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There is insufficient literature about solarized gas turbines that achieved high efficiency and solar share simultaneously. It is because the outlet temperature of a solar receiver is always much lower than a combustor and it is difficult to design a high-efficiency exhaust-heat recovery system except for a complicated Rankine cycle. A solar-assisted chemically recuperated gas turbine system is proposed and expected to achieve a good performance by combining with two-stage fuel-steam reforming. The first stage is a low-temperature reformer, recovering exhaust gas heat, and the second stage is a high-temperature one, absorbing concentrated solar radiation. Thermodynamic analyses and comparisons are conducted. This system is expected to have a competitive thermal efficiency of 47.7%, which is 10.6 percentage points higher than that of a solarized gas turbine system without reformers. Meanwhile, it has a solar share of 75.0%, which is 12.8 percentage points higher than that of a solarized gas turbine system with a low-temperature reformer. In the viewpoint of energy level, the two-stage fuel reforming upgrades low-level thermal energy of the turbine exhaust and solar receiver into high-level chemical energy, reducing exergy destruction. The relative upgrade of energy level is 38.2% for turbine exhaust and 17.4% for solar thermal energy. [ABSTRACT FROM AUTHOR]

A key issue in designing and optimizing Stirling engines is to build a precise thermodynamic model to predict the output power, thermal efficiency, and detailed performance properties and provide useful information for further improvement. In this study, a thermodynamic model called Improved Simple Analytical Model (ISAM) was proposed, carefully considering heat and power losses in Stirling engines. A 100 W β -type Stirling engine was built and tested with helium and nitrogen when pressure and rotary speed ranging from 1.6 MPa to 3 MPa and 260 r/min to 1380 r/min, respectively. Experimental information on performance, such as PV diagrams and temperatures of the heater and cooler, was much detailed. Increasing rotary speed brings a “thin” PV diagram because it made compression and expansion processes become more imperfect, indicating heat transfer enhancement was necessary for compression and expansion chamber in a high speed Stirling engine. Shaft power reached the maximum value of 30.1 W for helium and 21.0 W for nitrogen at rotary speeds of 1000 r/min and 650 r/min, respectively. Improving the mean pressure of gas increased the indicated power, cycle efficiency, shaft power, and electrical power. The maximum indicated power and cycle efficiency were 165 W and 16.5% for helium and 139 W and 12.2% for nitrogen in the same working conditions of 2.96 MPa and 1120 r/min. The ISAM agrees well with the experimental data with a deviation of 4.3–13.4% for helium and 1–7.1% for nitrogen. Analysis of energy losses with ISAM indicated that helium had larger shuttle and seal leakage losses and smaller flow resistance and regenerator heat transfer losses than nitrogen under the same working conditions. Flow resistance and regenerator heat transfer losses, which increased much more rapidly than seal leakage or shuttle heat losses with the increase in rotary speed and pressure, played an important role and resulted in different performances with the two working gases. This study provides comprehensive understanding of the influence mechanism of rotary speed, pressure and working gas in the view of heat/power losses for Stirling engine performance, and recommends that more work (e.g., mechanisms of heat and power losses and PV diagrams) should be performed to improve the precision of second-order models. [ABSTRACT FROM AUTHOR]

The high-temperature electrostatic precipitator (ESP) is a potentially efficient method for hot-gas cleaning in advanced technologies, e.g., the coal-staged conversion poly-generation system and IGCC. This paper investigates the characteristics of the ash layer on the internal surface of the anode pipe of a wire–cylinder ESP at temperatures ranging from 350 °C to 700 °C, including ash deposition forms, growth of ash layer and the effect of ash layer on back corona discharge. There are four typical ash deposition forms: the belt form, the slope with ribs form, the slope form and the slope with a thick bottom edge form. Ash layer thickness generally decreases with increasing height. When T ⩽ 500 °C, ash belts form under low port voltages, and with increasing port voltage, they will overlap each other to form ash ribs. When T ⩾ 500 °C, particles are deposited in the smooth slope form if the port voltage is great enough. When T ⩾ 700 °C, a thick bottom ash edge occurs. Ash deposition forms can vary under different operating conditions. As the operating time increases, the thickness growth rate at a given point decreases, and the ash layer height increases because of the repulsive electrical force between the ash layer and the particles. Back corona discharge always occurs on the thickest portion of the ash layer first. The back corona discharge onset voltage decreases nearly linearly with increasing ash layer thickness, from 19,787 V to 17,197 V as the maximum thickness of the ash layer increases from 0.34 to 2.02 mm when T = 500 °C, U p = 17,200 V and m in = 650 mg/N m 3 . [ABSTRACT FROM AUTHOR]

High-temperature electrostatic precipitation is a potential method for hot gas clean-up that is hindered by the issue of back corona discharge (BCD). This paper reports on the development of BCD at 350–700 °C in a wire-cylinder electrostatic precipitator (ESP). As the output voltage of power supply increases, BCD begins at the surface of the ash layer, and then it extends toward the electrode gap space, forming consecutive discharge channels that bridge the two electrodes, ultimately leading to spark breakdown (SB). The discharge process that follows BCD can be classified into different stages: the NCD & BCD stages, the weak NCD, BCD & glow discharge stage, and the BCD & SB stages. At high temperatures (500 °C or above), BCD is likely to convert to SB. In the NCD & BCD stages, the collection efficiency of the electrostatic precipitator is not affected, i.e., the collection efficiency is ~ 99.65%, regardless of whether BCD exists or not at a temperature of 350 °C and a port voltage of ~ 17,200 V. In the BCD & SB stages, the collection efficiency is greatly reduced, i.e., it is ~ 88.35% in the NCD-only stage at a temperature of 500 °C and a port voltage of ~ 14,000 V, whereas it is only ~ 67.42% in the BCD & SB stages. It should be noted that BCD results in an increase in the power consumption of the ESP for all stages. A physical model is proposed to explain the processes that initiate, maintain, and develop BCD. [ABSTRACT FROM AUTHOR]

Highlights: [•] BC formation from open burning and controlled combustion are summarized. [•] Different sampling and measuring processes for open burning and controlled combustion are compared. [•] BC inventory prediction methods and results are reviewed. [•] Results of BC inventory estimation in China showed lower values than other researches. [Copyright &y& Elsevier]

In this work, the effects of nanoparticle size, particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated. Both size and pH are found to significantly affect nanocolloid viscosity. Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion. The fractal concept is introduced to describe the irregular and dynamic aggregate structure. The structure of aggregates, which is considered to play an important role in viscosity, is affected by both intermolecular and electrostatic forces. The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction. The aggregate structure is also affected by the pH of the solution. Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force, the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure. [ABSTRACT FROM AUTHOR]

Abstract: High temperature combustion experiments of waste printed circuit boards (PCBs) were conducted using a lab-scale system featuring a continuously-fed drop tube furnace. Combustion efficiency and the occurrence of inorganic bromine (HBr and Br2) were systematically studied by monitoring the main combustion products continuously. The influence of furnace temperature (T) was studied from 800 to 1400°C, the excess air factor (EAF) was varied from 1.2 to 1.9 and the residence time in the high temperature zone (RTHT) was set at 0.25, 0.5, or 0.75s. Combustion efficiency depends on temperature, EAF and RTHT; temperature has the most significant effect. Conversion of organic bromine from flame retardants into HBr and Br2 depends on temperature and EAF. Temperature has crucial influence over the ratio of HBr to Br2, whereas oxygen partial pressure plays a minor role. The two forms of inorganic bromine seem substantially to reach thermodynamic equilibrium within 0.25s. High temperature is required to improve the combustion performance: at 1200°C or higher, an EAF of 1.3 or more, and a RTHT exceeding 0.75s, combustion is quite complete, the CO concentration in flue gas and remained carbon in ash are sufficiently low, and organobrominated compounds are successfully decomposed (more than 99.9%). According to these results, incineration of waste PCBs without preliminary separation and without additives would perform very well under certain conditions; the potential precursors for brominated dioxins formation could be destroyed efficiently. Increasing temperature could decrease the volume percentage ratio of Br2/HBr in flue gas greatly. [Copyright &y& Elsevier]

