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Thermal-hydraulic performance of novel louvered fin using flat tube cross-flow heat exchanger

DONG Junqi, CHEN Jiangping, CHEN Zhijiu

《能源前沿(英文)》 2008年 第2卷 第1期   页码 99-106 doi: 10.1007/s11708-008-0010-9

摘要: Experimental studies were conducted to investigate the air-side heat transfer and pressure drop characteristics of a novel louvered fins and flat tube heat exchangers. A series of tests were conducted for 9 heat exchangers with different fin space and fin length, at a constant tube-side water flow rate of 2.8 m/h. The air side thermal performance data were analyzed using the effectiveness-NTU method. Results were presented as plot of Colburn factor and friction factor against the Reynolds number in the range of 500–6500. The characteristics of the heat transfer and pressure drop of different fin space and fin length were analyzed and compared. In addition, the curves of the heat transfer coefficients vs. pumping power per unit heat transfer area were plotted. Finally, the area optimization factor was used to evaluate the thermal hydraulic performance of the louvered fins with differential geometries. The results showed that the and factors increase with the decrease of the fin space and fin length, and the fin space has more obvious effect on the thermal hydraulic characteristics of the novel louvered fins.

关键词: obvious effect     different     thermal hydraulic     constant tube-side     Colburn    

Numerical investigation on side heat transfer enhancement in 300 kA aluminum reduction cell

WANG Changhong, ZHU Dongsheng, LEI Junxi, ZHOU Jiemin

《能源前沿(英文)》 2008年 第2卷 第3期   页码 256-260 doi: 10.1007/s11708-008-0051-0

摘要: Industrial test and numerical simulation were synchronously applied to analyze the side heat transfer process and enhance heat transfer in aluminum reduction cell. The 3D slice finite element model of aluminum reduction cell was developed, with which the sidewall temperature field of the cell was computed by using software ANSYS. The main influencing factors on heat dissipation were analyzed and some effective measures were proposed to enhance sidewall heat transfer. The results show that the shell temperature of the test cell and the common cell is respectively 312°C and 318°C and the ledge thickness is 16 cm and 15 cm when side coefficient of heat transfer between the shell and the surroundings is 70 W/(mK). With the increase of the side coefficient of heat transfer between the shell and the surroundings, the temperature of the shell decreases but the thickness of the side ledge increases when the electrolytic temperature, the ambient temperature, the coefficient of heat transfer between molten bath and ledge, the eutectic temperature and the thermo-resistance of the side lining are constant.

关键词: constant     ambient temperature     thickness     electrolytic temperature     transfer process    

Air-side heat transfer and friction characteristics of biofouled evaporator under wet conditions

Hui PU, Guoliang DING, Xiaokui MA, Haitao HU, Yifeng GAO,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 306-312 doi: 10.1007/s11708-009-0067-0

摘要: The effects of biofouling on air-side heat transfer and friction characteristics under wet conditions of three biofouled finned tube heat exchangers and one clean finned tube heat exchanger were investigated experimentally. Experimental results indicate that the biofouled fin efficiency of the evaporator decreases by 15.5% compared with the clean evaporator under the condition of the biofouled area ratio of 60% at the inlet air velocity of 2.0m/s; The ranges of friction fouling factor and heat transfer fouling factor are 19.8%―43.1% and ―15.6%―13.1%, respectively; a small quantity of biofouled particles can enhance heat transfer at low Reynolds number, and the enhancement effect decreases with the increase of Reynolds number.

