Computational Fluid Dynamics ANSYS Research Articles

PARTICLE SWARM OPTIMIZATION AND CFD ANALYSIS OF A HEAT SINK FOR FORCED CONVECTIVE COOLING OF A DC/AC INVERTER

Power inverters play a crucial role in converting DC voltage and current to AC voltage and current. Its efficient operation relies on effective thermal management of the semiconductor devices, such as the IRF 3205 MOSFET chip which facilitate the switching operations to prevent thermo-mechanical stress that could to failure. This research developed and optimize a heat sink for an IRF 3205 MOSFET chip in a 3.5 KVA power inverter, using the Particle Swarm Optimization technique and experimented with a 3.5 KVA 24 V power inverter operating a 1.5HP air-conditioning unit. The heat sink geometry has 26 fins, 4 mm fin thickness, 40 mm fin height, 3 mm fin spacing, 2 mm fin base thickness, 179 mm length, 80 mm width and a thermal resistance of 60.75 °C/W. The thermal performance was evaluated using ANSYS Computational Fluid Dynamics (CFD) and results showed maximum base temperature of 65.85°C and experimental temperature of 64°C after two hours of steady operation dissipating heat of 45W. The results from both numerical and experimental data demonstrate the effectiveness of the optimized heat sink in maintaining the chip's temperature below its maximum working threshold of 170°C.

A Comparative Analysis of Aerodynamic Performance: Straight Fin and Curved Fin Rockets using Computational Fluid Dynamics (CFD)

This investigation seeks to discern the aerodynamic differentials between rockets featuring straight fins and those with curved fins, focusing on the drag coefficient (cd), lift coefficient (cl), and moment coefficient (cm). Employing the computational fluid dynamics (CFD) methodology within ANSYS Fluent software, the research endeavors to provide comprehensive insights. The rockets under scrutiny share a common cylindrical body configuration, boasting a 70 mm diameter, a conical nose, and four symmetrically positioned fins along the lower body. The CFD analyses encompass subsonic Mach 0.6 and supersonic Mach 1.2 scenarios, with the angle of attack systematically varying from 0° to 25° at 5° intervals for each velocity setting. The outcomes of the simulations reveal notable trends: both cd and cl exhibit an upward trajectory, while cm experiences a decrement with escalating angles of attack and velocities. The culmination of Ansys CFD simulations for both rocket configurations unequivocally indicates superior flight performance for the straight fin rocket. This discernment is grounded in the observed amplification of drag and lift coefficients, coupled with the concomitant reduction in the moment coefficient, thus elucidating the nuanced aerodynamic distinctions between straight fin and curved fin rockets across varying flight conditions.

A Numerical Analysis on the Performance and Optimization of the Savonius Wind Turbine for Agricultural Use

Given the state of the world nowadays, renewable energy is becoming more and more essential rendering wind turbine electricity quite important. Its shape and the fact that the Savonius vertical axis wind turbine runs at relatively low wind speeds with high torque values makes it suitable for practical uses such as that of an irrigation system in agriculture industry. This paper utilizes numerical research with Computational Fluid Dynamics (CFD) to investigate the performance of a vertical-axis wind turbine. The ANSYS CFD program was engaged to construct the simulations during the pre- and post-processing stages. Wind speed remained constant while the angular velocity was altered to enable analysis of the flow through the wind turbine. Because of its mechanical simplicity, the primary profile of a semicircle has remained a typical option for turbines that generate high torque based on drag force. The effects of using elliptical curves and the fluctuation in thickness along the profile chord were both examined in this study. Equivalently, an attempt to optimize the rotor's design was made. After the performance of a numerical simulation, a geometry consisting of simple circle arcs was developed, with a 10.9% improvement in the power coefficient, analogous to prior optimizations with more complicated geometries. The numerical results derived include the torque coefficient evolution throughout a full rotation as well as the distribution of vorticity magnitude at different rotor points.

