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Multi-objective residential load scheduling approach for demand response in smart grid

SUSTAINABLE CITIES AND SOCIETY 2022年第0期76卷 103530-103530页

作者： Chen, Zhe Chen, Yongbao He, Ruikai Liu, Jingnan Gao, Ming Zhang, Lixin 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 Tongji Univ Dept Mech Engn Shanghai 201804 Peoples R China

In recent years, with the rapid growth of electricity demand and the development of smart grids, demand-side management had an important role. As the penetration rate of distributed renewable energy generation in the grid increases, the diurnal peak of the net load demand curve in the urban area is offset by renewable energy sources such as photovoltaics and the peak load time gradually shifts from afternoon to evening. The peak electricity load of residential buildings usually occurs in the evening, which aggravates the power balance problem. To this end, this study proposes a demand response (DR) scheduling approach for residential buildings, aimed for four types of residential building loads: interruptible and deferrable loads, noninterruptible and deferrable loads, noninterruptible and nondeferrable loads, and air conditioning loads. Nondominated sorting genetic algorithm II is used as a multi-objective optimization algorithm to search for the minimal electricity cost and minimal inconvenience index. Finally, the ASHRAE 140 standard building is used as a case and the proposed scheduling approach is evaluated under two scenarios of working and nonworking days. The proposed scheduling approach can effectively shave the peak load to off-peak load time, reduce electricity bills, and meet the occupants' comfort.

关键词： Demand response Smart grid Building energy flexibility Household energy management system

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Fault diagnosis for building chillers based on data self-production and deep convolutional neural network

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JOURNAL OF BUILDING engineering 2021年 34卷

作者： Gao, Jiaqing Han, Hua Ren, Zhengxiong Fan, Yuqiang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Fault diagnosis is of great importance in the field of building chiller application, which can reduce energy waste and maintenance cost, ensure stable operation and better service. To improve the diagnosis performance, this study presents a novel fault diagnosis method based on data self-production and deep convolutional neural network (SP-CNN), in which a simple, effective data augmentation technology is proposed to well utilize the excellent feature extraction and pattern recognition capability of deep CNN to diagnose typical chiller faults. Instead of transforming the fault data into a picture for the model to process into digital type, the SP-CNN model directly transforms the data into a digitized image to avoid possible errors caused by multi-transformation. The proposed data self-production technique can effectively augment the diagnosis information and help improve the performance. The results show that the proposed method is effective and the diagnosis accuracy of the SP-CNN with SP scale of 16 reaches 97.03%, higher than that of CNN without data self-production by about 1.63%. Due to the possible occurrence of over-fitting or under-fitting, it does not necessarily mean that the larger the SP scale, the better the performance. The proposed SP-CNN model also shows a better performance than back propagation (BP) network and another CNN method in terms of the overall diagnosis accuracy and the individual accuracy for each fault. It is also found that unlike the application in computer vision, for a fault diagnosis problem, the feature sequence has a great influence on the model performance. The accuracy is further improved to 98.02% by re-arrangement of features.

关键词： Convolutional neural network Data augmentation Self-production Fault diagnosis Digitized image

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Boosting SO2-depolarized electrolysis with anodic HI for efficient and energy-saving hydrogen production

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JOURNAL OF power SOURCES 2021年 491卷 229589-229589页

作者： Ying, Zhi Yang, Jingyang Zheng, Xiaoyuan Dou, Binlin Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The SO2-depolarized electrolysis (SDE) is a promising method for SO2 capture and hydrogen production. But the SDE is limited by the high overpotential and slow kinetics of anodic SO2 oxidation reaction (SOR). Herein, to boost SDE process, we add hydroiodic acid (HI) to the anolyte and form HI-assisted SO2-depolarized electrolysis (HASDE). The mechanism of HI assisted SOR is explored, the existence of HI reduces the onset potential and impedance, but increases current density and reaction rate of SOR. HI is supposed to change the single-step SOR into three-step reactions, without changing the overall anodic reaction. A HI concentration of less than or equal to 0.02 mol/L and an operating temperature of 50 degrees C or less are recommendable. The comparison of SDE and HASDE processes indicates that HASDE delivers a lower cell voltage than SDE during continuous constant current electrolysis, and has negligible effect on cathodic H-2 evolution, while it achieves 27.03-48.65% reduction in electric energy consumption compared with SDE. The present work provides an innovative strategy for improving SDE and energy-saving production of value-added chemicals like H2SO4 and H-2.

