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  • Zhang, Di  (11)
  • 1
    Online Resource
    Online Resource
    Numerical Investigation of Non-Newtonian Flow and Heat Transfer Characteristics in Rectangular Tubes with Protrusions
    Hindawi Limited ; 2015
    In:  Mathematical Problems in Engineering Vol. 2015 ( 2015), p. 1-11
    Details
    In: Mathematical Problems in Engineering, Hindawi Limited, Vol. 2015 ( 2015), p. 1-11
    Abstract: Flow characteristics and heat transfer performances in rectangular tubes with protrusions are numerically investigated in this paper. The thermal heat transfer enhancement of composite structures and flow resistance reduction of non-Newtonian fluid are taken advantage of to obtain a better thermal performance. Protrusion channels coupled with different CMC concentration solutions are studied, and the results are compared with that of smooth channels with water flow. The comprehensive influence of turbulence effects, structural effects, and secondary flow effects on the CMC’s flow in protrusion tubes is extensively investigated. The results indicate that the variation of flow resistance parameters of shear-thinning power-law fluid often shows a nonmonotonic trend, which is different from that of water. It can be concluded that protrusion structure can effectively enhance the heat transfer of CMC solution with low pressure penalty in specific cases. Moreover, for a specific protrusion structure and a fixed flow velocity, there exists an optimal solution concentration showing the best thermal performance.
    Type of Medium: Online Resource
    ISSN: 1024-123X , 1563-5147
    URL: Article
    DOI: 10.1155/2015/121048
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2015
    detail.hit.zdb_id: 2014442-8
    SSG: 11
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  • 2
    Online Resource
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    Heat Transfer Enhancement in Gas Turbine U-shaped Channel with Rib Tabulators Under Rotational Effect
    Elsevier BV ; 2014
    In:  Energy Procedia Vol. 61 ( 2014), p. 2501-2504
    Details
    In: Energy Procedia, Elsevier BV, Vol. 61 ( 2014), p. 2501-2504
    Type of Medium: Online Resource
    ISSN: 1876-6102
    URL: Article
    DOI: 10.1016/j.egypro.2014.12.032
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 2490671-2
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  • 3
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    Numerical Study on Flow and Heat Transfer Performance of Rectangular Heat Sink with Compound Heat Transfer Enhancement Structures
    SAGE Publications ; 2014
    In:  Advances in Mechanical Engineering Vol. 6 ( 2014-01-01), p. 457650-
    Details
    In: Advances in Mechanical Engineering, SAGE Publications, Vol. 6 ( 2014-01-01), p. 457650-
    Abstract: Modern gas turbine blade is operating at high temperature which requires abundant cooling. Considering both heat transfer rate and pumping power for internal passages, developing efficient cooling passages is of great importance. Ribbed channel has been proved as effective heat transfer enhancement technology for considerable heat transfer characteristics; however, the pressure loss is impressive. Dimple and protrusion are frequently considered as new heat transfer augmentation tools for their low friction loss in recent years. Numerical simulations are adopted to investigate the thermal performance of rectangular channel with compound heat transfer enhancement structures with ribs, dimples, and protrusions. Among all configurations, the nondimensional dimple/protrusion depths are 0.2. The results present the flow structures of all channel configurations. The Nu/Nu 0 distributions of channel section are discussed for each case. The pressure penalty f/ f 0 and the thermal performance TP are also considered as important parameters for heat transfer enhancement. It can be concluded that the optimal structure of the compound heat transfer enhancement structure is rib + protrusion ( D = 6 mm) + dimple ( D = 15 mm).