关键词: finned tube     evaporator     fouling     heat transfer     friction    

Experimental study of primary and secondary side coupling natural convection heat transfer characteristics

Zhimin QIU, Daogang LU, Jingpin FU, Li FENG, Yuhao ZHANG

《能源前沿(英文)》 2021年 第15卷 第4期   页码 860-871 doi: 10.1007/s11708-021-0744-1

摘要: Passive residual heat removal heat exchanger (PRHR HX), which is a newly designed equipment in the advanced reactors of AP1000 and CAP1400, plays an important role in critical accidental conditions. The primary and secondary side coupling heat transfer characteristics of the passive residual heat removal system (PRHRS) determine the capacity to remove core decay heat during the accidents. Therefore, it is necessary to investigate the heat transfer characteristics and develop applicable heat transfer formulas for optimized design. In the present paper, an overall scaled-down natural circulation loop of PRHRS in AP1000, which comprises a scaled-down in-containment refueling water storage tank (IRWST) and PRHR HX models and a simulator of the reactor core, is built to simulate the natural circulation process in residual heat removal accidents. A series of experiments are conducted to study thermal-hydraulic behaviors in both sides of the miniaturized PRHR HX which is simulated by 12 symmetric arranged C-shape tubes. For the local PRHR HX heat transfer performance, traditional natural convection correlations for both the horizontal and vertical bundles are compared with the experimental data to validate their applicability for the specific heat transfer condition. Moreover, the revised natural convection heat transfer correlations based on the present experimental data are developed for PRHR HX vertical and lower horizontal bundles. This paper provides essential references for the PRHRS operation and further optimized design.

关键词: passive residual heat removal heat exchanger (PRHR HX)     C-shape tube     revised heat transfer correlations     coupled natural convection    

Research progress on low dielectric constant modification of cellulose insulating paper for power transformers

《化学科学与工程前沿(英文)》 2023年 第17卷 第8期   页码 991-1009 doi: 10.1007/s11705-022-2259-7

摘要: Because of the increase in the transmission voltage levels, the demand for insulation reliability of power transformers has increasingly become critical. Cellulose insulating paper is the main insulating component of power transformers. To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size, reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired. Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties, renewability, biodegradability and abundance. The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification. This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers. All the mentioned methods are analyzed in this study. Finally, some recommendations for future modified cellulose insulating paper research and applications are proposed. This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future.

关键词: low dielectric constant     chemical and physical modification     cellulose insulating paper     transformer     nanomaterials.    

Hysteretic behavior of cambered surface steel tube damper: Theoretical and experimental research

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 606-624 doi: 10.1007/s11709-023-0925-6

摘要: A novel cambered surface steel tube damper (CSTD) with a cambered surface steel tube and two concave connecting plates is proposed herein. The steel tube is the main energy dissipation component and comprises a weakened segment in the middle, a transition segment, and an embedded segment. It is believed that during an earthquake, the middle weakened segment of the CSTD will be damaged, whereas the reliability of the end connection is ensured. Theoretical and experimental studies are conducted to verify the effectiveness of the proposed CSTD. Formulas for the initial stiffness and yield force of the CSTD are proposed. Subsequently, two CSTD specimens with different steel tube thicknesses are fabricated and tested under cyclic quasi-static loads. The result shows that the CSTD yields a stable hysteretic response and affords excellent energy dissipation. A parametric study is conducted to investigate the effects of the steel tube height, diameter, and thickness on the seismic performance of the CSTD. Compared with equal-stiffness design steel tube dampers, the CSTD exhibits better energy dissipation performance, more stable hysteretic response, and better uniformity in plastic deformation distributions.

关键词: cambered surface steel tube damper     energy dissipation capacity     finite element model     hysteretic performance     parametric study    

Performance analysis of series/parallel and dual side LCC compensation topologies of inductive power

P. Srinivasa Rao NAYAK, Dharavath KISHAN

《能源前沿(英文)》 2020年 第14卷 第1期   页码 166-179 doi: 10.1007/s11708-018-0549-z

摘要: In an inductive battery charging system, for better power transfer capability and attaining required power level, compensation is necessary. This paper analyzes series/parallel (S/P) and dual side inductor-capacitor-capacitor (LCC) compensation topologies for inductive power transfer of electric vehicle (EV) battery charging system. The design and modeling steps of inductive power transfer for electric vehicle battery charging system are presented. Besides, the equivalent electrical circuits are used to describe the circuit compensation topologies. The results convey that the efficiency of dual side LCC compensation is higher than that of S/P compensation at variable mutual inductance (misalignment).

