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Yongping Yang
National Research Center for Thermal Power Engineering and Technology Research Center, North China Electric Power University, Beijing 102206, P.R. China

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Journal article
Published: 01 April 2021 in Global Energy Interconnection
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Integrated energy systems (IESs) represent a promising energy supply model within the energy internet. However, multi-energy flow coupling in the optimal configuration of IES results in a series of simplifications in the preliminary planning, affecting the cost, efficiency, and environmental performance of IES. A novel optimal planning method that considers the part-load characteristics and spatio-temporal synergistic effects of IES components is proposed to enable a rational design of the structure and size of IES. An extended energy hub model is introduced based on the “node of energy hub” concept by decomposing the IES into different types of energy equipment. Subsequently, a planning method is applied as a two-level optimization framework—the upper level is used to identify the type and size of the component, while the bottom level is used to optimize the operation strategy based on a typical day analysis method. The planning problem is solved using a two-stage evolutionary algorithm, combing the multiple-mutations adaptive genetic algorithm with an interior point optimization solver, to minimize the lifetime cost of the IES. Finally, the feasibility of the proposed planning method is demonstrated using a case study. The life cycle costs of the IES with and without consideration of the part-load characteristics of the components were $4.26 million and $4.15 million, respectively, in the case study. Moreover, ignoring the variation in component characteristics in the design stage resulted in an additional 11.57% expenditure due to an energy efficiency reduction under the off-design conditions.

ACS Style

Chengzhou Li; Yongping Yang; Zhuo Wang; Ningling Wang; Ligang Wang; Zhiping Yang. Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment. Global Energy Interconnection 2021, 4, 169 -183.

AMA Style

Chengzhou Li, Yongping Yang, Zhuo Wang, Ningling Wang, Ligang Wang, Zhiping Yang. Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment. Global Energy Interconnection. 2021; 4 (2):169-183.

Chicago/Turabian Style

Chengzhou Li; Yongping Yang; Zhuo Wang; Ningling Wang; Ligang Wang; Zhiping Yang. 2021. "Energy hub-based optimal planning for integrated energy systems considering part-load characteristics and synergistic effect of equipment." Global Energy Interconnection 4, no. 2: 169-183.

Journal article
Published: 11 March 2021 in Applied Energy
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Electrical energy storage systems are indispensable for the electrical grid with high penetration renewables. Reversible solid-oxide cell stack based power-to-x-to-power systems, which can switch between power generation and power storage, can achieve a high round-trip efficiency and are technology neutral for, e.g., hydrogen, methane, methanol, ammonia and syngas. This paper evaluates, with a systematically decomposition-based optimization method, the economic feasibility of such dual-direction plants to assist wind farms for reliable electricity supply, under various scenarios with 150%/200%/250% wind electricity penetration and strong/weak interactions with chemical markets. The economic feasibility is represented by Plant CAPEX Target (€/ref-stack), defined as maximum affordable total plant investment costs divided by the equivalent number of reference stacks (5120 cm2 active cell area). The results show that, with strong interaction with chemical markets, hydrogen pathway is the most economically potential, especially under high wind electricity penetration (200, 250%). Plant CAPEX target of hydrogen pathway reaches 2300 €/ref-stack, followed by syngas (1900 €/ref-stack), while the methane, methanol and ammonia ones are less economically-feasible with targets around 1000 €/ref-stack. Economic feasibility of hydrogen pathway is less sensitive (above 2000 €/ref-stack) to hydrogen price when it is below 4 €/kg. Deploying multiple plants with operation-coordination freedom allows for the reduction of lost wind rate and the enhancement of profit. Plant designs with either high round-trip efficiency or good match with imbalance characteristics are preferred. When the chemicals produced are not sold to markets, syngas and methane pathways are more economically-feasible, with plant CAPEX target within 500–1000 €/ref-stack due to affordable onsite fuel storage and high round-trip efficiency.

ACS Style

Yumeng Zhang; Ningling Wang; Xiaofeng Tong; Liqiang Duan; Tzu-En Lin; François Maréchal; Jan Van Herle; Ligang Wang; Yongping Yang. Reversible solid-oxide cell stack based power-to-x-to-power systems: Economic potential evaluated via plant capital-cost target. Applied Energy 2021, 290, 116700 .

AMA Style

Yumeng Zhang, Ningling Wang, Xiaofeng Tong, Liqiang Duan, Tzu-En Lin, François Maréchal, Jan Van Herle, Ligang Wang, Yongping Yang. Reversible solid-oxide cell stack based power-to-x-to-power systems: Economic potential evaluated via plant capital-cost target. Applied Energy. 2021; 290 ():116700.

Chicago/Turabian Style

Yumeng Zhang; Ningling Wang; Xiaofeng Tong; Liqiang Duan; Tzu-En Lin; François Maréchal; Jan Van Herle; Ligang Wang; Yongping Yang. 2021. "Reversible solid-oxide cell stack based power-to-x-to-power systems: Economic potential evaluated via plant capital-cost target." Applied Energy 290, no. : 116700.

