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Energy efficiency evaluation method for plate heat exchanger

Kexue Tongbao/Chinese Science Bulletin 2016年第8期61卷 802-808页

作者： Zhang, Yanfeng Jiang, Chen Shou, Binan Zhou, Wenxue Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Technology Service Center CO. LTD Beijing100011 China LanZhou Guanyu Heat Transfer and Energy Saving Engineering and Technology Research CO. LTD Lanzhou730050 China

In heat exchangers, heat transfer between the cold and the hot fluid consumes pumping power. Evaluating the energy efficiency of this process scientifically and quantitatively is an urgent issue for both academic research and industrial applications, and has important significance to energy saving and emission reduction. We comprehensively analyzed the flow and heat transfer characteristics of water-water heat transfer process without phase-change in a heat exchanger, and proposed the energy efficiency index (=k/pn, k is overall heat transfer coefficient and p is flow pressure gradient). EEI reflects the inherent energy efficiency properties of a heat exchanger, which represents the overall heat transfer coefficient per equivalent flow pressure drop consumption. At a given temperature difference and fluid flow rate, for the heat exchangers with the same heat transfer area and fluid flow length, bigger EEI means a lager heat transfer rate per equivalent pumping power consumption. EEI is independent on the heat transfer area;no dependence or weak dependence on the flow velocity can be achieved by choosing the index n reasonably, indicating a good stability of EEI. Evaluation result based on national standard of heat exchanger performance test measured could represent the energy efficiency of the heat exchanger. Combined with the water-water heat transfer process without phase-change flow and heat transfer performance database of the plate heat exchangers, the value of index n and the overall EEI distribution of plate heat exchangers in industry are obtained, providing a basis for the classification of the energy efficiency of plate heat exchangers. © 2016, Science Press. All right reserved.

关键词： Heat exchangers

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Design on the Experimental Table for CO2 Refrigeration System with Turbo Expander

Design on the Experimental Table for CO2 Refrigeration Syste...

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The 5thInternational Conference on Cryogenics and Refrigeration ICCR 2013(第五届国际低温制冷会议)

作者： Ma J.L. Liu C.H. Sun W. Wang M. Lai T.W. Hou Y. State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong UniversityXi''an 710049China School of Energy and Power Engineering Xi''an Jiaotong UniversityXi''an 710049China School of Energy and Power EngineeringXi''an Jiaotong UniversityXi''an 710049China

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Supercritical Co2 -Promoted Degradation of Polystyrene to Aromatic Oils with Nio@C Catalyst

SSRN

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SSRN 2024年

作者： Liu, Yanbing Shi, Jinwen Zhuang, Zitong Kang, Xing Mao, Liuhao Li, Yi Jin, Hui Zhao, Qiuyang Guo, Liejin International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 28 West Xianning Road Shaanxi Xi’an710049 China

Exploring new system for chemical recycling of plastic is an effective way to convert plastic waste into energy. Herein, the use of supercritical CO2 (Sc-CO2) to promote the catalytic degradation of polystyrene (PS) with high yield of aromatic oils was proposed. Sc-CO2 provided a homogeneous environment for the reaction, which not only facilitated the swelling of PS, but also inhibited the formation of coke, beneficial for the degradation of PS to aromatic oils. Importantly, CO2 was be consumed as an oxidant to generate new product and reduce greenhouse gas emission. The doped carbon material in NiO, which was stable in Sc-CO2 and had a simple preparation process, enriched the porous structure and increased the acidic sites, thus improving the catalytic activity. Under the co-action of Sc-CO2 and NiO@C, the yield of aromatic oils produced from PS was up to 89.3 ± 0.6 wt% at 300oC with a reaction time of 2 h and a catalyst loading amount of 10 wt%. Moreover, the NiO@C catalyst were used for three cycles without obvious change in the catalytic performance. The efficient catalytic degradation of PS to aromatic oils by Sc-CO2 promoted NiO@C catalysis provides a potential route for simultaneously recycling plastic and sequestering carbon. © 2024, The Authors. All rights reserved.

关键词： Carbon dioxide

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Sustainable Agriculture Reviews 60 1

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丛书名： Sustainable Agriculture Reviews

1000年

作者： N.K. Singh Anirudha Chattopadhyay Eric Lichtfouse

ISBN: (数字)9783031241819

ISBN: (纸本)9783031241802;9783031241833

In the context of rising adverse effects of climate change on agriculture, there is a need for advanced methods and practices to manage soils for production of food and energy. This book presents the latest advances in microbial processes that control plant growth, with focus on genomic tools, microbial interactions with the plant and soils habitats, mobilization of plant nutrients, agricultural waste management, biodegradation, bioremediation, carbon sequestration, land reclamation, plant growth promotion, suppression of plant pathogens, induced systemic resistance and tolerance against biotic and abiotic stresses.

