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Experimental investigation on the performance of an ethane loop heat pipe with different line lengths based on pulse tube refrigerator

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JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY 2022年第8期147卷 5225-5235页

作者： Chen, Beibei Chen, Xi Xiang, Jiajia Xie, Rongjian Wu, Yinong Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Chinese Acad Sci Shanghai Inst Tech Phys 500 Yutian Rd Shanghai 200083 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer 516 Jungong Rd Shanghai 200093 Peoples R China

The loop heat pipe is a passive high-efficiency two-phase transfer device. To study the effects of the liquid and vapor line lengths on the performance of ethane loop heat pipe (ELHP), a performance test system has been set up based on a pulse tube refrigerator (PTR). The lengths of liquid line (LL) and vapor line (VL) of the ELHP are changed in this test system. The LL length is set as 180 mm, 500 mm, 800 mm, 1100 mm and 1500 mm, respectively, when the VL length is 500 mm. In addition, the VL length is set as 800 mm, 1100 mm, and 1500 mm, respectively, as the LL length is 500 mm. The thermal performances of ELHP including startup performance, thermal resistance and temperature difference are investigated in detail under 170 similar to 240 K temperature regions. The experiment results show that the lengths of LL have an important effect on the startup performance when the heat load (HL) of the ELHP is 0 W. The shorter the LL length is, the easier the startup is at 0 W HL. When the LL length is longer, the ELHP is more stable and the temperature oscillation is smaller. The effect of the VL length on the ELHP startup performance is the same as that of the LL length. Due to the thermophysical properties of ethane, the ELHP in the 240 K temperature region has the best performance.

关键词： Ethane loop heat pipe Liquid line Vapor line Startup Thermal resistance

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Depth from Defocus Technique for High Number Densities and Non-spherical Particles

arXiv

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arXiv 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and Technology Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. Both advancements build on recent theoretical work, utilizing not only the gray level of the blurred, out-of-focus images, but also the gradient of the gray level normal to the nominal particle or particle ensemble contour. This gray-level gradient is used to estimate the width of the blur kernel, which is assumed to remain Gaussian. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, CC BY.

关键词： Spheres

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Effect of stress on corrosion behavior of martensitic and austenitic steels in supercritical carbon dioxide at 550?C and 20 MPa

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JOURNAL OF SUPERCRITICAL FLUIDS 2023年 192卷

作者： Yang, Yingying Mao, Shijie Yang, Qiguo Xu, Ziyuan Ren, Yan Wu, Weidong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Corrosion of alloys in supercritical carbon dioxide (S-CO2) Brayton cycle power generation systems is a critical issue. In this study, we investigated the corrosion behaviors of martensitic AISI 616 and austenitic AISI 304 exposed to S-CO2 at 550 degrees C and 20 MPa. The effect of stress loading on the corrosion behavior was studied. A 9 mu m-thick double-layer oxide with an outer layer of Fe3O4 and an inner layer of (Fe, Cr)-rich oxide was formed on the surface of the AISI 616. When stress was applied, the oxide layer thickness increased significantly to 15 mu m. Stress loading thus promoted carbon deposition, accelerated the oxidation rate, and increased oxide thickness. AISI 304 generated a monolayer of (Fe, Cr)-rich oxide that was much thinner than that of AISI 616 owing to its high Cr content. In addition, the effect of stress on the corrosion of AISI 304 was weaker than that of AISI 616.