Journal article
Published: 04 November 2020 in Energies
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The efficient and clean use of fuel is very important for the sustainable development of energy. In this article, a numerical study of molten carbonate fuel cell (MCFC) unit is carried out, and the source, distribution, and extent of six irreversible losses (fluid friction loss, mass transfer loss, ohmic loss, activation loss, heat transfer loss, the coupling loss between heat and mass transfer) are described and quantified. The effects of the operation temperature, current density, CO2 concentration, and cathode CO2 utilization rate on the exergy destruction and exergy efficiency during the power generation process are investigated. The results show that the main source of entropy generation in MCFC is the potential difference, which affects the ohmic and activation entropy generation, especially when the CO2 concentration is very low. The second is the temperature gradient, which causes the entropy production of the heat transfer. With the rise of the CO2 concentration at the cathode inlet, the exergy destruction reduces and the exergy efficiency increases. With the rise of the cathode CO2 utilization rate, the exergy destruction rises and the exergy efficiency reduces. Therefore, analyzing the irreversible process transfer mechanism in MCFC can provide the theoretical basis for its thermal performance optimization and structure design.

ACS Style

Jing Bian; Liqiang Duan; Jing Lei; Yongping Yang. Study on the Entropy Generation Distribution Characteristics of Molten Carbonate Fuel Cell System under Different CO2 Enrichment Conditions. Energies 2020, 13, 5778 .

AMA Style

Jing Bian, Liqiang Duan, Jing Lei, Yongping Yang. Study on the Entropy Generation Distribution Characteristics of Molten Carbonate Fuel Cell System under Different CO2 Enrichment Conditions. Energies. 2020; 13 (21):5778.

Chicago/Turabian Style

Jing Bian; Liqiang Duan; Jing Lei; Yongping Yang. 2020. "Study on the Entropy Generation Distribution Characteristics of Molten Carbonate Fuel Cell System under Different CO2 Enrichment Conditions." Energies 13, no. 21: 5778.

Journal article
Published: 23 February 2020 in Energies
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The main purpose of this paper is to quantitatively analyze the sensitivity of operating parameters of the system to the thermodynamic performance of an oxyfuel combustion (OC) power generation system. Therefore, the thermodynamic model of a 600 MW subcritical OC power generation system with semi-dry flue gas recirculation was established. Two energy consumption indexes of the system were selected, process simulation was adopted, and orthogonal design, range analysis, and variance analysis were used for the first time on the basis of single-factor analysis to conduct a comprehensive sensitivity analysis and optimization research on the changes of four operating parameters. The results show that with increasing oxygen purity, the net standard coal consumption rate first decreases and then increases. With decreasing oxygen concentration, the recirculation rate of dry flue gas in boiler flue gas ( χ 1 ) and an increasing excess oxygen coefficient, the net standard coal consumption rate increases. The net electrical efficiency was just the opposite. The sensitivity order of two factors for four indexes is obtained: the excess oxygen coefficient was the main factor that affects the net standard coal consumption rate and the net electrical efficiency. The influence of oxygen concentration and oxygen purity was lower than that of excess oxygen coefficient, and χ 1 has almost no effect.

ACS Style

Zhiyu Zhang; Rongrong Zhai; Xinwei Wang; Yongping Yang. Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods. Energies 2020, 13, 998 .

AMA Style

Zhiyu Zhang, Rongrong Zhai, Xinwei Wang, Yongping Yang. Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods. Energies. 2020; 13 (4):998.

Chicago/Turabian Style

Zhiyu Zhang; Rongrong Zhai; Xinwei Wang; Yongping Yang. 2020. "Sensitivity Analysis and Optimization of Operating Parameters of an Oxyfuel Combustion Power Generation System Based on Single-Factor and Orthogonal Design Methods." Energies 13, no. 4: 998.

Journal article
Published: 01 February 2020 in Applied Thermal Engineering
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An innovative heat supply design for cogeneration systems has been proposed. Instead of the conventional heat source (extraction steam of the turbine), the low-pressure feedwater of the heat regeneration system is employed to provide district heat in the new scheme, through warming the supply-water of the primary heating network in a plate heat exchanger. A detailed thermodynamic analysis was conducted to evaluate the proposed design compared with the traditional one, based on a large-scale coal-fired power plant that needed to be retrofitted into cogeneration. The results show that the net power output of the cogeneration system is boosted by 4.68 MW owing to the novel concept. Furthermore, the total system efficiency and effective electric efficiency of the cogeneration system are promoted by 0.43 and 0.46 percentage points. This is because the exergy efficiency of the supply-water heating process is raised by 29.65 percentage points, and the exergy efficiency of the cogeneration system is improved by 0.42 percentage points. Finally, the new design was economically analyzed, and the results indicate that the net present value reaches 16543.2 thousand USD (8381.5 thousand USD more than that of the conventional design). Therefore, the proposed concept is feasible and profitable in engineering.

ACS Style

Heng Chen; Yunyun Wu; Shuai Xu; Gang Xu; Yongping Yang; Wenyi Liu. Thermodynamic and economic evaluation of a novel heat supply design using low-pressure feedwater in a cogeneration plant. Applied Thermal Engineering 2020, 166, 114672 .

AMA Style

Heng Chen, Yunyun Wu, Shuai Xu, Gang Xu, Yongping Yang, Wenyi Liu. Thermodynamic and economic evaluation of a novel heat supply design using low-pressure feedwater in a cogeneration plant. Applied Thermal Engineering. 2020; 166 ():114672.

Chicago/Turabian Style

Heng Chen; Yunyun Wu; Shuai Xu; Gang Xu; Yongping Yang; Wenyi Liu. 2020. "Thermodynamic and economic evaluation of a novel heat supply design using low-pressure feedwater in a cogeneration plant." Applied Thermal Engineering 166, no. : 114672.