关键词： Hydrogen SO2-Depolarized electrolysis (SDE) HI assisted SO2-Depolarized electrolysis (HASDE) SO2 oxidation reaction (SOR) SO2 electro-oxidation HI

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Research on coupling performance of heat transfer and throttling of microchannel J-T effect cryocoolers

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APPLIED THERMAL engineering 2022年 202卷 1页

作者： She, Hailong Cui, Xiaoyu Weng, Jianhua Chang, Zhihao Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai 200093 Peoples R China Shanghai Univ Elect Power Sch Energy & Mech Engn Shanghai 200090 Peoples R China

To solve the shortcomings of small cooling capacity of the current Joule-Thomson (J-T) cryocooler, a multi-layer microchannel J-T cryocooler is designed and fabricated by printed circuit board technology. The characteristic of the cryocooler is that there exists heat transfer while throttling. The coupling effect of heat transfer and throttling affects the overall performance of cryocooler. Therefore, the steady-state model was established for each part of the cryocooler. The P-h diagram of N-2 was calculated by the model. Considering the variation of J-T coefficient (mu(jt)) in the process, the coupling performance of heat transfer and throttling in the J-T cryocooler were analyzed. A new parameter, J-T efficiency (eta(jt)), was proposed to evaluate the J-T effect. Additionally, according to the dependence of mu(jt) with temperature and pressure, the refrigeration performance of the cryocooler under different working conditions was simulated. The results show that the heat transfer in the throttle can enhance the throttling effect. When the inlet temperature is 285.0 K and the inlet pressure increases to 18.00 MPa, the N-2 temperature at the cold end reaches 116.3 K, and the gross cooling capacity is 4.55 W. When the inlet pressure is 6.00 MPa and the inlet temperature reduces to 195.0 K, the temperature at the cold end can reach to the saturated temperature of 103.2 K, and the maximum gross cooling capacity is 7.68 W. For the two groups of working conditions, the heat transfer in the throttle can enhance the J-T effect. eta(jt) reaches 95.87% and 94.76%, the proportion of temperature drop caused by J-T effect is 56.10% and 68.03% of the total temperature drops, respectively. Finally, the variation laws of inlet temperature and eta(jt) are analyzed when N-2 reaches saturated temperature under different pressures to guide the selection of inlet parameters.

关键词： J-T cryocooler Printed circuit heat exchanger (PCHE) heat transfer and throttling Performance prediction Cooling capacity

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Modeling and prediction of ultrasonic attenuations in liquid-solid dispersions containing mixed particles with Monte Carlo method

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Particuology 2019年第2期17卷 84-91页

作者： Jianfei Gu Fengxian Fan Yunsi Li Huinan Yang Mingxu Su Xiaoshu Cai Institute of Particle and Two-Phase Flow Measurement/Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China

We develop a theoretical model for predicting the ultrasonic attenuation in the liquid-solid system containing mixed particles. The ultrasonic attenuation coefficient is obtained by counting the number of phonons that reach the receiver. Using the Monte Carlo method (MCM), numerical simulations were performed to predict the ultrasonic attenuations with not only a single particle type but also monodisperse and polydisperse mixed particles. The simulation results for the systems with a single particle type were compared with various standard models. The results show that they agree well at relatively low particle volume concentrations (within 10%). For systems with mixed particles, the particle volume concentrati on was found to in crease to around 10%, and the variation of the ultrasonic attenuation agai nst the mixing ratio yields a nonlinear trend. Moreover, the ultrasonic attenuation is significantly affected by particle properties. The numerical results also show that both the particle type and particle size distribution should be carefully taken into account in the dispersions with polydisperse mixed particles, where the MCM can give a more direct description of the physics of sound propagation compared with the conventional models.

