POWDER TECHNOLOGY
·
2022
·
IF 5.64
Jinxin Zhang,Xiaoping Luo,Liangfeng Wang,Zhenfei Feng,Tengfei Li
In this work, electric field and nanofluid are coupled to enhance flow boiling heat transfer in minichannel. Pin electrodes are adopted to create non-uniform electric field. The effects of nanoparticle mass concentration, surfactant type and mass concentration under electric field on nanofluid flow boiling heat transfer are studied. Image analysis technique is used to quantify boiling bubble behaviors. The results demonstrate that without electric field, bubbles for nanofluid flow boiling are smaller and more discrete than R141b. Under electric field, bubble size reduces and the number of bubbles increases, which reveals synergy effect of electric field and nanofluid on bubble behaviors is effective. Besides, electric forces mitigate bubble coalescence and delay transition from bubbly to slug flow. Maximum heat transfer coefficient of nanofluid is 80% higher than R141b. Under electric field, boiling heat transfer of nanofluid modified by anionic surfactant (SDBS) is better than cationic (CTAB) and nonionic (Span80) surfactant.
研究领域:
热力学
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2017
·
IF 2.942
Yanwei Hu,Ziyu Liu,Yurong He
Boiling heat transfer is widely used in energy power equipment, while the poor thermal property conventional fluids cannot meet the increase of heat transfer demand. The addition of nanoparticles into base fluids can modify the properties of base fluids and is a potential way to improve heat transfer characteristics. In present work, amorphous SiO 2 nanoparticles with an average size of 98 nm were synthesized via Stober process. And they were added into water with different mass fractions to investigate the pool boiling heat transfer characteristics. The heat transfer coefficient and critical heat flux were analyzed. Results show that the heat transfer coefficient of all fluids increases rapidly in the natural convective region but then rises gradually in the nucleate boiling region. Moreover, owing to the deposition of SiO 2 nanoparticles, the heat transfer coefficients of SiO 2 -H 2 O nanofluids are lower than that of the base fluid and reduce as the concentration increase. On the other hand, because of the wettability improvement of the heating wire surface caused by the deposition of SiO 2 nanoparticles, the critical heat fluxes of nanofluids are higher than that of the base fluid. When the concentration is 0.081%, the critical heat flux achieves a peak improvement of approximately 68.8%.
研究领域:
热力学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL MONITORING AND ASSESSMENT
·
2024
·Vol. 196
·期 2
·1-18
·
IF 2.9
Yue Xiupeng,Shan Yongping,Zhang Yaping,Jiao Wentao,Shen Kai
The transfer of heat and contaminants by alternating current (AC) and the removal mechanism of polycyclic aromatic hydrocarbons (PAHs) in electrical resistance heating (ERH) need further study. The main factors affecting heat transfer and water evaporation in the ERH experiment were studied, and the desorption efficiency, temporal and spatial distribution and kinetic behavior under various conditions were analyzed. The results suggested that moisture content was a necessary condition to ensure effective heating of soil, and soil moisture content above 30% was recommended. Higher voltage intensity and/or ion concentration meant stronger input power, resulting in the rapider heating process and the shorter the boiling time. At a low desorption temperature (about 100°C), the Phe desorption mainly depended on the volatilization of surface Phe and the co-boiling of Phe-water. In ERH, the participation of AC would accelerate the diffusion of pollutants from the internal pores of soil particles and their redistribution with water phase, thus improving the Phe removed by co-boiling. It was noteworthy that AC just greatly promoted solid-liquid mass transfer, but it hardly promoted desorption directly, and the removal still depended on Phe-water co-boiling. The Phe desorption efficiency could be significantly improved from 14.0~18.4% to 59.6~70.8% under the combined action of current strengthening Phe diffusion and co-boiling. Thermogravimetric and product analysis confirmed that no new organic matter was generated, but only Phe entered the gas phase through phase change.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
·
2022
·
IF 4.779
Tao Wen,Jielin Luo,Kai Jiao,Lin Lu
Enhancing heat transfer performance of pool boiling is attractive in practical applications, while the utilization of nanofluid is regarded as an effective approach. However, existing knowledge of boiling enhancement with nanofluid is still limited in terms of the influences of its type, concentration, deposition and boiling time. In this paper, the pool boiling performance of a highly self-dispersion TiO 2 nanofluid with mass concentration from 0.0001% to 0.1% was experimentally investigated and compared with Al 2 O 3 and ZnO nanofluid. The effect of boiling-induced deposition layer was studied by means of repeatability test, wettability test and macro/micro morphology test. Results indicated that a super-hydrophilic micro-porous deposition layer formed on nanofluid boiling surface and led to nearly twice higher CHF than distilled water, and nanofluid itself had negligible influence on CHF enhancement. Increasing concentration of nanofluid led to occasional falling off of the deposition on surface and resulted in complicated and unpredictable boiling performance. Nanofluid type and concentration had limited influence on CHF, whose value kept around 1800 kW/m 2 . 0.0001% TiO 2 and Al 2 O 3 nanofluids had similar boiling curves, but ZnO nanofluid exhibited lower heat transfer coefficient . Finally, a novel criterion to predict the occurrence of film boiling in advance was proposed based on wall superheat change rate threshold. The present study will contribute to design guidance and security control of nanofluid-based pool boiling device.
