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AbstractA novel porous multi-jet impingement cooling technology since the current conventional cooling technologies are insufficient for thermal engineering devices. This innovative numerical study explores the effect of various metal foam sizes (h/H), jet numbers (n) and wavy jet target plates (C) on the hydrothermal performance and thermodynamical performance at varying Reynolds numbers (Re). The novel results of multi-objective optimum design are a unique aspect of this work by combining the results of RSM with CFD, where low porosity (ε = 0.1), low applied heat flux (Q = 100 × 103 W/m2) and low location jet ratio (LRVin = 0.26) were achieved the aim of the optimum hydrothermal performance (NumP/NumS = 25-30 times and Tb Reduction% = 83.5%-89.5%) and the thermodynamical performance (EG Reduction% = 93%-96% and CoPCarnot = 2.3-6.5 times). Thus, a valuable procedure for the optimal design of the hydrothermal and thermodynamical performance for porous multi-jet impingement cooling is proposed. [ABSTRACT FROM AUTHOR]

A numerical model was used to simulate natural convection heat transfer in a two-dimensional square enclosure filled with nanofluid and saturated with porous media. The enclosure contained three heated tubes with Rayleigh numbers (Ra) ranging from 102 to 3 × 104. The governing equations with Boussinesq approximation for natural convection were solved iteratively using the finite volume technique through ANSYS FLUENT-CFD commercial package. The Darcy–Forchheimer–Brinkman and Local Thermal Equilibrium models were applied for water and nanofluid flow across the porous zone. The numerical analysis was executed systematically for significant parameters that have a substantial impact on natural convection heat transfer, namely, aspect ratio (AR = 1.25 − 3.75), nanoparticle volume fraction (Φ = 0.25%, 0.5%, 0.7% and 1%), and the porosity of metal foam (ε = 0.3, 0.4, 0.5, 0.6 and 0.7). The aspect ratio was found to have a considerable impact on the averaged Nusselt number (Nuave). For AR = 3.75, the value of Nuave for all Rayleigh numbers increased by approximately 5.22 times compared to AR = 1.25. Moreover, Nuave remained approximately constant as the concentration of alumina-water nanofluid increased from 0.25% to 1%. The novelty of this study lies in the multi-objective optimal design approach adopted by adopting DX-12 with the outcomes of ANSYS FLUENT-CFD. The averaged Nusselt number and convection heat transfer rate reached their optimal values by nearly 13 and 9 times, respectively, at the lowest possible porosity (ε = 0.3), the lowest possible nanofluid concentration (Φ = 0), and the highest possible aspect ratio value (AR = 3.75). [ABSTRACT FROM AUTHOR]

The application of natural convection heat transfer within a novel Ϻ-shaped cabinet filled with single-phase pure water/metal foam is investigated numerically. Natural convection is modeled throughout the porous zone using the Local-Thermal-Equilibrium mode and Darcy-Forchheimer-Brinkman law. A novel Ϻ-shaped cabinet with varies Ϻ ratio (0 ≤ Ϻ ≤ 0.8) and temperature difference (10 K ≤ ΔT ≤ 40 K) is applied at a constant porosity of ε = 0.85. Furthermore, the current research is conducted to analyze the response surface methodology (RSM) accompanied by a computational simulation for optimizing the multi-objective function of the M-shaped cabinet in terms of two computed responses: maximizing the Nusselt number ratio (NNR) and minimizing the entropy generation ratio (EGR). The optimization study considers the various pore per inch (10 ≤ PPI ≤ 50), Darcy number (10-9 ≤ Da ≤ 10-1) and uniform magnetic fields (0 ≤ Ha ≤ 100). The results showed that the optimum working conditions consistent with the desired aim are achieved in the maximization of NNR by nearly 20.84 times and the minimization of EGR of 0.895 obtained at Ha = 100, Da = 10-1 and PPI = 30. Thus, the current investigation is a unique application study of CFD and RSM which provides a helpful reference for the optimum design cooling efficiency and entropy performance of a novel Ϻ-shaped cabinet. [ABSTRACT FROM AUTHOR]

