Heat Transfer In Fin Arrays Research Articles

Influence of Dimple Height on Turbulent Heat Transfer of Fin Array with Alternate Convex/Concave Dimples

This study analyzes transient turbulent modeling of three-dimensional multiple dimpled fin array using large eddy simulation (LES). The Navier–Stokes equations as well as the energy equation were constructed by the finite volume method and then discretized to form algebraic equations, which were solved by semi-implicit method for pressure-linked equation (SIMPLE). The solutions of temperature and velocity were obtained by iterating computation until it converged within each step. This simulation places nine fins on the bottom surface of a channel and changes the height of the dimple (0.4, 0.8, and 1.2 mm) with three different levels of Reynolds number (Re) (3500, 5000, and 6500) to investigate the temperature and flow field without gravity in forced convection. The results indicate that the dimpled fin array can generate vortices between the convex/concave dimples and the fin base and increase the influences of the height of the dimple on the flow field around the fin array. The averaged time-mean of the Nusselt number (Nu) for the dimple height of 0.8 mm is higher than that of the no-dimple case up to 14.4%, while the averaged time-mean Nu for the dimple height of 1.2 mm is lower than that of the no-dimple case up to 11.6%.

Investigation of Hydraulic and Thermal Performances of Fin Array at Different Shield Positions without By-pass

In this paper, we present some findings from an experimental and numerical study aimed to obtain physical insight into the influence of the presence of the shield and its position on the hydraulic and thermal performance of square pin fin heat sink without top by-pass. The variation of the Nusselt number and friction factor is obtained under varied parameters such as Reynolds number and shield position. The numerical code is validated by comparing the numerical results with the available experimental data. It is shown that, there is a good agreement between the temperature predictions based on the model and the experimental data. Results show that, as the presence of the shield, the heat transfer of fin array is enhanced and the flow resistance increased. The surface temperature distribution of the heat sink base is more uniform when the dimensionless shield position equals to 1/3 or 2/3. The comprehensive performance evaluation approach based on identical pumping power criteria is adopted and shows that the optimum shield position is at x/L=0.43 where the smallest energy consumption is.

Investigation of Hydraulic and Thermal Performances of Fin Array at Different Shield Positions without By-Pass

In this paper, we present some findings from an experimental and numerical study aimed to obtain physical insight into the influence of the presence of the shield and its position on the hydraulic and thermal performance of square pin fin heat sink without top by-pass. The variation of the Nusselt number and friction factor is obtained under varied parameters such as Reynolds number and shield position. The numerical code is validated by comparing the numerical results with the available experimental data. It is shown that, there is a good agreement between the temperature predictions based on the model and the experimental data. Results show that, as the presence of the shield, the heat transfer of fin array is enhanced and the flow resistance increased. The surface temperature distribution of the heat sink base is more uniform when the dimensionless shield position equals to 1/3 or 2/3. The comprehensive performance evaluation approach based on identical pumping power criteria is adopted and shows that the optimum shield position is at x/L=0.43 where the smallest energy consumption is.

Experimental investigation on the heat transfer and flow performances of the fin array with shield in bypass

The heat transfer performances of the fin array with shield in the bypass had been experimentally investigated. The variations of the mean Nusselt number and friction factor were obtained under varied parameters, such as the heated power input, the Reynolds number, the position and height of the shield. The optimum position and height of shield were analyzed under the identical pressure drop and the identical pumping power criteria. Experimental results indicated that the heat transfer and flow performances of fin array were marginally influenced by the power input. As the presence of the shield, the heat transfer of fin array was enhanced and the flow resistance increased. The heat transfer coefficient increased as the dimensionless shield position decreased and the shield height increased. The friction factor increased with the dimensionless position and height of shield. Evaluated under the identical pressure drop and the identical pumping power criteria, the optimum position of shield was the position where the dimensionless shield position equaled 0, and the optimum shield height was half of the fin height. Finally, the correlations of mean Nusselt number and friction factor were fitted considering the influences of Reynolds number, the shield position and the shield height. The predicted values fitted the experimental data with the deviations less than ±15.0%.

A nongray analysis of radiating–convecting rectangular plate-fin arrays

A complete analysis of heat transfer in rectangular fin arrays has been conducted taking into consideration convection and radiation at all surfaces, as well as radiative exchange between the fins and all neighboring surfaces. The analysis assumes diffuse nongray surfaces and uses the spectral optical properties of stainless steel AISI 430. Three different gray models were proposed in order to assess the effect of the gray assumption on the heat-transfer characteristics. Results are presented for the temperature and radiative-flux distributions along the fin, the radiative flux along the base, the contribution of the radiative component to the overall heat transfer, and the effectiveness of the fin array. Significant deviations in some of these results were found between the nongray model and the gray models. In general, convection was found to be the more effective mode of heat transfer in fin arrays and the effectiveness of the array decreases as the contribution of the radiative component increases.

Radiative and Convective Conducting Fins on a Plane Wall, Including Mutual Irradiation

The radiative and convective heat transfer from a fin array consisting of longitudinal rectangular fins on a plane surface has been theoretically investigated by mathematically describing the interaction among the heat conduction in the fin, the convective heat transfer to the fluid medium, and the radiant exchange of the fin with the neighboring elements. Solutions for the fin temperature distribution, the local radiative heat fluxes over the fin and base surfaces, the total radiative heat transfer, the total convective heat transfer, and the effectiveness of the fins were found. In the primary range of physical interest, the fins usually cause a considerable increase in the convective component of the heat transfer but either cause decreases or only slight increases in the radiative component. Thus convection is generally the more effective mode of heat transfer in fin arrays, and the effectiveness of the fins decreases as the radiative component increases.