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Electroreduction of carbon dioxide to multi-electron reduction products using poly(ionic liquid)-based Cu-Pd catalyst

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Fundamental Research 2022年第6期2卷 937-945页

作者： Xiao-Qiang Li Guo-Yi Duan Xian-Xia Yang Li-Jun Han Bao-Hua Xu Beijing Key Laboratory of Ionic Liquids Clean Process CAS Key Laboratory of Green Process and EngineeringState Key Laboratory of Multiphase Complex SystemsInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China National Fundamental Research Laboratory of New Hazardous Chemicals Assessment and Accident Analysis Institute of Applied ElectrochemistryBeijing University of Chemical TechnologyBeijing 100029China

Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multi-electron(>2e–)products provides a green and sustainable route for producing fuels and *** the second metal element is a feasible strategy for"managing"the key intermediate on Cu-based materials to further improve the CO_(2)RR catalytic *** this work,palladium,which promises the generation of CO,was introduced into the poly(ionic liquid)-based copper hybrid(Cu@PIL)to construct a novel Cu-Pd bimetallic electrocatalyst(Cu@PIL@Pd).Remarkably,with a small dosage of palladium(2.0 mol%compared with Cu),a high faradaic efficiency(FE)for C_(2+)products(68.7%)was achieved at–1.01 V(with respect to the reversible hydrogen electrode(RHE),the same below)with a high partial current density of 178.3 mA cm^(-2).Meanwhile,high selectivity towards CH4(FE=42.5%)and corresponding partial current density of 172.8 mA cm^(-2)were obtained on the same catalyst at–1.24 V,signifying a significant potential-dependent *** studies reveal that both copper and palladium oxides are reduced to metallic states during the CO_(2)*** presence of the adjoint copper phase and the highly dispersed electrostatic layer promote the generation of CO on the palladium components(both the PdO_(2)phase and the Pd(II)site).Besides,the local CO^(*)was enriched by the significant diffusion resistance of CO in the PIL *** spillover of CO^(*)from Pd sites to the adjoint Cu sites,accompanied by the increased local concentration of CO^(*)around Cu sites,accounted for the observed good CO_(2)RR catalytic performance,especially the high C_(2+)product selectivity.

关键词： CO_(2)conversion Bimetallic catalyst Cu-Pd material Electrolysis High-value products

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Heat Transfer Prediction of Supercritical Carbon Dioxide in Vertical Tube Based on Artificial Neural Networks

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Journal of Thermal Science 2021年第5期30卷 1751-1767页

作者： ZHU Bingguo ZHU Xinjie XIE Jian XU Jinliang LIU Huan Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power UniversityMinistry of EducationBeijing102206China School of Mechanical&Electronical Engineering Lanzhou University of TechnologyLanzhou730050China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing102206China

Accurate prediction of supercritical CO_(2)(scCO_(2))heat transfer is important for heat exchanger design and safe operation of scCO_(2)power *** main prediction method is empirical *** paper demonstrates an alternative way by artificial neural networks(ANN)model with two hidden *** assess widely cited correlations and newly developed ANN model,scCO_(2)heat transfer experiment in vertical tube with pressure up to 20.8 MPa was performed to extend experiment database,which includes 2674 *** with empirical correlations,the ANN model is promising for following advantages:(1)ANN model has much better prediction *** mean relative error,mean absolute relative error and the root-mean-square relative error between predicted and measured wall temperatures are eA=0.38%,eR=4.88%and eS=7.29%,respectively.(2)ANN model performs faster computation speed.(3)ANN model can accurately and speedily predict scCO_(2)heat transfer performance for both normal heat transfer and heat transfer deterioration *** trained ANN program is provided with this paper,which is a useful tool and can be directly applied in engineering of scCO_(2)heat transfer.