THERMAL ANALYSIS OF A PLATE HEAT EXCHANGER (PHE) FITTED WITH CARDING TOOL PATTERNS USING CFD MODELING

Inspired by the wool carding tools, a new plate heat exchanger (PHE) design was developed, tested, and analyzed numerically. The present research work used computational fluid dynamics (CFD) simulations to examine the impact of various parameters, such as the rib type (continuous and discrete), the arrangement type (rectangular, square, and triangular), and the geometrical parameters (transversal and longitudinal pitches) on the PHE hydraulic and thermal performances. A three-dimensional (3D) evaluation of turbulent flow over a plate fitted with carding tool patterns was conducted using the<i> k-ε </i>turbulence model within the Reynolds number range from 400 to 1800. The numerical results were compared to previous experimental research to validate the dependability of the technique, and a mesh independence analysis was performed to confirm the precision and the accuracy of the CFD method. The results show that CFD ANSYS software can effectively predict the pressure drop across the carding tools and provide valuable insights into the fluid flow behavior within the system in terms of calculating the thermal hydraulic performance parameter (THPP) and the thermal effectiveness <i>ε </i>. The ultimate goal of this research work was to identify the ideal arrangement with the highest heat transfer rate and the lowest pressure losses in terms of determining the best THPP. Compared to the conventional chevron-type PHE, the thermal performance of the novel PHE design was enhanced by 25.63% and 47% in terms of nondimensional parameters e and THPP, respectively.

Investigation of Thermo-Hydraulic Performances of Artificial Ribs Mounted in a Rectangular Duct

This research investigates the fluid flow characterization and thermohydraulic performances (THP) of rib surfaces, using computational and experimental methods. ANSYS computational fluid dynamics (CFD) software was used to predict and validate the findings in the experimental setup. Artificial rib surfaces, including polygonal and forward trapezoidal-shaped ribs, were placed in the absorber plate at different relative pitch distances (p/e) = 6.7, 10, 13.4 and relative height (e/d) = 20, and the mass flow rate of air (working fluid) varied at Reynolds numbers ranging from 2000 to 20,000. According to the validation results, the RNG renormalization k-ε model was selected for the investigation. The results show that strong turbulence occured closer to the wall surface and behind the rib surface, enhancing thermal performances due to the sharp edge shape of the rib. A polygonal rib with a pitch distance of p/e = 6.7 achieved a higher Nusselt number (Nu) and thermohydraulic performance of 2.95 at Re 4000. An empirical correlation between the Nusselt number (Nu) and friction factor (f) was developed using linear regression analysis and was compared with the predicted values. The comparison results show a close range of ±8% between the experimental and predicted values.

Wind resource assessment and influence of atmospheric stability on wind farm design using Computational Fluid Dynamics in the Andes Mountains, Ecuador

In recent years, research has revealed that hydropower designs in Ecuador have not adequately considered sensitivity to climate change. In addition, variations in rainfall patterns cause a drought from July to October. Therefore, it would decrease the flow of the rivers that feed the dams for hydroelectric generation, which would result in a significant reduction of its generating capacity.To prevent this inconvenience from occurring, it is necessary to promote the use of wind energy to diversify the Ecuadorian energy matrix. This matrix is made up of 70% hydropower and 0.26% wind power. Moreover, the Ecuadorian Andes has significant untapped wind potential due to their complex topography. Currently, there are no detailed studies on wind potential or wind energy prediction in the Andes. As a result, wind resource characterization is necessary. In order to address the challenges mentioned above, promote wind energy development, assess wind potential, and diminish the need for thermal generators. This article describes a methodology for wind resource characterization over complex terrain using measured data from two meteorological towers installed in the mountainous zone of study and wind characteristics modeling through the Ansys Computational Fluid Dynamics (CFD) software for the positioning of 11 Goldwind 70/1500 kW wind turbines to optimize the Annual Energy Production (AEP) of a hypothetical wind farm.The study’s main findings indicate that the wind passing between two volcanoes has a high wind potential. This potential is dependent on meteorological variables, orography, and the accelerating effect of wind speed. These favorable conditions make it possible to install a wind farm in this area with 11 high-power wind turbines. Furthermore, the most suitable turbulence model for wind farm design using Ansys Fluent CFD is the K-epsilon which can model with high precision the profile of wind characteristics over a simulated mountain under the influence of atmospheric stability on the state of the air mass to assist in the decision-making process when selecting the best wind farm locations over complex terrain in the Ecuadorian Andes.