关键词: series/parallel compensation     electric vehicle (EV)     dual side LCC compensation     inductive power transfer    

Analysis and characterization of wind-solar-constant torque spring hybridized model

Shantanu ACHARYA,Subhadeep BHATTACHARJEE

《能源前沿(英文)》 2014年 第8卷 第3期   页码 279-289 doi: 10.1007/s11708-014-0312-z

摘要: Solar and wind are the most promising renewable energy resources. But their unpredictable and varying nature prevents them from being used as the sole resource for power generation. This paper presents a model of wind and solar thermal hybrid power plant with a spring storage system which is expected to play an efficient role in combating with the drawbacks related to renewable power generation. In the proposed scheme, wind energy is harnessed by a hybrid vertical axis wind turbine, solar energy is utilized by a Stirling engine, and the surplus energy is stored in a winding spring. The paper discusses the working methodologies and analyses the performance of such 2.6 kW hybrid power plant model. It has been observed that the plant is capable of consistently generating 50% of its rated capacity irrespective of limitations in solar and wind resources.

关键词: hybrid vertical axis wind turbine     Stirling engine     solar-thermal energy     wind energy     constant torque spring    

Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mounted

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 333-345 doi: 10.1007/s11708-009-0061-6

摘要: The tube bank fin is commonly used to increase the area of the heat transfer surface with a small heat transfer coefficient of a heat exchanger. If vortex generators (VGs) are punched on the fin surface, the heat transfer performance of the fin can be improved. This paper focused on the effect of transversal tube pitch on the local heat transfer performance of the three-row flat tube bank fin mounted with VGs. On the fin surface, constructing the flow channel but without mounted VGs, the transversal tube pitch was greater, and the span averaged Nusselt number downstream was larger because fewer interactions of vortices would be generated from different VGs located upstream. When the area goodness factor was used as the criteria on the condition of one tube unit of heat exchanger for commonly used fin materials and fin thickness, the transversal tube pitch has considerable effect on the heat transfer enhancement of VGs. Large transversal tube pitch is more sensitive to fin material than to fin thickness.

关键词: heat transfer enhancement     vortex generator     finned flat tube bank     heat exchanger    

Optimal dynamic emergency reserve activation using spinning, hydro and demand-side reserves

S. Surender REDDY,P. R. BIJWE,A. R. ABHYANKAR

《能源前沿(英文)》 2016年 第10卷 第4期   页码 409-423 doi: 10.1007/s11708-016-0431-9

摘要: This paper proposes an optimal dynamic reserve activation plan after the occurrence of an emergency situation (generator/transmission line outage, load increase or both). An optimal plan is developed to handle the emergency, using the coordinated action of fast and slow reserves, for secure operation with minimum overall cost. It considers the reserves supplied by the conventional thermal generators (spinning reserves), hydro power units and load demands (demand-side reserves). The optimal backing down of costly/fast reserves and bringing up of slow reserves in each sub-interval in an integrated manner is proposed. The proposed reserve activation approaches are solved using the genetic algorithm, and some of the simulation results are also compared using the Matlab optimization toolbox and the general algebraic modeling system (GAMS) software. The simulation studies are performed on the IEEE 30, 57 and 300 bus test systems. These results demonstrate the advantage of the proposed integrated/dynamic reserve activation plan over the conventional/sequential approach.

关键词: demand-side reserves     dynamic reserve activation approach     hydro power units     post contingency     sequential reserve activation approach     spinning reserves    

Energy distribution between liquid hydrogen and liquid oxygen temperatures in a Stirling/pulse tube refrigerator