Stirling engine has become preferable for high attention towards the use of alternate renewable energy resources like biomass and solar energy. Stirling engine is the main component of dish Stirling system in thermal power generation sector. Stirling engine is an externally heating engine, which theoretical efficiency is as high as Carnot cycle's, but actual ones are always far below compared with the Carnot efficiency. A number of studies have been done on multi-objective optimization to improve the design of Stirling engine. In the current study, a multi-objective optimization method, which is a combination of multiple optimization algorithms including differential evolution, genetic algorithm and adaptive simulated annealing, was proposed. This method is an attempt to generalize and improve the robustness and diversity with above three kinds of population based meta-heuristic optimization techniques. The analogous interpreter was linked and interchanged to find the best global optimal solution for Stirling engine performance optimization. It decreases the chance of convergence at a local minimum by powering from the fact that these three algorithms run parallel and members from each population and technique are swapped. The optimization considers five decision variables, including engine frequency, mean effective pressure, temperature of heating source, number of wires in regenerator matrix, and the wire diameter of regenerator, as multiple objectives. The Pareto optimal frontier was obtained and a final optimal solution was also selected by using various multi-criteria decision making methods including techniques for Order of Preference by Similarity to Ideal Solution and Simple Additive Weighting. The multi-objective optimization indicated a way for GPU-3 Stirling engine to obtain an output power of more than 3 kW and an increase by 5% in thermal efficiency with significant decrease in power loss due to flow resistance. [ABSTRACT FROM AUTHOR]

Photon-enhanced thermionic emission (PETE) is an advanced technology that combines both the photoelectric and the thermionic effects synergistically into a single device for direct electricity generation. However, its industrial-level application is still missing partly due to the lack of advanced models to analyze its operating characteristics and to understand the synergistic mechanism. Herein, we develop a numerical model of PETE by fully considering the optical, the electrical and the thermodynamic aspects with one-dimensional steady-state continuity equations of carriers in the semiconductor cathode. A hybrid PETE-Stirling cycle system is also proposed to yield an output power density of 162.65 kW/m2 with 32.8% conversion efficiency. The PETE conversion efficiency keeps ∼20% with the optimal electron affinity increases from 0.5 to 1.14 eV as solar concentration ratio varies from 100 to 500. The cathode thickness should be optimized by considering both solar absorption and photon enhancement, where the thickness range of 0.78–1.52 μm is obtained for 50–500 suns. The interelectrode gap is also found to significantly affect the PETE performance by regulating both the space-charge effect and near-field radiation, where the range of 0.5–2 μm is recommended. This work can serve as a foundation to understand the working mechanism of PETE converters and provide guidelines for the performance evaluation. [Display omitted] • Numerical models are developed for photon-enhanced thermionic emission converters. • Coupled effects of optical, electrical and thermodynamic fields are fully considered. • Characteristics of the converter for various scenarios are analyzed in detail. • A hybrid system is proposed with a 162.65 kW/m2 power density and a 32.8% efficiency. [ABSTRACT FROM AUTHOR]

Solar air Brayton cycle is a promising option to adjust the renewable power fluctuation due to its quick load regulation capacity. For the successful design and deployment of the solar air Brayton cycle system, the dynamic operation performance of solar collectors under real operating conditions are of great importance. In this study, experiments of a solar collector consisting of the heliostat field and the air receiver are carried out. Based on the experimental investigation of the operating characteristics for the solar collector, a dynamic model is further developed and well-validated to couple the heliostat field and air receiver. The dynamic performance of the air receiver is studied with various factors, including the DNI change and the receiver heat capacity. The results show that the receiver outlet temperature can reach up to 882 °C with a pressure loss of 7.10 kPa and a thermal power of 132 kW during the experiment. Two operation strategies of the air receiver are compared by carrying out the intraday simulation and the constant-outlet-temperature control strategy is more suitable for fast start-up. The method developed in this paper can serve as an efficient tool for the understanding, design and optimization of solar collectors. • Pressured air is heated over 880 °C by a solar receiver. • The operation performance of solar air receiver is explored. • Dynamic model coupling heliostat field and receiver is developed. • The dynamic model is validated by the experimental data. • Two operation strategies of the solar air receiver are compared. [ABSTRACT FROM AUTHOR]

High temperature air is a potential candidate as a heat transfer fluid to transport energy from concentrated solar power to gas turbines. A 15-turn helically coiled tube cavity receiver with an optical splitter at the bottom is designed and fabricated. Its performance is investigated with a five 7-kW Xe-arc lamps array system as heat source. Eight K-type thermocouples are placed from top to bottom with an equal interval. The outlet temperature experimentally ranges from 593 °C to 546 °C when the air flow rate increases from 1 m 3 /h to 5 m 3 /h for up-flows, while it ranges from 662 °C to 570 °C for down-flows, when the average flux on aperture is around 120 kW/m 2 . The Monte-Carlo ray-tracing method and the Lambert testing method with a charge-coupled device (CCD) camera are used to simulate and evaluate the concentrating radiation energy distribution on the cavity’s internal walls, and then the actual flux distribution of each turn of the helically coiled tube is obtained. A comprehensive simulation model is proposed and validated by the experimental results, where the outlet temperature deviations are within 8.0% and 2.5% for down and up-flows, respectively. The model provides a detailed analysis of heat flows at different conditions, and indicates optimization ways to improve the efficiency and reduce heat losses. The simulation results show that the outlet temperature can increase up to around 800 °C at 5 m 3 /h under an average flux of 300 kW/m 2 , and the thermal efficiency can be improved from around 56% to around 64% by decreasing the inner radius from 6 mm to 4 mm at the expense of increasing pressure drop of around 56 kPa. [ABSTRACT FROM AUTHOR]

A spiral solar particle receiver (SSPR) with a conical cover was proposed, and the performance was experimentally and numerically investigated. The SSPR was heated by a concentrated radiant flux of ∼5 kW over a 10 cm-diameter aperture with a maximum irradiance of over 700 kW/m 2 . The experimental results indicated the particle temperature increase reached over 625 °C in a single pass with an optical and a thermal efficiency of ∼87% and ∼60%, respectively, when the mass flow rate was 0.21 kg/min. The optical performances of the solar simulator and the receiver were combined and simulated by the Monte-Carlo ray-tracing method. Based on the optical model, a dynamic thermal conversion model was built, which indicated the particle temperature and the overall efficiency of SSPR would reach 628–673 °C and 58.9–63.7%, respectively, when the SSPR was coupled with a 3 m two-stage dish concentrator with a solar inclination angle ranging from 60° to 120°. [ABSTRACT FROM AUTHOR]

Various impeded flow particle receivers were proposed to prolong the particle residence time but always faced the risk of thermal deterioration and the difficulty of real-time particle velocity control. Herein, we reported a novel impeded flow particle receiver to solve above problems and further have the potential to control the particle velocity distribution, which could provide a heat source with better stability, better uniformity and higher temperature for subsequent thermal power generation and other thermal applications. In this receiver, the friction along the path and the gate valves at outlet act as the obstruction structures to allow the particles to move slowly and controllably in the form of a sliding-bed, which is why we call this receiver a sliding-bed receiver. The sliding-bed receiver's structural validity and operational characteristics at different working conditions were detailly investigated with both experimental and numerical methods. Experimental results showed that the outlet particle temperature and efficiency could reach 847 °C and 77.2% under a solar simulator of 4 kW. An optical and thermal coupling model was developed and revealed an improved particle temperature of 1350 °C and efficiency of 82% under higher incident power. The effects of the effects of the incident power distribution, the particle velocity distribution and the quartz glass on aperture on the receiver performance were detailly analyzed, which could also help optimize the design and operation of other particle receivers such as free-falling particle receivers. [Display omitted] • A sliding-bed particle receiver was elaborately designed and tested. • Better stability and controllability of endothermic process was achieved. • Outlet temperature of 847 °C was reached under a solar simulator of 4 kW. • Outlet temperature of 1350 °C would be achieved under higher incident power. • Some design and operation guidelines for particle receivers were given. [ABSTRACT FROM AUTHOR]

