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Yunfei Yan
Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing, 400044, China

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Journal article
Published: 11 July 2021 in International Journal of Hydrogen Energy
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Targeted at improving the energy output of thermophotovoltaic system, a novel micro combustor with spiral fin is proposed. The multi-structure factors of spiral fin concluding spiral fin length, spiral fin pitch, spiral fin number and spiral fin opening size impact the thermal and energy performance of micro combustor are investigated in this study. The method of Taguchi experimental design is introduced to determine the testing cases, Orthogonal design table L16(44). Then, grey relational grade is adopted to obtain the influence of four factors on performance parameters. The evaluation indexes of each testing case include mean outer wall temperature, outer wall temperature uniformity and pressure drop, which are closely connected with the thermal and energy performance of micro combustors. Moreover, the results calculated by grey relational grade are verified by analysis of variance. Results show that the optimal combination of the structure is micro combustor inserting with spiral fin, in which the spiral fin is 16 mm, the spiral fin pitch is 1.57 mm, the spiral fin number is 8 and spiral fin opening size is 0.2 mm. Meanwhile, the spiral fin length has the greatest impact on the comprehensive performance of the micro combustor, with a contribution of 48.522%.

ACS Style

Ting Zhao; Yunfei Yan; Ziqiang He; Zhongqing Yang. Influence of multi-structure optimization on the comprehensive performance of micro-cylindrical combustor inserting with spiral fin by using grey relational analysis and analysis of variance. International Journal of Hydrogen Energy 2021, 46, 28327 -28337.

AMA Style

Ting Zhao, Yunfei Yan, Ziqiang He, Zhongqing Yang. Influence of multi-structure optimization on the comprehensive performance of micro-cylindrical combustor inserting with spiral fin by using grey relational analysis and analysis of variance. International Journal of Hydrogen Energy. 2021; 46 (55):28327-28337.

Chicago/Turabian Style

Ting Zhao; Yunfei Yan; Ziqiang He; Zhongqing Yang. 2021. "Influence of multi-structure optimization on the comprehensive performance of micro-cylindrical combustor inserting with spiral fin by using grey relational analysis and analysis of variance." International Journal of Hydrogen Energy 46, no. 55: 28327-28337.

Article
Published: 10 July 2021 in Journal of Thermal Analysis and Calorimetry
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The electronic devices are facing the challenge of high heat flux. To improve the thermal and hydraulic performance of micro heat sinks with ribbed pin-fins and single heating input, the geometrical parameters, including shapes, arrangements, width and height, are numerically investigated. The results show that the micro heat sinks with arc ribbed pin-fins exhibit the best comprehensive performance comparing with triangle and rectangle ribbed pin-fins. Meanwhile, even for the single heating input, the staggered ribs arrangement exhibits better comprehensive performance than that of the in-line ribs arrangement the same Reynolds number. Moreover, the average Nu number increases first and then decreases with the increase in the rib width. At Re = 1342, the average Nusselt number of Dp/D0 = 1/2 can reach up 44.3, which is 1.8 times of Dp/D0 = 3/2. Increasing the Hp/H0 plays a positive effect on improving thermal performance but with higher pressure loss. At higher Hp/H0, increasing Hp/H0 does not show obvious effect on reduction total thermal resistance under the same pump power. To better balance the thermal resistance and pressure drop, the value of Dp/D0 and Hp/H0 should be chosen properly.

ACS Style

Ziqiang He; Yunfei Yan; Li Zhang. Thermal-hydraulic investigation on micro heat sinks with ribbed pin-fin arrays and single heating input: parametrical study. Journal of Thermal Analysis and Calorimetry 2021, 1 -17.

AMA Style

Ziqiang He, Yunfei Yan, Li Zhang. Thermal-hydraulic investigation on micro heat sinks with ribbed pin-fin arrays and single heating input: parametrical study. Journal of Thermal Analysis and Calorimetry. 2021; ():1-17.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Li Zhang. 2021. "Thermal-hydraulic investigation on micro heat sinks with ribbed pin-fin arrays and single heating input: parametrical study." Journal of Thermal Analysis and Calorimetry , no. : 1-17.

Journal article
Published: 11 June 2021 in International Journal of Hydrogen Energy
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Targeting at optimizing the energy output and thermal performance of the micro combustor in the application of micro-thermophotovoltaic (MTPV) systems, but the introduction of spiral fins brings higher pressure loss. Thus, a novel design of the micro combustor with the spiral fin opening is developed. The influence of inlet velocities, the hole size and hole number of the spiral fin on the pressure drop and thermal characteristic and energy characteristic are numerically investigated. It's illustrated that the spiral fin opening is conductive to decrease the pressure loss and optimize the outer wall temperature distribution, but has a negative influence on increasing the mean outer wall temperature of the micro combustor and energy output in the MTPV systems. With the increase of the hole size and hole number of the spiral fin, the pressure loss decreases and the outer wall temperature uniformity increases significantly, while the mean outer wall temperature drops and total energy output decreases. The better performance obtains when the micro combustor with spiral fin with four 0.5 mm holes.