关键词： Ultrasound Ultrasonic attenuation Monte Carlo method Particle size measurement

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Correlation between vorticity, Liutex and shear in boundary layer transition

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COMPUTERS & FLUIDS 2022年 238卷 105371-105371页

作者： Dong, Xiangrui Hao, Chunyang Liu, Chaoqun Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai 200093 Peoples R China Univ Texas Arlington Dept Math Arlington TX 76019 USA

Correlation analysis on the vorticity, Liutex and the anti-symmetric shear, is discussed in this paper based on the new introduced vortex definition of Liutex, to explore the mechanism of the vortex generation in laminar flow transition and the relation between the fluctuation and the rotation. Compared with the volume vorticity as a good measurement to evaluate the statistical fluctuations, a new concept named volume Liutex is introduced in this study to predict the turbulence, which is an accurate yardstick to quantitatively evaluate the degree of the transition from laminar flow to turbulence. A relatively high correlation between the fluctuation and the rotation is discovered in the transitional flow. It is found that the laminar flow transition must be promoted by transforming the anti-symmetric shear to the rotation;the fluctuation of the flow in transition is mainly caused by the flow rotation, or, the turbulence is caused by Liutex generation and growth. In addition, the Reynolds stress is found concentrated in the surrounding area of the vortex core which has a high Liutex value inside.

关键词： DNS Vortex Volume vorticity volume Liutex Anti-symmetric shear Boundary layer transition

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Renewable hydrogen production from chemical looping steam reforming of biodiesel byproduct glycerol by mesoporous oxygen carriers

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CHEMICAL engineering JOURNAL 2021年 416卷 127612-127612页

作者： Dou, Binlin Zhao, Longfei Zhang, Hua Wu, Kai Zhang, Hao Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The selection of metal oxides and supports to improve catalytic activity and stability of oxygen carriers (OCs) is crucial for chemical looping steam reforming (CLSR) to hydrogen production. In this study, the Ni-based MCM41 and SBA-15 OCs with and without CeO2 promoter were prepared by direct synthesis and impregnation methods. The BET, XRD, TEM, ICP-AES, H2-TPR and DSC-TGA were used to analyze the synthesized OCs. Hydrogen production by CLSR using biodiesel byproduct glycerol was studied in a fixed-bed reactor with fuel and air stages. The DSC-TGA experiments were carried out to determine the thermal decomposition of biodiesel byproduct glycerol and the results indicated the exothermic and/or endothermic reactions as a result of secondary reactions and, the main degradation with the mass loss of 85.5 wt% occurred in the stages of 150?500 ?C. The mesoporous OCs presented high specific surface area, large pore volume, and uniform pore size. It was found that the NiO and CeO2 in the mesoporous OCs were first reduced by fuels and the reduced OCs was responsible of steam reforming and water gas shift (WGS) to hydrogen production, and hydrogen selectivity was up to 90% using CeNiO/SBA-15. The mesoporous OCs with Ce promoter greatly shortened ?dead time? (the reduce time of OCs), and effectively suppressed carbon deposited on OCs. High loading of NiO and CeO2 on SBA-15 improved oxygen transfer and achieved excellent cyclic stability. These findings provide the fundamental understanding and principle of design on the conventional Ni-based OCs with room for further developments in chemical looping process.

关键词： Chemical looping steam reforming (CLSR) Ni-based oxygen carriers (OCs) MCM-41 SBA-15 Biodiesel byproduct glycerol

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Unraveling the effect of CDI electrode characteristics on Cs removal from the perspective of ion transfer and energy composition

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JOURNAL OF HAZARDOUS MATERIALS 2023年第1期452卷 131263页

作者： Mao, Yunfeng Qin, Huai Zhang, Hua Wu, Weidong Wu, Deli 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 Tongji Univ Coll Environm Sci & Engn State Key Lab Pollut Control & Resources Reuse Shanghai 200092 Peoples R China Shanghai Inst Pollut Control & Ecol Secur Shanghai 200092 Peoples R China

Capacitive deionization (CDI) is surprisingly efficient to remove the aqueous Cs ion due to its small hydrated size and low hydration energy. But current experimental techniques fail in investigating deeply into the influence of some key electrode characteristics due to the difficulty in experimentally fabricating the electrodes as desired. This work presents a dynamic transport model of salt ions in a flow-by CDI cell. By using this model, the electrode thickness, macro-and micro-porosity are investigated to evaluate Cs ion removal efficiency and energy efficiency particularly from the aspect of ion transfer by the approach of decomposing energy contribution. The results indicate that the thick electrode coupled with the high current could greatly improve the effluent quality, but reduce the salt adsorption capacity (SAC). The increasement of the current density from 3 A/m2 to 6 A/m2 greatly decreases the SAC from 4.0 mg/g to 0.8 mg/g. Lower current could prolong the charging period, leading to more ions stored in the micropore. Not all the electrical energy is consumed for separating ions from the feed as desired, but some are used for driving ions diffusing in the electrodes. Consequently charging efficiency will be reduced especially when the electrodes are characterized with high porosity. It is highlighted that future work is required to further consider the complex details of porous structure and pore connectivity.