Abstract: This paper attempts to categorize solar stills into six sorts based on the design guidelines used in each device. The properties of these design guidelines are detailed and evaluated from the angle of enhancing the productivity of solar stills. Preferred design guidelines are recommended for various climate conditions. Fundamental heat and mass transfer process analyses are presented to provide a comprehensive understanding of design principles and to serve as a theoretical guide for structure modification. Most of popular heat and mass transfer correlations in literatures are summarized and evaluated here. [Copyright &y& Elsevier]

• A system is proposed combining solar micro gas turbine with steam injection and ORC. • A thermodynamic model of the system is validated by experimental/referenced data. • Solar energy share can be up to 86.0%, with a system power efficiency of 19.9%. • By adding steam injection and ORC, the power output can be increased by 37.7%. • Steam injection and ORC increase the system flexibility for complex loading conditions. Micro gas turbine (MGT) is an important section in solar-driven power systems, as it can improve system efficiency and provide unique flexibility to meet quickly changing demands. Herein, a solar micro gas turbine (MGT) combined with steam injection and organic Rankine cycle (ORC) is proposed to improve efficiency and flexibility. A steam receiver that produces the steam injected into the MGT is placed around the air receiver aperture to increase the receiver intercept efficiency. A thermodynamic model including a heliostat field, a solar receiver, an MGT and an ORC is developed to investigate the performance of the proposed system, where each sub-model is validated with experimental/referenced data for the subsequence optimization of design and operating parameters. For a 100 kW MGT driven by a solar heliostat field, the simulation results show that the optimized aperture diameter of the air receiver is 1.1 m. On four typical days of a year, i.e. the spring equinox, the summer solstice, the autumn equinox, and the winter solstice, the average optical efficiency of the heliostat field is 0.672, 0.754, 0.672 and 0.597, respectively. Fuel consumption of the MGT during the four days is reduced by 14.8%, 24.6%, 22.4% and 3.7%, respectively. The solar energy share can reach up to 86.0% with a system power efficiency of 19.9% at 12:30 of the autumn equinox. By adding steam injection and ORC, the power output can be increased by 8.29 kW and 30.37 kW, respectively, bringing an increase of the total power output by 37.7% and improving the system efficiency and flexibility. The proposed system can benefit the distributed energy systems especially for remote areas or islands as a flexible option. [ABSTRACT FROM AUTHOR]

A two-dimensional particle population balance model has been developed for the particle size and density distributions in a circulating fluidized bed (CFB) boiler furnace based on analysis of particle properties and the core–annulus hydrodynamic model. The model, incorporating modules to consider fuel particle fragmentation, char combustion, particle attrition and gas–solid separation, is part of an overall model developed earlier by the authors to simulate the operation of a 12 MW CFB boiler. The model predictions for particle population in a CFB furnace agree well with the measurement data. [Copyright &y& Elsevier]

A micro gas turbine (MGT) is a potential option for distributed energy systems driven by fuel and solar energy. The dynamic characteristics of a solar-hybrid microturbine system are essential to its control development and performance assessment. In this paper, a dynamic model is proposed, including an MGT (T100), a tubular air receiver and a sensible thermal energy storage system, which are experimentally validated well. Based on the developed model, the dynamic responses of a solar-hybrid microturbine system in stand-alone mode are studied considering load and Direct Normal Irradiance (DNI) changes. Results show that the fuel consumption is greatly reduced by integrating solar energy, which comes at the cost of system instability; if the investigated system experiences a significant load decrease, heliostats must be oriented away from the air receiver to ensure a stable operation, whereas the load must be increased incrementally to avoid a compressor surge in the case of a significant load increase. Compared to load change, DNI change will cause smaller overshoots of the MGT's rotational speed and surge margin. The system is simulated with measured DNI and shows that the thermal energy storage can reduce the fluctuation of combustor inlet temperature from 130.8 °C to 12.8 °C. • A dynamic model including micro gas turbine, solar receiver and thermal energy storage sub-models is experimentally validated. • Dynamic performance of a solar-hybrid microturbine system is investigated with changing load or solar irradiation. • Control strates are proposed for the investigated system. • The maximum share of solar energy reaches 64.7% for the system with an electrical efficiency of 24.1%. [ABSTRACT FROM AUTHOR]

Circulating fluidized bed (CFB) technology has been continuously developing with an increasing number of large-capacity and supercritical CFB boilers being put into operation. This article reviews the current developments in large capacity CFB boilers in China and presents a note on the most recent development trends. It includes discussions on (1) gas-solid hydrodynamics in large-size CFB furnaces, (2) heat transfer on suspended surfaces, (3) combustion atmosphere and emissions, (4) 3-D CFD numerical simulation for large-scale supercritical CFB boilers, (5) integrated energy saving technologies, (6) optimal operation of an integrated desulfurization system, (7) erosion and protection of heat transfer surfaces, (8) problems in operation and their solutions, (9) combustion of coal with high alkali content. Unlabelled Image • Large-capacity and supercritical CFB boilers operated in China increased. • Current development trends of large capacity CFB boilers are discussed and noted. • Key aspects and issues during CFB development are discussed and noted. [ABSTRACT FROM AUTHOR]

Abstract In this work, microwave-assisted hydrothermal process is applied to the PCDD/F degradation of municipal solid waste incineration (MSWI) fly ash. The effects of water-washing pretreatment and the Na 2 HPO 4 reagent on the degradation efficiency of PCDD/Fs are investigated. The PCDD/F content in MSWI fly ash is detected by high-resolution gas chromatography-mass spectrometry (HRGC/MS). The experimental results show that the efficiency of total PCDD/F degradation increases from 60.6% to 83.3% after water-washing pretreatment, with 5 wt % Na 2 HPO 4 added for 2 h of microwave heating at 220 °C. With more Na 2 HPO 4 (10 wt %), the degradation efficiency of PCDD/Fs reaches 91.8%, and remarkably, the WHO-TEQ is as low as 0.255 ng g−1. Analysis of the degradation pathway of PCDD/Fs indicates that a chlorination reaction happens during the microwave-assisted hydrothermal process, as do dechlorination and destruction reactions. Water-washing effectively weakens the chlorination reaction for the decrease of chlorine in fly ash, which contributes to PCDD/F degradation. The reagent Na 2 HPO 4 has a greater effect on the dechlorination of high-chlorinated congeners. Furthermore, the results indicate that the removal efficiency of PCDDs is higher than that of PCDFs under microwave conditions. Several linear correlations between indicative congener content and I/WHO-TEQ values are summarized. Overall, microwave-assisted hydrothermal process is a promising disposal method and should receive further study for large-scale application. Highlights • Microwave accelerates the PCDD/F degradation. • Water-washing greatly increases the degradation of PCDD/Fs. • Degradation efficiency of PCDD/Fs reaches 91.8% with Na 2 HPO 4 added. [ABSTRACT FROM AUTHOR]