AbstractThe cooling and entropy efficiencies of natural convection inside cavities within fully saturated metal foam play a vital role in thermal engineering applications systems. The current study employed response surface methodology (RSM) coupled with ANSYS FLUENT-CFD for a two-dimensional W-shaped cavity, which has not been examined previously. Several effective physical factors were considered, including the aspect ratio (W = h/H = 0, 0.2, 0.4, 0.6 and 0.8) and the applied temperature variation (ΔT = Th − Tc = 10, 20, 30 and 40 K). Additionally, the thermal performance (NumW/NumO and QW/QO) and entropy generation (EGW/EGO) improved under the optimum design of pore per inch (10 ≤ PPI ≤ 30), the number of wave amplitude (1 ≤ n ≤ 3) and aspect ratio (0.2 ≤ W ≤ 0.8) utilizing both RSM and CFD. The results showed that the optimal design of natural convection within a fully saturated metal foam W-shaped cavity at PPI = 10, n = 3 and W = 0.8 resulted in enhancements of approximately 2.875 times for both NumW/NumO and QW/QO while maintaining reasonable EGW/EGO at 1.193 times. Moreover, the novelty aspect of this research lies in the successful achievement of multi-objectives improving NumW/NumO, QW/QO and EGW/EGO by applying the RSM approach in combination with ANSYS FLUENT-CFD. Thus, the optimal working procedure of RSM and CFD is aligned with the desired goals, as the cooling and entropy efficiencies of the porous W-shaped cavity are considered acceptable and satisfactory. [ABSTRACT FROM AUTHOR]

Over the past few decades, researchers have shown significant interest in enhancing the thermal efficiency of heat sinks while simultaneously increasing the power generation capacity of electronic devices and reducing their size. In this study, the focus lies on the originality of employing conical perforated pin heat sinks with multiple perforations (N = 0, 1, 2, and 3) and various conical pins inclination angles (Φ = 0°, 1°, 2°, 3°, and 4°). The study aimed to numerically investigate the effects of a perforated conical pin and cone inclination angle on heat transfer, pressure drop, CPU temperature, and hydrothermal performance (HTP) across the heat sinks using a three‐dimensional, turbulent flow as k–ω SST model combined with the thermal conjugate model. A validated CFD model is employed to conduct a parametric analysis of the effects of the quantity and placement of circular holes. A summary of the results reveals that Model B3 exhibited the highest HTP value, reaching approximately 1.15 at U = 10 m/s, with a commendable reduction in heat sink mass of over 18%. Ultimately, the perforated conical pin heat sink demonstrates the potential to fulfill the primary objective of this investigation, which is achieving an overall improvement in Nusselt number, CPU temperature, pressure drop, and reduced heat sink mass. [ABSTRACT FROM AUTHOR]

The hydraulic‐thermal characteristics of 3D pinned heat sink designs have been numerically compared as the first part of a three‐part investigation. Five different pin geometries (circular, square, triangular, strip, and elliptic pins) and an unpinned heat sink with three types of nanofluids (Al2O3–H2O, SiO2–H2O, and CuO–H2O) are considered for laminar forced convection. The range of Reynolds number is from 100 to 1000, and volume fractions vary between 0% and 5%. The finite volume method is employed to solve the Navier–Stokes and energy equations by employing a SIMPLE algorithm for a computational solution. Three parameters are presented—the Nusselt number, the bottom temperature, and the hydrothermal performance of the heat sink with pressure drop data. The findings indicated that the overall hydrothermal performance of elliptic‐pinned (EP) heat sinks produces the most substantial value of 3.10 for pure water. For different nanofluids, the SiO2–water nanofluids with EPs have the most significant hydrothermal performance. Also, this factor is enhanced with an increase in nanofluid concentration up to nearly 3.34 for 5% of SiO2–water. Consequently, applying the elliptic‐pinned heat sinks is recommended with pure water for considering an increase in the pressure drop, with 5% of SiO2–water nanofluids, regardless of an enlargement of pressure drop for heat‐dissipation applications. [ABSTRACT FROM AUTHOR]

The energy and exergy characteristics of 3D‐pinned heat sink (HS) designs have been computationally compared as the second part of a three‐part investigation. Different pin profiles, such as circular, square, triangular, strip and elliptic pins, and without pin HS are conducted with three different types of nanofluids—Al2O3‐water, SiO2‐water, and CuO‐water for laminar forced convection. The concentrations of nanofluids vary from 0 to 5 vol% with different Reynolds numbers ranging between 100 and 1000. The finite volume method employing the SIMPLE algorithm for a computational solution is applied to solve the Navier–Stokes and energy equations. Four criterions studies are explained—energy efficiency, exergy loss, and exergy efficiency of HSs with pressure drop. The results showed that the highest energy and exergy efficiencies are nearly 76% and 57%, respectively, for elliptic‐pinned HSs using pure water, while about 82% and 62% using 5 vol% of SiO2‐water nanofluids. Besides, the elliptic‐pinned HSs have a favorable reduction in the exergy loss, nearly 17% using 5 vol% of SiO2‐water nanofluids. Subsequently, the elliptic‐pinned HS is recommended to apply with pure water considering the development in pressure drop required. However, the elliptic‐pinned HSs could be employed with 5 vol% of SiO2‐water nanofluids regardless of the development in pressure drop required for thermal energy dissipation applications with more exergy efficiency and reduction of exergy loss. [ABSTRACT FROM AUTHOR]