《能源前沿(英文)》 2023年 第17卷 第4期   页码 516-526 doi: 10.1007/s11708-022-0844-6

摘要: A two-stage gas-coupled Stirling/pulse tube refrigerator (SPR), whose first and second stages respectively involve Stirling and pulse tube refrigeration cycles, is a very promising spaceborne refrigerator. The SPR has many advantages, such as a compact structure, high reliability, and high performance, and is expected to become an essential refrigerator for space applications. In research regarding gas-coupled regenerative refrigerator, the energy flow distribution between the two stages, and optimal phase difference between the pressure wave and volume flow, are two critical parameters that could widely influence refrigerator performance. The effects of displacer displacement on the pressure wave, phase difference, acoustic power distribution, and inter-stage cooling capacity shift of the SPR have been investigated experimentally. Notably, to obtain the maximum first-stage cooling capacity, an inflection point in displacement exists. When the displacer displacement is larger than the inflection point, the cooling capacity could be distributed between the first and second stages. In the present study, an SPR was designed and manufactured to work between the liquid hydrogen and liquid oxygen temperatures, which can be used to cool small-scale zero boil-off systems and space detectors. Under appropriate displacer displacement, the SPR can reach a no-load cooling temperature of 15.4 K and obtain 2.6 W cooling capacity at 70 K plus 0.1 W cooling capacity at 20 K with 160 W compressor input electric power.

关键词: Stirling/pulse tube refrigerator     displacer displacement     space application     phase shift     energy distribution    

Development of a fan-stirred constant volume combustion chamber and turbulence measurement with PIV

《能源前沿(英文)》 2022年 第16卷 第6期   页码 973-987 doi: 10.1007/s11708-021-0762-z

摘要: A fan-stirred combustion chamber is deve-loped for spherically expanding flames, with P and T up to 10 bar and 473 K, respectively. Turbulence characteristics are estimated using particle image velocimetry (PIV) at different initial pressures (P = 0.5–5 bar), fan frequencies (ω = 0–2000 r/min), and impeller diameters (D = 100 and 114 mm). The flame propagation of methanol/air is investigated at different turbulence intensities (u′=0–1.77 m/s) and equivalence ratios (φ = 0.7–1.5). The results show that u′ is independent of P and proportional to ω, which can be up to 3.5 m/s at 2000 r/min. LT is independent of P and performs a power regression with ω approximately. The turbulent field is homogeneous and isotropic in the central region of the chamber while the inertial subrange of spatial energy spectrum is more collapsed to –5/3 law at a high ReT. Compared to laminar expanding flames, the morpho-logy of turbulent expanding flames is wrinkled and the wrinkles will be finer with the growth of turbulence intensity, consistent with the decline of the Taylor scale and the Kolmogorov scale. The determined SL in the present study is in good agreement with that of previous literature. The SL and ST of methanol/air have a non-monotonic trend with φ while peak ST is shifted to the richer side compared to SL. This indicates that the newly built turbulent combustion chamber is reliable for further experimental study.

关键词: fan-stirred combustion chamber     turbulence characteristics     particle image velocimetry (PIV)     methanol     turbulent expanding flames    

Genetic evidence in planar cell polarity signaling pathway in human neural tube defects

null

《医学前沿(英文)》 2014年 第8卷 第1期   页码 68-78 doi: 10.1007/s11684-014-0308-4

摘要:

Neural tube defects (NTDs) are a group of birth anomalies having a profound physical, emotional, and financial effects on families and communities. Their etiology is complex, involving environmental and genetic factors that interact to modulate the incidence and severity of the developing phenotype. The planar cell polarity (PCP) pathway controls the process of convergent extension (CE) during gastrulation and neural tube closure and has been implicated in the pathogenesis of NTDs in animal models and human cohorts. This review summarizes the cumulative results of recent studies on PCP signaling pathway and human NTDs. These results demonstrate that PCP gene alterations contribute to the etiology of human NTDs.

关键词: planar cell polarity     neural tube defects     rare mutations    

Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linear

《工程管理前沿(英文)》   页码 452-461 doi: 10.1007/s42524-022-0209-1

摘要: This study combines multi-regional input–output (MRIO) model with linear programming (LP) model to explore economic structure adjustment strategies for the reduction of carbon dioxide (CO2) emissions. A particular feature of this study is the identification of the optimal regulation sequence of final products in various regions to reduce CO2 emissions with the minimum loss in gross domestic product (GDP). By using China’s MRIO tables 2017 with 28 regions and 42 economic sectors, results show that reduction in final demand leads to simultaneous reductions in GDP and CO2 emissions. Nevertheless, certain demand side regulation strategy can be adopted to lower CO2 emissions at the smallest loss of economic growth. Several key final products, such as metallurgy, nonmetal, metal, and chemical products, should first be regulated to reduce CO2 emissions at the minimum loss in GDP. Most of these key products concentrate in the coastal developed regions in China. The proposed MRIOLP model considers the inter-relationship among various sectors and regions, and can aid policy makers in designing effective policy for industrial structure adjustment at the regional level to achieve the national environmental and economic targets.