Journal article
Published: 08 January 2020 in Energy
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An advanced waste-to-energy system integrated with a coal-fired power plant has been proposed to improve the energy utilization of municipal solid waste. In the new design, the energy gained from the waste-to-energy boiler is employed to heat the feedwater and partial cold reheat steam of the coal power plant, and the feedwater of the waste-to-energy boiler is provided by the heat regeneration system of the coal power plant. Consequently, the energy obtained from the waste incineration products is injected into the steam cycle of the coal power plant, and the waste-to-electricity efficiency can be significantly boosted. Based on a 500 t/day waste-to-energy plant and a 630 MW coal power plant, the proposed hybrid scheme was evaluated compared with the conventional separate one. The results show that the waste-to-electricity efficiency is promoted by 9.16% points with an additional net power output of 3.71 MW, attributed to the suggested integration. Furthermore, the energy-saving mechanism of the novel concept was revealed by energy and exergy analyses. Finally, the new design was economically examined, which indicates that the dynamic payback period of the proposed waste-to-energy plant is only 3.55 years, which is 5.87 years shorter than that of the conventional one.

ACS Style

Heng Chen; Meiyan Zhang; Kai Xue; Gang Xu; Yongping Yang; Zepeng Wang; Wenyi Liu; Tong Liu. An innovative waste-to-energy system integrated with a coal-fired power plant. Energy 2020, 194, 116893 .

AMA Style

Heng Chen, Meiyan Zhang, Kai Xue, Gang Xu, Yongping Yang, Zepeng Wang, Wenyi Liu, Tong Liu. An innovative waste-to-energy system integrated with a coal-fired power plant. Energy. 2020; 194 ():116893.

Chicago/Turabian Style

Heng Chen; Meiyan Zhang; Kai Xue; Gang Xu; Yongping Yang; Zepeng Wang; Wenyi Liu; Tong Liu. 2020. "An innovative waste-to-energy system integrated with a coal-fired power plant." Energy 194, no. : 116893.

Journal article
Published: 05 November 2019 in Energies
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The distributed renewable energy system, integrating various renewable energy resources, is a significant energy supply technology within energy internet. It is an effective way to meet increasingly growing demand for energy conservation and environmental damage reduction in energy generation and energy utilization. In this paper, the life cycle assessment (LCA) method and fuzzy rough sets (FRS) theory are combined to build an environmental evaluation model for a distributed renewable energy system. The ReCiPe2016 method is selected to calculate the environmental effect scores of the distributed energy system, and the FRS is utilized to identify the crucial activities and exchanges during its life cycle from cradle to grave. The generalized evaluation method is applied to a real-world case study, a typical distributed energy system located in Yanqing District, Beijing, China, which is composed of wind power, small-scale hydropower, photovoltaic, centralized solar thermal power plant and a biogas power plant. The results show that the environmental effect of per kWh power derived from the distributed renewable energy system is 2.06 × 10−3 species disappeared per year, 9.88 × 10−3 disability-adjusted life years, and 1.75 × 10−3 USD loss on fossil resources extraction, and further in the uncertainty analysis, it is found that the environmental load can be reduced effectively and efficiently by improving life span and annual utilization hour of power generation technologies and technology upgrade for wind turbine and photovoltaic plants. The results show that the proposed evaluation method could fast evaluate the environmental effects of a distributed energy system while the uncertainty analysis with FRS successfully and effectively identifies the key element and link among its life span.

ACS Style

Chengzhou Li; Ningling Wang; Hongyuan Zhang; Qingxin Liu; Youguo Chai; Xiaohu Shen; Zhiping Yang; Yongping Yang. Environmental Impact Evaluation of Distributed Renewable Energy System Based on Life Cycle Assessment and Fuzzy Rough Sets. Energies 2019, 12, 4214 .

AMA Style

Chengzhou Li, Ningling Wang, Hongyuan Zhang, Qingxin Liu, Youguo Chai, Xiaohu Shen, Zhiping Yang, Yongping Yang. Environmental Impact Evaluation of Distributed Renewable Energy System Based on Life Cycle Assessment and Fuzzy Rough Sets. Energies. 2019; 12 (21):4214.

Chicago/Turabian Style

Chengzhou Li; Ningling Wang; Hongyuan Zhang; Qingxin Liu; Youguo Chai; Xiaohu Shen; Zhiping Yang; Yongping Yang. 2019. "Environmental Impact Evaluation of Distributed Renewable Energy System Based on Life Cycle Assessment and Fuzzy Rough Sets." Energies 12, no. 21: 4214.

Journal article
Published: 11 September 2019 in Energies
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Adverse wind effects on the thermo-flow performances of air-cooled condensers (ACCs) can be effectively restrained by wind-proof devices, such as air deflectors. Based on a 2 × 300 MW coal-fired power generation unit, two types (plane and arc) of air deflectors were installed beneath the peripheral fans to improve the ACC’s cooling performance. With and without air deflectors, the air velocity, temperature, and pressure fields near the ACCs were simulated and analyzed in various windy conditions. The total air mass flow rate and unit back pressure were calculated and compared. The results show that, with the guidance of deflectors, reverse flows are obviously suppressed in the upwind condenser cells under windy conditions, which is conducive to an increased mass flow rate and heat dissipation and, subsequently, introduces a favorable thermo-flow performance of the cooling system. When the wind speed increases, the leading flow effect of the air deflectors improves, and improvements in the ACC’s performance in the wind directions of 45° and –45° are more satisfactory. However, hot plume recirculation may impede performance when the wind direction is 0°. For all cases, air deflectors in an arc shape are recommended to restrain the disadvantageous wind effects.