Abstract Due to the problems of municipal solid waste (MSW) during the expanding urbanization, strategy to find an environmentally friendly, energy efficient, cost-effective, and socially acceptable MSW management system is essential for sustainable development. This study establishes a novel environment-energy-economy-society (3E + S) model from a life cycle perspective for sustainability assessment: life cycle assessment for evaluating environmental performance and energy consumption, life cycle costing for recording economic burden, and social life cycle assessment for reflecting social impacts; based on the individual 3E + S results, the final ranking of alternatives is obtained by multi-criteria decision making, which is integrated with analytic hierarchy process and entropy weight method. This model is implemented to identify a sustainable MSW management system among four typical treatment alternatives. Results show that incineration with fluidized bed furnace is the best choice in this study; incineration with moving grate furnace follows after with a slight gap; landfill with and without energy recovery rank the third and the last. The framework of SLCA on MSW field is built in this study and sensitivity analysis is provided for further discussion on social impacts. The calculation method of weight factors reduces man-made disturbances and the sensitivity analysis demonstrates strong robustness of the results and effectiveness of the modification for the model. Highlights • A 3E + S model on sustainability assessment from a life cycle perspective is built. • This model consists of LCA, LCC and SLCA, and integrates the results by MCDM. • Weight factors are calculated by AHP and entropy weight method. • Sensitivity analysis demonstrates the improvement of this novel model. • This model is utilized to find the sustainable MSW management system. [ABSTRACT FROM AUTHOR]

Photo‐thermochemical cycle (PTC) is a promising method to converting CO2 to solar fuels. To study the mechanism of CO2 reduction based on PTC, sol‐gel synthesized titanium dioxide (ST) and Mn‐doped TiO2 (MT) films were produced and applied to the PTC under simulated solar light irradiation. Commercial P25 (PT) was used as a reference. Experiments show that Mn‐doped TiO2 produced more CO than undoped TiO2 and P25. The average CO production of 1.0 wt% MT by the PTC was 32.19 μmol⋅m−2⋅h−1), 4.36 times than that of ST and 3.63 times that of PT. Various characterization methods were conducted to investigated the effect of Mn ions doping on the photoresponse and charge transfer of samples. Density functional theory (DFT) calculations were also performed to verify the analysis and enhance the PTC mechanism. In conclusion, several key factors that Mn ions promote CO2 conversion have been clarified. Combine solar heat and light! To reduce CO2, photo‐thermochemical (PTC) cycle involves both solar light and thermal energy. Photo‐induced oxygen vacancy (VO) is the key to reduce CO2 in thermal step. Introducing Mn to TiO2 significantly broadens its visible light response and decreases the VO formation energy by DFT calculations. Experimental results show that doping TiO2 with Mn significantly enhances CO2 reduction by PTC under simulated solar light irradiation. [ABSTRACT FROM AUTHOR]

Abstract There is a significant increase in the volume of Municipal Solid Waste (MSW) that is being generated across the world. Faced with this challenge and the associated environmental issues, MSW management (MSWM) in Hangzhou, China has made various positive changes in order to adapt. During the last 10 years, MSW source-separated collection was launched, which was accompanied by estimations of a new waste-to-energy (incineration) plant and food waste separate treatment methods. The aim of this study is to investigate the related evolution of the environmental performance of MSWM system in Hangzhou from 2007 to 2016 by using life cycle assessment (LCA). LCA is a scientific tool to quantify factors such as environmental impacts from a life cycle perspective and provides valuable inputs to decision-makers, thus leading to proper strategy determination. Results illustrate that the annual environmental performance has an overall downward trend with some minor fluctuations. The MSWM system in 2010 had the lowest weighted result of 0.0349 PE/t-MSW due to the highest incineration rate and implementation of source-separated collection. Incineration shows better environmental performance than landfill, while source-separated collection can benefit the MSWM. While the importance of source-separated collection is significant, it is also essential to concentrate on the food waste treatment technology. It is suggested that anaerobic digestion (AD) can be considered as a primary option for food waste treatment. Highlights • The evolution of environmental performance of MSWM from 2007 to 2016 is assessed. • Several waste treatment technologies and strategies are modeled and assessed by LCA. • Higher incineration rate can improve the environment impacts of MSWM. • Source-separated system optimizes the MSWM system. [ABSTRACT FROM AUTHOR]

Abstract Waste-to-Energy (WtE) has gradually constituted one of the most important options to achieve energy recovery from municipal solid waste (MSW). However, the environmental sustainability of a specific WtE system varies with used technologies and geographic differences. As a result, three representative WtE systems are compared using life cycle assessment (LCA): a gasification-based WtE plant in Finland, mechanical-grate incineration in France, and circulating fluidized bed incineration in China. Results show that the overall environmental performance of the gasification system is better than incineration. The use of gasification technology, attributed to an intermediate syngas purification step, can provide benefits of both reducing the stack emissions and increasing the energy efficiency. Regional waste management, especially related to MSW caloric value and emission regulation, are determining factors for a preferable performance of the incineration in France over that in China. Sensitivity and uncertainty analyses further address key variations such as choice of MSW composition, basis of displaced electricity, energy recovery mode, and application of "best-available technology" dedicated to incineration. It is found that the most sensitive parameters influencing the LCA results are: electricity recovery, CO 2 emission, and NO x emission. In the future, use of the source-separated high caloric waste combined with a more stringent emission standard can efficiently improve MSW incineration in China. Bottom ash recycling for metals and materials is highly applicable regarding incineration in France. This presented study can overall contribute to the development of specific WtE technology and local waste management plan for decision-makers. Highlights • Life cycle assessment of gasification and incineration Waste-to-Energy is conducted. • Three countries are analysed to reflect both technical and geographic differences. • The key factors (process, emission) contributed to the total impacts are identified. • Environmental impacts of gasification are lower due to syngas cleaning. • Increase MSW quality, use of CHP and ash recycling are potential improvements. [ABSTRACT FROM AUTHOR]

Photon-enhanced thermionic conversion, an innovative solar power technology, combines photovoltaic and thermionic effects into a single process, and has the potential to surpass the Shockley–Queisser limit and conventional photo-thermal limit. However, there is little understanding about the energy conversion process from a thermodynamic point of view. A detailed thermodynamic model is proposed, encompassing energy and exergy balance, and entropy analysis to evaluate a process for solar photon-enhanced thermionic conversion. The correlation of photons, phonons and electrons is presented, as well as the energy transfer pathway in solar thermionic conversion. The total solar-to-electricity efficiency of energy and exergy are 54.32% and 58.42%, respectively, for a photon-enhanced thermionic converter combined with a Carnot engine, at a 1.20 eV bandgap with an electron affinity of 1.20 eV when the concentrated solar flux is 500 kW/m 2 . The combination of photoexcitation and thermalization facilitates the overall thermionic emission exergy ratio up to 62.36%, higher than that of conventional thermionic conversion by 10.92%. Temperature-entropy diagrams with quantitative analysis are proposed for the thermodynamic processes of thermionic and photon-enhanced thermionic conversion. The electron fluid cycles from the Fermi level of the anode back to the valance band of the cathode with a reduced entropy, while being thermalized from the conduction band in photon-enhanced thermionic conversion, contributing to the entire conversion of photoexcited energy to electricity. [ABSTRACT FROM AUTHOR]

In this work, microwave-assisted hydrothermal process was applied to modify the municipal solid waste incineration (MSWI) fly ash and get zeolitic production. The condition of hydrothermal process was fixed at 200 °C and 30 min. The 1 mol/L Na 2 HPO 4 was selected as the additive, and the liquid to solid ratio was 3 ml/g. X-ray diffraction results revealed that analogous zeolite crystals formed by the MSWI fly ash during the hydrothermal process. The cation exchange capacity (CEC) was 0.498 meq/g of the modified fly ash, which increased about 22 times compared to the raw MSWI fly ash. To obtain the adsorption mechanism of the modified fly ash, the experiments of adsorption isotherm and kinetics were researched. The adsorption isotherms of heavy metal cations in mixed solution could be described by Langmuir isotherm equations, with a high correlation coefficient value. The experimental products were better fitted by the pseudo second-order kinetics rather than the pseudo first-order kinetics. Although the adsorption capacity of the modified fly ash needs to be promoted, it is a potential utilization for MSWI fly ash to be the original materials as adsorbents. [ABSTRACT FROM AUTHOR]

