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Dynamic modeling of a NG-fueled SOFC-PEMFC hybrid system coupled with TSA process for fuel cell vehicle

Energy Procedia 2019年 158卷 2215-2224页

作者： Zhen Wu Meng Ni Pengfei Zhu Zaoxiao Zhang Building Energy Research Group Department of Building and Real Estate The Hong Kong Polytechnic University Hong Kong P.R. China State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an 710049 P.R. China

Fuel cell power technology has drawn extensive attentions due to its high efficiency, low emission and noise. Solid oxide fuel cell (SOFC) could generate the power by diverse fuels, such as natural gas (NG), while proton exchange membrane fuel cell (PEMFC) only feeds on pure H 2 . More and more attentions are paid on the combination of SOFC and PEMFC for high efficiency and convenient refueling in the practical applications. To obtain H 2 fuel with high purity from SOFC as a reformer, the gas processing subsystem for H 2 separation and purification should be applied between SOFC and PEMFC. In this present study, the gas processing subsystem, consisting of water gas shift (WGS) and thermal swing adsorption (TSA), is introduced into the SOFC-PEMFC hybrid system. Then, the SOFC-WGS-TSA-PEMFC hybrid system is modelled to investigate the transient behaviors under different operations. The simulation results show that the SOFC-WGS-TSA-PEMFC hybrid system has an improved energy conversion efficiency of approximately 64%, which is higher than the only-SOFC and the reform-PEMFC. The waste heat recovery for driving the TSA reaction accounts for the higher net electricity efficiency compared with the SOFC-PEMFC hybrid system based on the pressure swing adsorption (PSA) for H 2 separation. Since the SOFC and PEMFC have completely different transient responses to the change of the loading, the influences of operating conditions of fuel cell vehicles on the transient behaviors of single SOFC and PEMFC and the overall performance of the SOFC-WGS-TSA-PEMFC hybrid system are further investigated. Through the analysis and discussion based on the dynamic modelling, the operation strategy is unveiled in this paper for the performance optimization of the hybrid system when installed in the fuel cell vehicles.

关键词： SOFC PEMFC Metal hydride Transient behavior High efficiency

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Investigation of the Effect of Phosphate in Wastewater on the Electrochemical Performance of Cofe-Ldh@Ni Foam Adsorbents as Supercapacitor Electrode Materials

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SSRN 2022年

作者： Hong, Xianyong Shi, Mingxing Li, Jinghua Xia, Mingzhu Du, Ping Wang, Fengyun School of Chemistry and Chemical Engineering Nanjing University of Science and Technology Nanjing210094 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Reducing P(V) in the environment is the key to solving the problem of eutrophication in water bodies. In this work, CoFe-LDH@NF composites were successfully prepared by a simple one-step hydrothermal method and efficiently obtained P(V) from wastewater. The P(V) in the phosphate undergoes a reduction reaction under a high temperature H2 atmosphere and reacts with the metal salt to form a metal phosphide (Co-Fe-P@NF). The electrochemical analysis shows that the reaction of P with metal elements to form the corresponding phosphide can effectively enhance the electrochemical properties of the composite. The specific capacitance of Co-Fe-P@NF is as high as 3.71 F/cm2 at a current density of 1 mA/cm2 and the specific capacitance retention rate is 81.7% after 2000 cycles of charging and discharging at a current density of 10 mA/cm2 . Furthermore, asymmetric supercapacitors (ASCs) were assembled with activated carbon (AC) as the negative electrode and Co-Fe-P@NF as the positive electrode with a voltage window of up to 1.6 V. Co-Fe-P@NF//AC ASC device allows the timer to operate generally for more than 75 mins. The excellent energy storage performance on the supercapacitor electrode material provides an effective solution for recycling the adsorbent. © 2022, The Authors. All rights reserved.