ACS Style

Ting Zhao; Yunfei Yan; Ziqiang He; Wei Gao; Zhongqing Yang. Influence of hole size and number on pressure drop and energy output of the micro-cylindrical combustor inserting with an internal spiral fin with holes. International Journal of Hydrogen Energy 2021, 46, 26594 -26606.

AMA Style

Ting Zhao, Yunfei Yan, Ziqiang He, Wei Gao, Zhongqing Yang. Influence of hole size and number on pressure drop and energy output of the micro-cylindrical combustor inserting with an internal spiral fin with holes. International Journal of Hydrogen Energy. 2021; 46 (52):26594-26606.

Chicago/Turabian Style

Ting Zhao; Yunfei Yan; Ziqiang He; Wei Gao; Zhongqing Yang. 2021. "Influence of hole size and number on pressure drop and energy output of the micro-cylindrical combustor inserting with an internal spiral fin with holes." International Journal of Hydrogen Energy 46, no. 52: 26594-26606.

Journal article
Published: 04 June 2021 in Chemical Engineering and Processing - Process Intensification
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To improve temperature distribution is uneven in Y-shaped microchannel (Y) heat sink, connected Y-shaped microchannel (CY) is proposed and heat dissipation performance is compared. Results revealed that CY model has a lower peak temperature and makes temperature distribution more uniform due to two symmetrical vortexes are formed at both sides of branch structure, while there are still high temperature zones in the second stage channels under high heat flux. Therefore, the micro pin fins are embedded in CY heat sink (FCY) to examine heat transfer performance. Results illustrated that there is more pressure loss in FCY heat sinks, while temperature uniformity of FCY model is better than CY heat sink, which strengthens heat dissipation of the second stage channels. Heat transfer coefficients of FCY-1, FCY-2 and FCY-3 heat sinks are 1.12, 1.28 and 1.11 times than CY model, respectively. The composite performance factor, both FOM2/1 and FOM2/3 are greater than 1. The FCY-2 model demonstrates a good thermal and hydraulic performance can achieve the best cooling capacity.

ACS Style

Yunfei Yan; Kaiming Shen; Ying Liu; Zi Qiang He. Thermal-hydraulic performance enhancement of miniature heat sinks using connected Y-shaped fractal micro-channels. Chemical Engineering and Processing - Process Intensification 2021, 166, 108487 .

AMA Style

Yunfei Yan, Kaiming Shen, Ying Liu, Zi Qiang He. Thermal-hydraulic performance enhancement of miniature heat sinks using connected Y-shaped fractal micro-channels. Chemical Engineering and Processing - Process Intensification. 2021; 166 ():108487.

Chicago/Turabian Style

Yunfei Yan; Kaiming Shen; Ying Liu; Zi Qiang He. 2021. "Thermal-hydraulic performance enhancement of miniature heat sinks using connected Y-shaped fractal micro-channels." Chemical Engineering and Processing - Process Intensification 166, no. : 108487.

Journal article
Published: 01 June 2021 in Applied Thermal Engineering
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Facing the challenge of high heat flux in electronic devices, effective heat dissipation with low consumption has drawn great attention. Based on the constructal theory, the optimal structures of fractal heat sinks are obtained by genetic algorithm (GA) optimization. The optimal branching level is 4. Furthermore, the Taguchi experimental design is employed to conduct the CFD simulation, and the grey analysis and variance analysis are used to investigate the influence rank and contribution of impact factors (branching levels, fractal number, heat flux, and flow rate) on the performance parameters (maximum temperature, pressure drop and comprehensive performance). It is found that the heat flux exhibits the highest contributions of 74.75% and 79.26% on the performance value of maximum temperature and comprehensive performance, respectively. For the pressure drop, the fractal number show the highest contribution of 67.99%. This work provides a novel method and guidance for the design and analysis of heat sinks.

ACS Style

Ziqiang He; Yunfei Yan; Ting Zhao; Li Zhang; Zhien Zhang. Multi-objective optimization and multi-factors analysis of the thermal/hydraulic performance of the bionic Y-shaped fractal heat sink. Applied Thermal Engineering 2021, 195, 117157 .

AMA Style

Ziqiang He, Yunfei Yan, Ting Zhao, Li Zhang, Zhien Zhang. Multi-objective optimization and multi-factors analysis of the thermal/hydraulic performance of the bionic Y-shaped fractal heat sink. Applied Thermal Engineering. 2021; 195 ():117157.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Ting Zhao; Li Zhang; Zhien Zhang. 2021. "Multi-objective optimization and multi-factors analysis of the thermal/hydraulic performance of the bionic Y-shaped fractal heat sink." Applied Thermal Engineering 195, no. : 117157.

