A pin-fin is a compact size extended surface. It plays a role to transfer heat from the hot surface to the surrounding air. They are mounted on the hot surface. It can be mounted internally as well as externally. Usually the pin-fin is made of highly conductive aluminum material. Because of cost effectiveness and light weight, the aluminum is popular in industrial and commercial applications. The pin-fins are constructed by using casting, forming, machining and fabrication. Their usage is expanded in the field of aerospace industry to cool the gas turbine blades, in power plant and refinery heat exchangers, cooling of electronic components etc. Moreover, the efficiency and effectiveness of each pin-fin is quite low. Therefore, to have better enhanced efficiency and effectiveness the pin-fins are implied in the form of arrays and the calculations are carried out accordingly.
On the contrast of pin-fins, a computational analysis on symmetrical aerofoil pin-fin arrays has been investigated. The computational study on micro pin-fins and circular pin-fins have been carried out by R.B. Gurav et al. and M.T.Malazi et al., respectively [1, 2]. It is to be noted that the pin-fin geometry plays a key role to enhance effectiveness of pin-fins. So, it is found that a computation study has been carried out to know the influence of pin-fin patterns and geometry on the effectiveness by L. Ludick et al. [3].
The pin-fin optimization study and analysis also is advancement in research and analysis. W.H.Chen et al. [4] performed varied numbers of square pin fins in a flow channel by computational fluid dynamics. In the field of aerospace applications, pin-fin trial and analysis is a trending research. Computational analysis of rectangular, stepped and elliptical pin-fin profiles for space vehicle thermal control systems have been performed by M.P. Narayanasamy et al. [5] and they obtained that in comparison with flat pin-fins, elliptical pin-fins increase heat transfer by an average of 20%. The perforations in the pin-fin are one form of optimization and enhancement of heat transfer rate. A computational analysis of perforation effect on the micro pin-fin heatsink has been carried out by D. Gupta et al. [6] and they achieved that one to two circular perforation improves performance by 30% followed by square and elliptical perforation.
It is to be noted that the pin-fin clearance plays a vital role in pressure drop analysis. In this regard C. Liang et al. [7] carried out a detailed computational analysis on the heat transfer and pressure loss of a turbulent flow in detached pin fin arrays with various clearance values and obtained that compared with the pin fin arrays, the pressure loss is decreased by up to 30.5% with the increase of the clearance value for the detached pin fin arrays.
The pin-fin compatibility in central processing unit (CPU) cooling also is under investigation by the global eminent researchers because of enhancement in system speed. In this contrast, M. W. Alam et al. [9] carried out the computational analysis, the finite volume method based general purpose computational fluid dynamics software ANSYS Fluent 15.0 on CPU heat sink cooling by introducing triangular shape micro-pin-fin and they observed that turbulence intensity 15% and 20% at inlet produce very high efficiency, η of about 3.33 and 3.66 for micro-pin-fin diameter, d = 0.8 mm, respectively. Furthermore, in the CPU and motherboard chip cooling, the cooling capability of the pin-fin plays a key role. S. Bhattacharyya et al. [10] investigated by using computational shear stress transport (SST) model of micro-pin-fin heat sink cooling in the mainboard chip of a CPU and they have observed that the use of micro-pin-fin of diameter 0.8 mm and turbulence intensity (TI) of 15–20% at inlet is advantageous.
As far as the phase change material (PCM) heat sink with pin-fin is concern, it is one of the cooling rate enhancing elements and is under investigation by the eminent researchers, worldwide. After conducting optimization research on triangular pin-fin arrangements, the full melt time was shortened by 14.3% and the heat dissipation power was increased by up to 15.2%, when compared with the PCM heat sink with triangular pin-fins, H. Pan et al. [11]. In the investigation of heat transfer performance for through-silicon via embedded in micro pin fins in 3D integrated chips, it is obtained by the W. He et al. [12] that the best comprehensive heat transfer performance was achieved with an extended fin angle of 30 degrees for the micro pin fins.
The various trending research on pin-fin geometries are going on. A computational design and optimization of pin fin heat sinks with single, rectangular slotted or notched perforations were carried out by A. A. Damook et al. [13] and their results show that the heat transfer increases monotonically while the pressure drop decreases monotonically as the size of the rectangular perforation increases. In the gas turbine trailing edge cooling, the pin-fin investigation also plays a major role. The performance of pin-fin arrays installed in the trailing edge internal cooling channel of a turbine blade was investigated computationally using three-dimensional Reynolds-averaged Navier-Stokes equations, M. A. Moon and K. Y. Kim [14]. A numerical model for various pin-fin array heat sinks was developed and verified experimentally and from the analysis results, the staggered pin-fin radial heat sink was identified as the optimal configuration, demonstrating improved thermal performance by up to 10% while maintaining the same mass or reducing the mass by up to 12% for a given thermal resistance, S. J. Park et al. [15].
It is found that the researches performed investigation and analysis on pin-fin compatibility in the hydrothermal channel applications. In the CFD (Computational Fluid Dynamics) study on hydro thermal performance of heat sink using perforated twisted and grooved pin fins is conducted and the results showed an improvement of the average Nusselt number (Nu) by 32%, M. R. Haque et al. [16]. Further, it is to be noted that C. Balachandar et al. [17] carried out computational heat transfer analysis and combined artificial neural network (ANN) – Genetic Algorithm (GA) of solid and optimized hollow cylindrical pin-fin on a vertical base plate and their analysis shows that the hollow fins provide an increased heat transfer and a weight reduction of about 90% when compared to solid cylindrical pin fins. For instance, it is found that the computational modelling of hybrid nanofluid in micro pin fin heat sink for electronic cooling has been investigated by N. B. Sukhor et al. [18] and they have observed that the Nusselt number increased from 14.00 at transverse pitch of 3.81 mm to 17.00 at a transverse pitch of 1.81 mm and this corresponds to 16.05% enhancement of Nusselt number. Computation of natural convection in channels with pin fins have been analyzed by D. S. Boyalakuntla et al. [19] and their results are useful in designing augmented cooling schemes in portable electronics.
A part from core mechanical and electronic device cooling, the pin fin compatibility research has been implied by the researchers in the field of solar heater system. In this contrast, the M. S. Manjunath et al. [20] performed computational fluid dynamics analysis of a flat plate solar air heater in the presence of a pin fin array and in their analysis the results show that the pin fin array exhibits a relatively superior effective efficiency to a maximum extent of about 73% for lower flow rate conditions. It is noted that the experimental and computational analysis of transient, non-linear heat flux in circular pin fin of length = 0.35 m, cross-section area = 7.85×10 − 5 m2 has been performed by M. Singhal et al. [21]. Further it is noted that a numerical simulation study of a pin–fin staggered manifold microchannel (PFSMMC) heat sink has been analyzed by Y. H. Pan et al. [22] and their results show that the PFSMMC heat sink has better heat transfer capability and more uniform heating surface temperature.