ACS Style

Xianwei Huang; Lin Chen; Yang; Xiaoze Du; Chen; Du; Lijun Yang; Yongping Yang. Cooling Performance Enhancement of Air-Cooled Condensers by Guiding Air Flow. Energies 2019, 12, 3503 .

AMA Style

Xianwei Huang, Lin Chen, Yang, Xiaoze Du, Chen, Du, Lijun Yang, Yongping Yang. Cooling Performance Enhancement of Air-Cooled Condensers by Guiding Air Flow. Energies. 2019; 12 (18):3503.

Chicago/Turabian Style

Xianwei Huang; Lin Chen; Yang; Xiaoze Du; Chen; Du; Lijun Yang; Yongping Yang. 2019. "Cooling Performance Enhancement of Air-Cooled Condensers by Guiding Air Flow." Energies 12, no. 18: 3503.

Journal article
Published: 01 April 2019 in Global Energy Interconnection
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The development of electrical engineering and electronic, communications, smart power grid, and ultra-high voltage transmission technologies have driven the energy system revolution to the next generation: the energy internet. Progressive penetration of intermittent renewable energy sources into the energy system has led to unprecedented challenges to the currently wide use of coal-fired power generation technologies. Here, the applications and prospects of advanced coal-fired power generation technologies are analyzed. These technologies can be summarized into three categories: (1) large-scale and higher parameters coal-fired power generation technologies, including 620/650/700 °C ultra-supercritical thermal power and double reheat ultra-supercritical coal-fired power generation technologies; (2) system innovation and specific, high- efficiency thermal cycles, which consist of renewable energy-aided coal-fired power generation technologies, a supercritical CO2 Brayton cycle for coal-fired power plants, large-scale air-cooling coal-fired power plant technologies, and innovative layouts for waste heat utilization and enhanced energy cascade utilization; (3) coal-fired power generation combined with poly-generation technologies, which are represented by integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) technologies. Concerning the existing coal-fired power units, which are responsible for peak shaving, possible strategies for enhancing flexibility and operational stability are discussed. Furthermore, future trends for coal-fired power plants coupled with cyber-physical system (CPS) technologies are introduced. The development of advanced, coal-fired power generation technologies demonstrates the progress of science and is suitable for the sustainable development of human society.

ACS Style

Yongping Yang; Chengzhou Li; Ningling Wang; Zhiping Yang. Progress and prospects of innovative coal-fired power plants within the energy internet. Global Energy Interconnection 2019, 2, 160 -179.

AMA Style

Yongping Yang, Chengzhou Li, Ningling Wang, Zhiping Yang. Progress and prospects of innovative coal-fired power plants within the energy internet. Global Energy Interconnection. 2019; 2 (2):160-179.

Chicago/Turabian Style

Yongping Yang; Chengzhou Li; Ningling Wang; Zhiping Yang. 2019. "Progress and prospects of innovative coal-fired power plants within the energy internet." Global Energy Interconnection 2, no. 2: 160-179.

Journal article
Published: 28 March 2019 in Entropy
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High back-pressure (HBP) heating technology has been identified as an effective approach to improve the efficiency of combined heat and power (CHP). In this study, the novel concept of a HBP heating system with energy cascade utilization is developed and its probability examined. In the reformative design, the extracted heating steam from the intermediate-pressure turbine (IPT) is first drawn to an additional turbine where its excess pressure can be converted into electricity, then steam with a lower pressure can be employed to heat the supply water. As a consequence, the exergy destruction in the supply water heating process can be reduced and the efficiency of the cogeneration unit raised. A detailed thermodynamic investigation was performed based on a typical coal-fired HBP–CHP unit incorporating the proposed configuration. The results show that the artificial thermal efficiency (ATE) promotion was as much as 2.01 percentage points, with an additional net power output of 8.4 MW compared to the reference unit. This was attributed to a 14.65 percentage-point increment in the exergy efficiency of the supply water heating process caused by the suggested retrofitting. The influences of the unit power output, unit heat output, supply water and return water temperatures and turbine back pressure on the thermal performance of the modified system are discussed as well. In addition, the economic performance of the new design is assessed, indicating that the proposed concept is financially feasible.

ACS Style

Heng Chen; Yunyun Wu; Jidong Xu; Gang Xu; Yongping Yang; Wenyi Liu; Gangye Shi. Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units. Entropy 2019, 21, 342 .

AMA Style

Heng Chen, Yunyun Wu, Jidong Xu, Gang Xu, Yongping Yang, Wenyi Liu, Gangye Shi. Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units. Entropy. 2019; 21 (4):342.

Chicago/Turabian Style

Heng Chen; Yunyun Wu; Jidong Xu; Gang Xu; Yongping Yang; Wenyi Liu; Gangye Shi. 2019. "Thermodynamic and Economic Analyses of Reformative Design for High Back-Pressure Heating in Coal-Fueled Cogeneration Units." Entropy 21, no. 4: 342.