关键词： Supercritical carbon dioxide Brayton cycle Stress corrosion Steel High -temperature corrosion Oxidation

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Exploration of the Responsiveness of the Atomization Field in a Centrifugal Nozzle to Variations in Inlet Pressure

SSRN

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SSRN 2023年

作者： Xu, Wen Yang, Jianwen Yang, Bin Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Xi’an Aerospace Propulsion Institute Xi’an710100 China

As the crucial atomization unit in the propellant supply system for liquid rocket engines, the centrifugal nozzle's atomization performance is of paramount importance. However, due to flow oscillations within the propellant supply system, the resulting spray from nozzle atomization tends to oscillate, adversely impacting fuel atomization efficiency. This paper employs a VOF-to-DPM multiphase flow model to simulate the nozzle's atomization field under different inlet pressures, which is subsequently compared with experimental results. Next, the UDF is used to introduce pressure pulsation sources with varying frequency sizes at the nozzle inlet, from which the following conclusions are drawn: (1) The numerical simulation-derived atomization angle of the nozzle under different inlet pressures slightly deviates below the experimental value, but consistently maintains a similar trend, with errors not exceeding 5%;(2) Under constant inlet pressure, the nozzle's atomization field exhibits a stable, smooth, hollow cone liquid film formation, and particle droplets produced by liquid film atomization coalesce at the hollow cone's lower end;(3) When pressure pulsations with diverse frequencies and magnitudes are loaded at the nozzle inlet, the atomization field undergoes varying degrees of oscillation. When f = 100 Hz, the hollow cone liquid film disappears completely after undergoing initial formation during a pulsation cycle, and the atomized particles' number experiences the most significant change relative to constant inlet pressure. When f = 400 Hz, the broken droplets gradually reform the hollow cone liquid film within a pulsation period and maintain its form but undergo subsequent breaking. When f = 800 Hz, there is no apparent alteration in the shape of the hollow cone liquid film or total particle count during a pulsation cycle. However, the liquid film's surface appears uneven, showing wavy water marks. © 2023, The Authors. All rights reserved.

关键词： Atomization

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Control of two-phase flow around a cylinder with a cylindrical attachment: A numerical study

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Ocean engineering 2025年 334卷

作者： Wang, Ziqing Hu, Yu Huang, Shengxian Zhang, Yongxing Moghtaderi, Behdad Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China National Engineering Laboratory for Pipeline Safety/MOE Key Laboratory of Petroleum Engineering/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum – Beijing Beijing102249 China Centre for Innovative Energy Technologies The University of Newcastle CallaghanNSW2308 Australia

Mitigating flow separation, vortex shedding and sediment-induced erosion around cylindrical structures is critical for enhancing marine engineering safety. This study investigates the hydrodynamic performance of a two-phase flow around a cylinder equipped with an auxiliary cylinder under realistic ocean conditions. key parameters include the clearance ratio (G/D), particle characteristics (size and concentration), and vibration modes of the auxiliary body. This study investigates real ocean conditions, focusing on the influence of clearance ratio (G/D) and an auxiliary cylinder on flow field changes with varying particle characteristics. The results demonstrate that: (1) A clearance ratio G/D = 0.1 yields the optimal drag reduction (57.18 %) for the primary cylinder in single-phase flow;(2) Larger particles weaken vortex-particle interactions, while higher particle concentrations exacerbate uneven deposition near the cylinder;(3) Transverse vibration of the auxiliary body (amplitude ratio = 0.025, frequency ratio = 0.65) reduces drag by 18.7 % compared to stationary configurations. These findings provide insights into flow control strategies for offshore structures subjected to sediment-laden flows. © 2025 Elsevier Ltd

关键词： Marine safety

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Novel Matching Strategy for the Coupling of heat Flux in Furnace Side and CO_(2)Temperature in Tube Side to Control the Cooling Wall Temperatures

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Journal of Thermal Science 2021年第4期30卷 1251-1267页

作者： LIU Chao MIAO Zheng XU Jinliang XU Zeyu LI Mingjia Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing 102206China Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power UniversityMinistry of EducationBeijing 102206China Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy&Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