研究领域:
工程热物理
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2024
·
IF 4.5
Jinxin Zhang,Xiaoping Luo,Zhenfei Feng
In this study, electrohydrodynamic (EHD) and nanofluid were synergistically employed to improve minichannel flow boiling. R141b, TiO 2 /R141b and TiO 2 /Span80/R141b nanofluids are employed as working fluids. Flow boiling characteristics in minichannels under electric field were evaluated experimentally. Laser confocal microscope was used to examine the effect of EHD and surfactant on nanofluid stability, particularly nanoparticle deposition on heated surfaces. Electric field can effectively enhance heat transfer, and the enhancement is more significant for nanofluids compared to pure fluid. Heat transfer performance is higher for TiO 2 /R141b than TiO 2 /Span80/R141b, while TiO 2 /Span80/R141b shows higher pressure drop than TiO 2 /R141b. The maximum enhancement ratio of 1.58 and 1.85 is found for TiO 2 /R141b and TiO 2 /Span80/R141b under electric field. Besides, heat transfer mechanism enhanced by EHD and nanofluid was discussed. Nanofluid stabilization induced by electric field and surfactant play crucial role in EHD enhancement for nanofluid. The findings suggest that TiO 2 /Span80/R141b nanofluid is well-suited for integration with EHD.
研究领域:
热力学
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
PROGRESS IN ORGANIC COATINGS
·
2024
·
IF 6.5
Junzhe Fan,Zhengqing Yang,Qiang Zhang,Wen Sun,Lida Wang,Yine Ren,Guichang Liu
The synergistic improvement of corrosion protection and heat transfer properties has always been the challenge of coating research. In this article, the silicon carbide was hydrophobically modified and combined with blended fluorine resins to fabricate a multifunctional superhydrophobic coating by electrophoretic deposition. The prepared composite coating exhibits exceptional corrosion resistance (10 10 Ω·cm 2 in 10 wt% H 2 SO 4 at 60 °C for 50 days) and a heat transfer coefficient 1.26 times higher than the coating without fillers. The water contact angle of the composite coating surface is 160.5°, and the sliding angle is 2.3°, achieving a superhydrophobic state. The superhydrophobicity of the coating surface supports the barrier against corrosive media and droplet condensation, improving both corrosion protection and condensation heat transfer properties. It also has good thermal, wear and chemical stability.
研究领域:
材料科学
·
表面工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF FOOD ENGINEERING
·
2024
·
IF 5.3
Guangyuan Jin,Qingyu Zheng,Zhengshan Zhu,Chunfang Song,Zhenfeng Li,Feihu Song,Jing Li,Boru Chen
To address the need for enhanced biochemical reactions and overcome the shortcomings associated with passive and active mixer fabrication, reactor designs must utilize the coupled mixing concept to address the lack of insufficient heat and mass transfer through notable alterations of the physical properties. This study introduces a tubular microwave reactor based on chaotic flow dynamics, attempting to combine the concept of active and passive mixing to stimulate the development of eddy and secondary flows through electromagnetic fields and geometric disturbance enhance heat and mass transfer. Experiments and simulation analysis validate the validity of the prediction model, and reveal the fluid flow, mixing, electromagnetic and thermal characteristics and their synergistic mechanism, and shows the potential to enhance the mass and heat transfer performance at low Reynolds number, which provides a new idea for the design of chemical reactors and biological analysis.
