy), CNRS/PROMES laboratory is developing a 4 MWth pressurized air solar receiver with a surface absorber based on a compact heat exchanger technology. The first step of this development consists in designing and testing a pilot scale (1/10 scale, e.g., 360 kWth) solar receiver based on a metallic surface absorber. This paper briefly presents the hydraulic and thermal performances of the innovative pressurized air solar absorber developed in a previous work. The goal is to be capable of preheating pressurized air from 350 °C at the inlet to 750 °C at the outlet, with a maximum pressure drop of 300 mbar. The receiver is a cavity of square aperture 120 cm × 120 cm and 1 m deepness with an average concentration in the aperture of more than 300. The square shaped aperture is chosen due to the small scale of the receiver; indeed, the performances are not enhanced that much with a round aperture, while the manufacturability is much more complicated. However in the perspective of PEGASE, a round aperture is likely to be used. The back of the cavity is covered by modules arranged in two series making the modular and multistage absorber. The thermal performances of one module are considered to simulate the thermal exchange within the receiver and to estimate the energy efficiency of this receiver. The results of the simulation show that the basic design yields an air outlet temperature of 739 °C under design operation conditions (1000 W/m2 solar irradiation, 0.8 kg/s air flow rate). Using the cavity walls as air preheating elements allows increasing the air outlet temperature above 750 °C as well as the energy efficiency up to 81% but at the cost of a critical absorber wall temperature. However, this wall temperature can be controlled by applying an aiming point strategy with the heliostat field.

scholarly journals Method for assessing the energy efficiency of a vehicle taking into account the load under operating conditions

2021 ◽  
Vol 264 ◽  
pp. 05033
Author(s):  
Umidulla Abdurazzokov ◽  
Bakhramjan Sattivaldiev ◽  
Ravshan Khikmatov ◽  
Shakhnoza Ziyaeva
Keyword(s):  
Energy Efficiency ◽  
Combustion Engine ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Mechanical Work ◽  
Energy Costs ◽  
Test Results ◽  
Engine Torque ◽  
Operation Conditions ◽  
Available Information

In operation conditions, the transport work of a vehicle is estimated by the increment in the mass of the freight over the distance traveled. This criterion does not characterize the mechanical work of the vehicle in the transport process. Without analyzing the energy costs of performing mechanical work, it is impossible to assess the energy efficiency of a vehicle. The energy efficiency of a vehicle is defined as the ratio of the mechanical work performed by the vehicle to the potential energy of the source. In this paper, it is proposed to determine the engine torque by fuel consumption. The engine torque value depends on the energy required for driving the vehicle. Based on the analysis of the results of computational and experimental studies, a method for assessing the energy efficiency of a vehicle with an internal combustion engine is proposed. The reliability of the results obtained is substantiated by the test results and the available information in practice.

scholarly journals On-Surface Porphyrin Transmetalation by Pb/Cu Redox Exchange

2020 ◽  
Author(s):  
Jan Herritsch ◽  
Stefan R. Kachel ◽  
Qitang Fan ◽  
Mark Hutter ◽  
Lukas Heuplick ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Scanning Tunneling ◽  
Side Reactions ◽  
Metal Exchange ◽  
Exchange Reactions ◽  
Tunneling Microscopy ◽  
Operation Conditions

Metal complexes at surfaces and interfaces play a prominant role in many areas of modern technology, including catalysis, sensors, and organic electronics. An important aspect of these interfaces is the possible exchange of the metal center, because this reaction can drastically alter the properties of the metal complex and thus of the interface. Here, we demonstrate that such metal exchange reactions are indeed possible and can proceed already at moderate temperatures even in the absence of solvents. Specifically, we studied the redox transmetalation of a monolayer of lead(II)-tetraphenylporphyrin (PbTPP) with copper from a Cu(111) surface under ultrahigh-vacuum (UHV) conditions using multiple surface-sensitive techniques. Temperature dependent X-ray photoelectron spectroscopy (XPS) reveals that the Pb/Cu exchange starts already below 380 K and is complete at 600 K. The identity of the reaction product, CuTPP, is confirmed by mass spectrometric detection in a temperature-programmed reaction (TPR) experiment. Scanning tunneling microscopy (STM) sheds light on the adsorbate structure of PbTPP at 300 K and uncovers the structural changes accompanying the transmetalation and side-reactions of the phenyl substituents. Moreover, individual free Pb atoms are observed as a product of the metal exchange. Our study suggests that surfaces functionalized with metal complexes may consist of other species than intended under operation conditions, which often involve elevated temperatures.

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