Municipal solid waste (MSW) pyrolysis and gasification are in development, stimulated by a more sustainable waste-to-energy (WtE) option. Since comprehensive comparisons of the existing WtE technologies are fairly rare, this study aims to conduct a life cycle assessment (LCA) using two sets of data: theoretical analysis, and case studies of large-scale commercial plants. Seven systems involving thermal conversion (pyrolysis, gasification, incineration) and energy utilization (steam cycle, gas turbine/combined cycle, internal combustion engine) are modeled. Theoretical analysis results show that pyrolysis and gasification, in particular coupled with a gas turbine/combined cycle, have the potential to lessen the environmental loadings. The benefits derive from an improved energy efficiency leading to less fossil-based energy consumption, and the reduced process emissions by syngas combustion. Comparison among the four operating plants (incineration, pyrolysis, gasification, gasification-melting) confirms a preferable performance of the gasification plant attributed to syngas cleaning. The modern incineration is superior over pyrolysis and gasification-melting at present, due to the effectiveness of modern flue gas cleaning, use of combined heat and power (CHP) cycle, and ash recycling. The sensitivity analysis highlights a crucial role of the plant efficiency and pyrolysis char land utilization. The study indicates that the heterogeneity of MSW and syngas purification technologies are the most relevant impediments for the current pyrolysis/gasification-based WtE. Potential development should incorporate into all process aspects to boost the energy efficiency, improve incoming waste quality, and achieve efficient residues management. [ABSTRACT FROM AUTHOR]

Second-order and third-order models are the two main methods for Stirling cycle analysis. A second-order one has relatively reliable accuracy without detailed cyclic information, while a third-order one provides relatively comprehensive operational information with uncertainty. In this work, a third-order model, Sage, is tried to be improved by a second-order model, Improved Simple Analytical Model, and 100 W β -type Stirling engine is used as a modelling prototype engine. As suggested by Improved Simple Analytical Model, the gap of the piston seal and the empirical multiplier for heat transfer of cooler in Sage should be adjusted. This is accomplished by combining these two models so that the effects of seal leakage loss, gas spring hysteresis loss, and piston friction loss could be considered in an improved Sage. The improved Sage indicates that the overall relative errors for the indicated power output and the thermal efficiency are reduced by over 30 percentage points and 20 percentage points, respectively. Pressure–volume diagrams provided by the improved Sage are much closer to the experimental ones, and the pattern similarities of pressure–volume diagrams increase from 78.6–81.4% to 80.8–85.0%. Performance simulation of the Stirling engine is carried out by the improved Sage and the results show that regenerator takes a major role in improving the performance of the 100 W β -type Stirling engine. Lengths of regenerator, heater and cooler are optimized for the maximum indicated power output and the maximum thermal efficiency respectively, and the optimized values are increased by 15.9% and 25.2%, respectively. [ABSTRACT FROM AUTHOR]

Commercial catalysts for the catalytic oxidation of chloroaromatics are mainly based on either noble metals or transition metal oxides supported on a suitable carrier. This paper reviews studies relative to these two generic groups of catalysts and their performances for chloroaromatic decomposition, i.e. conversion efficiency, stability and selectivity towards harmless products (e.g., CO 2 ), and in particular, avoiding the formation of polychlorinated by-products. The various approaches towards improved catalysts, including tuning the support, adding dopants or promoters, improving the preparation methods, or auxiliary means such as the introduction of ozone (O 3 ) or hydrogen peroxide (H 2 O 2 ) in the gas to be treated, and combination with non-thermal plasma treatment are systematically reviewed. This review also appraises various modes of deactivation (i.e., originating from fouling, coking, poisoning, sintering of the catalyst, and from volatilization of its active phases) as well as possible methods for regeneration. [ABSTRACT FROM AUTHOR]

Concentrating solar power (CSP) is a mainstream of solar energy utilization, and thermionic emission is a potential way to convert concentrated solar radiation into power with a theoretical efficiency of 50–70%, surpassing both Shockley-Queisser limit and photo-thermal limit. This literature attempts to provide a comprehensive understanding of and an insight into solar thermionic energy conversion. The fundamentals of electron emission from electrodes and electron transport in vacuum gap are presented, as well as the state of the art of solar thermionic energy conversion technologies, including heat-induced thermionics and photon-enhanced thermionics. The former is driven by thermal energy, whereas the latter takes advantage of both quantum photon energy and thermal energy. Burgeoning research indicates that photon-enhanced thermionic conversion is a promising technology for concentrating solar power due to the high efficiency and simple operating mode. Now, it is important to develop novel materials and coating technologies to facilitate electron emission and reduce space charge effect in interelectrode vacuum. Structural design of thermionic converters and top–bottom configuration of solar-electricity systems are suggested for practical applications. [ABSTRACT FROM AUTHOR]

The mesoscale Weather Research and Forecasting (WRF) model coupled with wind farm parameterization is newly developed to simulate the wake flow and power production of a real onshore wind farm. First, wind farm flow field simulations are conducted with 1000 m, 500 m and 200 m horizontal resolutions, and the simulation results capture the wind farm observed data well. In addition, wind farm flow characteristics, power output, and influence on the atmosphere boundary layer (ABL) are resolved at a horizontal resolution of 200 m. The wake interactions, wind speed, and power output deficit in the wind farm are analyzed. The power comparison results prove that the proposed method can be applied to simulate the power output of a real onshore wind farm with high accuracy in real time. The influence of the wind farm on the ABL is also discussed. The results show that wind farm effects on the ABL occur mainly within the turbine rotor-spanned heights and the downstream regions behind the wind farm within 10 km, within which the speed deficit ratio can exceed 10%. For the region that is 18 km downstream of the wind farm, the average speed deficit ratio is only about 2%. This study is the first attempt to reproduce the wake flow and power output of a real onshore wind farm by the WRF model at such high resolution. [ABSTRACT FROM AUTHOR]

The heating values, particularly lower heating values of burning municipal solid waste are critically important parameters in operating circulating fluidized bed incineration systems. However, the heating values change widely and frequently, while there is no reliable real-time instrument to measure heating values in the process of incinerating municipal solid waste. A rapid, cost-effective, and comparative methodology was proposed to evaluate the heating values of burning MSW online based on prior knowledge, expert experience, and data-mining techniques. First, selecting the input variables of the model by analyzing the operational mechanism of circulating fluidized bed incinerators, and the corresponding heating value was classified into one of nine fuzzy expressions according to expert advice. Development of prediction models by employing four different nonlinear models was undertaken, including a multilayer perceptron neural network, a support vector machine, an adaptive neuro-fuzzy inference system, and a random forest; a series of optimization schemes were implemented simultaneously in order to improve the performance of each model. Finally, a comprehensive comparison study was carried out to evaluate the performance of the models. Results indicate that the adaptive neuro-fuzzy inference system model outperforms the other three models, with the random forest model performing second-best, and the multilayer perceptron model performing at the worst level. A model with sufficient accuracy would contribute adequately to the control of circulating fluidized bed incinerator operation and provide reliable heating value signals for an automatic combustion control system. [ABSTRACT FROM AUTHOR]