关键词： supercritical CO_(2) heat transfer prediction ANN model correlations

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The Thermal Effect of Flame-Wall Interaction on the Nox Emission Characteristics of Ammonia Swirling Flames in a Model Combustor

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SSRN 2022年

作者： Zhang, Meng Xu, Wanying Wang, Ruixiang Wei, Xutao Wang, Jinhua Huang, Zuohua Tan, Houzhang State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xian Jiaotong University Xian710049 China

Ammonia (NH 3 ) combustion is regarded as one of the most promising solutions to realize zero CO 2 emission. However, the low reactivity, low heat release result in a strong flame-wall interaction (FWI) which significantly affects the flame stabilization and the NOx emission characteristics. In this study, an air film cooling on the swirling combustion chamber was designed to investigate the thermal effect of the FWI on NOx emission. The flame structure and NO production are measured with the OH-/NO-PLIF techniques. The NOx emission is analyzed by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Large eddy simulation is also conducted to extend the understandings of experimental findings. For the current combustion chamber, the temperature difference is increasing as downstream location, resulting a larger convection heat loss. The heat loss shows no apparent effect on the flame structure and NO production at the symmetrical plane. The flame tends to be more fragmentized and the NO production is largely decreased at near wall region and the outer recirculation zone with increasing heat loss. This can be understood that NO production rate from the oxidation of NH i by O, H and OH radicals through HNO is largely decreasing in these regions. Therefore, a decreasing NO trend is found at the chamber outlet. NO emission shows a decreasing trend with heat loss at lean condition, which is mainly caused by the decreased NO production at near wall region resulting from the lower combustion efficiency. However, N 2 O, a more serious greenhouse gas, significantly increases as the heat loss increases. This is mainly because that the production of N 2 O from NO is promoted and N 2 O decomposition is suppressed within the thermal boundary. Thus, N 2 O might become a more serious emission component in NH 3 fuelled gas turbines. Moreover, a tradeoff behaviour between NO and N 2 O is observed as increasing heat loss. This study suggests the thermal effect of FWI on t

关键词： Heat losses

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Comparison of Lifetime Performance of Pemfc Stacks with Two Cooling Strategies Under Different Humidity

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SSRN 2024年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Lv, Jizu Hu, Chengzhi Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

While reducing the size and Pt loading can achieve a lower proton exchange membrane fuel cell (PEMFC) stack cost, it is also very important to focus on the performance changes of the PEMFC stack during the long-term operation. A 3D PtCo catalysts long-term performance model is established in this study, and PEMFC stacks with one cooling unit per cell (1-cell stack) and three cells (3-cell stack) are employed as the computational domains, respectively. The effective area of each cell is 50 cm2, and the changes in current density as well as effective catalytic area of PEMFC stacks with two cooling strategies before and after long-term operation under different humidity conditions are investigated at low Pt loadings. The results show that there are large differences in the output voltage and current density distributions between the three cells due to the poor membrane hydration affected by the non-uniform temperature distribution, although the 3-cell stack can significantly reduce the size. Localized catalyst degradation in both 3-cell and 1-cell stacks is closely related to the geometry of the cathodic flow field, and non-uniform catalyst degradation is found to increase the activation and mass transfer losses and change the distribution of current density within the membrane. In addition, the 3-cell stack is found to perform even better in terms of durability, especially under high humidity conditions, which provides a potential solution to improve the durability of PEMFC stacks operating in harsh conditions. © 2024, The Authors. All rights reserved.

关键词： Durability

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Steam Entrainment and Heat Transfer Characteristic of Steam Submerged Jet Condensation within Steam-Water Mixture Layer

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SSRN 2022年

作者： Zhao, Quanbin Fu, Pengfei Chong, Daotong Chen, Weixiong Liu, Jiping Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China MOE Key Laboratory of Thermal Fluid Science and Engineering Xi'an Jiaotong University Xi'An710049 China

Steam-water interface and mixture layer are the key window for understanding the heat and mass transfer mechanism of steam submerged jet condensation. In this paper, the steam-water two-phase mixture layer is captured and the interfacial vortex is observed with a quasi-two-dimensional submerged steam jet visualization experimental platform. Then, the volume heat transfer capacity of steam-water mixture layer and heat transfer coefficient with steam-water inner interface are obtained. Furthermore, a new turbulent eddy entrainment model is developed to calculate the local entrainment mass rate and local condensation heat transfer coefficient. Both the local entrainment mass rate and local condensation heat transfer coefficient increases along steam jet direction, and reaches the maximum value at the tail of the mixture layer. The calculated condensation heat transfer coefficient ranges from 0.88 to 2.94 MW·m -2 ·K -1 , which is about the half of the value of hypothetical heat transfer coefficient with inner interfacial area. © 2022, The Authors. All rights reserved.