Ever since the rapid increase in both the demand for the miniature electronic devices and their applications, heat dissipation in the electronic components has been a serious issue. A miniature plate‐pin heat sink model with square, circular, and elliptic pins is considered to enhance the hydrothermal performance of this kind of compact heat sink (CHS). Water and 3% of SiO2‐water nanofluids of volume fraction were used with different Reynolds number ranges (100‐1000). The findings show that the base temperature of heat sink reduces while the Nusselt number enhances by using nanofluids and increasing Reynolds number. The lowest value of the base temperature is nearly 25% for the square pins and circular pins CHSs compared with a plate–fin heat sink at 3% of nanofluids. Furthermore, the highest value of the Nusselt number is about 98% at 3% SiO2 for circular pin CHSs compared with the plate–fin heat sink. However, the pressure drop of CHSs is higher than that of plate–fin heat sink. Moreover, the most significant hydrothermal performance value is about 1.44 for water and around 1.51 for SiO2 as using the CHS with circular and elliptic pins depends on the Reynolds number. Thus, applying CHSs with nanofluids instead of the traditional heat sinks might produce a substantial enhancement in the hydrothermal performance of heat sinks. HIGHLIGHTS: 1.Miniature compact heat sinks. 2.Hydrothermal performance enhancement of heat sinks. 3.Compact heat sinks using SiO2‐water nanofluids. [ABSTRACT FROM AUTHOR]

In this study, two models have been analysed numerically to examine the impact of the geometry and the working fluid under laminar flow on heat and flow characteristics. The first model is a perforated pinned heat sink (PPHS) and the second is a new design of a uniform micro-channel having different shapes of vortex generators (VGs) positioned at intervals along the base of the channel. The VG shapes are circular, triangular and rectangular, and are compared to each other based on constant volume. Models with Reynolds number in the range of 50 to 2300 are subjected to a uniform heat flux relevant to microelectronics air and water cooling. Validations against previous micro-channel studies were conducted using the COMSOL Multiphysics® software package and found to be in good agreement. The results show that there is no significant enhancement in heat transfer using water in PPFHS. However, the VGs described here are shown to offer significant potential in combatting the challenges of heat transfer in the technological drive toward lower weight/smaller volume electrical and electronic devices. It is also found that the circular VGs offer the best heat performance among the proposed shapes. [ABSTRACT FROM AUTHOR]

The generated heat from photovoltaic (PV) cells, electronic device, transformer, internal combustion (IC) engine, and so forth can be mentioned as the most critical issues confronting modern industries. Leading to high temperature causes a problem in devices and sometimes cause damage. A mini‐heat sink is one of the common ways to cool and remove created heat from these engineering devices. This research used compact heat sinks, combined pins, and plate fins, with using SiO2‐water nanofluids for enhancing the hydro‐thermal performance and entropy generation of heat sinks. The computational investigation and simulation of compact heat sinks are performed by using ANSYS‐FLUENT 14.5. The compact heat sinks include three different pins cross‐section: circular (PCP), square (PSP), and elliptic (PEP) as well as flat finned heat sinks as a standard case. SiO2‐water nanofluids with the various nanoparticles volume fraction of 0% to 5% have been examined for Reynolds number range between 100 and 1,000. The main data display that the supreme Nusselt number is for PCP around 93% and 100% for 0% and 5% SiO2‐water, respectively compared with plate fins heat sink. The PCP and PSP have the lowest base temperature, around 25% for 0% and 5% nanofluids. Furthermore, at Re = 1,000, the highest hydro‐thermal performance is for PEP at 1.44 and 1.52 for pure water and SiO2‐water, respectively. While, the most magnificent hydro‐thermal performance is for PCP at 1.44 and 1.50 for pure water and SiO2‐water, respectively, as Re = 800. Moreover, the PCP and PSP have the smallest total entropy generation, approximately 42% for pure water and 5% SiO2‐water among other heat sinks. Thus, it is recommended to use this kind of heat sinks with nanofluids instead of traditional coolant of PV cells. [ABSTRACT FROM AUTHOR]