关键词： Agriculture Microbial Ecology Microbial Ecology

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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryton Cycle Coaxial Integrated Unit

Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryto...

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Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Xiaokang Xu Yi Yang Jiangfeng Wang Juwei Lou Liangqi Chen State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and Technology National University of Defense Technology Changsha China

The rotor system plays a very important role in supercritical carbon dioxide Brayton cycle system, and its dynamic problem will directly affect the motion stability and safety of the whole unit. In this paper, the rotor dynamic model of supercritical CO 2 coaxial unit is established by finite element method, and the critical speed, modal shape and unbalance response of the rotor are studied. The first seven critical speed of the rotor and the first seven natural frequency of the rotor at the working speed are calculated. The bending modal of the rotor and the position where the rotor amplitude is the largest are analyzed, which can provide reference for the optimization design of the rotor stability. The influences of mass unbalances at the operational speed of rotor are analyzed. The research can provide some suggestions for the optimal design and actual operation of the supercritical CO 2 coaxial integrated unit.

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Synchronized Measurement Method of Burning Rate and Combustion Temperature of Solid Propellant Specimen

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SSRN 2023年

作者： Ni, Hu Fan, Rong Hu, Haihang Yang, Bin Wang, Zhixin Cao, Di Yang, Yang Shi, Zhiquan School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Space Propulsion Technology Research Institute Shanghai201109 China

To characterize solid propellant combustion, the measurement method of burning rate and combustion temperature of solid propellant specimen is developed that simultaneously combines shadow and radiation imaging methods. Shadow and radiation images of solid propellant specimen combustion are simultaneously captured by using light splitting and wavelength filtering imaging measurement system. Burning rate and combustion temperature of solid propellant specimen are synchronized obtained by burning surface identification and radiation image temperature measurement algorithm. Measurement accuracies of burning rate and combustion temperature of solid propellant specimen are validated by other independent measurement methods. Compared with target-line measurement method, the burning rate measurement relative deviation is less than 3.1%. Compared with thermocouple measurement, the temperature measurement relative deviation is less than 1.7%. On this basis, the synchronized measurements of burning rate and combustion temperature of different formulations of solid propellant specimens under different working conditions are carried out. The results show that burning rate and combustion temperature are important characterization parameters of solid propellant combustion performance. For a certain formula solid propellant specimen, the burning rate can be greatly increased by increasing the pressure, but the combustion temperature is not much increased. Therefore, the synchronized measurement of burning rate and combustion temperature can provide more direct data support for the evaluation of solid propellant combustion performance. © 2023, The Authors. All rights reserved.

关键词： Solid propellants

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Design and Simulation of a New Type of Fin-and-Tube Heat Exchanger with Trapezoidal Slit Fins

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SSRN 2024年

作者： Zhang, Tianjiao Su, Mengyang Zhang, Hua Liu, Chuang Ouyang, Xinping School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Key Laboratory of Thermo-Fluid Science and Engineering Ministry of Education Xi’an Jiaotong University Xi’an710049 China

Slit fin-and-tube heat exchangers are extensively utilized in industry, and optimizing the fin structure is conducive for improving energy efficiency and reducing energy losses. Therefore, a heat exchanger featuring trapezoidal slit fins was proposed in this study. To determine the structure of the slit fins, physical and mathematical models of the heat exchanger with a fin spacing Fp of 2.65 mm were established. We used a numerical simulation to investigate the structural parameters of the fin-and-tube heat exchanger, including the slit height Sh, slit width Sw, transverse tube spacing Pt, and longitudinal tube spacing Pl. Based on the simulation results, the effects of the four structural parameters on the comprehensive performance were evaluated. Additionally, the optimal parameter combination was determined through an orthogonal test, resulting in the following values: Sh = 1.47 mm, Sw = 4 mm, Pt = 42 mm, and Pl = 27.5 mm. This study provides significant theoretical and practical guidance. © 2024, The Authors. All rights reserved.