关键词： Condensation

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Neutronic/Thermal-Hydraulic Coupling Analysis of Heat Pipe Reactor Nuster-100 Based on Comsol

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SSRN 2022年

作者： Zhang, Yin Nie, Jingyu Wang, Chenglong Guo, Kailun Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Heat pipe cooled nuclear reactor plays an important role in future space and ocean exploration missions due to its advantages such as high inherent safety, removability, passive safety. Xi’an Jiatong University proposed a concept design of 100kWe nuclear reactor named NUclear Silent ThermoElectric heat pipe cooled Reactor (NUSTER-100). To explore NUSTER core’s performances, COMSOL are used for neutronic/thermal-hydraulic coupling calculation. Neutron diffusion equations are used to calculate NUSTER’s neutron flux distribution by partial differential equation (PDE) model. Dragon code is used to solve the group constants of neutron diffusion equations. The heat transfer module of COMSOL is used to calculate NUSTER’s temperature distribution. for NUSTER-100, the keff calculated by the neutron diffusion module of COMSOL is 1.0372. The calculation results of three-dimensional NUSTER show that the maximum temperature of heat pipe is 1226.2 K and that of fuel rod is 1447.1K. The calculated temperatures have not exceeded the limit. The unified calculation of neutron physics and temperature distribution is realized in COMSOL platform. This work provides a preliminary basis for neutronic/thermal-hydraulic coupling calculation for heat pipe reactor. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

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Numerical Study on Transverse Mixing Characteristics of flow Sweeping in Helical Cruciform Rod Bundle

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SSRN 2022年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Gguanhui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi'An710049 China

In the chemical industry, nuclear energy, electronics, and other industries, heat transfer enhancement has been the focus of significant attention. To enhance the flow heat transfer performance of coolant in the nuclear fuel assembly, helical cruciform fuel rods are designed as a foundation fuel element. The transverse mixing characteristics of flow sweeping of heat conduction oil in the present study using the numerical approach in helical cruciform rod bundle. The fluid in the helical cruciform rod bundle exhibits a substantial flow sweeping crossflow phenomena as a result of the impact of the helical structure. The transverse mixing velocity and temperature profiles are analyzed. The subchannel conservation equation is optimized, and the link between flow sweeping mixing parameters and dimensionless local gap width in various Reynolds number ranges is determined by fitting. Furthermore, the turbulent mixing parameters of the cylindrical rod bundle are analyzed. It can be concluded that the helical cruciform rod bundle has considerable transverse mixing, which enhances the flow heat transfer performance of the reactor core. This study provides a guide for the numerical study of flow heat transfer in helical structures, and a foundation for the development of the subchannel mixing model. © 2022, The Authors. All rights reserved.

关键词： Mixing

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Gold/oxide heterostructured nanoparticles for enhanced SERS sensitivity and reproducibility

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Rare Metals 2020年第7期39卷 834-840页

作者： Qi-Kui Fan Ting-Zhuo Liu Hou-Shen Li Shu-Meng Zhang Kai Liu Chuan-Bo Gao Frontier Institute of Science and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710054China College of Chemistry and Material Science Shandong Agricultural UniversityTaian 271018China

In surface-enhanced Raman scattering(SERS),it is highly desirable to obtain Raman signals with high sensitivity and reproducibility from noble metal nanoparticle substrates,which remains a great challenge due to the inhomogeneity of the plasmonic coupling that is sensitive to the interparticle *** this work,we report that the interparticle plasmonic coupling could be circumvented by first synthesizing Au/metal or nonmetal oxide heterostructured nanoparticles and then depositing them uniformly onto the substrates,leading to high reproducibility of the Raman *** plasmonic coupling has been found at the Au/oxide interface,which enables high sensitivity of the SERS analysis that accompanies the excellent signal *** different oxides investigated(SiO2,TiO2 and Fe2O3),the Au/Fe2O3 heterostructured nanoparticles demonstrate the highest Raman enhancement *** believe our strategy opens a promising route to fabricate SERS substrates that are capable of sensitively and quantitatively detecting molecules of interest in a much reliable manner.

