Constructal design of multi-scale diamond-shaped pin fins cooled by mixed convection

Mustafa, Ahmed Waheed

doi:10.1016/j.ijthermalsci.2019.106018

Cited by 25 publications

(15 citation statements)

References 31 publications

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“…In conclusion, the previous constructal designs of forced convection from circular, elliptic, rhombic, and flat tubes show that the optimal spacing between these tubes exists, and the heat flow reaches to the maximum at this optimal spacing. Same conclusion was found for different rows of tubes cooled by natural convection as can be seen in Page et al 8 and Mustafa et al 9 Constructal design of multiscale single row of different tubes with forced, natural, and mixed convection can be found in Bello‐Ochende and Bejan, 10 Bello‐Ochende et al, 11 Page et al, 12 and Mustafa 13 . Tubes with staggered arrangement in both forced and mixed convections where the optimal arrangement was found by constructal design can be seen in Barrows et al 14 and Teixeira et al 15 …”

Section: Introductionmentioning

confidence: 54%

Constructal design of longitudinally finned tubes cooled by forced convection

2020

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The constructal design method is used in the present study to find the configuration of longitudinally finned tubes cooled by forced convection. The finned tubes are arranged in parallel inside a fixed two-dimensional domain. Two degrees of freedom inside the domain are considered for the design. The first degree of freedom is the tube-to-tube spacing, and the second is the length of the longitudinal fin.For both these degrees of freedom, a three-fin position inside the domain is considered. The fin is placed in the front, back, and front and back of the tube in the first, second, and third positions, respectively. Maximization of the heat flow density (heat transfer/ volume) from the finned tubes to the cold cross flow is the objective function of the present study. For the three fin positions, the constant pressure difference between the upstream and the downstream drives the cross flow. The dimensionless continuity, momentum, and energy equations for two dimensional, steady, and incompressible flows are solved by discretizing it according to the finite volume method. The thermal condition of the fins and the tubes is constant surface temperature. The dimensionless pressure drop known as Bejan number is varied in the range of 10 3 ≤ Be ≤ 10 5 . The fin length is changed from L f = 0 (unfinned tube) to L f = 0.2, 0.4, and 0.4. The tubes are cooled by air (Prandtl number = 0.71).The results illustrated that for the considered Bejan numbers and fin positions, the spacing between the unfinned and the finned tubes can be adjusted to optimal spacing such that the heat flow from the tubes to the coolant is maximum. K E Y W O R D SBejan number, constructal design, forced convection, longitudinally finned tubes

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Section: Introductionmentioning

confidence: 54%

Constructal design of longitudinally finned tubes cooled by forced convection

2020

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“…This is due to the fact that the change in heat densities is less than 0.5% when these lengths are doubled. The validation of the present code is conducted in the previous studies 9,14,16 . For briefness purpose, this validation is not mentioned in the present study.…”

Section: Grid Independence Test and Validationmentioning

confidence: 99%

“…Bello‐Ochende and Bejan 8 showed that the heat transfer from pin fins in forced convection can be increased when the diameters and the heights of the fins are nonuniform. Mustafa 9 used the constructal design method to find the optimal confirmation of multiscale pin fins cooled by mixed convection. The pin fins are diamond‐shaped and arranged in two scales in one row.…”

Section: Introductionmentioning

confidence: 99%

Constructal design of multiscale elliptic tubes in crossflow

Mustafa

Elqadir

2020

Heat Trans

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The optimal configuration of two-scale elliptic tubes in crossflow is found on the basis of the constructal design. The larger tubes are installed inside a domain of fixed length and height. In the same domain, smaller tubes are inserted between the larger tubes in the entrance region at the mid leading edge to leading edge distance of the larger tubes. The spacing between the larger tubes, the semiminor axis of the larger tubes, the major axis of the smaller tubes, and the semiminor axis of the smaller tubes are varied inside the domain freely to find the optimal configuration. There are two optimal configurations: one without the smaller tubes and the other with the presence of the smaller tubes. Both the larger and the smaller tubes are heated at a constant surface temperature. The flow is induced by a fixed pressure difference. The equations for steady, laminar, twodimensional, and incompressible flow are solved by finite volume method. In the absence of the smaller tubes, the range of Bejan number (dimensionless pressure drop) is Be 10 < < 10 3 5 , and in the presence of the smaller tubes, Bejan number is Be = 10 5 . The range of the dimensionless larger tubes semiminor axis is 0.1 ≤ B ≤ 0.4. Air is used to cool the row of the tubes with Prandtl number equal to 0.7. The results show that for different semiminor axes of the larger tubes, the heat transfer rate is enhanced when the smaller tubes are placed between the larger tubes. K E Y W O R D SBejan number, constructal design, crossflow, elliptic tubes

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“…For heat transfer optimization, the studies following constructal law can be classified as single-objective optimization, multi-objective optimization and multi-disciplinary optimization by optimization objectives; and these also can be classified as heat conduction optimization, convective heat and mass transfer optimization and various device and component optimization by study objects, and so on [ 4 , 5 , 6 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 24 ]. It has also been applied to the designs of cavities and fin heat sinks [ 24 , 61 , 62 , 63 ], channel heat sinks [ 64 , 65 ], heat exchangers [ 66 , 67 , 68 , 69 ], nonuniform heat generating units [ 70 , 71 ], evaporators [ 72 , 73 , 74 ], boiler superheater [ 75 ], tubular arrangements [ 76 , 77 ], dual-pressure turbine [ 78 , 79 ], etc., in recent years. For the constructal design in engineering, heat sources [ 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ,…”

Section: Introductionmentioning

confidence: 99%

Constructal Design of Elliptical Cylinders with Heat Generating for Entropy Generation Minimization

Wang

Xie

Yin

et al. 2020

Entropy

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A heat dissipation model of discrete elliptical cylinders with heat generation on a thermal conduction pedestal cooled by forced convection is established. Constructal design is conducted numerically by taking the distributions of thermal conductivity and heat generating intensity as design variables, the dimensionless entropy generation rate (DEGR) as performance indicator. The optimal designs for discrete elliptical cylinders with heat generating are obtained respectively, i.e., there are optimal distributions of heat generating intensity with its fixed total amount of heat sources, and there are optimal distributions of thermal conductivity with its fixed total amount of heat sources. These optimums for minimum DEGRs are different at different Reynolds numbers of airflow. The heat generating intensity can be decreased one by one appropriately in the fluid flow direction to achieve the best effect. When the Reynolds number of airflow is smaller, the thermal conductivity of heat source can be increased one by one appropriately in the fluid flow direction to achieve the best effect; when the Reynolds number of airflow is larger, the thermal conductivity of each heat source should be equalized to achieve the best effect. The results can give thermal design guidelines for the practical heat generating devices with different materials and heat generating intensities.

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Constructal design of multi-scale diamond-shaped pin fins cooled by mixed convection

Cited by 25 publications

References 31 publications

Constructal design of longitudinally finned tubes cooled by forced convection

Constructal design of longitudinally finned tubes cooled by forced convection

Constructal design of multiscale elliptic tubes in crossflow

Constructal Design of Elliptical Cylinders with Heat Generating for Entropy Generation Minimization

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