Journal article
Published: 26 March 2019 in Energies
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Supercritical once-through utility boilers are increasingly common in flexible operations in China. In this study, the tube temperature changes at a vertical water-cooled wall are analyzed during a fluctuating flexible operation. There are considerable differences in the temperatures of the parallel tubes at the minimum load, and the resulting thermal stress distributions at a front water-cooled wall are established using structural calculation software ANSYS 17.1, USA. A wide thermal stress distribution occurs among the parallel tubes, and the local cyclic stress amplitudes under flexible operation are higher than those under cold, warm, hot, or load-following operations. Because of the water wall expansion structure at the furnace, the higher tube temperature areas suffer from compressive stress, while the lower tube temperature areas suffer from tensile stress. During flexible operation, combustion uniformity and a two-phase flow distribution can improve the safety of vertical water-cooled wall operation. The minimum load of the utility boiler should be set as a limitation, and the tube temperature is an important parameter affecting the thermal and cyclic stresses.

ACS Style

Liping Pang; Size Yi; Liqiang Duan; Wenxue Li; Yongping Yang. Thermal Stress and Cyclic Stress Analysis of a Vertical Water-Cooled Wall at a Utility Boiler under Flexible Operation. Energies 2019, 12, 1170 .

AMA Style

Liping Pang, Size Yi, Liqiang Duan, Wenxue Li, Yongping Yang. Thermal Stress and Cyclic Stress Analysis of a Vertical Water-Cooled Wall at a Utility Boiler under Flexible Operation. Energies. 2019; 12 (6):1170.

Chicago/Turabian Style

Liping Pang; Size Yi; Liqiang Duan; Wenxue Li; Yongping Yang. 2019. "Thermal Stress and Cyclic Stress Analysis of a Vertical Water-Cooled Wall at a Utility Boiler under Flexible Operation." Energies 12, no. 6: 1170.

Journal article
Published: 22 March 2019 in Energies
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For the large scale air-cooled heat exchanger of a natural draft dry cooling system (NDDCS) in power plants, its thermo-flow characteristics are basically dominated by crosswinds. Unfortunately however, the detailed mechanisms of the crosswind effects have yet to be fully uncovered. Therefore, in this research, the local flow and heat transfer performances of the cooling deltas, which are also termed as the fundamental cells of the large-scale air-cooled heat exchanger, are specifically investigated with full consideration for the cell structure and the water-side temperature distribution at various wind speeds. A 3D CFD method with a realizable k-ε turbulence model, heat exchanger model, and porous media model is developed, and the accuracy and credibility of the numerical model are experimentally validated. With the numerical simulation, the overall 3D outlet air temperature of the large-scale air-cooled heat exchanger, and the corresponding local air velocity and temperature fields of the cooling deltas are qualitatively analyzed. Furthermore, the air-mass flow rate and heat rejection are also quantitatively studied at both the global and local views. The results depict that with an increase in the wind speed, the air mass flow rate and heat rejection will increase greatly for the frontal deltas; however, they will drop dramatically for the middle-front deltas. As for the middle- as well as the middle-rear deltas, the thermo-flow performances vary markedly at various wind speeds, which behave in the most deteriorated manner at a wind speed of 12 m/s. The rear deltas show the best thermo-flow performances at a wind speed of 12 m/s, but the worst at 16 m/s. A detailed analysis of the variable fields for each cooling delta may contribute to the performance improvement of the large-scale air-cooled heat exchanger of NDDCS.

ACS Style

Yanqiang Kong; Weijia Wang; Zhitao Zuo; Lijun Yang; Xiaoze Du; Chao Xu; Yongping Yang. Influencing Mechanisms of a Crosswind on the Thermo-Hydraulic Characteristics of a Large-Scale Air-Cooled Heat Exchanger. Energies 2019, 12, 1128 .

AMA Style

Yanqiang Kong, Weijia Wang, Zhitao Zuo, Lijun Yang, Xiaoze Du, Chao Xu, Yongping Yang. Influencing Mechanisms of a Crosswind on the Thermo-Hydraulic Characteristics of a Large-Scale Air-Cooled Heat Exchanger. Energies. 2019; 12 (6):1128.

Chicago/Turabian Style

Yanqiang Kong; Weijia Wang; Zhitao Zuo; Lijun Yang; Xiaoze Du; Chao Xu; Yongping Yang. 2019. "Influencing Mechanisms of a Crosswind on the Thermo-Hydraulic Characteristics of a Large-Scale Air-Cooled Heat Exchanger." Energies 12, no. 6: 1128.

Review
Published: 27 December 2018 in Energies
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To reach optimal/better conceptual designs of energy systems, key design variables should be optimized/adapted with system layouts, which may contribute significantly to system improvement. Layout improvement can be proposed by combining system analysis with engineers’ judgments; however, optimal flowsheet synthesis is not trivial and can be best addressed by mathematical programming. In addition, multiple objectives are always involved for decision makers. Therefore, this paper reviews progressively the methodologies of system evaluation, optimization, and synthesis for the conceptual design of energy systems, and highlights the applications to thermal power plants, which are still supposed to play a significant role in the near future. For system evaluation, both conventional and advanced exergy-based analysis methods, including (advanced) exergoeconomics are deeply discussed and compared methodologically with recent developments. The advanced analysis is highlighted for further revealing the source, avoidability, and interactions among exergy destruction or cost of different components. For optimization and layout synthesis, after a general description of typical optimization problems and the solving methods, the superstructure-based and -free concepts are introduced and intensively compared by emphasizing the automatic generation and identification of structural alternatives. The theoretical basis of the most commonly-used multi-objective techniques and recent developments are given to offer high-quality Pareto front for decision makers, with an emphasis on evolutionary algorithms. Finally, the selected analysis and synthesis methods for layout improvement are compared and future perspectives are concluded with the emphasis on considering additional constraints for real-world designs and retrofits, possible methodology development for evaluation and synthesis, and the importance of good modeling practice.

