Porous Pin Fins Research Articles

Numerical investigation of thermal and hydraulic characteristics in porous pin fin heat sinks using single phase nanofluids

This study aims to numerically investigate the thermal performance of porous square pin-fin heat sinks, considering three different configurations: inline, staggered, and 45° inline. Six different nanofluids, comprising CuO, Al2O3, and TiO2 nanoparticles dispersed in water and water–ethylene glycol mixtures at two volume fractions (φ = 0.5 % and 2 %), are employed as coolants. The impact of porosity on the thermal and fluidic behavior is also examined for the CuO–Water nanofluid (φ = 2 %) at porosity values of 40 %, 50 %, and 60 %. The commercial CFD code: Ansys Fluent 2020R1 is utilized for this numerical analysis and the results are compared to relevant experimental works for validation. The effects of heat sink geometry, nanofluid type, and porosity on heat transfer performance are systematically analyzed. The results show that the 45° inline configuration of the square pin-fin heat sink exhibits superior heat transfer enhancement compared to both the inline and staggered configurations. The use of nanofluids as coolants significantly improves the thermal performance compared to conventional fluids, with CuO–Water nanofluid demonstrating the most promising results. This comprehensive analysis provides valuable insights for the design optimization of high-performance cooling systems for electronic devices.

Performance enhancement for exhaust thermoelectric power generation system by using porous pin fins based on a fully automatic optimization method

An intelligent optimization method combining Non-dominated Sorting Genetic Algorithm-II (NSGA-II) algorithm and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) decision is implemented to design the optimal arrangement of porous pin fins in the flow channel of the exhaust thermoelectric power generation (ETEG) system. This method realizes the optimal arrangement of the porous pin fins while considering the two contradictory performance indicators at the optimization level: system output power (P) and pressure drop (Pd). In this work, the design of porous and solid pin fins is first compared. Secondly, four typical pin fins arrangement models are established with preliminary analysis. Finally, the NSGA-II-TOPSIS intelligent optimization method is implemented, which takes P and Pd as objective function, the position, number and relative distance of the porous pin fins as optimization variables simultaneously. Through iterative optimization, the optimal arrangement scheme achieves a proper balance between P and Pd. The main conclusions include: The design of the porous pin fins can increase 22.89% for P of the ETEG system while reduces 82.98% for Pd. The distribution of dense downstream of porous pin fins can best improve the ETEG system performance. After optimization, higher P and lower Pd of the ETEG system are obtained with fewer pin fins. A new index is proposed to evaluate optimal solutions, the optimal design with 2 porous pin fins reaches the highest value: 5.86 W Pa−1, which means that each pin fin is fully used.

Thermohydraulic Performance of Chevron Pin-Fins

The present study focuses on the optimum design effectiveness in heat removal for small surfaces. Pin-fin made of solid and porous cylindrical shape forming chevron is investigated numerically using the finite element method. The design consists of 3-chevron and 5-chevron configurations connected to a heated block with fluid circulating between the chevron and above them. Variable Reynolds number and pin-fins height ranging from 2 mm to 8 mm are investigated. The full Navier–Stokes equation combined with the energy equation was solved in the presence of the solid pin-fins. The Darcy–Brinkman model with the effective energy equation is used in the presence of the porous pin-fins. The system is solved for Reynolds numbers ranging from 50 to 1000, thus remaining in the laminar regime. Results revealed that the best performance evaluation criterion is higher for the 8 mm porous pin-fins regardless of their permeability. If one ignores the pressure drop and friction contribution, a solid pin-fin having a height of 4 mm showed the best heat absorption mechanism.

Improved design of heat sink including porous pin fins with different arrangements: A numerical turbulent flow and heat transfer study

Recently, there exist rapid advancements in different parts of some devices that produce significant heat. Active or passive methods, in different ways, can be used to cool down and dissipate the generated heat of these devices. Besides, the hot surface area of the heat sink adjacent to the cooling fluid plays a vital role in heat transfer increment. Utilizing the porous fins with metal foams can provide a better fluid–solid contact condition. However, this method requires more pumping power for coolant fluids. In the present study, numerical simulations of turbulent flow forced convection heat transfer of air in the presence of porous pin fins, for cooling thermal parts of devices, is investigated. Five fin structures (rectangular, increasing, decreasing, V-shaped, and wedge-shaped) and two different fin arrangements (aligned and staggered), three various Darcy numbers (Da = 10−1, 10−2, 10−4), are examined and the effects of these parameters on the heat sink performance are analyzed. Results are presented in terms of the effectiveness, heat transfer coefficients, performance evaluation criteria – considering both the friction and the heat transfer factors – and temperature and stream function contours. It is concluded that, among the studied cases, the decreasing-aligned pin fin configuration with the highest Darcy number provides the best performance.