Journal article
Published: 26 May 2021 in International Journal of Hydrogen Energy
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Micro-scale combustion is facing the problems of ignition difficulty, combustion instability, and low combustion efficiency. Therefore, it is necessary to improve the combustion characteristics in micro-combustor to expand the application range of micro-combustor. Focusing on the problem of the weak preheating effect of the micro cavity-combustor, the guide vanes are constructed to enhance the combustion near the cavity, and further combine with the bluff body to enhance combustion. The combustion characteristics of three types of cavity combustors with guide vanes (CCGV), bluff body (CCBB), bluff body, and guide vanes (CCGB) respectively are compared and analyzed under different inlet velocities (8–32 m/s), equivalence ratios (0.6–1.4), and wall materials (quartz glass, steel, and SiC). Results show that the guide vanes can greatly improve the combustion intensity near the cavity and improve the combustion stability of the cavity combustor. The combustion efficiency of CCGV and CCGB are increased by 43.04% and 85.96% respectively than CCBB when the inlet velocity is 32 m/s. The reaction heat of CCGV is 244.5 W when inlet velocity is 32 m/s, which is 0.55 times and 1.57 times that of CCGV and CCBB, respectively. The temperature uniformity and mean temperature of the outer wall of CCGV and CCGB both are better than that of CCGB. The combustion efficiency of CCGB is the highest among three combustors under the same equivalence ratio, especially when the equivalence ratio is less than 1. The reaction intensity in the cavity of the CCGV and CCGB with steel wall material is highest than that of the combustor with the other two wall materials. Wall materials with high thermal conductivity have a better preheating effect. Compared with quartz as the wall material, the mean temperature of the external wall of CCGV and CCGB using steel and silicon carbide as the wall material both increase by more than 130 K, and the wall heat loss both increase by more than 50%.

ACS Style

Wei Gao; Yunfei Yan; Lujing Huang; Kaiming Shen; Ziqiang He; Bo Gao. Numerical comparison of premixed H2/air combustion characteristic of three types of micro cavity-combustors with guide vanes, bluff body, guide vanes and bluff body respectively. International Journal of Hydrogen Energy 2021, 46, 24382 -24394.

AMA Style

Wei Gao, Yunfei Yan, Lujing Huang, Kaiming Shen, Ziqiang He, Bo Gao. Numerical comparison of premixed H2/air combustion characteristic of three types of micro cavity-combustors with guide vanes, bluff body, guide vanes and bluff body respectively. International Journal of Hydrogen Energy. 2021; 46 (47):24382-24394.

Chicago/Turabian Style

Wei Gao; Yunfei Yan; Lujing Huang; Kaiming Shen; Ziqiang He; Bo Gao. 2021. "Numerical comparison of premixed H2/air combustion characteristic of three types of micro cavity-combustors with guide vanes, bluff body, guide vanes and bluff body respectively." International Journal of Hydrogen Energy 46, no. 47: 24382-24394.

Journal article
Published: 04 May 2021 in International Journal of Hydrogen Energy
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The energy output and energy conversion efficiency of MTPV system are relatively low due to the energy loss. In order to improve the energy output of micro-thermophotovoltaic (MTPV) system, the internal straight and spiral fins are introduced into the micro combustor. The impact of hydrogen mass flow rate, equivalence ratio, and materials on the thermal performance are investigated. The increase of hydrogen mass flow rate brings higher average outer wall temperature, but the temperature difference also increases and the temperature uniformity becomes worse. The equivalence ratio of 1 is suggested to obtain higher average outer wall temperature and better temperature uniformity. The materials with higher thermal conductivity can obtain better thermal performance. Meanwhile, the higher thermal conductivity can also reduce the impact of introduction of internal fins.

ACS Style

Ziqiang He; Yunfei Yan; Xiuquan Li; Kaiming Shen; Junnan Li; Zhien Zhang. Comparative investigation of combustion and thermal characteristics of a conventional micro combustor and micro combustor with internal straight/spiral fins for thermophotovoltaic system. International Journal of Hydrogen Energy 2021, 46, 22165 -22179.

AMA Style

Ziqiang He, Yunfei Yan, Xiuquan Li, Kaiming Shen, Junnan Li, Zhien Zhang. Comparative investigation of combustion and thermal characteristics of a conventional micro combustor and micro combustor with internal straight/spiral fins for thermophotovoltaic system. International Journal of Hydrogen Energy. 2021; 46 (42):22165-22179.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Xiuquan Li; Kaiming Shen; Junnan Li; Zhien Zhang. 2021. "Comparative investigation of combustion and thermal characteristics of a conventional micro combustor and micro combustor with internal straight/spiral fins for thermophotovoltaic system." International Journal of Hydrogen Energy 46, no. 42: 22165-22179.

Journal article
Published: 01 April 2021 in International Communications in Heat and Mass Transfer
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With the high energy output of electronic devices, effective heat dissipation with low energy consumption has drawn great attention. Based on the construction theory, the flow resistance of the generalized bionic Y-shaped fractal networks is theoretically analyzed. It is found that the symmetrical width has a positive effect on reducing the hydraulic resistance, while the symmetrical length plays a negative influence. Then, the optimal designs of symmetrical and asymmetrical bionic Y-shaped fractal heat sinks are obtained by multi-objective optimization with genetic algorithm (GA). The pressure loss in the asymmetrical bionic Y-shaped fractal heat sink is always lower than that of the symmetrical bionic Y-shaped fractal heat sink at the same fractal number. As the constraint of thermal resistance reduces from 0.045 K/W to 0.042 K/W, the pumping power difference between symmetrical and asymmetrical bionic Y-shaped fractal heat sinks increases from 70.1 mW to 99.1 mW. Furthermore, according to the CFD investigation, it is noted that the symmetrical heat sink exhibits a lower temperature difference and more uniform temperature distribution.

