Flow and Heat Transfer Characteristics in Latticework Cooling Channels With Dimple Vortex Generators

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Yu Rao ◽  
Shusheng Zang
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Numerical Study ◽  
Vortex Generators ◽  
Vortical Flow ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Cooling Channels ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

A comparative experimental and numerical study has been conducted on the flow and heat transfer characteristics in a latticework cooling channel with U-shaped subchannels combined with dimple vortex generators over the Reynolds number range of 7700–36,985. The average Nusselt number and friction factor of the latticework channel have been obtained. The comparisons between the experimental and numerical data have shown that the numerical computation model can reasonably well predict the heat transfer and pressure loss in the latticework cooling channels. Additional numerical computations were further performed to investigate the effects of subchannel configurations on the flow and heat transfer in the latticework channel, and three different subchannel configurations were studied, which are the dimpled U subchannel, U subchannel, and rectangular subchannel. The experimental data of the heat transfer and pressure loss of the latticework channel with dimpled U subchannels have also been compared with those of the ribbed channels and pin fin channel from the literature. The present study indicated that the superior heat transfer enhancement capability of the latticework cooling is mainly due to the remarkably increased heat transfer area, turning effects producing strong vortical flow in the subchannels, and the interactions between the flow in the crossing subchannels, as well as the interactions between the flow and the crossing ribs on the opposite side.

Numerical Investigation of Impingement Heat Transfer on Concave- and Convex-Dimpled Plate With Different Dimple Arrangements

2016 ◽  
Author(s):  
Feng Zhang ◽  
Xinjun Wang ◽  
Jun Li ◽  
Rui Tan ◽  
Dongliang Wei
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Pressure Loss ◽  
Heat Transfer Performance ◽  
Numerical Study ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Impingement Cooling ◽  
Transfer Characteristics

The present numerical study is conducted to investigate the flow and heat transfer characteristics for impingement cooling on concave or convex dimpled plate with four different dimple arrangements. The investigation of the impingement cooling on the flat plate is also conducted to serve as a contrast and these results are compared with experimental measurements to verify the computational method. Dimples studied here are placed, relative to impingement holes, in either spanwise shifted, in staggered, in in-line, or in streamwise shifted arrangements. The flow structure, pressure loss and heat transfer characteristics of the concave and convex dimpled plate of four different dimple arrangements have been obtained and compared with flat plate for the Reynolds number range of 15000 to 35000. The results show that compared with flat plate, the added concave or convex dimples only causes a negligible increase in the pressure loss, and the pressure loss is insensitive to concave or convex dimple arrangement patterns. In addition, compared with flat plate, both spanwise shifted and staggered concave dimple arrangements show better heat transfer performance, while in-line concave dimple arrangement show worse results. Besides that, the heat transfer performance for streamwise shifted concave dimple arrangement is the worst. Furthermore, compared with flat plate, all convex dimple arrangements studied here show better heat transfer performance.

Numerical Study on the Flow and Heat Transfer Characteristics in Rectangular Channels With Grooves and Different Protrusions

2017 ◽  
Author(s):  
Feng Zhang ◽  
Xinjun Wang ◽  
Jun Li ◽  
Daren Zheng ◽  
Junfei Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Rectangular Channels

The present work represents a numerical study on the flow and heat transfer characteristics in rectangular channels with protrusion-grooved turbulators. The Reynolds averaged Navier-Stokes equations, coupled with SST turbulence model, are adopted and solved. In this paper, six geometric protrusion shapes (circular, rectangular, triangular, trapezoidal, circular with leading round concave and circular with trailing round concave) are selected to perform the study. The flow structure, heat transfer enhancement, friction factor as well as thermal performance factor of the rectangular channel fitted with combined groove and different protrusions have been obtained at the Reynolds number ranging from 5000 to 20000. The results indicate that the protrusion shapes affect the velocity distribution near the groove surface. The case of circular protrusion with leading round concave provides the highest overall heat transfer enhancement, while it also causes the highest pressure loss penalty. The case of rectangular protrusion has the lowest overall heat transfer enhancement with high pressure loss penalty. The case of circular protrusion has similar overall heat transfer enhancement with cases of trapezoidal protrusion as well as circular protrusion with trailing round concave, but the pressure loss penalty of the case of circular protrusion is the lowest. In addition, the best overall thermal performance can be observed for circular protrusion-grooved channel.

