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Concentrating Solar Thermochemical Hydrogen Production by Biomass Gasification in Supercritical Water

Energy Procedia 2015年 69卷 444-450页

作者： B. Liao L.J. Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xianning West Road No.28 Xi’an Shaanxi 710049 China

Solar receiver reactor is the key component of supercritical water gasification of biomass using concentrating solar energy, and itsthermal performance directly affects the thermal efficiency and biomass gasification results. The temperature distributions of solar receiver reactor and reactant fluid are *** results showed that direct normal solar irradiation (DNI) have prominent effect on the temperature of cavity type solar receiver reactor, thus affecting the SCWG reaction behaviors and gasification results. A series of on-sun experiments were carried out,temperature is relatively stable withDNI small fluctuations, and the nominal fluid temperatures at the outlet of reactor varied in the range 500–650 o C, which could completely meet the need of the temperature for biomass gasification in supercritical *** compounds of biomass (ethylene glycol, ethanol,glycerin and glucose) were continuously gasified under SCW conditions to generate hydrogen-rich fuel gas in the apparatus. Gas yields, carbon gasification efficiency and the total gasification efficiency increase with increasing DNI. The range of GE and CE is 48.5-105.8%, 37.5-95.6%, *** thermal performance and gasification results show thatsolar receiver/reactor used in this study is one of the good configurations that can be used for SCWG of biomass using concentrating solar energy.

关键词： Solar receiver reactor thermochemical hydrogen production supercritical water gasification

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Research on the penetration length of submerged sonic/supersonic steam jet

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2015年第10期36卷 2169-2172页

作者： Yuan, Fang Fan, Peng-Fei Wu, Lin-Fei Zhao, Quan-Bin Chen, Wei-Xiong Chong, Dao-Tong Yan, Jun-Jie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China CNNC Nuclear Power Operations and Management Co. Ltd Jiaxing314000 China

The continuous steam region generated by high-speed steam jet discharging into subcooled water is called the steam plume. The plume penetration length is an important index for heat exchange capability of steam jet. In this paper, the penetration length of sonic/supersonic steam jet at the stable condensation regime was investigated experimentally. It was found that the dimensionless penetration length increased with increasing steam mass ux and water temperature. Besides, the dimensionless penetration length of supersonic steam jet was smaller than that of sonic steam jet and decreased with the diminishing designed pressure ratio of supersonic nozzles. Moreover, a correlation was proposed based on the experimental data;the discrepancies between predicted and experimental penetration length were within ±15%. © 2015, Science Press. All right reserved.

关键词： Steam

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Theoretical Investigation on the Partial Load Feedwater Heating System with Thermal Vapor Compressor in a Coal-fired power Unit

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Energy Procedia 2015年 75卷 1102-1107页

作者： Liu Jiping Han Wei Wang Xin Han Xiaoqu Chong Daotong Yan Junjie Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi’an Jiaotong University Xi’an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

When a coal-fired unit operates at a partial load, the decrease at regenerative steam pressure leads to a decrease in boiler feedwater temperature, affecting not only the thermal economical efficiency, but also the selective catalytic reduction (SCR) denitrification effect and the boiler combustion stability. A feedwater system with the thermal vapor compressor has been studied in the present paper. The high pressure regenerative steam is injected by the live steam to heat boiler feedwater to increase its temperature. Mathematical models of the thermal vapor compressor, boiler and turbine regenerative system are established to calculate the performance of a 660MW supercritical air cooling unit at a 60% load. It was found that although the energy-saving effect is small, it is positive to improve the SCR denitrification effect and stabilize the boiler combustion.