ACS Style

Ziqiang He; Yunfei Yan; Shuai Feng; Zhongqing Yang; Li Zhang; Zhien Zhang. Multi-objective optimizations on thermal and hydraulic performance of symmetric and asymmetric bionic Y-shaped fractal networks by genetic algorithm coupled with CFD simulation. International Communications in Heat and Mass Transfer 2021, 124, 105261 .

AMA Style

Ziqiang He, Yunfei Yan, Shuai Feng, Zhongqing Yang, Li Zhang, Zhien Zhang. Multi-objective optimizations on thermal and hydraulic performance of symmetric and asymmetric bionic Y-shaped fractal networks by genetic algorithm coupled with CFD simulation. International Communications in Heat and Mass Transfer. 2021; 124 ():105261.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Shuai Feng; Zhongqing Yang; Li Zhang; Zhien Zhang. 2021. "Multi-objective optimizations on thermal and hydraulic performance of symmetric and asymmetric bionic Y-shaped fractal networks by genetic algorithm coupled with CFD simulation." International Communications in Heat and Mass Transfer 124, no. : 105261.

Journal article
Published: 16 February 2021 in Applied Thermal Engineering
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Targeting at addressing the low exergy efficiency of micro thermophotovoltaic (MTPV) system, a novel micro combustor with internal spiral fins is proposed. The geometrical parameters, including internal spiral fin number, length and pitch distance, on the thermal performance and exergy efficiency are numerically investigated. The introduction of internal spiral fins can effectively improve the exergy efficiency and energy output of MTPV system, but with higher pressure loss. The results show that the micro combustor with 8 spiral fins exhibits the highest exergy efficiency of 66.9%, which is 6.9% higher than that of the conventional one at the inlet velocity of 5 m/s. Moreover, the micro combustor with 8 spiral fins obtains the highest energy output is 5.01 W at inlet velocity of 8 m/s. Taking the pressure loss into consideration, the optimal internal spiral fins length of 10 mm is suggested.

ACS Style

Ziqiang He; Yunfei Yan; Ting Zhao; Shuai Feng; Xiuquan Li; Li Zhang; Zhien Zhang. Heat transfer enhancement and exergy efficiency improvement of a micro combustor with internal spiral fins for thermophotovoltaic systems. Applied Thermal Engineering 2021, 189, 116723 .

AMA Style

Ziqiang He, Yunfei Yan, Ting Zhao, Shuai Feng, Xiuquan Li, Li Zhang, Zhien Zhang. Heat transfer enhancement and exergy efficiency improvement of a micro combustor with internal spiral fins for thermophotovoltaic systems. Applied Thermal Engineering. 2021; 189 ():116723.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Ting Zhao; Shuai Feng; Xiuquan Li; Li Zhang; Zhien Zhang. 2021. "Heat transfer enhancement and exergy efficiency improvement of a micro combustor with internal spiral fins for thermophotovoltaic systems." Applied Thermal Engineering 189, no. : 116723.

Review articles
Published: 12 February 2021 in Journal of Energy Resources Technology
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Ammonia borane (AB) is deemed to be the most promising energy storage material with varieties of exceptional properties, most reports mainly discuss its application in hydrogen storage and release as the hydrogen storage materials, which intends to address the hydrogen storage issues of on-board hydrogen fuel cell. However, some other promising applications of AB have also been confirmed by researchers, although these applications have not been intensively studied like its application of hydrogen storage materials. The article mainly introduce the synthesis, dehydrogenation (themolysis, hydrolysis, and methanolysis), and regeneration of AB and highlight the applications in green propulsion system of rocket, portable hydrogen source for on-board fuel cell, chemical catalysis, and electrochemical energy systems. In the meantime, the main achievements, current developments, limitations, and challenges in AB for advanced energy technology applications are briefly discussed. This article will provide inspiration for expanding the application of AB in the future.

ACS Style

Haojie Li; Yunfei Yan; Shuai Feng; Yanrong Chen; Hu Fan. Ammonia Borane and Its Applications in the Advanced Energy Technology. Journal of Energy Resources Technology 2021, 143, 1 .

AMA Style

Haojie Li, Yunfei Yan, Shuai Feng, Yanrong Chen, Hu Fan. Ammonia Borane and Its Applications in the Advanced Energy Technology. Journal of Energy Resources Technology. 2021; 143 (11):1.

Chicago/Turabian Style

Haojie Li; Yunfei Yan; Shuai Feng; Yanrong Chen; Hu Fan. 2021. "Ammonia Borane and Its Applications in the Advanced Energy Technology." Journal of Energy Resources Technology 143, no. 11: 1.