Non-thermal plasma with different O 2 concentration in discharge atmosphere was applied to synthesize manganese and cerium mixed-oxides catalysts, which were compared in NO oxidation activity. Discharge atmosphere displayed a crucial influence on the performance of the catalysts prepared by plasma. Relatively low O 2 concentration in discharge atmosphere allows synthesizing manganese-cerium oxides catalysts in a moderate environment and therefore is favorable for better physicochemical properties which lead to superior catalytic behavior. The best catalyst was obtained by treatment with 10% O 2 /N 2 plasma and presented over 80% NO conversion in the temperature range of 275–325 °C, whereas catalyst prepared in pure O 2 discharge atmosphere had the same activity with a catalyst prepared by calcinations. A correlation between the surface properties of the plasma prepared catalysts and its catalytic activity in NO oxidation is proposed. The amount of the surface adsorbed oxygen has an obvious linear correlation with the amount of Ce 3+ , the H 2 consumption at low temperatures and the catalytic performance. The superior catalytic performance is mainly attributed to the stronger interaction between manganese oxides and ceria, and the formation of poorly crystallized Mn-O-Ce phase in the catalyst which resulted from the slow decomposition of nitrates and organics during plasma treatment. Catalysts prepared in relatively low O 2 concentration have large specific surface area and is abundant in Ce 3+ species and active oxygen species. The study suggests that plasma treatment with proper discharge gas components is a promising method to prepare effective manganese- cerium oxides catalyst for NO oxidation. [ABSTRACT FROM AUTHOR]

The flue gas generated from glass furnaces contains particles with high concentrations of alkali metals and hazardous heavy metals, which could reduce the lifespan of selective catalytic reduction (SCR) catalysts and lead to catalyst deactivation. Removing the particles before SCR could improve system operation reliability and reduce nitric oxides (NOx) emission. In this paper, the characteristics of fly ash from glass furnaces and the particle removal properties in the electrostatic precipitator (ESP) from 363 K to 623 K were studied. The particle collection efficiency was found to decrease with increasing temperature. A method of enhancing particle removal was proposed and tested through particle conditioning in a lab-scale experiment. In order to change the characteristics of the fly ash, calcium carbonate powders were used as conditioning particles and the particle collection efficiency increased from 65.8% to 87.6% at 623 K. This method was further applied in an industrial high-temperature ESP for a glass furnace. When the ratio in mass between the particles from the glass furnace and from the conditioning proportion was 1:1.5, the particle collection efficiency of the ESP was improved significantly and the outlet particle concentrations decreased from 103.23 mg/Nm 3 to 39.25 mg/Nm 3 . [ABSTRACT FROM AUTHOR]

Compared with municipal solid waste incineration, studies on the PCDD/F emissions of hazardous waste incineration (HWI) under transient conditions are rather few. This study investigates the PCDD/F emission level, congener profile and removal efficiency recorded during startup and shutdown by collecting flue gas samples at the bag filter inlet and outlet and at the stack. The PCDD/F concentration measured in the stack gas during startup and shutdown were 0.56–4.16 ng I-TEQ Nm −3 and 1.09–3.36 ng I-TEQ Nm −3 , respectively, far exceeding the present codes in China. The total amount of PCDD/F emissions, resulting from three shutdown-startup cycles of this HWI-unit is almost equal to that generated during one year under normal operating conditions. Upstream the filter, the PCDD/F in the flue gas is mainly in the particle phase; however, after being filtered PCDD/F prevails in the gas phase. The PCDD/F fraction in the gas phase even exceeds 98% after passing through the alkaline scrubber. Especially higher chlorinated PCDD/F accumulate on inner walls of filters and ducts during these startup periods and could be released again during normal operation, significantly increasing PCDD/F emissions. [ABSTRACT FROM AUTHOR]

The combination of plasma and heterogeneous catalysis has been considered as an attractive and promising process for the synthesis of fuels and chemicals. In this work, plasma-catalytic reforming of biogas is carried out over Ni/γ-Al 2 O 3 catalysts with different Ni loadings (6 wt.%, 8 wt.% and 10 wt.% Ni) in a novel rotating gliding arc (RGA) plasma reactor. In the plasma reforming of biogas without a catalyst, the CH 4 conversion can reach up to 52.6% at a CH 4 /CO 2 molar ratio of 3:7 and a total flow rate of 6 L/min. The combination of the RGA with the Ni/γ-Al 2 O 3 catalysts enhances the performance of the plasma biogas reforming: increasing Ni loading enhances the conversion of CH 4 and the maximum CH 4 conversion of 58.5% is achieved when placing the 10 wt.% Ni/γ-Al 2 O 3 catalyst in the downstream of the RGA reactor. The presence of the 10 wt.% Ni/γ-Al 2 O 3 catalyst in the RGA reactor also increases the H 2 yield by 17.6% compared to the reaction in the absence of a catalyst. A comparison of biogas reforming using different plasma technologies shows that the RGA plasma provides a higher conversion, significantly enhanced processing capacity and reduced energy cost for biogas conversion and syngas production. In addition, compared to biogas reforming using other non-thermal plasmas (e.g. dielectric barrier discharge), the RGA reforming process produces much cleaner gas products in which syngas is the major one. [ABSTRACT FROM AUTHOR]

Micro gas turbines are a promising technology for distributed power generation because of their compact size, low emissions, low maintenance, low noise, high reliability and multi-fuel capability. Recuperators preheat compressed air by recovering heat from exhaust gas of turbines, thus reducing fuel consumption and improving the system efficiency, typically from 16–20% to ∼30%. A recuperator with high effectiveness and low pressure loss is mandatory for a good performance. This work aims to provide a comprehensive understanding about recuperators, covering fundamental principles (types, material selection and manufacturing), operating characteristics (heat transfer and pressure loss), optimization methods, as well as research hotspots and suggestions. It is revealed that primary-surface recuperator is prior to plate-fin and tubular ones. Ceramic recuperators outperform metallic recuperators in terms of high-temperature mechanical and corrosion properties, being expected to facilitate the overall efficiency approaching 40%. Heat transfer and pressure drop characteristics are crucial for designing a desired recuperator, and more experimental and simulation studies are necessary to obtain accurate empirical correlations for optimizing configurations of heat transfer surfaces with high ratios of Nusselt number to friction factor. Optimization methods are summarized and discussed, considering complicated relationships among pressure loss, heat transfer effectiveness, compactness and cost, and it is noted that multi-objective optimization methods are worthy of attention. Moreover, 3D printing and printed circuit heat exchanger technologies deserve more research on manufacturing of recuperators. Generally, a metallic cost-effective primary-surface recuperator with high effectiveness and low pressure drop is a currently optimal option for a micro gas turbine of an efficiency of ∼30%, while a ceramic recuperator is suggested for a high efficiency micro gas turbine (e.g. 40%). [ABSTRACT FROM AUTHOR]

Regenerator is one of heat exchangers (heater, regenerator and cooler) in a Stirling engine, whose flow characteristics are very important for developing Stirling engine design methodology. A combined experimental and simulation study is carried out to investigate characteristics of regenerator in an oscillating flow, using steady flow as reference. It is found that the oscillating flow can share the same correlation equations of steady flow for friction factor within the measured kinetic Reynolds number range (2.59 × 10 −2 –2.04 × 10 −1 for 100 mesh, 6.60 × 10 −3 –5.22 × 10 −2 for 200 mesh, 2.74 × 10 −3 –2.16 × 10 −2 for 300 mesh and 1.43 × 10 −3 –1.13 × 10 −2 for 400 mesh) and dimensionless fluid displacement, and the maximum deviation between the experimental data and simulation results is found less than 9.6%. It is also found that the effect of gas compression can’t be ignored for the steady and oscillating flows through a regenerator with the increase of mass flow, and the pressure drop per unit length decreases as the length of regenerator increases. The velocities at both ends of regenerator are also affected by the compression of gas, and it is found that theoretical velocity based on piston velocity can be used if the dimensionless pressure drop of the whole system is less than 4.22 × 10 −2 in this experiment. After all, it should be noted that oscillating flow has its own characteristics, and obvious flow perturbations are found at downstream of regenerator, which are exactly detected by a hot wire anemometer. The effect of mesh size, frequency and mean pressure on the perturbation is investigated, and a correlation equation for the duration of perturbation is proposed based on dimensionless pressure drop of regenerator. [ABSTRACT FROM AUTHOR]