关键词： Capacitive deionization Mass transfer model CDI electrode Faradaic reaction Energy efficiency

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The Influence of Tube Diameter Parameters on the flow Resistance and heat transfer Characteristics of Supercritical Co2 in Horizontal Tubes

SSRN

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SSRN 2023年

作者： Cheng, Liangyuan Xu, Jingliang Wang, Qingyang Dong, Xinyu Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power University Beijing102206 China Key Laboratory of Power Station Energy Transfer Conversion and System of Ministry of Education China Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology North China Electric Power University Baoding071003 China

The diameter parameters of tubes can affect flow and heat transfer characteristics of supercritical fluids, which is crucial for improving the efficiency and safe operation of thermal power generation systems. Based on the above, experimental research was conducted to investigate the influence of tube diameter parameters on the flow resistance and heat transfer of supercritical carbon dioxide(sCO2) in horizontal tubes. Stainless steel smooth circular tubes with diameters of 8 mm, 10 mm, and 12 mm were used as the test section, and various experiments were carried out under the range of mass flux: 509.23-1267.34 kg/m2s, heat flux: 97.91-410.43 kW/m2, and operating pressure: 5.542-15.427 MPa. The results reveal that the tube diameter parameters have a greater influence on the heat transfer in the two-phase-like regime, while a relatively small influence on the heat transfer in the liquid-like and vapor-like regimes;Furthermore, it is found that the influence of tube diameter on heat transfer is more significant at the top generatrix through the analysis of local heat transfer. In addition, the sudden change of frictional pressure drop (DPf) near the pseudo-critical point is also related to the tube diameter parameters, and the tube diameter influence is almost negligible when the pressure exceeded 1.5Pc. Based on the pseudo-boiling theory, the tube diameter parameters influence the flow stratification of sCO2 in horizontal tubes, and correlations of the maximum wall temperature difference between the top and bottom generatrix (DTmax) for different diameter tubes between the supercritical boiling number (SBO) and the supercritical Reynolds number of LL phase (ReLL) was established. Our work can provide a new research direction for flow and heat transfer characteristics of supercritical fluid in horizontal tubes, and theoretical guidance for the design of heat exchange tubes in engineering. © 2023, The Authors. All rights reserved.

关键词： heat transfer

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Optimized design of wind turbine airfoil aerodynamic performance and structural strength based on surrogate model

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OCEAN engineering 2023年第Part2期289卷

作者： Zhang, Qiang Miao, Weipao Liu, Qingsong Xu, Zifei Li, Chun Chang, Linsen Yue, Minnan 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 Liverpool John Moores Univ Liverpool Logist Offshore & Marine LOOM Res Inst Byrom St Liverpool L3 3AF England

Though offshore wind turbines have great potential for applications in ocean energy harvesting, their subject to complex unsteady aerodynamic loads. To obtain wind turbine airfoils with both aerodynamic performance and structural strength, an airfoil optimization method was proposed by adding the torsion constant to the objective function under the premise of improving the lift-to-drag ratio. The optimization method characterizes the airfoil geometric profile by using Class/Shape function transformation (CST) parameterization. The airfoil aerodynamics and the structural properties were solved by the computational fluid dynamics (CFD) method and Matlab program, respectively. To reduce the number of CFD calculations, a Kriging surrogate model was established. The combination of an optimized Latin hypercube sampling method and expected improvement (EI) points infill criteria is to improve surrogate modeling efficiency. The NREL 5 MW wind turbine blade was used as the research object. The NACA64618 with 18% relative thickness, the DU91-W2-250 with 25% and the DU97-W350 with 35% were optimized by assigning different weights to aerodynamic and structural objectives based on airfoil position in the blade. The results showed that the aerodynamic performance of the optimized airfoils was improved. Subsequently, the three optimized airfoils were replaced in the same positions of the blade for lay-up design. The blade structural properties were calculated by finite element method (FEM) and it found that the blade torsion angle was reduced, which indicated that adding structural objectives in the airfoil optimization could enhance the blade structural performance.

关键词： Wind turbine airfoil Aerodynamic performance Structural strength Surrogate model Optimization design

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