Journal article
Published: 30 January 2021 in International Journal of Hydrogen Energy
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To improve the combustion stability at micro scale, the micro combustor with a central and bilateral slotted blunt body (MCSB) exhibiting significant combustion performance improvement is designed. The new one can not only effectively prevent the flame tip opening, but also exhibit higher combustion efficiency and blown-off limit. Its blown-off limit can reach 756 cm3/s at the flow rate ratio of 0.2 and the bluff body angle of 90°, which is 61.5% higher than that of the conventional one with the blown-off limit of 468 cm3/s. The combustion efficiency improves with the growth of the flow rate ratio, while the blown-off limit of MCSB increases first and then decreases. The blown-off limit of MCSB with the bluff body angle of 90° reaches to the peak value of 792 cm3/s at the flow rate ratio of 0.15. Moreover, the increase of the bluff body angle provides better combustion efficiency and stability.

ACS Style

Ziqiang He; Yunfei Yan; Ruiming Fang; Zhiliang Ou; Zhonghui Zhang; Zhongqing Yang; Zhien Zhang. Numerical investigation of a novel micro combustor with a central and bilateral slotted blunt body. International Journal of Hydrogen Energy 2021, 46, 23564 -23579.

AMA Style

Ziqiang He, Yunfei Yan, Ruiming Fang, Zhiliang Ou, Zhonghui Zhang, Zhongqing Yang, Zhien Zhang. Numerical investigation of a novel micro combustor with a central and bilateral slotted blunt body. International Journal of Hydrogen Energy. 2021; 46 (45):23564-23579.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Ruiming Fang; Zhiliang Ou; Zhonghui Zhang; Zhongqing Yang; Zhien Zhang. 2021. "Numerical investigation of a novel micro combustor with a central and bilateral slotted blunt body." International Journal of Hydrogen Energy 46, no. 45: 23564-23579.

Research article
Published: 11 January 2021 in International Journal of Energy Research
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Aiming at improving the energy output and energy conversion efficiency of thermophotovoltaic systems, a micro‐combustor with high and uniform outer wall temperature is desirable. Therefore, the micro‐cylindrical combustor with a novel micro‐spiral fin is proposed to improve the thermal performance. The effect of inlet velocities of premixed hydrogen/air, the critical design parameters of the spiral fin length (L) and the spiral fin pitch (W) on the thermal performance of the micro‐cylindrical combustor are numerically investigated. Results show that micro‐spiral fin is beneficial to improve the outer wall temperature value and uniformity, which can significantly increase the emitter power and energy conversion efficiency of micro‐cylindrical combustor. However, the improvement of thermal performance is at the cost of higher pressure loss. Furthermore, compared with all the investigated geometrical models, the micro‐cylindrical combustor with spiral fin length at the size of 14 mm and spiral fin pitch at the size of 2.355 mm obtains the best comprehensive heat transfer performance.

ACS Style

Ting Zhao; Yunfei Yan; Ziqiang He; Zhongqing Yang; Li Zhang. Numerical investigations on the emitter power and energy conversion efficiency improvement of micro‐cylindrical combustor by an internal spiral fin for micro‐thermophotovoltaic systems. International Journal of Energy Research 2021, 45, 8684 -8698.

AMA Style

Ting Zhao, Yunfei Yan, Ziqiang He, Zhongqing Yang, Li Zhang. Numerical investigations on the emitter power and energy conversion efficiency improvement of micro‐cylindrical combustor by an internal spiral fin for micro‐thermophotovoltaic systems. International Journal of Energy Research. 2021; 45 (6):8684-8698.

Chicago/Turabian Style

Ting Zhao; Yunfei Yan; Ziqiang He; Zhongqing Yang; Li Zhang. 2021. "Numerical investigations on the emitter power and energy conversion efficiency improvement of micro‐cylindrical combustor by an internal spiral fin for micro‐thermophotovoltaic systems." International Journal of Energy Research 45, no. 6: 8684-8698.

Journal article
Published: 02 January 2021 in Chemical Engineering and Processing - Process Intensification
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Targeted at improving microfluidic cooling for the use of micro heat sink in electronic chips, a novel fin-shaped pin-fin array heat sink is proposed. In this study, the mechanism of flow and heat transfer, the arrangements of pin-fin layout, the characteristics of single-phase flow and heat transfer among the micro cylinder pin-fin heat sink, micro fin-shaped pin-fin heat sink of A、B、C types are investigated. It’s showed that stagger micro fin-shaped A pin-fin (SMFAP) exhibits the best hydro-thermal performance. At high Reynolds number, the average Nusselt number of SMFAP reaches up to two times of the in-line micro cylinder pin-fin (IMCP). Moreover, the structure of fin-shaped pin-fin can enhance heat transfer by increasing Nu, while weaken heat transfer by large pressure drop. Therefore, the non-dimensional parameter PEC is adopted to evaluate the heat transfer performance of heat sink. When Re is 800, the PEC of SMFAP reaches to its maximum value of 1.4. SMFAP can effectively enhance heat transfer, while stagger micro fin-shaped B pin-fin(SMFBP) and stagger micro fin-shaped C pin-fin (SMFCP) are not obviously. It’s concluded that different structures of fin-shaped pin-fin will affect the separation point of flow, thus affecting the size of vortex behind the cylinder.

ACS Style

Yunfei Yan; Ting Zhao; Ziqiang He; Zhongqing Yang; Li Zhang. Numerical investigation on the characteristics of flow and heat transfer enhancement by micro pin-fin array heat sink with fin-shaped strips. Chemical Engineering and Processing - Process Intensification 2021, 160, 108273 .

