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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

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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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Numerical Investigation of Vibrational and Misalignment Effects on Atomization Characteristics of Impinging Jets

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SSRN 2023年

作者： Dai, Qingwen Yang, Jianwen Yang, Bin Wang, Ying School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China Xi’an Aerospace Propulsion Institute Xi’an710100 China

To explore the influence of vibration, misalignment and their combined effects on the atomization characteristics of the impingement process, this paper utilizes the polyhedral mesh adaptive refinement algorithm and VOF-to-DPM multiphase flow model to simulate the atomization process of impinging jets atomization. Additionally, compared the results with experimental data to ensure accurate calculations. The whole process of liquid film broke into liquid filaments and further atomized into droplets under different working conditions are analyzed in this paper. The results show that the proposed algorithm and model can better simulate the two impinging liquid jets atomization. Vibrations cause fluctuations in mass flow, which will lead to the offset of the impingement point by the impinging jets atomization. With the increase of vibration frequency, the performance of atomization become worse. When the vibration frequency is 1000 Hz, the back splash phenomenon becomes more apparent. When the misaligned degree is small, low-amplitude, high frequency vibrations can weaken the influence of misaligned impingement, resulting in improved atomization performance. However, when the degree of misalignment is large, a larger deflection angle of the liquid film results in a smaller broken length of the liquid film and a worse atomization quality. At this time, the vibrations lead to vortices in the atomization field and have an entrainment effect on the atomization field. Therefore, the vibrations have adverse effects on engine thermal protection. © 2023, The Authors. All rights reserved.

关键词： Atomization

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Experimental study on unsteady aerodynamic characteristics of deformed blades for vertical axis wind turbine

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RENEWABLE ENERGY 2021年 173卷 808-826页

作者： Tong, Hui Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China COMAC Shanghai Aircraft Customer Serv Co Ltd Shanghai 200126 Peoples R China

Based on the self-deforming blade model and the related wind tunnel test platform, the experiments with synchronous deformation and pitch of the blade were carried out to simulate the operating condition of the blade on the vertical axis wind turbine (VAWT). Taking NACA0012 as the reference blade, the unsteady aerodynamic characteristics of the blade deformation at different deformation frequencies and amplitudes were investigated at low Reynolds number of 2.5 x 10(5). It is found that the maximum lift force of the blade with deformation amplitude of 0.06c is raised by nearly 60% compared with that of the rigid blade. Secondly, by applying the same deceleration frequency, same pitch amplitude and different initial angles of attack to the blade, it is observed that the flow hysteresis phenomena are obviously different from that of applying various synchronous pitch and deformation amplitudes, and the special aerodynamic characteristic curves are obtained. The lift force increases significantly with the rise of deformation amplitude and drag force, while the lift-drag ratio increases in one cycle. The study in this paper proves the applicability of the blade with this deformation law in the VAWT, and provides a reference for its application on the design of VAWT. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Experiment Unsteady aerodynamic characteristics Vertical axis wind turbines Deformed blades

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Research on the Combustion Effect and Mechanism of Aluminum Droplets in Ap/Htpb Composite Propellant

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SSRN 2023年

作者： Yang, Bin Wang, Jiahao Lou, Yongchun Zhao, Yu Wang, Ji Wang, Ying 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 Shanghai Space Propulsion Technology Research Institute Shanghai201109 China

To investigate the combustion phenomenon of aluminum droplets within propellants, this study amalgamates the evaporation combustion process of aluminum droplets with the AP/HTPB (Ammonium perchlorate/Hydroxyl-terminated polybutadiene) multi-flame structure model. Consequently, a numerical simulation approach is established to depict the combustion behavior of aluminum droplets in a high-temperature gas environment. The paper scrutinizes the dynamics, deformations, combustion characteristics, and their influence on the propellant flow field under diverse conditions. The findings of this research affirm that the non-uniform flow velocity at the AP and HTPB inlets imparts distinct pressures on the droplets' surface, thereby precluding their spherical morphology. As the droplet diameter diminishes, the effect of deformation gradually abates, leading the droplets to gravitate towards the AP region. The addition of aluminum droplets disrupts and enhances heat transfer within the external flow field of propellant combustion, while their own combustion engenders a substantial amount of heat, thus elevating the overall combustion temperature of the propellant. Moreover, aluminum droplets perturb the distribution of different components in the flow field, affording more opportunities for intermolecular encounters, and consequently augmenting the efficiency of the overall reaction compared to scenarios without aluminum droplets. Remarkably, the combustion efficiency of aluminum droplets is amplified in high-pressure environments. © 2023, The Authors. All rights reserved.