研究领域:
化学工程
·
生物分析
✓ 已验证
产品关联
DOI
高影响因子
Energy Science & Engineering
·
2023
·Vol. 11
·期 12
·4481-4492
·
IF 3.8
Hao Zhu,Liwen Fan
The understanding of the enhanced thermal conductivity mechanism in nanofluids remains elusive, underscoring the necessity for investigating their influence on heat conduction. A comparative analysis was carried out on the overall heat transfer coefficients of SiO 2 , TiO 2 , MgO, ZrO 2 , CeO 2 , Al 2 O 3 , and Fe 3 O 4 , yielding 346.5, 442.9, 569.2, 465.6, 663.2, 562.4, and 706.2 W/m 2 K, respectively. Our investigation further extended to the differential impacts of various nanofluids on heat transfer conduction coefficients, with Fe 3 O 4 nanofluids demonstrating the greatest, and SiO 2 the least, heat transfer coefficients. Importantly, these nanofluids play a cooperative role in enhancing heat transfer coefficients. Previous studies have largely concentrated on the effects of individual and mixed nanofluids on overall heat transfer coefficients, neglecting the combined effects of different nanofluids. Moreover, the mechanisms underlying these effects remain vague, with insufficient corresponding characterizations. Our study seeks to address these limitations. We also studied the impact of nanofluid concentration, pH, and temperature on heat conduction. Our results suggest that the overall heat transfer coefficient escalates with increasing nanofluid concentration and temperature. For example, the overall heat transfer coefficients for SiO 2 nanofluids surged from 346.5 W/m 2 K at 25°C to 369.4 W/m 2 K at 35°C, 411.4 W/m 2 K at 45°C, and 427.6 W/m 2 K at 55°C. A rise in pH also led to an increase in overall heat transfer coefficients up to a certain point, after which they started decreasing. The zeta potentials of the aforementioned nanofluids were −12.1, −24.8, −28.6, −23.2, −35.9, −31.3, and −40.4 mV, respectively, and these potentials dwindled with an increase in pH. The influence of nanofluids on overall heat transfer may have implications for the enhanced oil recovery effect.
研究领域:
热力学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Engineering Applications of Computational Fluid Mechanics
·
2023
·
IF 6.1
Mohamed Boujelbene,Sohail Rehman,Sultan Alqahtani,Sultan Alshehery,Sayed M. Eldin
This study enlightens the magnetohydrodynamic Jeffery-Hamel flow under an inclined Lorentz force through a non-uniform conduit having slip at walls, which is frequently applied in geothermal applications, electronic cooling devices, and modern energy systems, etc. Therefore, the performance of a two-dimensional purely radial flow inside a converging-diverging channel is explored from the perspective of second law of thermodynamics for Carreau nanofluids. The intersecting walls of conduit are inclined with horizontal plane to construct a converging flow for negative angle (α<0) and a diverging flow for positive angle (α>0). Additionally, second law thermodynamic evaluation offers an effective method for improving thermal performance by reducing entropy production. To accomplish the main objective, rigorous physical theories and assumptions are implemented based on the passive control approach of Buongiorno's model. By applying distinctive modifications, the governing equations are renovated into a system of ordinary differential equations, which are solved numerically by a collocated technique based on finite difference code. Simple shear near the wall influences the flow configurations allow compression in a local flow topology in regions of divergent channel. The temperature profiles increase with sophisticated heat source and Brinkman number. Entropy is minimum and uniform with optimum channel angle and velocity slip.