AMA Style

Yunfei Yan, Ting Zhao, Ziqiang He, Zhongqing Yang, Li Zhang. Numerical investigation on the characteristics of flow and heat transfer enhancement by micro pin-fin array heat sink with fin-shaped strips. Chemical Engineering and Processing - Process Intensification. 2021; 160 ():108273.

Chicago/Turabian Style

Yunfei Yan; Ting Zhao; Ziqiang He; Zhongqing Yang; Li Zhang. 2021. "Numerical investigation on the characteristics of flow and heat transfer enhancement by micro pin-fin array heat sink with fin-shaped strips." Chemical Engineering and Processing - Process Intensification 160, no. : 108273.

Journal article
Published: 01 January 2021 in International Journal of Hydrogen Energy
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ACS Style

Ziqiang He; Yunfei Yan; Shuai Feng; Xiuquan Li; Ruiming Fang; Zhiliang Ou; Zhongqing Yang. Numerical investigation on a multi-channel micro combustor fueled with hydrogen for a micro-thermophotovoltaic system. International Journal of Hydrogen Energy 2021, 46, 4460 -4471.

AMA Style

Ziqiang He, Yunfei Yan, Shuai Feng, Xiuquan Li, Ruiming Fang, Zhiliang Ou, Zhongqing Yang. Numerical investigation on a multi-channel micro combustor fueled with hydrogen for a micro-thermophotovoltaic system. International Journal of Hydrogen Energy. 2021; 46 (5):4460-4471.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Shuai Feng; Xiuquan Li; Ruiming Fang; Zhiliang Ou; Zhongqing Yang. 2021. "Numerical investigation on a multi-channel micro combustor fueled with hydrogen for a micro-thermophotovoltaic system." International Journal of Hydrogen Energy 46, no. 5: 4460-4471.

Research article
Published: 07 December 2020 in International Journal of Energy Research
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There are combustion difficulties and combustion instability problems in micro‐scale combustion due to the size effects. Focusing on the problem of combustion instability in micro‐scale, on the basis of catalytic combustion, the recirculation zone (RZ) is constructed by cavity and the effect of RZ is enhanced by gas inlet at cavity wall to keep the stability of combustion. The total conversion of CH4 in multi‐inlets channel with cavity was higher compared with single inlet channel and single inlet channel with cavity. Numerical analysis was carried out to study the effects of total gas intake quantity (TGIQ), the excess air coefficient (EAC) and the air distribution mode, respectively. With the increase of TGIQ, the area of RZ increased gradually and a third RZ was gradually formed in the cavity. When the TGIQ gradually increased to 0.1828 mg/s, the combustor temperature increased significantly and as it continued to increase, the combustor temperature had little change. The highest temperature in combustor decreased gradually and the severe reaction zone moved from the back section of the combustor to the front with the increase of EAC. Moreover, the concentration of OH in cavity increased gradually and the mass flow rate of CH4 in cavity decreased gradually. Increasing the air volume on the back cavity wall, the high‐temperature zones and concentration of OH in cavity continuously improved when the TGIQ was same. The combustion process was enhanced and the catalytic reaction was stabled. The temperature of main channel first increased and then decreased.

ACS Style

Yunfei Yan; Wei Gao; Hongyan Guo; Hongyu Yan; Kaiming Shen; Li Zhang; Zhongqing Yang. Catalytic combustion characteristics of CH 4 in the micro cavity‐combustor under different types of air inlet distribution. International Journal of Energy Research 2020, 45, 3870 -3882.

AMA Style

Yunfei Yan, Wei Gao, Hongyan Guo, Hongyu Yan, Kaiming Shen, Li Zhang, Zhongqing Yang. Catalytic combustion characteristics of CH 4 in the micro cavity‐combustor under different types of air inlet distribution. International Journal of Energy Research. 2020; 45 (3):3870-3882.

Chicago/Turabian Style

Yunfei Yan; Wei Gao; Hongyan Guo; Hongyu Yan; Kaiming Shen; Li Zhang; Zhongqing Yang. 2020. "Catalytic combustion characteristics of CH 4 in the micro cavity‐combustor under different types of air inlet distribution." International Journal of Energy Research 45, no. 3: 3870-3882.

Journal article
Published: 03 December 2020 in International Journal of Hydrogen Energy
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Hydrogen fuel has great application prospect in micro combustion power systems because of its great advantages. The combustion characteristics of bluff body and cavity combined (BC) micro combustor, slotted bluff body and cavity combined (SC) micro combustor and controllable central slotted bluff body and cavity combined (CC) micro combustor with premixed H2/air at different inlet volume flow rates and different controllable flow ratios (λ) were numerically investigated. CC micro combustor exhibits the highest combustion efficiency at the same volume flow rate. At high inlet volume flow rates, CC micro combustor can better extend the fuel residence time and maintain the combustion stability. When the λ of CC micro combustor is 0.1–0.4, the combustion efficiency can be improved by increasing the λ. However, the combustion becomes unstable gradually and the combustion efficiency drops sharply when the λ increases to 0.5 or above. To sum up, when λ is 0.4, CC combustor has the highest combustion efficiency. Therefore, the CC micro combustor with a controllable flow rate of 0.4 has the advantages of higher combustion efficiency and wider application range of inlet flow rate when hydrogen/air premixed combustion.