关键词： Supercapacitor

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Regulating Surface Terminals and Interlayer Structure of Ti3c2tx for Superior Nh3 Sensing

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SSRN 2024年

作者： Li, Jiazheng Li, Yanqiong Zeng, Wen Bai, Bofeng Ren, Shan College of Materials Science and Engineering Chongqing University Chongqing400030 China School of Electronic information & Electrical Engineering Chongqing University of Arts and Sciences Chongqing400030 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

MXene materials have exhibited potential in electrochemistry, particularly in gas sensing, due to their excellent conductivity, large specific surface area of layered materials, and unique functional groups. However, the gas sensing performance of intrinsic 2D MXene materials is often limited by their fluorine-containing terminals and interfacial structure. In this study, based on intrinsic Ti3C2Tx, we employed alkali treatment and annealing to prepare oxygen-rich Ti3C2(OH)x/Ti3C2Ox with expanded interlayer spacing, achieving enhanced gas sensing performance for NH3. By utilizing the intercalation effect of layered materials and the synergistic effect of regulating MXene unique surface terminations, the sensing materials prepared have achieved optimization of surface chemistry and structural. Compared to intrinsic Ti3C2Tx, the interlayer spacing of oxygen-rich Ti3C2(OH)x/Ti3C2Ox increased from 9.1 Å to 12.1 Å. The surface terminations of oxygen-rich Ti3C2(OH)x/Ti3C2Ox have been defluorinated and oxygenated. The maximum response value of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3 was 35.66, approximately twice that of the original Ti3C2Tx at an NH3 concentration of 200 ppm. DFT (Density functional theory) calculations and DRIFT (In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy) tests explained the interaction between the surface terminals and NH3, indicating good selectivity and sensitivity of oxygen-rich Ti3C2(OH)x/Ti3C2Ox to NH3. The results of this study demonstrate that the synergistic effects of surface chemistry and structural engineering are crucial for MXene to optimize the electrochemical performance, particularly the gas sensing performance. This provides a feasible approach for the performance optimization of intrinsic MXene materials. © 2024, The Authors. All rights reserved.

关键词： Oxygen

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Catalytic Gasification of Large Particle Size Biomass with Loaded Aaems Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Yang, Kaixuan Li, Yuhang Bai, Yang Jiang, Jiahao Huang, Xiaole Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

To evaluate the effect of alkali and alkaline earth metals species (AAEMs) on the catalytic gasification of large particle size biomass, a vertical fixed-bed reactor is conducted for candlenut wood gasification under the oxygen-stream atmosphere. The gasification chars derived from gasification are characterized by SEM, X-ray CT, BET, and FTIR. Tar and syngas are analyzed via GC-MS and GC respectively. Advanced X-ray CT technology provides beneficial visualization to assist in the interpretation of the catalytic gasification of large particle size biomass loaded with AAEMs. The results indicate a progressive augmentation of AAEMs content along the radial direction and end surface for all loaded samples and gasification chars, which could also be visualized from the 3D reconstruction of X-ray CT. Many large pores (40-60 μm) aligned along the grain direction collapse after gasified and generate numerous micropores in gasification chars. 10-20 μm pores are more prominent in chars loaded with KCl and CaCl2. The char loaded with CaCl2 has more well-developed pores, a larger specific surface area, and -OH compounds, aldehydes, ketones and carboxylic acids. The addition of AAEMs facilitates the high generation of M1 compounds (contains 1 benzene ring) in the tar and suppresses the enhancement of other compounds, M4 compounds, and long-chain alkanes. H2 and CO concentrations augments and declines by loading AAEMs. The highest H2 concentration of 62.1% is detected by the addition of CaCl2. When loaded with KCl, the syngas calorific value reduces by 1.37%, while loaded with NaCl, CaCl2, and MgCl2 show an augmentation of 11.48%, 10.56%, and 2.55%, respectively. A decrement of CnHx concentration in syngas derived from samples loaded with KCl and MgCl2 and an increment one loaded with NaCl and CaCl2 are acquired. © 2023, The Authors. All rights reserved.