ACS Style

Ligang Wang; Zhiping Yang; Shivom Sharma; Alberto Mian; Tzu-En Lin; George Tsatsaronis; François Maréchal; Yongping Yang. A Review of Evaluation, Optimization and Synthesis of Energy Systems: Methodology and Application to Thermal Power Plants. Energies 2018, 12, 73 .

AMA Style

Ligang Wang, Zhiping Yang, Shivom Sharma, Alberto Mian, Tzu-En Lin, George Tsatsaronis, François Maréchal, Yongping Yang. A Review of Evaluation, Optimization and Synthesis of Energy Systems: Methodology and Application to Thermal Power Plants. Energies. 2018; 12 (1):73.

Chicago/Turabian Style

Ligang Wang; Zhiping Yang; Shivom Sharma; Alberto Mian; Tzu-En Lin; George Tsatsaronis; François Maréchal; Yongping Yang. 2018. "A Review of Evaluation, Optimization and Synthesis of Energy Systems: Methodology and Application to Thermal Power Plants." Energies 12, no. 1: 73.

Journal article
Published: 05 December 2018 in Energy
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In this study, a new concept of the combustion air preheating system integrated with a bypass flue (BPF) configuration was put forward and its feasibility was evaluated. In the proposed system, the primary air and secondary air are heated separately with cascade heat exchange and the hot and cold bypassing primary air mixing is avoided, which contributes to enhancing the air preheating and waste heat utilization. Thermodynamic analysis was performed based on a typical 600 MW coal-fired power unit incorporating the new concept. The results indicated that owing to the proposed design, the power generation efficiency promotion reaches 0.78% (absolute value) with a standard coal consumption rate reduction of 5.52 g/kWh as compared to the reference unit, which are 0.14% (absolute value) higher and 0.94 g/kWh larger than those caused by the regular BPF retrofitting, respectively. The energy utilization is more rational in the new design according to the energy and exergy analysis, and the exergy efficiency of the primary air heating process is improved from 75.75% (original design) or 79.62% (regular BPF design) to 84.46% due to the proposed concept. The volume and heat exchange area of the APH decline significantly as well in the modified system.

ACS Style

Heng Chen; Yunyun Wu; Zhen Qi; Qiao Chen; Gang Xu; Yongping Yang; Wenyi Liu. Improved combustion air preheating design using multiple heat sources incorporating bypass flue in large-scale coal-fired power unit. Energy 2018, 169, 527 -541.

AMA Style

Heng Chen, Yunyun Wu, Zhen Qi, Qiao Chen, Gang Xu, Yongping Yang, Wenyi Liu. Improved combustion air preheating design using multiple heat sources incorporating bypass flue in large-scale coal-fired power unit. Energy. 2018; 169 ():527-541.

Chicago/Turabian Style

Heng Chen; Yunyun Wu; Zhen Qi; Qiao Chen; Gang Xu; Yongping Yang; Wenyi Liu. 2018. "Improved combustion air preheating design using multiple heat sources incorporating bypass flue in large-scale coal-fired power unit." Energy 169, no. : 527-541.

Journal article
Published: 23 October 2018 in Energies
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Doping of CeO2 on activated carbon (AC) can promote its performance for mercury abatement in flue gas, while the Hg0 removal mechanism on the AC surface has been rarely reported. In this research, density functional theory (DFT) calculations were implemented to unveil the mechanism of mercury removal on plain AC and CeO2 modified AC (CeO2-AC) sorbents. Calculation results indicate that Hg0, HCl, HgCl and HgCl2 are all chemisorbed on the adsorbent. Strong interaction and charge transfer are shown by partial density of states (PDOS) analysis of the Hg0 adsorption configuration. HCl, HgCl and HgCl2 can be dissociatively adsorbed on the AC model and subsequently generate HgCl or HgCl2 released to the gas phase. The adsorption energies of HgCl and HgCl2 on the CeO2-AC model are relatively high, indicating a great capacity for removing HgCl and HgCl2 in flue gas. DFT calculations suggest that AC sorbents exhibit a certain catalytic effect on mercury oxidation, the doping of CeO2 enhances the catalytic ability of Hg0 oxidation on the AC surface and the reactions follow the Langmuir–Hinshelwood mechanism.

ACS Style

Li Zhao; Yang-Wen Wu; Jian Han; Han-Xiao Wang; Ding-Jia Liu; Qiang Lu; Yong-Ping Yang. Density Functional Theory Study on Mechanism of Mercury Removal by CeO2 Modified Activated Carbon. Energies 2018, 11, 2872 .

AMA Style

Li Zhao, Yang-Wen Wu, Jian Han, Han-Xiao Wang, Ding-Jia Liu, Qiang Lu, Yong-Ping Yang. Density Functional Theory Study on Mechanism of Mercury Removal by CeO2 Modified Activated Carbon. Energies. 2018; 11 (11):2872.

Chicago/Turabian Style

Li Zhao; Yang-Wen Wu; Jian Han; Han-Xiao Wang; Ding-Jia Liu; Qiang Lu; Yong-Ping Yang. 2018. "Density Functional Theory Study on Mechanism of Mercury Removal by CeO2 Modified Activated Carbon." Energies 11, no. 11: 2872.

