Thermal-Hydraulic Performance Enhancement by the Combination of Rectangular Winglet Pair and V-Shaped Dimples

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Inderjot Kaur ◽  
Prashant Singh ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Performance Enhancement ◽  
Numerical Study ◽  
Hydraulic Performance ◽  
Channel Height ◽  
Transfer Enhancement ◽  
Spacing Variation ◽  
Lower Heat

Abstract This paper presents numerical study on heat transfer enhancement due to the combination of rectangular winglet pair with V-dimples in an array-type arrangement. Array of rectangular winglet pairs results in heat transfer enhancement, however, at a cost of significant pressure drop, resulting in reduced thermal-hydraulic performance (THP). On the other hand, dimples are associated with lower heat transfer enhancement levels at relatively lower pumping power penalty. To this end, a combination of rectangular winglet pair and V-shaped dimples has been studied in this paper, where the arrangements were intended to achieve enhanced thermal-hydraulic performance. Three different configurations, namely, rectangular winglet pair, rectangular winglet pair with one V-dimple between two consecutive winglets, and rectangular winglet pair with two V-dimples packed in a pitch, are studied here. The variation of heat transfer enhancement, pressure drop gain, and THP with respect to winglet-to-winglet (S) spacing variation for rectangular winglet pair and rectangular winglet pair with one V-dimple configuration is presented at a Reynolds number of 25,000. The THP of the rectangular winglet pair configuration decreases up to S/H equal to 2.5 and then increases (H: channel height). For rectangular winglet pair with one V-dimple, three values of winglet-to-dimple (P) spacings are analyzed. For fixed S/H, the highest P/H configuration provided highest heat transfer enhancement and THP. Among the three configurations studied, rectangular winglet pair with two V-dimples resulted in the highest thermal-hydraulic performance.

Vortex Heat Transfer Enhancement in Narrow Channel by Oval Dimples Arrangement

2013 ◽  
Author(s):  
Sergey Isaev ◽  
Yaroslav Chudnovsky ◽  
Alexander Leontiev ◽  
Nikolai Kornev ◽  
Egon Hassel
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Numerical Study ◽  
Heated Surface ◽  
Spherical Shape ◽  
Narrow Channel ◽  
Constant Heat Flux ◽  
Hydraulic Performance ◽  
Equivalent Diameter ◽  
Transfer Enhancement

There are many passive techniques of heat transfer enhancement ranging from surface (2D) to volumetric (3D) vortex generators, however only a few of them are capable to provide a reliable increase in a heat transfer rate overrunning the increase in pressure losses. One of such successful techniques is the profiling of a heat transfer surface with the regulated arrangement of 3D cavities (dimples). The authors explored that the deviation of the dimple geometry from the spherical shape affects the flow structure and thermal and hydraulic performance of the dimpled wall. Detailed numerical simulation of fluid flow and heat transfer has been performed in the narrow channel with the 2.5 × 0.33 cross section normalized by the equivalent diameter of the dimple footprint at the constant Reynolds number Re = 10,000 and the constant heat flux through the dimpled wall. The oval dimple geometry was varied by changing the aspect ratio of the dimple footprint from 1 to 4.5 keeping the same footprint area. In the course of the numerical study, the optimal geometry, the arrangement and the orientation of oval dimples on the heated surface to achieve the superior thermal and hydraulic performance over the spherical cavities are established. Numerical results of local and integral heat transfer characteristics enhanced with the visual representation of the generated vortices clearly illustrated the flow restructuring and an increase in the thermal and hydraulic performance.

scholarly journals 460 A Numerical Study on Heat Transfer Enhancement and Pressure drop Decrease of Heat Exchanger by Setting Inserted Plates in Duct

2005 ◽  
Vol 2005.15 (0) ◽  
pp. 541-544
Author(s):  
Himsar AMBARITA ◽  
Kouki KISHINAMI ◽  
Kazuhiko SATO ◽  
Masasi DAIMARUYA ◽  
Hiromu SUGIYAMA ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Numerical Study ◽  
Transfer Enhancement

Computational Study of Flow and Heat Transfer in Matrix Cooling Channels

2014 ◽  
Author(s):  
Sivasankara Reddy Ramireddy ◽  
Siddappa Pallavagere Gurusiddappa ◽  
V. Kesavan ◽  
S. Kishore Kumar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Numerical Study ◽  
Computational Study ◽  
Side Wall ◽  
Transfer Enhancement ◽  
Cooling Channels ◽  
Aspect Ratios ◽  
The Matrix

A Numerical study of fluid flow, heat transfer and pressure drop in a stationary matrix cooling channel having an angle of 45 degrees for the three Reynolds numbers (24000<Re<60000) and four sub-channel aspect ratios (0.5<W/H<1.2) have been performed. This includes different shaped sub-channels such as Rectangular, U, and then two, three layered matrix combined with open and closed matrix channels. The simulation shows the development of vortices along the channel. The flow turning and impingement after hitting the side wall have significant contribution to the heat transfer enhancement. The Nusselt number and friction factor have been evaluated and compared with limited experimental results. The highest heat transfer enhancement is found at impingement region as the flow takes turn and impinges on to the wall. But slight enhancement in heat transfer is observed at turning region. The sub-channel aspect ratio has less impact on heat transfer enhancement, but more effect on pressure drop. The performance of closed matrix is relatively better than the open matrix one. The overall thermal performance (η) of the matrix having U sub-channel is nearly 10% higher than the rectangular sub-channel.