Analysis of the Effect of Dimensional Variation and Number of Air Inlets on the Efficiency of Gasification Stoves using Computational Fluid Dynamic (CFD) Simulation

Nowadays, the consumption of non-renewable energy is high. As a result, the availability of this energy is decreasing. Because of this, other energy alternatives are needed. One example of another option is the use of biomass. An example of using biomass is the gasification process. This process was carried out in a device called a gasification stove, namely a gasifier. A gasifier has been developed to produce an optimal combustion system. The constraints in this development are costs for manufacture and the potential for failure. Therefore, simulations using Ansys Computational Fluid Dynamics (CFD) software student versions were carried out to reduce the costs for manufacture and the potential for failure of the gasifier. The simulation contains dimensional variations and the number of air inlets of gasifier of downdraft gasifier, updraft gasifier, and entrained flow gasifier. Further, the influence of the dimensions and quantity of inlet that affect each design’s efficiency and the temperature was examined. The simulation results show that the best dimensions for the downdraft gasifier, updraft gasifier, and entrained flow gasifier are height and diameter of 50cm; 14.5cm (A1), 144cm; 70cm (C1), and 900cm; 300cm (B3), respectively. The best number of air inlets of A1, C1, and B3 gasifiers is 6, 1, and 6, respectively. Thus, the efficiency of each gasifier A1, C1, and B3 are 11.393%, 9.354%, and 50.885%, respectively. Furthermore, the A1, C1, and B3 gasifiers temperatures were 1055.25 K, 1383.44 K, and 3580.15 K, respectively. Therefore, this study suggested that the gasifier development could be optimized using simulation to reduce manufacturing costs and failures.

Development of CFD simulation model of earth air heat exchanger for space cooling of a 36 m2 house in tropical climate Banda Aceh, Indonesia

The global warming makes the ambient temperature hotter and greater efforts are made to reach a comfortable temperature. The continuous use of air conditioners that consume electricity is also unsustainable for the surrounding environment. Several studies on thermal comfort have been conducted by various researchers. Earth-air heat exchangers (EAHE) with air-working fluids can be used as a passive contribution to reduce building energy requirements for heating or cooling purposes. It should be noted that there is very little information in the literature on the development of a CFD (Computational Fluid Dynamic) simulation model of an EAHE for space cooling of a 36 m2 house in a tropical climate, such as Banda Aceh, Indonesia. Therefore, this study aims to examine the performance of EAHE with several variations in design parameters, such as pipe length, pipe diameter, number of pipe bends, and the type of soil where the EAHE is installed, as well as the thermal regime of a 36 m2 house either with or without the use of EAHE. The simulation in this study was conducted with CFD ANSYS Fluent software. The inlet air temperature of EAHE was set to be the same as the ambient air temperature, namely 31.4oC. The simulation results reveal that for variations in pipe length, the highest drop in outlet air temperature was yielded by the 47 m pipe length, which is 26.8°C. In which an increase in pipe length causes a decrease in air outlet temperature. The variation in pipe diameter does not significantly affect the outlet air temperature. Where the average air temperature drop at the EAHE exit is 0.046oC. The variation in number of turns shows that the drop in outlet air temperature is identical, namely 28.2°C, despite the fact that their pressure drop values are different. In addition, it was found that the performance of EAHE buried under different types of soil is distinct. The highest drop in outlet air temperature was generated when the EAHE was buried in silty soil, namely 26.1°C. A case study on a 36 m2 house shows that the utilization an underground heat exchanger can reduce the house’s indoor temperature by 2°C, with an average house temperature of 30.4°C compared to that with a natural ventilation.