关键词： Gold nanoparticles Au/oxide heterostructures Hot spots Surface-enhanced Raman scattering Reproducibility

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Interfacial Mass Transfer Enhancement for Photoelectrochemical Water Splitting Using 3d flow Field Structure

SSRN

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SSRN 2022年

作者： Wang, Baoyuan Yang, Suyi Lai, Yongquan Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Hydrogen production using solar energy water splitting is an economical and feasible clean energy solution. It is recognized that the efficiency of photoelectrochemical water splitting is not only related to the electrode material, but also influenced by the mass transport at the electrode surface. To investigate that relationship, we design a novel photoelectrochemical water splitting reactor, which generates a turbulent flow at the electrode/electrolyte interface, and change the temperature of the electrolyte. It was found that the flow rate and temperature of the electrolyte mainly affect the mass transport and charge transfer at the photoelectrode/electrolyte interface. Based on the results of LSV, EIS, and the calculation of mass transfer coefficient, the photoelectrochemical performance of the system at flow rate ranging from 0 to 145 ml/min and temperature between 20-90 °C is analyzed. The influence of the flow rate on the photocurrent density is more significant during the transition of the flow state and at the high flow rate. The best performance is achieved at the flow rate of 127 ml/min, and the temperature of 90 °C. The electrochemical impedance spectroscopy results show that in the test range, ion transport impedance decreases with increasing electrolyte temperature, as a result, the photocurrent density at 90 °C is increased about 2.2 times compared to that at 20 °C. It is also shown that the design of the 3D step-like structure has a more significant effect on the electrolyte flow than the planar structure, and the photocurrent density is increased about 1.3 times. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

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flow and Thermal Analysis of the Transition Scheme between Micro-Channel and Micro-Jet Cooling Solution

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SSRN 2022年

作者： Guo, Yuming Fan, Liang-Liang Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi'An China

With the rapid development of high-power electronics, the thermal management of these emerging devices is challenging due to the danger of ultra high heat flux and uneven temperature distribution. In this perspective, as promising cooling technologies, micro-channel and micro-jet cooling designs have been extensively investigated. In the past decade, certain heat-dissipation technologies based on micro-channel and micro-jet cooling have utilized geometrically identical heat sinks;however, their corresponding flow and thermal characteristics are dissimilar including micro-channel cooling technologies often have large temperature gradients as well as high heat transfer coefficients, while microjet technologies are more advantageous in terms of temperature distribution uniformity but larger pressure drop penalty. To characterize the enhanced heat-transfer mechanism driving this dissimilitude, a transition scheme between micro-channel and micro-jet was designed, featuring a gap on the channel fins top to provide extra flow area, and investigated experimentally and numerically. By controlling the volumetric flow ratio of the channel and jet, the flow and thermal characteristics of the transition scheme could be interchangeably transformed between the micro-channel and micro-jet. Moreover, we investigated the effect of the vortex generated by the jet impingement on channel bottom and fins top, an important factor causing the distinctions between the two schemes. The results revealed that the vortex in the stagnation zone enhanced the local heat-transfer coefficient corresponding to the channel bottom and promoted temperature uniformity;however, it caused the thermal boundary layer on the fins top to thicken. Although the vortex was favorable for the forced convection in the acceleration zone, the vortex intersections formed by adjacent jets introduced a greater pressure-drop penalty and flow blockage, which were not conducive to enhancing the heat transfer. Subsequently,

关键词： Vortex flow

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