An Estimate of Heat Generation, Electric, and Magnetic Parameters From Temperature Fields in Porous Fins for Electronic Cooling Systems

In the present investigation, a numerically driven direct and inverse study is conducted for the simultaneous prediction of the internal heat generation, electric field, and magnetic field strengths in porous pin fins from the surface temperature profile in electronic cooling applications. Consideration under imposed electrical and magnetic fields along with all modes of heat transport is given. Initially, duly-verified forward solutions are generated for the calculation of the temperature profile, and subsequently, three unknown parameters are predicted at the same time using the inverse methodology assisted by the artificial bee colony (ABC) algorithm. Here, numerical case studies have been presented to discover a suitable relation between the three parameters estimated by the ABC methodology. The current research envisages that even though a wide range of probable parametric combinations exist sustaining the prescribed thermal profile, however, the magnetic field parameter mostly governs the thermal phenomenon, while, the effect of mutual interplay among the electrical field and internal heat generation parameters is responsible for the temperature distribution under a given measurement error. Even with the influence of random perturbations, the ABC-assisted inverse methodology is observed to precisely simulate and determine the required thermal criterion and establish the available thermal field within the 4.55% error margin. Toward meeting a necessary heat transfer rate from porous pin fins, the proposed strategy is claimed to be valuable for appropriately controlling the electric and magnetic fields along with the indefinite state of interior heat generation rate.

Heat Transfer by Porous Pin Fins and Nanofluid in Rectangular Microchannels

The forced convective heat transfer with 3D, triangular, porous pin fins as bundle of MWCNTs at the bottom of rectangular mini channels made of silicon. Overall heat transfer performances in porous pin fins are much better than those in traditional solid pin fins. As nanofluid volume concentration increases, pressure drops and heat fluxes in porous pin fin channels increase and maximal overall heat transfer are obtained at 0.01% concentration. Enhancement in Nu were 6% with respect to porosity and 88 % with respect to 0.01% Al 2 O 3 /H 2 O. With the same physical parameters, the Nu in the staggered triangular porous pin fin channels of CNTs with fin height of 0.75 mm, smaller fin width of 0.5 mm and spacing double the fin width using 0.01% CuO/H 2 O nanofluid showed the highest enhancement of 91% at higher Re with a corresponding decrease in pressure drop of 25%. DOI: http://dx.doi.org/10.5755/j01.mech.24.1.17284

Cumulative effects of using pin fin heat sink and porous metal foam on thermal management of lithium-ion batteries

Three-dimensional transient thermal analysis of an air-cooled module was carried out to investigate cumulative effects of using pin fin heat sink and porous metal foam on thermal management of a Li-ion (lithium-ion) battery pack. Five different cases were designed as Case 1: flow channel without any pin fin or porous metal foam insertion, Case 2: flow channel with aluminum pin fins, Case 3: flow channel with porous aluminum foam pin fins, Case 4: fully inserted flow channel with porous aluminum foam, and Case 5: fully inserted flow channel with porous aluminum foam and aluminum pin fins. The effects of porous aluminum insertions, pin fin types, air flow inlet temperature, and air flow inlet velocity on the temperature uniformity and maximum temperature inside the battery pack were systematically investigated. The results showed that using pin fin heat sink (Case 2) is appropriate only for low air flow velocities. In addition, the use of porous aluminum pin fins or embedding porous aluminum foam inside the air flow channel (Cases 3 and 4) are not beneficial for thermal management improvement. The combination of aluminum pin fins and porous aluminum foam insertion inside the air flow channel (Case 5) is a proper option that improves both temperature reduction and temperature uniformity inside the battery cell.

Numerical simulations and optimization of porous pin fins in a rectangular channel

ABSTRACTIn this study, the multiparameter constrained optimization procedure integrating the design of experiments (DOE), genetic algorithm (GA), and computational fluid dynamics (CFD) is proposed to design three-dimensional porous pin fins in a rectangular channel. The Forchheimer–Brinkman extended Darcy model and the two-equation energy model are adopted to describe the fluid flow and heat transfer characteristics in the porous media. The elliptical, coupled, steady-state, and three-dimensional governing partial differential equations for laminar forced convection with porous pin fins in a rectangular channel are solved numerically using the finite volume approach. The numerical optimization provides a reliable and economic mean of designing a heat transfer channel with porous pin fin arrays.