Optimisation of the Aerodynamic Shape of a Monorail Suspended Unibus

The aerodynamic optimisation of the shape of a monorail suspended unibus of string transport has been described within the study on the influence of geometric and structural elements on aerodynamic characteristics. The estimate was carried out through a comparative analysis of the features of two shapes of a model with a further change and recalculation of the model being finalised. The comparison was focused on the drag force and the shape drag coefficient. The calculations used a gas dynamics model based on the Reynolds equations using the Menter SST-k-ω (shear stress transport) turbulence model. To solve the equations to find the design functions, an upwind second-order discretisation scheme was used applying the «pressure–velocity» refinement procedure in the framework of SIMPLE algorithm of Patankar–Spalding with the ANSYS Computational Fluid Dynamics Software. The dimensions of the computational domain were chosen considering the geometric dimensions of the 3D model of the shape. Boundary conditions were identified in the solver. The simulation was carried out for the case of motion of a vehicle at a constant speed. The calculations have shown the importance and influence of the geometry of the transition sections of the vehicle body, the mandatory use of wheel fairings and the advantages of the S-shaped tail. The proposed design optimisation made it possible to reduce the drag force and coefficient by 16,9 %. The studies have resulted in selection of the optimal vehicle model which has the lowest aerodynamic drag coefficient, which made it possible to improve the energy efficiency of the system and its environmental friendliness, and consequently, the profit potential of the transportation process.

CFD Analysis of the Eccentricity Ratio on Journal Bearing due to Differences in Lubrication Type

Lubrication on journal bearings plays a vital role in reducing metal-to-metal friction, separates the reliable components. Often there is a decrease in lubrication conditions, which will cause failure or a change in roughness to the inner surface. Direct metal-to-metal contact between the bearing's inner and journal surface will gradually deform the bearing. In diesel engine applications, lubrication is aiming to minimize failure or damage to the journal bearing. This paper investigates a 3D CAD model of a journal bearing using the ANSYS Computational Fluid Dynamics software. The effect of eccentricity ratio is analyzed for semisynthetic lubricating oil R3 10W-30 and synthetic oil. The result shows that synthetic oil has a considerable pressure compared to R3 10W-30, especially at a higher eccentricity ratio.

New Designed Main Nozzle of Air-Jet Weaving Machine for Optimizing Air Consumption using CFD Simulation

The air-jet weaving machine is widely used in the textile industry and the main nozzle and acceleration tube is one of its key components of the machine. In this paper, the influence of some parameters, including the input air pressure with air inlet length and the structure of the nozzle core and its internal diameter, on the internal flow field of the main nozzle is analyzed to get the velocity of flow at the optimum air pressure that optimizing the air consumption. The flow field inside an air-jet loom main nozzle is studied by simulating the design of the main nozzle and acceleration tube, by means of a two-dimensional model implemented in the Ansys computational fluid dynamics (CFD) code Fluent, by designing the new main nozzle by working on the structural geometry of the main nozzle and acceleration tube. In order to determine the optimum air pressure for the required air velocity with optimum air consumption to flow weft yarn in an air-jet weaving machine.

Centrifugal Pump Design: An Optimization

A centrifugal pump is an efficient piece of machinery that is often used in the activities of our everyday lives as well as the production of industrial goods. Due to the ever-increasing demands of our contemporary lifestyle, the process of designing a pump is becoming more authoritarian and demanding. In order to assist designers in overcoming these limits, an optimization algorithm would be suggested. This algorithm would help designers use optimum design methodologies and reduce risk throughout the manufacturing stage. ANSYS's Computational Fluid Dynamics (CFD) tool was used to develop numerical models for simulation. These models were created using ANSYS. For the purpose of the multi-objective optimization design, the simulation's best-chosen model was taken into consideration. This algorithm was used throughout the process of designing the ideal solution. Several design models were created by selecting characteristics such as the size of the pump volute casing section, the tongue's length, and the tongue's angle. The findings demonstrate that the provided strategy is viable for resolving the issue with the optimal design. These findings have the potential to serve as an encouraging reference for companies that manufacture centrifugal pumps, as well as researchers who are interested in applying their invention and development to the pump design sector in the future.