关键词: CO2 emissions     demand side regulation     multi-regional input–output model     linear programming model    

Synthesis and thermosensitive behavior of dextran graft copolymers containing poly (N-vinylcaprolactam) side

SHI Huangying, CHEN Wenjuan, ZHANG Liming

《化学科学与工程前沿(英文)》 2007年 第1卷 第1期   页码 72-75 doi: 10.1007/s11705-007-0015-7

摘要: New graft copolymers were synthesized by grafting N-vinylcaprolactam onto dextran. Their composition and structure were investigated by elemental analyses, infrared spectra and thermogravimetric analyses. By optical transmittance measurements, it was found that the aqueous solutions of these graft copolymers showed a temperature-dependent transmittance change due to the introduction of thermosensitive poly (-vinylcaprolactam) graft chains. Moreover, the lower critical solution temperature (LCST) of the graft copolymer in aqueous solution was dependent on its grafting extent and concentration. The LCST value was found to increase with the increase of the grafting extent and decrease with the increase of the copolymer concentration. With these stimuli-response properties, such polysaccharide derivative may hold potential applications in biomedicine and biotechnology.

关键词: transmittance     copolymer concentration     LCST     temperature     elemental    

标题 作者 时间 类型 操作

Thermal-hydraulic performance of novel louvered fin using flat tube cross-flow heat exchanger

DONG Junqi, CHEN Jiangping, CHEN Zhijiu

期刊论文

Numerical investigation on side heat transfer enhancement in 300 kA aluminum reduction cell

WANG Changhong, ZHU Dongsheng, LEI Junxi, ZHOU Jiemin

期刊论文

Air-side heat transfer and friction characteristics of biofouled evaporator under wet conditions

Hui PU, Guoliang DING, Xiaokui MA, Haitao HU, Yifeng GAO,

期刊论文

Experimental study of primary and secondary side coupling natural convection heat transfer characteristics

Zhimin QIU, Daogang LU, Jingpin FU, Li FENG, Yuhao ZHANG

期刊论文

Research progress on low dielectric constant modification of cellulose insulating paper for power transformers

期刊论文

Hysteretic behavior of cambered surface steel tube damper: Theoretical and experimental research

期刊论文

Performance analysis of series/parallel and dual side LCC compensation topologies of inductive power

P. Srinivasa Rao NAYAK, Dharavath KISHAN

期刊论文

Analysis and characterization of wind-solar-constant torque spring hybridized model

Shantanu ACHARYA,Subhadeep BHATTACHARJEE

期刊论文

Transversal tube pitch effects on local heat transfer characteristics of the flat tube bank fin mounted

Liangbi WANG, Zhimin LIN, Kangjie SUN, Yuanxin DONG, Song LIU, Yongheng ZHANG,

期刊论文

Optimal dynamic emergency reserve activation using spinning, hydro and demand-side reserves

S. Surender REDDY,P. R. BIJWE,A. R. ABHYANKAR

期刊论文

Energy distribution between liquid hydrogen and liquid oxygen temperatures in a Stirling/pulse tube refrigerator

期刊论文

Development of a fan-stirred constant volume combustion chamber and turbulence measurement with PIV

期刊论文

Genetic evidence in planar cell polarity signaling pathway in human neural tube defects

null

期刊论文

Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linear

期刊论文

Synthesis and thermosensitive behavior of dextran graft copolymers containing poly (N-vinylcaprolactam) side

SHI Huangying, CHEN Wenjuan, ZHANG Liming

期刊论文