    Type of Medium: Online Resource
    ISSN: 1687-8140 , 1687-8140
    URL: Article
    DOI: 10.1155/2014/457650
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2014
    detail.hit.zdb_id: 2501620-9
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  • 4
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    Numerical Calculations on Flow and Heat Transfer in Smooth and Ribbed Two-Pass Square Channels under Rotational Effects
    Hindawi Limited ; 2014
    In:  Mathematical Problems in Engineering Vol. 2014 ( 2014), p. 1-7
    Details
    In: Mathematical Problems in Engineering, Hindawi Limited, Vol. 2014 ( 2014), p. 1-7
    Abstract: U-shaped channel, which is also called two-pass channel, commonly exists in gas turbine internal coolant passages. Ribbed walls are frequently adopted in internal passage to enhance the heat transfer. Considering the rotational condition of gas turbine blade on operation, the effect of rotation is also investigated for the coolant channel which is close to real operation condition. Thus, the objective of this study is to discuss the effect of rotation on fluid flow and heat transfer performance of U-shaped channel with ribbed walls under high rotational numbers. Investigated Reynolds number is Re = 12500 and the rotation numbers are Ro b = 0.4 and 0.6. In the results, the spatially heat transfer coefficient distributions are exhibited to discuss the effect of rotation and roughened walls. It is found that ribbed walls enhance the heat transfer rate significantly. Under the rotational condition, the Nu in the first pass with outward flow is increased while that in the second pass is decreased. Finally, average Nu ratio, friction ratio, and thermal performance are all presented to discuss the thermal characteristics.
    Type of Medium: Online Resource
    ISSN: 1024-123X , 1563-5147
    URL: Article
    DOI: 10.1155/2014/981376
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2014
    detail.hit.zdb_id: 2014442-8
    SSG: 11
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  • 5
    Online Resource
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    Effect of bleed hole on flow and heat transfer performance of U-shaped channel with dimple structure
    Elsevier BV ; 2013
    In:  International Journal of Heat and Mass Transfer Vol. 66 ( 2013-11), p. 10-22
    Details
    In: International Journal of Heat and Mass Transfer, Elsevier BV, Vol. 66 ( 2013-11), p. 10-22
    Type of Medium: Online Resource
    ISSN: 0017-9310
    URL: Article
    DOI: 10.1016/j.ijheatmasstransfer.2013.07.008
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
    detail.hit.zdb_id: 240652-4
    detail.hit.zdb_id: 2012726-1
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  • 6
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    Online Resource
    Numerical predictions on fluid flow and heat transfer in U-shaped channel with the combination of ribs, dimples and protrusions under rotational effects
    Elsevier BV ; 2015
    In:  International Journal of Heat and Mass Transfer Vol. 80 ( 2015-01), p. 494-512
    Details
    In: International Journal of Heat and Mass Transfer, Elsevier BV, Vol. 80 ( 2015-01), p. 494-512
    Type of Medium: Online Resource
    ISSN: 0017-9310
    URL: Article
    DOI: 10.1016/j.ijheatmasstransfer.2014.09.057
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
    detail.hit.zdb_id: 240652-4
    detail.hit.zdb_id: 2012726-1
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  • 7
    Online Resource
    Online Resource
    Experimental and numerical study on heat transfer in trailing edge cooling passages with dimples/protrusions under the effect of side wall slot ejection
    Elsevier BV ; 2016
    In:  International Journal of Heat and Mass Transfer Vol. 92 ( 2016-01), p. 1218-1235
    Details
    In: International Journal of Heat and Mass Transfer, Elsevier BV, Vol. 92 ( 2016-01), p. 1218-1235
    Type of Medium: Online Resource
    ISSN: 0017-9310
    URL: Article
    DOI: 10.1016/j.ijheatmasstransfer.2015.09.042
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2016
    detail.hit.zdb_id: 240652-4
    detail.hit.zdb_id: 2012726-1
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  • 8
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    Numerical Analysis of Flow Structure and Heat Transfer Characteristics in Dimpled Channels With Secondary Protrusions
    ASME International ; 2016
    In:  Journal of Heat Transfer Vol. 138, No. 3 ( 2016-03-01)
    Details
    In: Journal of Heat Transfer, ASME International, Vol. 138, No. 3 ( 2016-03-01)
    Abstract: Dimple structure is an effective heat transfer augmentation approach on coolant channel due to its advantage on pressure penalty. The implication of secondary protrusion, which indicates protrusion with smaller dimension than dimple, will intensify the Nusselt number Nu inside dimple cavity without obvious extra pressure penalty. The objective of this study is to numerically analyze the combination effect of dimples and secondary protrusion. Different protrusion–dimple configurations including protrusion print-diameter Dp, protrusion–dimple gap P, and staggered angle α are investigated. From the results, it is concluded that the implication of secondary protrusion will considerably increase the heat transfer rates inside dimple cavity. Cases 4 and 6 possess the highest Nusselt number enhancement ratio Nu/Nu0 reaching up to 2.1–2.2. The additional pressure penalty brought by the protrusion is within 15% resulting in total friction ratio f/f0 among the range of 1.9–2.1. Dimpled channels with secondary protrusions possess higher thermal performance factor TP, defined as (Nu/Nu0)/(f/f0)1/3, among which cases 4 and 6 are the optimal structures. Besides this, the TP of protrusion–dimple channels are comparable to the other typical heat transfer devices, and higher TP can be speculated after a more optimal dimple shape or combination with ribs and fins.