关键词： Energy dissipation

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Stability and Emission Characteristics of Ammonia/Air Premixed Swirling Flames with Rotating Gliding Arc Discharge Plasma

SSRN

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SSRN 2022年

作者： Ju, Rongyuan Wang, Jinhua Zhang, Meng Mu, Haibao Zhang, Guanjun Yu, Jinlu Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Electrical Insulation and Power Equipment School of Electrical Engineering Xi’an Jiaotong University Xi’an710049 China School of Aeronautics Engineering Air Force Engineering University Xi’an710038 China

Ammonia received increased attention as a carbon-free fuel and hydrogen carrier. Poor combustion stability and high NOx emission are the main issue for ammonia combustion. Effects of rotating gliding arc (RGA) discharge plasma on the flame stability and NOx emission of NH3/air premixed swirling flames were investigated. The discharge characteristics of the RGA were studied. The flame stabilization mechanisms by plasma were revealed and analyzed according to the flame structure transition and the distribution of key intermediate OH radicals. The NOx emissions were measured by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Results showed that the RGA discharge plasma can enhance the stability and extend the lean blow-off (LBO) limits from 0.6 to approximately 0.43-0.57. A hysteresis phenomenon about the transition between the lift-off flame and the attached flame was observed without plasma and disappeared with plasma activation. The plasma reduces NO and NO2 emissions mainly due to the kinetic and cracking effects of plasma. Extremely low NO emission below 300 ppm can be observed for very lean ammonia flames with an equivalence ratio (f) lower than 0.6, which are stabilized by plasma, while a large amount of unburned NH3 emission is accompanied. © 2022, The Authors. All rights reserved.

关键词： Ammonia

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Influence of Bentonite on Copper Corrosion in Simulated Repository Electrolyte

SSRN

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SSRN 2024年

作者： Ning, Zhiyuan Zhou, Qulan Li, Na Macdonald, Digby D. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States

The impact of bentonite on the corrosion of oxygen-free copper (OF-Cu) and oxygen-free phosphorous copper (OFP-Cu) in prototypical groundwater environments (standard reference electrolyte, SRE) simulating the storage of copper High-Level Nuclear Waste (HLNW) cannisters in granitic rock repositories is explored. At low corrosion potentials (-0.1VSCE), bentonite suppresses copper corrosion in SRE through the anion-exclusion effect, with its inhibitory impact intensifying at higher bentonite concentrations. As the corrosion potential rises, bentonite’s enhanced adsorption of metal cations increases the corrosion current. Additionally, bentonite hydrolysis producing silicate ions that accelerates pitting corrosion, culminating in passive film breakdown. This dual mechanism may amplify intergranular corrosion. In environments where bentonite exacerbates corrosion, OFP-Cu demonstrates superior corrosion resistance, though the introduction of phosphorus may influence the acceleration of intergranular corrosion following passivity breakdown. © 2024, The Authors. All rights reserved.

关键词： Bentonite

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Slug flow Characteristics in Inclined and Vertical Channels

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Fluid Dynamics & Materials Processing 2019年第5期15卷 583-595页

作者： Zhihui Wang Wei Luo Ruiquan Liao Xiangwei Xie Fuwei Han Hongying Wang Petroleum Engineering Institute of Yangtze University WuhanChina Laboratory of Multiphase Pipe Flow Gas Lift Innovation CenterChina National Petroleum CorpWuhanChina The Branch of Key Laboratory of CNPC for Oil and Gas Production Yangtze UniversityJingzhouChina Exploration Department of Petro China Tarim Oilfield Company KorlaChina The Third Drilling Company of Bohai Drilling Engineering Co. Ltd.of CNPCTianjinChina Research and Development Center Tuha Oilfield CompanyCNPCTulufanChina

Horizontal well production technology gradually occupies a dominant position in the petroleum *** the rise in water production in the later stage of exploitation,slug flow phenomena will exist in horizontal,inclined and even vertical sections of gas *** grasp the flow law of slug flow and guide engineering practice,the flow law of slug flow at various inclination angles(30°~90°)is studied by means of the combination of laboratory experiments(including high frequency pressure data acquisition system)and finite element numerical *** results reveal that because of the delay of pressure variation at the corresponding position of pipeline resulting from gas expansion,the highest point of pressure change curve corresponds not to the highest point of liquid holdup curve(pressure change lags behind 0.125 s of liquid holdup change).Thus,the delay of pressure should be highlighted in predicting slug flow using pressure parameter change;otherwise the accuracy of prediction will be affected when slug flow *** is generally known that liquid holdup and pressure drop are the major factors affecting the pressure variation and stable operation of ***,the results of finite element numerical simulation and Beggs-Brill model calculation are compared with those of laboratory *** numerical simulation method is applicable to predicting the pressure drop of the pipeline,while the Beggs-Brill model is more suitable for predicting the liquid holdup variation of the *** research conclusion helps reveal the slug flow law,and it is of a scientific guiding implication to the prediction method of flow parameters under slug flow pattern in the process of gas well exploitation.

关键词： Slug flow volume liquid holdup pressure pressure drop flow pattern numerical simulation

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