Required by the supercritical carbon dioxide(s CO_(2))coal-fired power cycle,s CO_(2)entering a boiler has a high temperature and can cause overheating of *** eliminate the pressure drop penalty effect,the s CO_(2)boiler consists of several modules,each having different heat flux received from the furnace side(q)and different CO_(2)temperature in the cooling wall tube(T_f).We aim to search for the best matching strategy coupling furnace side and tube side to obtain the lowest temperature of *** theoretically analyzing the wall temperature influenced by q,T_f and a comprehensive thermal resistance C,two matching methods are introduced:the heat flux-temperature matching(HTM)which matches higher q with lower T_f,and the heat flux-heat flux matching(HHM)that matches higher q with higher allowable-heat-flux at the temperature limit of *** is a conventional method but HHM is newly proposed *** show that,if C is identical for different modules,the two methods coincide;otherwise,HHM is *** a s CO_(2)boiler driving 1000 MWe power plant,smaller cooling wall temperatures are obtained by HHM than *** on HHM,the mid-partition wall,heat transfer enhancement,and downward flow are comprehensively used,decreasing the wall temperature significantly.

关键词： sCO_(2)power cycle sCO_(2)modular boiler cooling wall temperature allowable heat flux matching strategy

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Fiber optic probe sensor for supercritical fluid heat transfer measurement 2

Fiber optic probe sensor for supercritical fluid heat transf...

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2nd International Conference on Sensors and Information Technology, ICSI 2022

作者： Cheng, Yiwei He, Xiaotian Xu, Jinliang Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University 2 Beinong Road Changping District Beijing China

ISBN: (纸本)9781510654860

To improve the efficiency of power generation systems, the boiling-like phenomenon in supercritical fluid heat transfer has attracted much attention. However, traditional tapered fiber optic probes are not suitable for supercritical fluid two-phase-like distribution detection. In this paper, a fiber optic probe sensor with a flat end face that can continuously measure the refractive index and density of fluids is developed and tested using water, CO2, and ethanol. The average relative error of density measurement is less than 0.1 %. Applied to a supercritical fluid pool heat transfer experimental system, the probe's signal coincided with the visualization phenomenon very well. The frequency of gas-like film detachment from the surface of the heating wire could be accurately measured using the probe. © 2022 SPIE.

关键词： Supercritical fluids

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Effects of the frequency conversion characteristics of fan and pump on the performance of heat pump driven humidification-dehumidification wastewater treatment system

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heat AND MASS transfer 2022年第12期58卷 2067-2083页

作者： Zhang, Huichen Liu, Jianhua Jiang, Linlin Zhang, Liang Wu, Qingqing Xu, Xiaojin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Nantong Vocat Univ Nantong 226007 Jiangsu Peoples R China Shanghai Highly Grp Co Ltd Shanghai 201206 Peoples R China CSCI Res Inst 704 Shanghai 200031 Peoples R China

An experimental study on use of humidification-dehumidification (HDH) technology for treating chemical milling wastewater containing high concentrations of sodium hydroxide and sodium aluminate has been carried out. heat pump is introduced to simultaneously supply cooling and heating loads of the HDH system. A parametric study is conducted to investigate influence of operational parameters including frequency conversion characteristics of circulating fan and pump on system performance. Performance parameters including pure water production amount (PWPA), pure water recovery rate (PWRR) and gain output ratio (GOR) are analyzed. Results indicate working frequency of pump and fan is not as high as possible, there is an optimal value. With frequency conversion of fan increases, PWPA and PWRR are increased, GOR shows a trend of first increasing and then decreasing, the optimal value of circulated air mass flow rate is 0.44 kg/s. With frequency conversion of pump increases, PWPA and GOR are increased, PWRR is decreased, the optimal value of inlet wastewater mass flow rate is 0.465 kg/s. When system is operating under optimal parameters, PWPA is 9.77 kg/h, PWRR is 0.58% and GOR is 0.781. Compare the indicators before and after treatment, pH, SS, COD, NH4-N and TP of purified water is 9.2, 4 mg/L, 53.2 mg/L, 0.028 mg/L, 0.278 mg/L, respectively. All these parameters decrease 31.9%, 97.6%, 97.5%, 77. 8%, 94.8%, respectively. Although the purified water has not yet reached the direct discharge standard or reclaimed water reuse standard, but HDH method shows feasible in the separation of highly corrosive solutions.

