Constructal multi-scale structure for maximal heat transfer density in natural convection

Silva, Alexandre K. da; Bejan, Adrian

doi:10.1016/j.ijheatfluidflow.2004.05.002

Cited by 75 publications

(45 citation statements)

References 13 publications

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“…This has lead researchers to study the optimized configurations for various architectures such as: the optimal spacing of parallel plates in forced convection, natural convection and mixed convection [1][2][3][4]; the optimal spacing of cylinders in forced convection and natural convection [5,6]; and various optimized multi-scale structures [7][8][9][10][11][12], etc.…”

Section: Introductionmentioning

confidence: 99%

Maximum heat transfer density rate enhancement from cylinders rotating in natural convection

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Bello‐Ochende

Meyer

2011

International Communications in Heat and Mass Transfer

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In this paper we investigate the thermal behaviour of an assembly of consecutive cylinders in a counter-rotating configuration cooled by natural convection with the objective of maximizing the heat transfer density rate (heat transfer rate per unit volume). A numerical model is used to solve the governing equations that describe the temperature and flow fields. The spacing between the consecutive cylinders is optimised for each flow regime (Rayleigh number) and cylinder rotation speed. It was found that the optimized spacing decreases as the Rayleigh number increases and the heat transfer density rate increases, for the optimized structure, as the cylinder rotation speed is increased. Results further shows that there is an increase in the heat transfer density rate of the rotating cylinders over stationary cylinders.

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Section: Introductionmentioning

confidence: 99%

Maximum heat transfer density rate enhancement from cylinders rotating in natural convection

Page

Bello‐Ochende

Meyer

2011

International Communications in Heat and Mass Transfer

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“…The optimal spacing idea was taken theoretically and numerically one step further in [1,7,15], where the flow structure had not one but several optimal-length scales. These were distributed non-uniformly through the flow space with more and smaller plates in the entrance region of the available volume.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional multi-scale plate assembly for maximum heat transfer rate density

Bello‐Ochende

Meyer

Dirker

2010

International Journal of Heat and Mass Transfer

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This paper extends the design concept for generating multi-scale structures in forced convection for a finite-size flow system to a three-dimensional heat-generating plate with the objectives of maximizing heat transfer rate density, or the heat transfer rate per unit volume. The heat generating plates, arranged in a stack form channels in which the fluids are forced through by an applied pressure difference. The first stage of this work consists of numerical simulation of the flow and heat transfer in a large number of flow configurations, to determine the optimum plate spacing, and the maximum heat transfer rate density. In the subsequent stages, shorter plates are inserted in the centers at adjacent (longer) plates in the entranced region were the boundary layer are thin and there is a core of unused fluid. The heat transfer density is further increased by progressively inserting another set of even shorter plates between the plates and then optimizing the whole structure. The resulting structure is an optimized multi-scale and multi channel structure with horizontal equidistant heated plates of decreasing lengths scales. Further more the effects of plate thickness and dimensionless pressure drop number on the multi-scale structure was investigated. The numerical results are found to be in good agreement with predicted analytical results.

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“…difference when comparing this optimal spacing with that reported by da Silva and Bejan [20]. The effect of the plate-to-plate spacing on the heat transfer density rate for P r = 0.72…”

Section: Parallel Platesmentioning

confidence: 66%

“…Similar to the work done in Ref [17], da Silva and Bejan [20] considered the parallel plate multi scale structure cooled by natural convection. Similar results were reported in that the maximized heat transfer density increases as the optimized complexity of the flow structure increases.…”

Section: Increased Geometric Complexitymentioning

confidence: 89%

Geometric Optimization for Maximum Heat Transfer Density Rate From Cylinders Rotating in Natural Convection

Page

2012

Proceeding of Proceedings of CHT-12. ICHMT International Symposium on Advances in Computational Heat Transfer.

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Un ni iv ve er rs si it ty y o of f P Pr re et to or ri ia a i Abstract Title: Geometric optimization for the maximum heat transfer density rate from cylinders rotating in natural convection Author:LG Page Supervisors: Prof T Bello-Ochende and Prof JP Meyer Department: Mechanical and Aeronautical Engineering University:University of Pretoria Degree:Masters in Engineering (Mechanical Engineering)In this study we investigates the thermal behaviour of an assembly of consecutive cylinders in a counter-rotating configuration cooled by natural convection with the objective of maximizing the heat transfer density rate (heat transfer rate per unit volume). A numerical model was used to solve the governing equations that describe the temperature and flow fields and an optimisation algorithm was used to find the optimal structure for flow configurations with two or more degrees of freedom. The geometric structure of the consecutive cylinders was optimized for each flow regime (Rayleigh number) and cylinder rotation speed for one and two degrees of freedom. Smaller cylinders were placed at the entrance to the assembly, in the wedge-shaped flow regions occupied by fluid that had not yet been used for heat transfer, to create additional length scales to the flow configuration.It was found that the optimized spacing decreases and the heat transfer density rate increases as the Rayleigh number increases, for the optimized structure. It was also found that the optimized spacing decreases and the maximum heat transfer density rate increases, as the cylinder rotation speed was increased for the single scale configuration at each Rayleigh number. Results further showed that there was an increase in the heat transfer density rate of the rotating cylinders over stationary cylinders for a single scale configuration.For a multi scale configuration it was found that there was almost no effect of cylinder rotation on the maximum heat transfer density rate, when compared to stationary cylinders, at each Rayleigh number; with the exception of high cylinder rotation speeds, which serve to suppress the heat transfer density rate. It was, however, found that the optimized spacing decreases as the cylinder rotation speed was increased at each Page iii Rayleigh number. Results further showed that the maximum heat transfer density rate for a multi scale configuration (with stationary cylinders) was higher than a single scale configuration (with rotating cylinders) with an exception at very low Rayleigh numbers.

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Constructal multi-scale structure for maximal heat transfer density in natural convection

Cited by 75 publications

References 13 publications

Maximum heat transfer density rate enhancement from cylinders rotating in natural convection

Maximum heat transfer density rate enhancement from cylinders rotating in natural convection

Three-dimensional multi-scale plate assembly for maximum heat transfer rate density

Geometric Optimization for Maximum Heat Transfer Density Rate From Cylinders Rotating in Natural Convection

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