关键词： Oxygen

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Preliminary safety analysis of the PWR with accident-tolerant fuels during severe accident conditions

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Annals of Nuclear Energy 2015年 80卷 1-13页

作者： Xiaoli Wu Wei Li Yang Wang Yapei Zhang Wenxi Tian Guanghui Su Suizheng Qiu Tong Liu Yongjun Deng Heng Huang State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University No. 28 Xianning West Road Xi’an Shanxi 710049 China China Nuclear Power Technology Research Institute A-1101 Fengde Plaza No. 6 Hangkong Road Chengdu Sichuan 610000 China

Experience gained in decades of nuclear safety research and previous nuclear accidents direct to the investigation of passive safety system design and accident-tolerant fuel (ATF) system which is now becoming a hot research point in the nuclear energy field. The ATF system is aimed at upgrading safety characteristics of the nuclear fuel and cladding in a reactor core where active cooling has been lost, and is preferable or comparable to the current UO 2 –Zr system when the reactor is in normal operation. By virtue of advanced materials with improved properties, the ATF system will obviously slow down the progression of accidents, allowing wider margin of time for the mitigation measures to work. Specifically, the simulation and analysis of a large break loss of coolant accident (LBLOCA) without ECCS and extended station blackout (SBO) severe accident are performed for a pressurized water reactor (PWR) loaded with ATF candidates, to reflect the accident-tolerance of ATF.

关键词： Safety analysis Accident-tolerant Severe accident

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Study of Saturated Pool Boiling Heat Transfer Characteristics of R1233zd(E) on Aluminum-Based Micro-Pin Finned Surfaces

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SSRN 2024年

作者： Yang, Xiaoping Bu, Shichao Jiang, Zhuye Chen, Hongqiang Sun, Zhen Zhang, Yonghai Wei, Jinjia School of Chemical Engineering and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China

With the continuous development of chip integration and information technology, the heat dissipation has become a major limitation on the performance of electronic devices such as 5G base station, data center and so on, and meanwhile a challenge of conventional single-phase convection cooling methods. Boiling is prospective in high heat flux cooling and energy saving due to the usage of latent heat. R1233zd(E), an environmentally friendly refrigerant (GWP=1, ODP=0) with a freezing point of -107°C, is a potential working fluid in phase-change heat sinks for geographical applications. Nevertheless, the poor boiling performance of R1233zd(E) on plain surface due to the limitation in thermophysical properties must be enhanced. Moreover, conventional heat sinks are mostly copper-based, which are inconvenient for transportation and installation, and costly for production as well. In this work, micro pin fins in the range of 100-500 μm are fabricated on the aluminum surface to enhance the pool boiling of R1233zd(E). Moreover, the influence of their size and saturation pressure on the bubble behavior, critical heat flux (CHF) and heat transfer coefficient (HTC) is experimentally and theoretically investigated. The results show that the increase of pressure, as well as the ensuing various nucleation site and capillary effect to rewet the evaporation region, can lead to an increase in the CHF and HTC. Notably, the 150-200 μm micro pin-finned surfaces reaches the highest CHF and 100 μm one owns the highest HTC, which is 214% and 383% higher than that of plain surface, respectively. BY considering the balance of capillary effect and bubble convolution effect, a model of CHF is proposed to reveal the mechanism of optimum size of the micro pin fins. The predicted CHFs have an inaccuracy of less than ±20% comparing to experimental values. This paper makes up for the lack of basic experimental data on pool boiling of R1233zd(E) on aluminum surface, which thus provides guidance for

关键词： Heat flux

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Leakage source parameters identification for CO 2 sequestration based on Occam method

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Energy Procedia 2014年 63卷 3815-3820页

作者： Denglong Ma Zaoxiao Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

CO 2 gases stored underground may escape from the reservoir site to other places and even through the soil layer into atmosphere, thus identify the leakage source is therefore a crucial problem after leakage occurring. The paper introduced a direct method to solve the inverse problem combined with the optimization method, which is Occam regularization method. This method was applied to estimate the source parameters. Firstly, the calculation process of Occam regularization method was introduced and then the feasibility of its application for source parameters identification was proved by simulation and experiment data. The results showed that, Occam regularization method is able to estimate source parameters successfully.