Journal article
Published: 19 September 2018 in Energies
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A conceptual high-back pressure (HBP) heating system cooperating raw coal pre-drying for combined heat and power (CHP) was proposed to improve the performance of the HBP-CHP unit. In the new design, besides of heating the supply-water of the heating network, a portion of the exhaust steam from the turbine is employed to desiccate the raw coal prior to the coal pulverizer, which further recovers the waste heat of the exhaust steam and contributes to raising the overall efficiency of the unit. Thermodynamic and economic analyzes were conducted based on a typical 300 MW coal-fired HBP-CHP unit with the application of the modified configuration. The results showed that the power generation thermal efficiency promotion of the unit reaches 1.7% (absolute value) owing to suggested retrofitting, and meanwhile, the power generation standard coal consumption rate is diminished by 5.8 g/kWh. Due to the raw coal pre-drying, the energy loss of the exhaust flue gas of the boiler is reduced by 19.1% and the boiler efficiency increases from 92.7% to 95.4%. The impacts of the water content of the dried coal and the unit heating capacity on the energy-saving effect of the new concept were also examined.

ACS Style

Heng Chen; Zhen Qi; Qiao Chen; Yunyun Wu; Gang Xu; Yongping Yang. Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit. Energies 2018, 11, 2487 .

AMA Style

Heng Chen, Zhen Qi, Qiao Chen, Yunyun Wu, Gang Xu, Yongping Yang. Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit. Energies. 2018; 11 (9):2487.

Chicago/Turabian Style

Heng Chen; Zhen Qi; Qiao Chen; Yunyun Wu; Gang Xu; Yongping Yang. 2018. "Modified High Back-Pressure Heating System Integrated with Raw Coal Pre-Drying in Combined Heat and Power Unit." Energies 11, no. 9: 2487.

Journal article
Published: 11 June 2018 in Energies
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An improved heating system integrated with waste pressure utilization (WPU) for combined heat and power (CHP) cogeneration was proposed. The new heating system efficiently utilized the excess pressure of the extraction heating steam to drive the WPU turbine and generator for producing electricity, achieving higher energy efficiency and lower fuel consumption of the CHP unit. The results of the detailed thermodynamic analysis showed that applying the proposed concept in a typical 300 MW coal-fired CHP unit could reduce the standard coal consumption rate by 9.84 g/(kW·h), with a thermal efficiency improvement of 1.97% (absolute value). Compared to that of the original heating process, the energy efficiency of the proposed process decreased by 0.55% (absolute value), but its exergy efficiency increased dramatically by 17.97% (absolute value), which meant that the proposed configuration could make better use of the steam energy and contribute to the better performance of the CHP unit. As the unit generation load and supply and return-water temperatures declined and the unit heating load rose, the WPU system would generate more electricity and its energy-saving benefit would be enhanced. This work provides a promising approach to further advance the CHP technology and district heating systems.

ACS Style

Heng Chen; Jidong Xu; Yao Xiao; Zhen Qi; Gang Xu; Yongping Yang. An Improved Heating System with Waste Pressure Utilization in a Combined Heat and Power Unit. Energies 2018, 11, 1515 .

AMA Style

Heng Chen, Jidong Xu, Yao Xiao, Zhen Qi, Gang Xu, Yongping Yang. An Improved Heating System with Waste Pressure Utilization in a Combined Heat and Power Unit. Energies. 2018; 11 (6):1515.

Chicago/Turabian Style

Heng Chen; Jidong Xu; Yao Xiao; Zhen Qi; Gang Xu; Yongping Yang. 2018. "An Improved Heating System with Waste Pressure Utilization in a Combined Heat and Power Unit." Energies 11, no. 6: 1515.

Journal article
Published: 23 May 2018 in Sustainability
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The transformation of the power generation industry from coal-based to more sustainable energy sources is an irreversible trend. In China, the coal-fired power plant, as the main electric power supply facility at present, needs to know its own sustainability level to face the future competition. A hybrid multi-criteria decision making (MCDM) model is proposed in this paper to assess the sustainability levels of the existing Chinese coal-fired power units. The areal grey relational analysis (AGRA) method is involved in the hybrid model, and a combined weighting method is used to determine the priorities of the criteria. The combining weight fuses the fuzzy rough set (FRS) and entropy objective weighting method together with the analytic hierarchy process (AHP) subjective weighting method by game theory. Moreover, an AHP weighting uncertainty analysis using Monte Carlo (MC) simulation is introduced to measure the uncertainty of the results, and a 95 percent confidence interval (CI) is defined as the uncertainty measurement of the alternatives. A case study about eight coal-fired power units is carried out with a criteria system, which contains five aspects in an operational perspective, such as the flexibility, economic, environmental, reliability and technical criterion. The sustainability assessment is performed at the unit level, and the results give a priority rank of the eight alternatives; additionally, the uncertainty analysis supplies the extra information from a statistical perspective. This work expands a novel hybrid MCDM method to the sustainability assessment of the power generation systems, and it may be a benefit to the energy enterprises in assessing the sustainability at the unit level and enhance its ability in future sustainable development.

ACS Style

Dianfa Wu; Zhiping Yang; Ningling Wang; Chengzhou Li; Yongping Yang. An Integrated Multi-Criteria Decision Making Model and AHP Weighting Uncertainty Analysis for Sustainability Assessment of Coal-Fired Power Units. Sustainability 2018, 10, 1700 .