关键词： regenerative cycle thermal vapor compressor thermo-economical analysis

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Research on Heat Recovery System of Turbine Exhaust Steam Using Absorption Heat Pump for Heating Supply Based on Heating Load Characteristics

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Energy Procedia 2015年 75卷 1502-1507页

作者： Jinshi Wang Kai Xia Weixiong Chen Ming Liu Datong Chong Jiping Liu Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi’an Jiaotong University Xi’an 710049 China

In order to improve the energy utilization efficiency of thermal power plants and to solve the heating shortage problem in China, the absorption heat pump is usually employed to recover the heat of turbine exhaust steam for heating supply. In the existing references, few researchers considered the heating load characteristics when designing the recovery system. In this paper, the design thought of heat recovery system of turbine exhaust steam using absorption heat pump for heating supply based on heating load characteristics was presented. With an engineering case, the heat recovery system was designed and its economic efficiency was calculated.

关键词： heating load heat pump heat recovery power

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Effect of turbulence model on prediction of subcooled boiling

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2015年第8期49卷 1366-1373页

作者： Zhang, Rui Tian, Wen-Xi Cong, Teng-Long Su, Guang-Hui Qiu, Sui-Zheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

The ANSYS FLUENT14.5 was employed to simulate the two-phase forced convection subcooled boiling in a vertical heated pipe. Different turbulence models, wall functions and two-phase turbulence treatments were utilized to each of four sets of grids. Results were compared with experiment data to analyze the effects of grids, turbulence model, wall functions and two-phase turbulence treatments. The results of k-Ε model show better agreement with experiment data than those of k-ω model. Dispersed and Per Phase treatments for two-phase turbulence parameters perform no better than Mixture treatment. The enhanced wall function can't achieve satisfactory results for the grid with near wall function Y+ 1. ©, 2015, Atomic Energy Press. All right reserved.

关键词： Turbulence models

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Study of depressurization process for supercritical fluid

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2015年第3期49卷 440-446页

作者： Zhang, Jing Tian, Wen-Xi Zhu, Da-Huan Qiu, Sui-Zheng Su, Guang-Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Nuclear Science and Technology Xi'an Jiaotong Univesity Xi'an710049 China

The loss of coolant accident (LOCA) research of the supercritical water-cooled reactor (SCWR) is the key and difficult task for the safety analysis, and especially the research of the depressurization process of the pressure vessel is of crucial importance. The reactor pressure vessel was simplified and mathematical physics models were established in this study. A transient calculating code was developed. A comparison between experimental and calculated results for supercritical carbon dioxide was carried out. It is showed that the predicted results by codes are in good agreement with the experimental data. The depressurization process was analyzed by the verified code. The influences of different initial conditions, breach areas and heating powers on the depressurization process were discussed. The results show that the models established in this study can simulate the depressurization process from supercritical to subcritical state, and the calculating results may provide a theoretical basis for accident analysis of the SCWR. ©, 2015, Atomic Energy Press. All right reserved.

关键词： Supercritical fluids

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Prediction of flow boiling heat transfer coefficient in horizontal channel by genetic neural network

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2015年第1期49卷 70-76页

作者： Zhang, Jing Cong, Teng-Long Su, Guang-Hui Qiu, Sui-Zheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

The three-layer back propagation network (BPN) and genetic neural network (GNN) were developed to predict the flow boiling heat transfer coefficient (HTC) in conventional and micro channels. The precision of GNN is higher than that of BPN (with root mean square errors of 17.16% and 20.50%, respectively). The inputs include vapor quality, mass flux, heat flux, diameter and physical properties and the output is HTC. Based on the trained GNN, the influences of input parameters on HTC were analyzed. HTC increases with pressure in conventional channels. The pressure has a negligible effect at low pressure region on HTC for micro channels. However, at high pressure region, HTC increases in low vapor quality region, while decreases in the high vapor quality region with the increase of pressure. HTC increases with the mass flux and heat flux, and HTC initially increases and then decreases as vapor quality increases. HTC increases inversely with the decrease of diameter. Dry-out arises at a lower quality in micro channels than that in conventional channels and more easily occurs in a smaller channel. ©, 2015, Atomic Energy Press. All right reserved.

关键词： Heat transfer coefficients

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Visible light-driven water oxidation using metal oxide quantum dots modified with a cobalt catalyst

Visible light-driven water oxidation using metal oxide quant...