关键词： Gas emission Parameters regularization Optimization Nonlinear inverse problem

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Proposal and Application of Supercritical Regeneration Process Based on Steam Rankine Cycle

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SSRN 2022年

作者： Sun, Enhui Qian, Qichen Ma, Wenjing Chang, Cheng Xu, Jinliang Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power University Ministry of Education Beijing102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Beijing102206 China

Regeneration process is widely used in power cycles. However, at present, the regeneration process of the supercritical Rankine cycle is carried out in the subcritical region. Therefore, the limitation of regeneration cannot be further addressed by the present optimization techniques. In this paper, the supercritical regeneration is proposed that involves compression and heat transfer process (compression regeneration process) to achieves heat recovery in supercritical region. Based on the supercritical regeneration, single-compression supercritical regenerative cycle with reheating (SSRC+RH) and recompression supercritical regenerative cycle with reheating (RSRC+RH) are constructed. Compared with the cycle without supercritical regeneration, the results show that the supercritical regeneration can significantly improve the cycle thermal efficiency, and the efficiency is mainly affected by the extraction pressure, compressor inlet temperature and pressure drop of heaters. When turbine inlet parameters are 620 oC/30 MPa, the maximum thermal efficiency of SSRC+RH and RSRC+RH are 51.4%, significantly higher than the Rankine cycle without supercritical regeneration (49.9%). Through analysis, under a wide range of parameters, supercritical regeneration increases the thermal efficiency by 0%-1.5% on the basis of subcritical regeneration. The supercritical regeneration proposed in this paper can effectively improve the thermal efficiency and provide a path for perfecting the regenerative theory. © 2022, The Authors. All rights reserved.

关键词： Rankine cycle

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Thermodynamic Analysis and Optimization of Two-Step Supercritical Water Desorption-Gasification System of Oily Sludge

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SSRN 2024年

作者： Zhang, Chenghao Wang, Gaoyun Zhao, Qiuyang Gao, Yunbo Ge, Zhiwei Jin, Hui Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No. 28 Xianning West Road Xi’an710049 China Technical Inspection Center Sinopec Shengli Oilfield Company Dongying257000 China

The two-step supercritical water desorption-gasification (TSSCWDG) technology can significantly improve the gasification efficiency of oil sludge. However, few works have been conducted to explore the influence of operating parameters on this process. In this paper, a novel desorption-gasification process modeling was constructed based on the supercritical water gasification (SCWG) of oily sludge and the influences of different operating parameters on the system efficiencies were investigated. Increasing the separation temperature and the desorption levels can achieve the rapid improvement of the efficiencies of the TSSCWDG system, but more desorption levels may increase the complexity of the system and the operating cost. The desorption temperature had a relatively small impact on the system efficiencies, but the lower desorption temperature was beneficial to the utilization of industrial waste heat and decreasing the operating cost. Moreover, the TSSCWDG system was optimized and analyzed, and the optimized system had achieved the energy matching between the gasification products and unites, resulting in significant reduction of the irreversible losses in each unit, which the energy efficiency of the optimized system reached 83.4%. This work could provide essential theoretical guidance for the scale-up and design of the industrial application of SCWG of oil sludge with hydrogen production. © 2024, The Authors. All rights reserved.

关键词： Desorption

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Carbon Exergy Footprint to Evaluate the Greenhouse Impact of Operating Units

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Energy Procedia 2017年 105卷 3179-3184页

作者： Zhen Qin Xiaomei Wu Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

Increasingly serious global warming caused by greenhouse gases has urged more and more focus on the sustainability. Exergy and carbon footprint are generally considered as two separate indicators to assess the greenhouse effect and sustainability of industrial production. In this paper we propose carbon exergy footprint (CEF) for quantitatively associating carbon footprint with exergy to evaluate the greenhouse effect of operating units. The indicator synthesizes the advantages of exergy and carbon footprint. Specific physical meaning for this novel indicator is illustrated on the basis of the second law of thermodynamics and life cycle assessment. The process of water-gas shift is chosen as the case for elaborating the behavior of CEF. Results show that CEF is competent for the objective evaluation for the greenhouse effect of the operating units. Additionally, CEF also maintains consistency with the conventional exergy analysis in terms of sustainability.

关键词： Carbon exergy footprint operating unit greenhouse impact indicator

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