ACS Style

Fulei Xu; Yunfei Yan; Ziqiang He; Zhongqing Yang; Li Zhang. Numerical study on the influence of controllable flow ratio on combustion characteristics of a controllable central slotted bluff body and cavity combined micro combustor. International Journal of Hydrogen Energy 2020, 46, 6901 -6914.

AMA Style

Fulei Xu, Yunfei Yan, Ziqiang He, Zhongqing Yang, Li Zhang. Numerical study on the influence of controllable flow ratio on combustion characteristics of a controllable central slotted bluff body and cavity combined micro combustor. International Journal of Hydrogen Energy. 2020; 46 (9):6901-6914.

Chicago/Turabian Style

Fulei Xu; Yunfei Yan; Ziqiang He; Zhongqing Yang; Li Zhang. 2020. "Numerical study on the influence of controllable flow ratio on combustion characteristics of a controllable central slotted bluff body and cavity combined micro combustor." International Journal of Hydrogen Energy 46, no. 9: 6901-6914.

Research article
Published: 24 November 2020 in Energy & Fuels
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In this study, β-SiC NWs, Ru/β-SiC NWs, Cu/β-SiC NWs, and RuCu/β-SiC NWs were prepared to investigate photothermal synergistic catalytic AB hydrolysis to produce hydrogen. The experimental and theoretical calculation results show the band gap values of prepared β-SiC NWs, Cu/β-SiC NWs, Ru/β-SiC NWs, and RuCu/β-SiC NWs are 2.36, 1.95, 1.71, and 1.49 eV, respectively. The Ru, Cu nanocluster deposited on β-SiC NWs is conducive to promote the separation and transport of photoinduced electron and hole pairs and increase the transition probability of photoinduced electrons. The transition metal catalyst Cu/β-SiC NWs modified with Ru dopant is beneficial to improve its catalytic activity; with the increase of blending ratio Ru/Cu, the catalytic activity increases gradually; when the mass ratio of Cu:Ru is 2:3, the catalyst Cu0.4Ru0.6/β-SiC NWs have the highest catalytic performance and fairly good reusability in catalyzing AB hydrolysis, which is much better than the catalytic performance of catalyst Cu/β-SiC NWs and comparable to Ru/β-SiC NWs. In the RuCu alloy nanoclusters of RuCu/β-SiC NWs, the electron conveyed from the Cu atom to the Ru atom and forms the of heterojunction Ru––Cu+ species, which further enhance the photothermal synergic catalytic performance of AB hydrolysis catalyzed by the RuCu/β-SiC NWs. The property of bimetallic synergy is of great significance in improving catalyst activity and reducing catalyst cost.

ACS Style

Haojie Li; Yunfei Yan; Shuai Feng; Yanrong Chen; Yilin Zhu. Highly Efficient Photothermal Difunctional Catalysts To Enhance Ammonia Borane Hydrolysis for Hydrogen Evolution. Energy & Fuels 2020, 34, 16948 -16955.

AMA Style

Haojie Li, Yunfei Yan, Shuai Feng, Yanrong Chen, Yilin Zhu. Highly Efficient Photothermal Difunctional Catalysts To Enhance Ammonia Borane Hydrolysis for Hydrogen Evolution. Energy & Fuels. 2020; 34 (12):16948-16955.

Chicago/Turabian Style

Haojie Li; Yunfei Yan; Shuai Feng; Yanrong Chen; Yilin Zhu. 2020. "Highly Efficient Photothermal Difunctional Catalysts To Enhance Ammonia Borane Hydrolysis for Hydrogen Evolution." Energy & Fuels 34, no. 12: 16948-16955.

Review
Published: 07 November 2020 in Energy
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The electronic equipment developing towards miniaturization and high integration is facing the danger of high heat flux and non-uniform temperature distribution which leads to the reduction of life and reliability of electronic devices. The micro heat sinks have gained significant attention in heat dissipation of electronic devices with high heat flux due to its large heat transfer surface to volume ratio, compact structure and outstanding thermal performance. In this review, we present the advantages and shortcomings of thermal enhancement technologies in different structural micro heat sinks. Moreover, the non-uniform temperature distribution which includes the temperature rising along the flow direction and hotspots, especially, the random hotspot with high heat flux, has been the serious issues in the thermal management of electronic devices. They are the main challenges for the efficient operation and service life of electronic components. Thus, it is urgent to develop an effective and economic process in automatic adaptive cooling of random hotspots. The purpose of this article is to introduce the existing thermal enhancement technologies in micro heat sinks and the reduction of non-uniform temperature distribution. Finally, the barriers and challenges for the developments of thermal management of electronic devices by micro heat sinks are discussed, and the further directions of the research topic are provided.

ACS Style

Ziqiang He; Yunfei Yan; Zhien Zhang. Thermal management and temperature uniformity enhancement of electronic devices by micro heat sinks: A review. Energy 2020, 216, 119223 .