AMA Style

Dianfa Wu, Zhiping Yang, Ningling Wang, Chengzhou Li, Yongping Yang. An Integrated Multi-Criteria Decision Making Model and AHP Weighting Uncertainty Analysis for Sustainability Assessment of Coal-Fired Power Units. Sustainability. 2018; 10 (6):1700.

Chicago/Turabian Style

Dianfa Wu; Zhiping Yang; Ningling Wang; Chengzhou Li; Yongping Yang. 2018. "An Integrated Multi-Criteria Decision Making Model and AHP Weighting Uncertainty Analysis for Sustainability Assessment of Coal-Fired Power Units." Sustainability 10, no. 6: 1700.

Journal article
Published: 23 March 2018 in Materials
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CeO2 is a promising catalytic oxidation material for flue gas mercury removal. Density functional theory (DFT) calculations and periodic slab models are employed to investigate mercury adsorption and oxidation by oxygen over the CeO2 (111) surface. DFT calculations indicate that Hg0 is physically adsorbed on the CeO2 (111) surface and the Hg atom interacts strongly with the surface Ce atom according to the partial density of states (PDOS) analysis, whereas, HgO is adsorbed on the CeO2 (111) surface in a chemisorption manner, with its adsorption energy in the range of 69.9–198.37 kJ/mol. Depending on the adsorption methods of Hg0 and HgO, three reaction pathways (pathways I, II, and III) of Hg0 oxidation by oxygen are proposed. Pathway I is the most likely oxidation route on the CeO2 (111) surface due to it having the lowest energy barrier of 20.7 kJ/mol. The formation of the HgO molecule is the rate-determining step, which is also the only energy barrier of the entire process. Compared with energy barriers of Hg0 oxidation on the other catalytic materials, CeO2 is more efficient at mercury removal in flue gas owing to its low energy barrier.

ACS Style

Li Zhao; Yangwen Wu; Jian Han; Qiang Lu; Yongping Yang; Laibao Zhang. Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO2 (111) Surface: A DFT Study. Materials 2018, 11, 485 .

AMA Style

Li Zhao, Yangwen Wu, Jian Han, Qiang Lu, Yongping Yang, Laibao Zhang. Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO2 (111) Surface: A DFT Study. Materials. 2018; 11 (4):485.

Chicago/Turabian Style

Li Zhao; Yangwen Wu; Jian Han; Qiang Lu; Yongping Yang; Laibao Zhang. 2018. "Mechanism of Mercury Adsorption and Oxidation by Oxygen over the CeO2 (111) Surface: A DFT Study." Materials 11, no. 4: 485.

Journal article
Published: 23 March 2018 in Entropy
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In recent years, coal-fired power plants contribute the biggest part of power generation in China. Challenges of energy conservation and emission reduction of the coal-fired power plant encountering with a rapid growth due to the rising proportion of renewable energy generation in total power generation. Energy saving power generation dispatch (ESPGD) based on power units sorting technology is a promising approach to meet the challenge. Therefore, it is crucial to establish a reasonable and feasible multi-index comprehensive evaluation (MICE) framework for assessing the performance of coal-fired power units accessed by the power grid. In this paper, a hierarchical multiple criteria evaluation system was established. Except for the typical economic and environmental indices, the evaluation system considering operational flexibility and power quality indices either. A hybrid comprehensive evaluation model was proposed to assess the unit operational performance. The model is an integration of grey relational analysis (GRA) with analytic hierarchy process (AHP) and a novel entropy-based method (abbreviate as BECC) which integrates bootstrap method and correlation coefficient (CC) into entropy principle to get the objective weight of indices. Then a case study on seven typical 600 megawatts coal-fired power units was carried out to illustrate the proposed evaluation model, and a weight sensitivity analysis was developed in addition. The results of the case study shows that unit 4 has the power generating priority over the rest ones, and unit 2 ranks last, with the lowest grey relational degree. The weight sensitivity analysis shows that the environmental factor has the biggest sensitivity coefficient. And the validation analysis of the developed BECC weight method shows that it is feasible for the MICE model, and it is stable with an ignorable uncertainty caused by the stochastic factor in the bootstrapping process. The elaborate analysis of the result reveals that it is feasible to rank power units with the proposed evaluation model. Furthermore, it is beneficial to synthesize the updated multiple criteria in optimizing the power generating priority of coal-fired power units.

ACS Style

Dianfa Wu; Ningling Wang; Zhiping Yang; Chengzhou Li; Yongping Yang. Comprehensive Evaluation of Coal-Fired Power Units Using Grey Relational Analysis and a Hybrid Entropy-Based Weighting Method. Entropy 2018, 20, 215 .

AMA Style

Dianfa Wu, Ningling Wang, Zhiping Yang, Chengzhou Li, Yongping Yang. Comprehensive Evaluation of Coal-Fired Power Units Using Grey Relational Analysis and a Hybrid Entropy-Based Weighting Method. Entropy. 2018; 20 (4):215.

Chicago/Turabian Style

Dianfa Wu; Ningling Wang; Zhiping Yang; Chengzhou Li; Yongping Yang. 2018. "Comprehensive Evaluation of Coal-Fired Power Units Using Grey Relational Analysis and a Hybrid Entropy-Based Weighting Method." Entropy 20, no. 4: 215.