    Type of Medium: Online Resource
    ISSN: 0022-1481 , 1528-8943
    URL: Article
    DOI: 10.1115/1.4031787
    Language: English
    Publisher: ASME International
    Publication Date: 2016
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  • 9
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    Thermal Performance of Miniscale Heat Sink With Jet Impingement and Dimple/Protrusion Structure
    ASME International ; 2017
    In:  Journal of Heat Transfer Vol. 139, No. 5 ( 2017-05-01)
    Details
    In: Journal of Heat Transfer, ASME International, Vol. 139, No. 5 ( 2017-05-01)
    Abstract: Cooling technique in a miniscale heat sink is essential with the development of high-power electronics, such as electronic chip. As heat transfer techniques, jet impingement cooling and convective cooling by roughened surface are commonly adopted. To obtain a good cooling efficiency, the cooling structure within the heat sink should be carefully designed. In the present study, the miniscale heat sink with a feature size of 1–100 mm is setup. Arrangement of the jet impingement and dimple/protrusion surface is designed as heat transfer augmentation approaches. The effect of dimple/protrusion configuration and depth to diameter ratio is discussed. From the result, the heat transfer coefficient h distribution of heat sink surface is demonstrated for each case. The pressure penalty due to the arrangement of roughened structure is evaluated. Also, thermal performance (TP) and performance evaluation plot are adopted as evaluations of cooling performance for each configuration. Comparing all the cases, optimal cooling structure considering the energy-saving performance is obtained for the miniscale heat sink. Referencing the statistics, a new insight has been provided for the design of cooling structure inside the miniscale heat sink.
    Type of Medium: Online Resource
    ISSN: 0022-1481 , 1528-8943
    URL: Article
    DOI: 10.1115/1.4036035
    Language: English
    Publisher: ASME International
    Publication Date: 2017
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  • 10
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    Thermal Performance of a Water-Cooled Microchannel Heat Sink With Grooves and Obstacles
    ASME International ; 2014
    In:  Journal of Electronic Packaging Vol. 136, No. 2 ( 2014-06-01)
    Details
    In: Journal of Electronic Packaging, ASME International, Vol. 136, No. 2 ( 2014-06-01)
    Abstract: With the rapid development of microelectromechanical systems (MEMS) in IT industry, the heat flux in microchannel has reached a high level which demands preferable cooling technology. Water cooling has become a favor cooling approach in electronic microdevices due to better thermal performance than air cooling method. In the present paper, thermal performance in microchannels with grooves and obstacles are investigated numerically. The height and width of the rectangular microchannel are 200 and 50 μm, respectively. As a simple modification of dimple/protrusion, the groove/obstacle diameter is 100 μm and the depth is 20 μm. Different arrangements of grooves and obstacles are considered on Reynolds range of 100–900. The numerical results show that groove/obstacle structure is effective for cooling enhancement in microchannel. Among the cases in this research, the normalized Nusselt number Nu/Nu0 is within the range of 1.446–26.19, while the pressure penalty f/f0 has a much larger range from 0.86 to 110.18 depending on specific orientation. Field synergy analysis and performance evaluation plot are adopted to discuss the mechanism of heat transfer enhancement and energy saving performance integrating the pumping performance. From the viewpoint of energy saving, groove on single surface (case 1) has the best performance. Furthermore, performances of grooved microchannels are compared with that of dimpled microchannels which were discussed in the author’s previous research. The results indicate grooved microchannels have larger range of both Nu/Nu0 and f/f0 and some grooved cases possess high TP than dimpled microchannels.
    Type of Medium: Online Resource
    ISSN: 1043-7398 , 1528-9044
    URL: Article
    DOI: 10.1115/1.4025757
    Language: English
    Publisher: ASME International
    Publication Date: 2014
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