THE EFFECT OF VORTEX GENERATOR BASE LENGTH ON THERMAL HYDRAULIC PERFORMANCE ACROSS FIN-AND-TUBE HEAT EXCHANGER

2017 ◽  
Vol 79 (7-3) ◽  
Author(s):  
Mohd Fahmi Md Salleh ◽  
Mazlan Abdul Wahid ◽  
Seyed Alireza Ghazanfari
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Vortex Generator ◽  
Hydraulic Performance ◽  
Base Length ◽  
Transfer Enhancement ◽  
Tube Heat Exchanger ◽  
Baseline Case

Heat transfer enhancement is believed can be achieved by using vortex generator. In the past decades, many researches have been performed to investigate the effect of various vortex generator geometry and parameters including vortex generator angle of attack and height. However, less study has been conducted to investigate the influence of vortex generator length at different arrangement towards the heat transfer performance across the fin-and-tube heat exchanger (FTHE). Therefore, the effects of different strategy on the rectangular winglet vortex generator (RWVG) base length towards the thermal hydraulic performance across the FTHE were numerically investigated in this study. Two types of RWVG arrangement known as common flow down (CFD) or common flow up (CFU) arrangement were used and placed behind four rows of tube in inline arrangement. Total of 7 cases were investigated including the default RWVG, extended front and extended back for both RWVG in CFD and CFU arrangement together with FTHE without vortex generator which was set as the baseline case. The Reynolds number ranged from 500 to 900. It was found that the size of the wake region behind the RWVG contributed to the additional pressure drop penalty across the FTHE. Meanwhile, different thermal characteristics were found for different base length strategy in CFD and CFU arrangement. For RWVG arranged in CFD and CFU arrangement, the extended back case shows the highest heat transfer enhancement with 5 – 25 % and 5 – 15 % increment compared to the baseline case respectively. Based on JF factor evaluation, default RWVG in CFU arrangement provide better heat transfer enhancement than the pressure drop penalty compared to other RWVG cases with average JF factor value is 0.8. Nonetheless, none of the tested cases shows higher JF factor value than the baseline case.  

Numerical Study of Forced Convection in a Partially Porous Channel With Discrete Heat Sources

1995 ◽  
Vol 117 (1) ◽  
pp. 46-51 ◽  
Author(s):  
H. A. Hadim ◽  
A. Bethancourt
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Pressure Drop ◽  
Heat Source ◽  
Heat Transfer Enhancement ◽  
Forced Convection ◽  
Numerical Study ◽  
Heat Sources ◽  
Transfer Enhancement ◽  
Discrete Heat Sources

A numerical study was performed to analyze steady laminar forced convection in a channel partially filled with a fluid-saturated porous medium and containing discrete heat sources on the bottom wall. Hydrodynamic and heat transfer results are reported for the configuration in which the porous layers are located above the heat sources while the rest of the channel is nonporous. The flow in the porous medium was modeled using the Brinkman-Forchheimer extended Darcy model. Parametric studies were conducted to evaluate the effects of variable heat source spacing and heat source width on heat transfer enhancement and pressure drop in the channel. The results indicate that when the heat source spacing was increased within the range considered, there was a negligible change in heat transfer enhancement while the pressure drop decreased significantly. When the heat source width was decreased, there was a moderate increase in heat transfer enhancement and a significant decrease in pressure drop.

Heat Transfer Enhancement of Air Flowing Across Grooved Channels: Joint Effects of Channel Height and Groove Depth

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
El Hassan Ridouane ◽  
Antonio Campo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Parallel Plate ◽  
Numerical Study ◽  
Local Heat Transfer ◽  
Groove Depth ◽  
Channel Height ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Maximum Heat Transfer

A numerical study was conducted to investigate convective heat transfer and laminar fluid flow in the developing region of two-dimensional parallel-plate channels with arrays of transverse hemicircular grooves cut into the plates. Air with uniform velocity and temperature enters the channel whose plates are at a uniform temperature. The finite-volume method is used to perform the computational analysis accounting for the traditional second-order-accurate QUICK and SIMPLE schemes. Steady-state results are presented for parallel-plate channels with and without hemicircular grooves for comparison purposes. The study revolves around four controlling parameters: (1) the height of the channel, (2) the relative groove depth, (3) the number of grooves, and (4) the Reynolds number. A prototypical 120‐cm-long channel contains two series of 3, 6, and 12 transverse grooves with four relative groove depths δ∕D of 0.125, 0.25, 0.375, and 0.5. Three ratios of channel height to groove print diameter H∕D of 0.5, 1, and 2 are employed. Computations are performed for Reynolds numbers based on the hydraulic diameter ranging from 1000 to 2500. It is found that the grooves enhance local heat transfer relative to a flat passage at locations near their downstream edge. The maximum heat transfer enhancement occurs at an optimal depth of the grooves. For purposes of engineering design, generalized correlation equations for the Nusselt number in terms of the pertinent Re, δ∕D, and the number of grooves N were constructed using nonlinear regression theory.

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