An Experimental and Numerical Study of Flow and Heat Transfer in Channels With Pin Fin-Dimple Combined Arrays of Different Configurations

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Yu Rao ◽  
Chaoyi Wan ◽  
Shusheng Zang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Experimental Conditions ◽  
Number Range ◽  
Pin Fin ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Reynolds Number Range

An experimental and numerical study was conducted to investigate the flow and heat transfer characteristics in channels with pin fin-dimple combined arrays of different configurations, where dimples are located transversely or both transversely and streamwisely between the pin fins. The flow structure, friction factor, and heat transfer characteristics of the pin fin-dimple channels of different configurations have been obtained and compared with each other for the Reynolds number range of 8200–50,500. The experimental study showed that, compared to the pin fin channel, depending on the configurations of the pin fin-dimple combined arrays the pin fin-dimple channel can have distinctively further improved convective heat transfer performance by 8.0%–20.0%, whereas lower or slightly higher friction factors over the studied Reynolds number range. Furthermore, three-dimensional and steady-state conjugate computations have been carried out for similar experimental conditions. The numerical computations showed detailed characteristics of the distribution of the velocity and turbulence level in the flow, which revealed the underlying mechanisms for the pressure loss and heat transfer characteristics in the pin fin-dimple channels of different configurations.

Flow and Heat Transfer Characteristics in Latticework Cooling Channels With Dimple Vortex Generators

2013 ◽  
Author(s):  
Yu Rao ◽  
Xiang Zhang ◽  
Shusheng Zang
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Average Nusselt Number ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Average Heat ◽  
Cooling Channels ◽  
Flow And Heat Transfer ◽  
Smooth Channel

A comparative numerical study has been conducted on the flow and heat transfer characteristics in the latticework cooling structure with three different subchannel configurations: rectangular subchannels, U shaped subchannels and U shaped subchannels with dimple vortex generators. Experiments have been conducted using the latticework structure with U shaped subchannels with dimples. The comparisons between the experimental and numerical data have shown that the numerical computation model can reasonably well predict the heat transfer and pressure loss in the latticework cooling channels. The computation results showed that the latticework cooling structure has significantly enhanced heat transfer performance, and remarkably increased heat transfer area. Over the Reynolds number range of 7,696–36,985, depending on the geometry of the subchannels the average Nusselt number of the latticework channel is about 1.9–2.3 times that of a smooth channel, but the friction factor is about 6.4–11.1 times that of a smooth channel. The U shaped subchannels with dimples provide the greatest heat transfer enhancement and the most uniform heat transfer both axially and laterally, whose average Nusselt number is about 16.0% higher than the other two subchannels. Compared to the U subchannel, the dimples in the U subchannels work as vortex generators and provide additional heat transfer enhancement, whereas distinctively increase the pressure loss. Compared to the latticework cooling with U subchannels, the latticework cooling with rectangular subchannels shows similar average heat transfer the latticework cooling with rectangular subchannels shows similar average heat transfer and pressure loss performance.

Heat transfer characteristics of nanofluids from a sinusoidal corrugated cylinder placed in a square cavity

2021 ◽  
pp. 095440622110272
Author(s):  
Salaika Parvin ◽  
Nepal Chandra Roy ◽  
Litan Kumar Saha ◽  
Sadia Siddiqa
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Average Nusselt Number ◽  
Numerical Study ◽  
Heat Transfer Characteristics ◽  
Number Range ◽  
Transfer Characteristics ◽  
Wide Range

A numerical study is performed to investigate nanofluids' flow field and heat transfer characteristics between the domain bounded by a square and a wavy cylinder. The left and right walls of the cavity are at constant low temperature while its other adjacent walls are insulated. The convective phenomena take place due to the higher temperature of the inner corrugated surface. Super elliptic functions are used to transform the governing equations of the classical rectangular enclosure into a system of equations valid for concentric cylinders. The resulting equations are solved iteratively with the implicit finite difference method. Parametric results are presented in terms of streamlines, isotherms, local and average Nusselt numbers for a wide range of scaled parameters such as nanoparticles concentration, Rayleigh number, and aspect ratio. Several correlations have been deduced at the inner and outer surface of the cylinders for the average Nusselt number, which gives a good agreement when compared against the numerical results. The strength of the streamlines increases significantly due to an increase in the aspect ratio of the inner cylinder and the Rayleigh number. As the concentration of nanoparticles increases, the average Nusselt number at the internal and external cylinders becomes stronger. In addition, the average Nusselt number for the entire Rayleigh number range gets enhanced when plotted against the volume fraction of the nanofluid.

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