AMA Style

Ziqiang He, Yunfei Yan, Zhien Zhang. Thermal management and temperature uniformity enhancement of electronic devices by micro heat sinks: A review. Energy. 2020; 216 ():119223.

Chicago/Turabian Style

Ziqiang He; Yunfei Yan; Zhien Zhang. 2020. "Thermal management and temperature uniformity enhancement of electronic devices by micro heat sinks: A review." Energy 216, no. : 119223.

Journal article
Published: 02 October 2020 in Applied Thermal Engineering
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Targeted at addressing practical thermal issues of 3D-IC chip, heat transfer characteristics and temperature uniformity of gradient distribution solid and annular-cavity micro-pin fins are experimentally and numerically investigated. At double side non-uniform heat flux condition (qb/qhs of 40/300 W/cm2), a significant deterioration of heat transfer is found with maximum temperature gradient of 44.6 K. With respect to uniform design, gradient distribution solid pin-fin chip provides considerable potentials to address a large hotspot heat flux (700 W/cm2) and improve temperature uniformity with a relatively small hotspot size (<200*200 um). Further thermal-path analysis reveals that pin-fin surfaces act as a key role to transfer and redistribute the heat with transferring more than 64% of heat into the fluid. To address critical multiple heat flux condition, novel gradient distribution annular-cavity pin fins are designed to increase heat transfer area and eliminate flow dead zones. Applying two-side symmetrical inlet cavity, the coolant from micro-channel like rushes into the center cavity and forms local acceleration to impinge the next pin-fins. The combined effect of increasing heat transfer area and forming acceleration zones leads to a maximum reduction of the local hotspot temperature and total thermal resistance by 9 K and 34.5%, respectively.

ACS Style

Shuai Feng; Yunfei Yan; Haojie Li; Li Zhang; Shilin Yang. Thermal management of 3D chip with non-uniform hotspots by integrated gradient distribution annular-cavity micro-pin fins. Applied Thermal Engineering 2020, 182, 116132 .

AMA Style

Shuai Feng, Yunfei Yan, Haojie Li, Li Zhang, Shilin Yang. Thermal management of 3D chip with non-uniform hotspots by integrated gradient distribution annular-cavity micro-pin fins. Applied Thermal Engineering. 2020; 182 ():116132.

Chicago/Turabian Style

Shuai Feng; Yunfei Yan; Haojie Li; Li Zhang; Shilin Yang. 2020. "Thermal management of 3D chip with non-uniform hotspots by integrated gradient distribution annular-cavity micro-pin fins." Applied Thermal Engineering 182, no. : 116132.

Journal article
Published: 03 August 2020 in Journal of Energy Resources Technology
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In view of high-energy consumption, high baking cost, and serious pollution emission during the baking process of tobacco leaves, thermogravimetric analysis is employed to investigate the combustion characteristics of coal, tobacco straw, and cinder. Analyzing thermogravimetric-derivative of thermogravimetric (TG-DTG) characteristics of samples with different blending ratios and based on the ignition temperature and burnout temperature, the combustion characteristics of the samples are obtained. Compared with the individual combustion of coal, the blending ratio of the optimal positive effect is obtained. It is illustrated that different blending ratios of coal, tobacco straw, and cinder result in different effects between promotion and inhibition. Tobacco straw is beneficial to burn on fire but adverse to keep combustion of fixed carbon. Compared with the TG and DTG characteristics in different blending ratios of coal, tobacco straw, and corresponding combustion characteristic parameter, it is illustrated that the best blending ratio of tobacco straw is 40%. According to the TG and DTG characteristics of different blending ratios of coal, cinder, and corresponding combustion characteristic parameter, it is shown that the more blending ratio of cinder, the more adverse effect to fixed carbon burning. The composite fuels with 40% tobacco straw, 10% coal cinder, and 50% coal have two obvious advantages. On the one hand, it can maintain quick burning and the volatile combustion of the tobacco straw at low-temperature stage. On the other hand, it can keep continuous combustion of the fixed carbon in coal at high-temperature stage.

ACS Style

Yunfei Yan; Ting Zhao; Hongliang Guo; Fulei Xu; Li Zhang; Zhongqing Yang; Jingyu Ran. Experimental Investigation on Mixed Combustion Characteristics of Coal, Tobacco Straw, and Cinder in an Energy-Saving Bake Process. Journal of Energy Resources Technology 2020, 143, 1 -30.

AMA Style

Yunfei Yan, Ting Zhao, Hongliang Guo, Fulei Xu, Li Zhang, Zhongqing Yang, Jingyu Ran. Experimental Investigation on Mixed Combustion Characteristics of Coal, Tobacco Straw, and Cinder in an Energy-Saving Bake Process. Journal of Energy Resources Technology. 2020; 143 (2):1-30.

Chicago/Turabian Style

Yunfei Yan; Ting Zhao; Hongliang Guo; Fulei Xu; Li Zhang; Zhongqing Yang; Jingyu Ran. 2020. "Experimental Investigation on Mixed Combustion Characteristics of Coal, Tobacco Straw, and Cinder in an Energy-Saving Bake Process." Journal of Energy Resources Technology 143, no. 2: 1-30.