关键词： flow fields

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

SSRN

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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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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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Oxygen-Induced Elemental Mercury Oxidation in Chemical Looping Combustion of Coal

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ACS OMEGA 2022年第24期7卷 20959-20967页

作者： Liu, Qiuqi Liu, Dunyu Ni, Mingguo Xu, Kailong Ma, Jingjing Liu, Zhuang Jin, Jing Shi, Huancong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Ningxia Univ Coll Chem & Chem Engn State Key Lab High Efficiency Utilizat Coal & Gre Yinchuan 750021 Ningxia Peoples R China

Mercury emission is an important issue during chemical looping combustion (CLC) of coal. The aim of this work is to explore the effects of different flue gas components (e.g., HCl, NO, SO2, and CO2) on mercury transformation in the flue gas cooling process. A two-stage simulation method is used to reveal the reaction mechanism of these gases affecting elemental mercury (Hg-0) oxidation. Furthermore, using this method, Hg-0 oxidation by eight oxygen carriers (Co3O4, CaSO4, CeO2, Fe2O3, Al2O3, Mn2O3, SiO2, and CuO) commonly used in CLC are investigated and their Hg-0 oxidation efficiencies were compared with the existing experimental results. The results show that HCl, NO, and CO2 promote Hg-0 oxidation during flue gas cooling, while SO2 inhibits Hg-0 oxidation. The stronger the oxygen release capacity of oxygen carriers, the higher the oxidation efficiency of Hg-0 becomes. The order of Hg-0 removal efficiency from high to low is Co3O4, CuO, Mn2O3, CaSO4, Fe2O3, CeO2, Al2O3, and SiO2, and this sequence is in good agreement with the existing experimental results. Different flue gas components directly or indirectly affect the O-2 content, thus affecting the content of gaseous oxidized mercury (Hg2+). Different oxygen carriers have different oxygen release capacities and different Hg-0 oxidation efficiencies. Therefore, O-2 is the core species affecting the mercury transformation in CLC.

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Numerical study on the performance of centrifugal blood pump with superhydrophobic surface

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INTERNATIONAL JOURNAL OF ARTIFICIAL ORGANS 2022年第12期45卷 1028页

作者： Li, Chengcheng Qiu, Huihe Ma, Jianying Wang, Ying Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Jungong Rd 516 Shanghai 200093 Peoples R China Hong Kong Univ Sci & Technol Dept Mech & Aerosp Engn Hong Kong Peoples R China Fudan Univ Zhongshan Hosp Shanghai Inst Cardiovasc Dis Dept Cardiol Shanghai Peoples R China

Aim: In order to reduce the blood damage of an artificial heart pump and optimize its hydraulic performance, a centrifugal blood pump with superhydrophobic characteristics is proposed in this study. Methods: To study the influence of superhydrophobic surface characteristics on the performance of centrifugal blood pumps, the Navier slip model is used to simulate the slip characteristics of superhydrophobic surfaces, which is realized by the user defined function of ANSYS fluent. The user defined functions with different values of slip length are verified by two benchmark solutions of laminar flow and turbulence in the pipeline. The blood pump model adopts the designed centrifugal blood pump, and its head, hydraulic efficiency and hemolysis index are calculated. The Navier slip boundary condition (a constant slip-length of 50 mu m) is applied to the walls of the blood pump impeller and a volute at different positions, and the influence of the superhydrophobic surface on the performance of the blood pump at the design point Q = 6 L/min was compared and analyzed. Results: The results show that the centrifugal blood pump model used in this paper has good blood compatibility and meets the design requirements;the superhydrophobic surface can significantly reduce the scalar shear stress in the blood pump. At the design point, when the slip length is 50 mu m, the mass-average scalar shear stress in the impeller area and the volute area reduction rate is about 5.9%, the hydraulic efficiency growth rate is about 3.8%, the hemolysis index reduction rate is about 18.4%, and the pressure head changes little with a growth rate of 0.3%. Conclusions: Centrifugal blood pumps with superhydrophobic surfaces can improve the efficiency of blood pumps and reduce hemolysis. Based on these encouraging results, vitro investigations for actual blood damage would be practicable.

关键词： Centrifugal blood pump numerical simulation hemolysis index superhydrophobic surface hydraulic efficiency

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