The solar dish is a point-focusing concentrator with a very high concentration ratio ranging from hundreds to thousands. Practical assessment and optimization methods are necessary to assemble solar dishes with satisfying concentration ratios and flux density distributions, which is very important for the overall solar thermal systems to achieve high efficiency. A solar dish usually consists of many mirror facets installed on a supporting structure with a dual-axis tracking system. Small mirror facets are easy to manufacture, but the alignment of many mirror facets is very challenging. A model-based approach for optical performance assessment and optimization of a solar dish was proposed, and flux density measurements were carried out to validate the approach. The simulation and experimental results showed very good consistency and suggested that the concentration ratio and the intercept factor could be increased from ∼500 to ∼1500 and 0.66 to 0.9 respectively after assembly optimization. [ABSTRACT FROM AUTHOR]

This paper investigated the enhancement of plasma on dimethyl sulfide (DMS) removal over commercial V-W/Ti catalysts. The effects of catalyst composition, discharge power, and gas temperature on DMS removal in the plasma-based system were analyzed. The results showed that the V0.9–W/Ti catalyst exhibited the best performance toward DMS removal due to its highest reducibility among the employed samples. The introduction of plasma exhibited a synergistic effect on catalysts and significantly enhanced the removal of DMS over the studied temperature range, especially in high discharge power cases. The activation energy Ea of DMS removal in the presence of plasma was dramatically reduced to less than 10% of the catalysis only case, indicating different DMS removal pathways in plasma-activated catalysis system. The reaction mechanisms of DMS were also discussed based on the reaction products. [ABSTRACT FROM PUBLISHER]

In this work, an integrated numerical model is presented and validated to investigate the particle charging and transport behaviors in a wire-plate electrostatic precipitator (ESP). Calculations of gas flow, electrostatics field and particle motions are coupled in the model, and the influences of electro-hydrodynamics (EHD) flows are also taken into account. The dynamic charging process of particles was treated with separate field and diffusion charging rates, and the trajectories of particles in the ESP were tracked with a Lagrangian-type method. Numerical results show that electric field strengths and charging ion densities varied largely in the computational domain, and inlet particles were initially charged primarily by diffusion charging mechanism. The particles were then charged to a near-saturation state in the discharging zone, while their transverse velocities showed considerable fluctuations along the trajectories. Numerical results indicate that particles with diameter between 0.2 and 1 μm normally exhibited lowest average transverse velocities, and longer residential time could slightly improve the transverse velocities for all sizes of particles. Moreover, increasing voltages could greatly improve the acquired charges and collecting performances for particles larger than 1 μm, while higher ion current value was more effective in achieving higher collection efficiencies for sub-micron particles. [ABSTRACT FROM AUTHOR]

The high power consumption of auxiliary equipment, particularly that of the primary air fan, in a coal-fired power plant provides ample scope for reducing power consumption. Therefore, a power-saving control strategy for the primary air fan is proposed that automatically calculates a primary air pressure offset value in real time, which, when combined with the existing primary air pressure setting, reduces the total pressure, and correspondingly decreases the power consumption of the primary air fan while maintaining the mill outlet temperature within the optimum range. The power-saving control strategy implements two models that are respectively applicable to normal conditions and mill outlet over-temperature conditions. Mechanistic modeling is implemented for the model applicable to normal conditions. The model evaluates the mill inlet hot air damper opening for determining the potential for reducing the power consumption, the mill inlet cold air damper opening is applied for adjust the mill outlet temperature, and the total pressure and corresponding power consumption are thereby reduced. The other model is controlled by a conventional proportional derivative controller, which employs the deviation of the mill outlet temperature as its input. The proposed power-saving control strategy is applied to a 1000 MW commercial power plant, and the power consumption of the primary fan is demonstrated to be reduced by as much as 465 kW for a 500 MW load, resulting in a power consumption reduction of 15%. [ABSTRACT FROM AUTHOR]

Non-thermal plasma is considered as an alternative treatment of tar present in the effluent from gasification processes. In this study, a novel rotating gliding arc (RGA) discharge reactor was developed for tar destruction. Toluene in nitrogen flow was used as a tar surrogate. The physical features of RGA discharge and its application to toluene destruction are investigated at different input concentrations and total gas flow rates. As a result, the highest destruction efficiency could exceed 95%, with a toluene concentration of 10 g/N m 3 and a total flow rate of 0.24 N m 3 /h. The two major gaseous products are H 2 and C 2 H 2 , with maximum selectivity of 39.35% and 27.0%, respectively. A higher input concentration slightly reduces this destruction efficiency but the energy efficiency further expanded, with a highest value of 16.61 g of toluene eliminated/kW h. In addition, the liquid and solid byproducts are collected downstream of the RGA reactor and determined qualitatively and semi-quantitatively. The amount and structure of these by-products is instructive for reaching a better comprehension of the chemical consequences of plasma treatment to the model compound and to the carrier gas nitrogen. [ABSTRACT FROM AUTHOR]

In this work, plasma-catalytic removal of low concentrations of acetone over CuO/γ-Al 2 O 3 catalysts was carried out in a cylindrical dielectric barrier discharge (DBD) reactor. The combination of plasma and the CuO/γ-Al 2 O 3 catalysts significantly enhanced the removal efficiency of acetone compared to the plasma process using the pure γ-Al 2 O 3 support, with the 5.0 wt% CuO/γ-Al 2 O 3 catalyst exhibiting the best acetone removal efficiency of 67.9%. Catalyst characterization was carried out to understand the effect the catalyst properties had on the activity of the CuO/γ-Al 2 O 3 catalysts in the plasma-catalytic reaction. The results indicated that the formation of surface oxygen species on the surface of the catalysts was crucial for the oxidation of acetone in the plasma-catalytic reaction. The effects that various operating parameters (discharge power, flow rate and initial concentration of acetone) and the interactions between these parameters had on the performance of the plasma-catalytic removal of acetone over the 5.0 wt% CuO/γ-Al 2 O 3 catalyst were investigated using central composite design (CCD). The significance of the independent variables and their interactions were evaluated by means of the Analysis of Variance (ANOVA). The results showed that the gas flow rate was the most significant factor affecting the removal efficiency of acetone, whilst the initial concentration of acetone played the most important role in determining the energy efficiency of the plasma-catalytic process. [ABSTRACT FROM AUTHOR]

This study investigated the influence of electrode configuration on corona discharge and particle collection from 300 K to 900 K. Electrodes of different shapes (rod, saw, and screw), diameters (3, 5, and 8 mm), and intervals (55, 110, and 165 mm) were tested in an experimental-scale electrostatic precipitator (ESP). Results showed that a high current was generated with a saw electrode and increased the particle collection efficiency, particularly for fine particles (diameter smaller than 0.1 μm), with the best particle collection efficiency being 99.8% at 300 K. However, with an increase in temperature, the rod electrode obtained an applied voltage higher than those of other electrode types and, as a result, generated relatively high particle collection efficiencies at 700 K and 900 K. Increasing the electrode diameter from 3 mm to 5 mm improved the applied voltage, whereas increasing this diameter from 5 mm to 8 mm reduced the discharge current. Among electrodes with different diameters, the electrode with a diameter of 5 mm achieved the best particle collection efficiency (87.4%) at 900 K. The applied voltages of the electrodes with different intervals were almost similar, but the discharge currents varied significantly. The best particle collection efficiencies were achieved by the electrode with an interval of 55 mm at 300 K and 500 K, but at 700 K and 900 K, the electrode with an interval of 110 mm obtained the best result. The interval between electrodes should be expanded with an increase in temperature to avoid the offsetting of electric field between neighboring electrodes. [ABSTRACT FROM AUTHOR]