研究领域:
工程热物理
·
流体力学
·
纳米科技
✓ 已验证
DOI
高影响因子
Entropy
·
2022
·Vol. 24
·期 6
·765
·
IF 2.738
Haopeng Zeng,Yu Zhang,Lei Zhang,Zhaoyang Chen,Xiaosen Li
Depressurization combined with brine injection is a potential method for field production of natural gas hydrate, which can significantly improve production efficiency and avoid secondary formation of hydrate. In this work, the experiments of hydrate production using depressurization combined with brine injection from a simulated excess-water hydrate reservoir were performed, and the effects of NaCl concentration on hydrate decomposition, temperature change, and heat transfer in the reservoir were investigated. The experimental results indicate that there is little gas production during depressurization in a excess-water hydrate reservoir, and the gas dissociated from hydrate is trapped in pores of sediments. The high-water production reduces the final gas recovery, which is lower than 70% in the experiments. The increasing NaCl concentration only effectively promotes gas production rate in the early stage. The final cumulative gas production and average gas production rate have little difference in different experiments. The NaCl concentration of the produced water is significantly higher than that which is in contact with hydrate in the sediments because the water produced by hydrate decomposition exists on the surface of undissociated hydrate. The high concentration of NaCl in the produced water from the reactor significantly reduces the promoting effect and efficiency of NaCl solution on hydrate decomposition. The injection of NaCl solution decreases the lowest temperature in sediments during hydrate production, and increases the sensible heat and heat transfer from environment for hydrate decomposition. The changes of temperature and resistance effectively reflect the distribution of the injected NaCl solution in the hydrate reservoir.
研究领域:
能源科学
·
地质学
·
化学工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
·
2021
·Vol. 116
·期 7
·2373-2385
·
IF 3.226
Guan Jiju,Ding Yunpeng,Gao Chao,Xu Zhengya,Xu Xuefeng,Wang Zhiliang
In this work, novel DPS/MWCNT composites were synthesized through filling multi-walled carbon nanotubes (MWCNTs) with dialkyl pentasulfide (DPS) using a wet-chemical method. A nanofluid that use the DPS/MWCNT composites as additives was then developed for achieving a high-performance turning. The performance of the developed nanofluid including dispersion stability, heat transfer capacity, and wettability was evaluated using thermophysical analytical methods. The machining performance of the DPS/MWCNT composites nanofluid was systematically investigated in the turning of AISI 52100 alloy steel, using a commercial emulsion coolant as a benchmark. The lubrication mechanism of the nanofluid involved in the turning process was reveal with the aid of X-ray photoelectron spectroscopy (XPS). The results showed that DPS was successfully filled into MWCNTs with a filling rate of around 25.7%. The nanofluid had an excellent dispersion performance and produced respective 105.0% and 23.6% improvements in the heat transfer and wetting performance, in comparison to a base fluid. During turning, the composites suspended in the nanofluid acted as microbearings to reduce the friction of sliding, while the DPS filled in the MWCNTs was released under pressure to generate a complex lubricating film at the tool-chip interface, leading to a low resistance to cutting. This thus resulted in 15% and 25% reductions in the cutting force and temperature as well as 16% and 22% improvements in the surface roughness and tool life, in comparison to a conventional turning.
研究领域:
材料科学
·
机械工程
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Xiong Zhao,Lei Huang,Junsheng Hou,Zihan Ding,Li Ma,Junjie Wu,Dongyu Li,Yilong Yao,Zhenzhen Chen,Nanjing Hao
The nanoparticles with uniform size and excellent stability scattered in fluid (termed as nanofluid) hold the potential to extricate high-performance electronics from the heat crisis. However, the simple, general, and large-scale production of nanofluids with high quality still remains a challenge. Here, we present a delicate design of microfluidic apparatus with extremely high throughput for silica (SiO 2 ) and titania (TiO 2 ) nanofluids synthesis to enhance flow boiling heat transfer. The microfluidic apparatus was composed of a three-microreactor array, and the spiral microchannel in the microreactor can efficiently mix the reagents by the secondary vortex. With the apparatus, 1 L of nanofluids can be generated in 20 min, and the synthesized nanofluids had a narrow size distribution below 100 nm and outstanding long-term stability at room (25 °C) and high (75 °C) temperature. The established heat transfer platform tested the heat transfer performance of SiO 2 /TiO 2 nanofluids that the enhancement increased with the flow rate and decreased with the nanofluid concentration. The SiO 2 nanofluid always performed better than the TiO 2 nanofluid in the same condition. Maximumly, the critical heat flux (CHF) and heat transfer coefficient (HTC) were improved by 77 % and 96 %, respectively, for SiO 2 nanofluid, and they were raised by 44 % and 56 %, respectively, for TiO 2 nanofluid. The underlying mechanism of the difference was analyzed from the deposition on the surface and the bubble’s coalescence. These results not only shed light on the industrial manufacture of various high-performance nanofluids, but also promote the thermal management of high-power electronics.
研究领域:
材料科学
·
热能工程
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）