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中国化学会第九届全国无机化学学术会议

作者： Fujun Niu Ning Zhang Shaohua Shen Liejin Guo International Research Center of Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

Conversion of sunlight to chemical fuels is the holy grail to deal with the energy and environment issue.1,2 Inspired by the natural photosynthesis, molecular based photocatalytic system has been widely investigated. Generally speaking, such a system contains three part: a sensitizer to absorb light, a reduction catalyst to generate H2, and an oxidation catalyst to produce O2. The oxidation of water has been proved to be the key of the entire water splitting process, as the reaction kinetic limitation step.3 In this work, we developed a novel system with Co3O4 quantum dots(QDs) or Fe2O3 QDs as photosensitizer, a salophen cobalt(II) complex(Co SLP) as catalyst, and persulfate(S2-2O8) as the sacrificial electron acceptor(Fig. 1). The photocatalytic oxygen evolution rate of the systems were 75μmol/h/g and 84μmol/h/g over the cobalt(II) complex when Co3O4 QDs or Fe2O3 QDs was employed, respectively. While no O2 evolution were observed when either salophen cobalt(II) complex or QDs was absent. This high efficiency might be attributed to the interfacial hole transfer from photoexcited QDs to the cobalt(II) complex.

关键词： artificial photosynthesis oxygen production quantum dots cobalt catalyst

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Simulation of a Novel Single-column Cryogenic Air Separation Process Using LNG Cold Energy

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Physics Procedia 2015年 67卷 116-122页

作者： Zheng Jieyu Li Yanzhong Li Guangpeng Si Biao Institute of Refrigeration and Cryogenics Xi’an Jiaotong University Xi’an710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an710049China

In this paper, a novel single-column air separation process is proposed with the implementation of heat pump technique and introduction of LNG coldenergy. The proposed process is verifiedand optimized through simulation on the Aspen Hysys® platform. Simulation results reveal that thepower consumption per unit mass of liquid productis around 0.218 kWh/kg, and the total exergy efficiency of the systemis 0.575. According to the latest literatures, an energy saving of 39.1% is achieved compared with those using conventional double-column air separation *** introduction of LNG cold energy is an effective way to increase the system efficiency.

关键词： heat pump cryogenic air separation single-column process LNG cold energy recovery Aspen Hysys® simulation

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Thermal-hydraulic analysis and metal temperature computation for the water wall of a 1000MW ultra supercritical tower boiler with double reheat

Thermal-hydraulic analysis and metal temperature computation...

引用

International Conference on power engineering, ICOPE 2015

作者： Yang, Dong Wang, Long Bi, Yanshuang Xie, Beibei Wang, Gang Yao, Danhua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an Shaanxi710049 China Shanghai Boiler Works Ltd. No.250 Huaning Road Minhang District Shanghai200245 China

The ultra supercritical boiler technology with double reheat can significantly increase the efficiency of a Rankine cycle power plant, and reduce fuel consumption for a given output. Recently China is developing 1000MW ultra supercritical boiler with double reheat which is arranged in tower type and the steam parameters are 350bar, 605oC/613oC/613oC. Thermal-hydraulic analysis is the key factors for the design and operation of ultra supercritical boiler with double reheat. According to the boiler structure and furnace-sided heat flux, the water wall of an ultra supercritical tower boiler with double reheat is treated in this paper as a flow network system consisting of series-parallel loops, pressure grids and connecting tubes. Based on the mass, momentum and energy conservations and some supplementary equations, a mathematical model is developed. Pressure drop, mass flux distribution, outlet vapor temperatures and metal temperatures data in the water wall at BMCR (boiler maximum continuous rating), 75% THA (turbine heat acceptance) and 30% THA load are obtained by iteratively solving the mathematical model. The results show that the water wall in the ultra supercritical boiler can operate safely. © 2015 The Japan Society of Mechanical Engineers.

关键词： Pressure drop

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