Heat Transfer Study Through Porous Pin Fins with Variable Section Shapes by Using Analytical Method

Heat Transfer Study Through Porous Pin Fins with Variable Section Shapes by Using Analytical Method

Analytical investigation of porous pin fins with variable section in fully-wet conditions

The present work investigates the temperature distribution, heat transfer rate, efficiency and optimization of porous pin fins in fully wet conditions. The thickness varies along the length of the fin and the lateral surface equation is defined as functions that include diversification fins (rectangular, triangular, convex parabolic and concave parabolic sections). Fins are made of aluminium and the tips of fins are insulated. Furthermore, it is assumed that the heat transfer coefficient depends on temperature and in the fin it changes according to temperature changes. In order to derivethe heat transfer equation, energy balance and Darcy model are used. After presenting the governing equation to obtain the temperature distribution, least squares method (LSM) is applied. Comparison of the results between analytical solution and numerical outcome (fourth order Runge–Kutta method) shows that LSM is a convenient and powerful method in engineering problems. Then the effects of various geometric and thermophysical parameters (power index for geometry (n), porosity, Biot number and relative humidity) on the dimensionless temperature fin, efficiency and heat transfer rate are examined. Optimum design analysis was also carried out.

Thermal Analysis of Porous Pin Fin used for Electronic Cooling

The present work investigates the temperature distribution, performance parameters and heat transfer rate through a porous pin fin in natural convection condition. This study is based on finite-length fin with insulated tip. To formulate the heat transfer equation for the porous fin, the energy balance and Darcy's model are used. An analytical technique called Adomian decomposition method (ADM) is proposed for the solution methodology. To validate the analytical results, a numeric scheme, namely, finite difference method is adopted. The results indicate that the numerical data and analytical approach are in agreement with each other. The effects of various geometric and thermophysical parameters on the dimensionless temperature distribution and fin performance are studied that may help in optimum design analysis of a porous pin fin. Finally, the increase in heat transfer is noticed by selecting porous medium condition in the fin.

Experimental analysis of pump-assisted and capillary-driven dual-evaporators two-phase cooling loop

Abstract A mechanical pump-assisted and capillary-driven two-phase cooling loop, with dual-evaporators whose liquid supply lines connected in parallel and series in one loop, was constructed to experimentally investigate the performance of the multi-evaporators cooling loop. In the evaporator, a porous membrane separating liquid and vapor spaces by capillary action is used to promote a thin-film boiling of low thermal resistance. The liquid in a reservoir is first supplied using a mechanical pump to the liquid space in the evaporator and back to the liquid reservoir. Then, a fraction of the liquid in the evaporator is pulled by capillary action through the porous membrane, to porous pin fins and is vaporized on the evaporator heater block where the heat is applied. In this study using the dual-evaporators loop, various heat load conditions were tested using the stepwise heat inputs up to 1200 Watts (102 W/cm 2 ), or 600 Watts for each evaporator. Difficulties and limitations experienced with both parallel and series tests are discussed. It is found from the tests that the total heat inputs in the two-phase system govern the system temperatures and pressures, while the individual heat input to each evaporator determines the evaporator temperatures. Setting up the evaporators in parallel allows for more heat load than series. Also, since the evaporators are connected through the vapor and liquid lines, one evaporator can change another evaporator’s boiling condition (thermal resistance) even though its heat input is not changed.

Forced Convection Heat Transfer Enhancement by Porous Pin Fins in Rectangular Channels

The forced convective heat transfer in three-dimensional porous pin fin channels is numerically studied in this paper. The Forchheimer–Brinkman extended Darcy model and two-equation energy model are adopted to describe the flow and heat transfer in porous media. Air and water are employed as the cold fluids and the effects of Reynolds number (Re), pore density (PPI) and pin fin form are studied in detail. The results show that, with proper selection of physical parameters, significant heat transfer enhancements and pressure drop reductions can be achieved simultaneously with porous pin fins and the overall heat transfer performances in porous pin fin channels are much better than those in traditional solid pin fin channels. The effects of pore density are significant. As PPI increases, the pressure drops and heat fluxes in porous pin fin channels increase while the overall heat transfer efficiencies decrease and the maximal overall heat transfer efficiencies are obtained at PPI=20 for both air and water cases. Furthermore, the effects of pin fin form are also remarkable. With the same physical parameters, the overall heat transfer efficiencies in the long elliptic porous pin fin channels are the highest while they are the lowest in the short elliptic porous pin fin channels.