关键词： Pumps

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Enhancing heat transfer in Immersion Cooling Via Guest Non-Condensable Gas Microbubbles

SSRN

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SSRN 2024年

作者： Luo, Peng Tong, Wei Wei, Lichuan Zhao, Yugang Zhang, Hua Cheng, Ping Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shenzhen Envicool Technology Co. Ltd. Shenzhen518129 China MOE Key Laboratory of Power Machinery and Engineering School of Mechanical Engineering Shanghai Jiaotong University Shanghai200240 China

Electronic systems produce increasingly high density of heat along with their performance elevated to meet the booming needs from industrials and human activities, and therefore more effective cooling methods are always in demand. Liquid immersion, both single-phase and dual-phase, is one of the most popular cooling methods developed, due to its simplicity, energy efficiency and operational feasibility. However, the heat dissipation capacity of single-phase immersion cooling is relatively low, while multi-phase only occurs above the boiling point of refrigerants. We here introduce a brand-new immersion cooling method with the injection of cold guest non-condensable gas (NCG) microbubbles. Experimental results show that the heat transfer rate is drastically enhanced, and in particular surface superheating is suppressed or even eliminated which is the key to maintaining the safety performance of micro-electronic chips. As bubbles approach the heating surface, they disturb the thermal boundary layer on the surface when their size is comparable with the layer thickness, attach to the surface serving as evaporation/boiling nuclei, and collide with existing bubbles to facilitate their departure. Also, the effects of bubble size distribution and pool subcooling are evaluated. The present cooling method performs better at a larger degree of pool subcooling while the effect of bubble size is relatively minor. This work demonstrates that guest NCG bubbles can drastically promote heat transfer in immersion cooling unlike others reported in the literature. The fundamental understanding of bubble dynamics upon impinging with the heating surface in subcooled liquid has promising applications in thermal management systems, such as electronic chips, nuclear reactors, heat exchangers, steam generators, and among others. © 2024, The Authors. All rights reserved.

关键词： Steam generators

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Investigation into the Anticoking Performances of Sol-Gel-Derived SiO2 and SiO2-CeO2 Coatings during Thermal Pyrolysis of Light Naphtha

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ENERGY & FUELS 2021年第3期35卷 2562-2578页

作者： Wang, Zhiyuan Ding, Xudong Guo, Xueyan Dou, Binlin Zhou, Jianxin Wang, Boyan Wang, Meng Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Sch Energy & Power Engn Shanghai 200093 Peoples R China Nanjing Tech Univ Sch Mech & Power Engn Nanjing 211816 Jiangsu Peoples R China

CeO2-based materials are widely applied in a three-way catalyst framework for catalytic combustion of diesel soot. For the application of CeO2 in coking inhibition during thermal cracking of hydrocarbons, SiO2-CeO2 and SiO2 coatings were prepared on HP40 alloy samples through sol-gel dip coating. The coatings were then characterized in terms of morphology and microstructure perspectives, and their anticoking performances were evaluated under conditions relevant to the practical applications during thermal cracking of naphtha. Results showed that the addition of ceria could improve the quality of the silica coating, which subsequently presented better anticoking properties by preventing formation of catalytic coking. Furthermore, thermogravimetric analysis (TGA) results of coke samples revealed that the ceria in the coating had the potential function as a coke oxidation catalyst. However, the silica-ceria coating lost its coking resistance after approximately ten repetitious coking/decoking cycles. Nevertheless, the combined application of anticoking coatings and addition of dimethyl disulfide (DMDS) into the naphtha feed could mitigate risks of coke formation more effectively compared with pure coatings only because of its preferential adsorption of sulfur-based radicals at the coating defects. In particular, the application of the SiO2-CeO2 coating combined with the addition of DMDS could still maintain a stable anticoking rate of above 60% throughout three cycles of coking/decoking operations.

关键词： Coating materials Layers Deformation Deposition Coke

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