High-temperature ESPs are proposed to improve energy efficiency and avoid damage to downstream equipment in integrated gasification combined cycle and pressurized fluidized-bed combustion. In this study, the effects of temperature and pressure on negative corona discharge characteristics were compared. Gas temperature varied from 373 K to 1073 K, and pressure varied from 30 kPa to 100 kPa to achieve the same gas density. The additional corona current Δ I t induced by high temperature was calculated, and the additional ion current Δ I i and electron current Δ I e were studied. A wire-type electrode, a spiral electrode, a ribbon electrode, and four gas compositions (N 2 /CO 2 /SO 2 /air) were investigated in the plate-type discharge configuration. Results show that corona current increases more rapidly with increasing gas temperature than that with decreasing pressure at the same gas density. The current density is 0.87 mA/m at 973 K and atmosphere pressure, which is higher than 0.45 mA/m at 30.9 kPa and room temperature. An additional temperature effect on corona discharge is proposed apart from the decrease of gas density as temperature increases. Δ I t increases with increasing temperature because of enhanced molecule kinetic energy and ionization rate. The electron-carried current is important at temperatures above 873 K. Δ I e /Δ I t increases from 0 to 0.941 when temperature increases from 773 K to 973 K. Compared with the Δ I t of wire and spiral electrodes, the Δ I t of ribbon electrode is significantly larger because of the enhanced electron avalanche and secondary electron emission. Negative corona discharge does not occur in N 2 , and corona onset voltages are in the following sequence: CO 2 > SO 2 (6000 ppm) > air, which is determined by gas molecule ionization energy. Δ I t / I P is smaller in gas atmosphere with strong electronegativity. [ABSTRACT FROM AUTHOR]

This study illustrated the interaction between NH 4 HSO 4 and V 2 O 5 /TiO 2 catalysts in the selective catalytic reduction of NO with NH 3 , along with the variation in the decomposition and reactivity of NH 4 HSO 4 with NO on the catalyst surface resulting from the interaction. On the catalyst surface, sulfur species transformed from HSO 4 − into bidentate SO 4 2− , which was subsequently bonded to TiO 2 sites; N-containing species remained as NH 4 + . Given NH 4 HSO 4 deposition on the catalyst surface, electrons around the Ti atoms deviated toward SO 4 2− because of the species’ strong electronegativity, thereby leaving Ti atoms in an electron-deficit state. Consequently, compared with those of crystallite NH 4 HSO 4 , the decomposition and reactivity of NH 4 HSO 4 with NO were promoted on the catalyst surface. An increase in NH 4 HSO 4 deposition amount led to the occurrence of the (NH 4 ) 2 TiO(SO 4 ) 2 phase, which adversely affected the decomposition and reactivity behaviors observed. High V 2 O 5 contents enhanced the reactivity of NH 4 HSO 4 with NO between 100 and 250 °C. H 2 O also exerted negative effects on the reactivity of NH 4 HSO 4 with NO. In situ diffuse reflectance infrared Fourier transform spectroscopy confirmed that the as-formed NH 4 HSO 4 functions as a reductant during reaction with NO, similar to the behavior of impregnated NH 4 HSO 4 . [ABSTRACT FROM AUTHOR]

High-temperature electrostatic precipitation is a potentially convenient method for hot gas clean-up. This paper reports the characteristics of electrostatic precipitation in a wire–cylinder configuration for a temperature range of 350 °C to 700 °C. Three parameters, i.e., particle collection efficiency, energy consumption index and the outlet mass concentration of particles, are investigated to evaluate the comprehensive performance of an electrostatic precipitator at high temperatures and to propose a method to choose an optimum combination of the operation parameters for different conditions. The collection efficiency can be greater than 0.996 when the gas temperature is 350–700 °C and the inlet mass concentration of particles is 200–3600 mg/Nm 3 . When the voltage applied to the two electrodes is high enough (greater than 15,900 V in this work), the collection efficiency is hardly influenced by the inlet mass concentrations of particles in the testing range. For example, at 620 °C when the applied voltage is 15,925 V, the fluctuations of the collection efficiency are within ~ 0.2% even if the inlet mass concentration increases ~ 10 times. For a given inlet mass concentration of particles, the collection efficiency increases rapidly as the applied voltage increases from the first stage to the second stage, while the collection efficiency increases slowly as the applied voltage increases from the second stage to the third stage. The relationship between the energy consumption index, the applied voltage and the inlet mass concentration of particles is given by φ = CU p 2 ( U p − U c )/ m in . As the temperature increases from 350 °C to 700 °C, the value of C increases from 1.0 × 10 − 5 to 3.2 × 10 − 5 and the value of U c decreases from 20,860 to 12,503. The electric energy consumed by an electrostatic precipitator increases rapidly with the increase in the temperature. [ABSTRACT FROM AUTHOR]

A plasma–catalyst reactor was used for the adsorption of elemental mercury at low temperatures. SiO 2 , TiO 2 and SiO 2 or TiO 2 supported transition metal oxide catalysts were packed in the plasma discharge zone for adsorption enhancement. The results indicated that non-thermal plasma could induce the adsorption of elemental mercury effectively by catalysts. TiO 2 displays much higher adsorption efficiency than SiO 2 does. The adsorption efficiency is greatly improved by loading transition metal oxides on TiO 2 . Mn/TiO 2 is the most efficient catalyst, and ~ 99% of Hg 0 adsorption efficiency can be obtained under a SED of 2.3 ± 0.3 J L − 1 . The interaction between the plasma and catalyst was also investigated. The chemical properties of the catalyst, such as the active sites and electron transfer capacity, are key factors that affect adsorption efficiency. The mercury adsorption in plasma–catalyst reactor results primarily from the interaction between weakly adsorbed mercury and activated oxygen on catalyst surface induced by plasma. In addition, the effect of the O 2 concentration and HCl on mercury adsorption efficiency was investigated. The adsorption efficiency has a logarithmic correlation with O 2 concentration in the gas flow. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) adsorption is an important method to control the emission of dioxins and dioxin-like congeners (polychlorinated dibenzo- p-dioxins and dibenzofurans [PCDD/Fs] and polychlorinated biphenyls [PCBs]), of other semi-volatiles (such as Polycyclic Aromatic Hydrocarbons) and heavy metals (mainly mercury) arising from municipal waste incineration and other effluents. Investigating the adsorption characteristics of AC for PCDD/Fs allows selection of the best AC types, to meet the new and more stringent PCDD/F emission standards. In this study, the adsorption of dioxins on three kinds of commercial AC was evaluated through three bench-scale experiments. A dioxin generator was applied to generate a PCDD/Fs containing gas stream with constant concentration. Physical properties of AC, including its density, Brunauer-Emmet-Teller-surface, pore volume, and pore size distribution, were considered. The results show that the removal efficiencies of PCDD/Fs correlate more strongly with pore volume ( r2>0.93) than with the surface area ( r2<0.48). Among the three types of AC tested, the coconut shell sample with wide pore size distribution reached the highest adsorption efficiency. Under the testing conditions used, the total removal efficiency reached over 96%, much more than the 81.7% efficiency achieved by lignite AC. In addition, the selectivity of lignite AC for 17 toxic PCDD/F congeners is distinct from the two other samples. [ABSTRACT FROM AUTHOR]

Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N 2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction. [ABSTRACT FROM AUTHOR]