Sand erosion modeling in generic compressor rig testing

AbstractBased on erosion coupon tests, a sand erosion model for 17-4PH steel was developed. The developed erosion model was validated against the results of compressor erosion tests from a generic rig and from other researchers. A high-fidelity computational fluid dynamics (CFD) model of the test rig was built, a user-defined function was developed to implement the erosion model into the ANSYS CFD software, and the turbulent, two-phase flow-field in multiple reference frames was solved. The simulation results are consistent with the test results from the compressor rig and with experimental findings from other researchers. Specifically, the sand erosion blunts the leading edge, sharpens the trailing edge and increases pressure-surface roughness. The comparisons between the experimental observations and numerical results as well as a quantitative comparison with three other sand erosion models indicate that the developed sand erosion model is adequate for erosion prediction of engine components made of 17-4PH steel.

Studi Karakteristik Termohidrolik Pada Kanal Pendingin Teras Reaktor SMART Menggunakan CFD Ansys Fluent

The Small Modular Reactor (SMR) type nuclear power plant is currently growing very rapidly by offering various kinds of safety features, both active and passive. One of the SMRs currently to be built and operated is the SMART (System-integrated Modular Advanced Reactor) reactor. The SMART reactor is designed to use conventional PWR fuel types but operates at a lower flow rate and core inlet temperature than conventional PWR. The existence of this basic difference needs to be a separate note for us in evaluating the safety of the SMART Reactor, especially for the thermohydraulic aspect. The thermohydraulic characteristics have been carried out previously using the MATRA code, however, the temperature distribution in the cooling sub channel is still unknown. Therefore, the purpose of this study is to calculate the temperature distribution in the cooling sub-channel on SMART. The program used in this study is CFD ANSYS. Ansys Fluent 2021 R1 Computational Fluid Dynamic (CFD) computer code was used to simulate coolant flow and heat transfer from fuel to coolant. The cooling sub channel was modeled consisting of four fuels with a diameter of 0.95 cm and a pitch of 1.26 cm in a rectangular arrangement surrounded by light water coolant. Based on the calculation, there is an increase in the average temperature of the coolant between the input and output sides of the coolant sub channel of 60 ℃, which is greater than the SMART reactor design. The fuel center and fuel cladding temperatures were calculated at 1100 ℃ and 350 ℃, respectively. This difference is caused by the modeling assumptions which is still far from the actual design. The model was assumed to consist of pure fuel and ignores the actual variations in fuel and fuel assembly. Keywords: SMART Reactor, CFD, Ansys Fluent, Thermal Hydraulic

Comparative Study of Flow Patterns around Rhizophora and Avicennia Mangrove Roots Using Computational Fluid Dynamics Simulation

The goal of this research is to visualize and compare the patterns of the fluid flow around stilt roots of Rhizophora mangrove species and pneumatophore roots of Avicennia mangrove species in Pichavaram mangrove forest to better understand how mangrove roots can potentially slow down heavy wind flow and thereby offer protection to the coast from natural disasters. The flow around the roots is simulated and analyzed using ANSYS Computational Fluid Dynamics (CFD) software using an unsteady k-ε turbulence model. Wind and water flow velocities vary with respect to time during tsunami, cyclones, typhoons, or hurricanes. Hence, inlet velocity taken as the step function is applied to simulate the change in speed of fluid flow to study the flow behavior. Velocity and pressure are measured at various points around Rhizophora and Avicennia mangrove roots. The findings of the simulation reveal that the Rhizophora stilt roots and pneumatophore roots of Avicennia marina continuously lower the fluid velocity. The Rhizophora mangrove roots can largely decrease the flow velocity because of the complexity and its root dimensions in comparison to Avicennia roots. The data obtained from this research can be applied to increase the efficiency of breakwater models and, as a result, safeguard the shore from natural disasters.

Experimental investigation of the failure of shield grease seals under the influence of environmental factors: A case study

Shield tail sealing is a critical problem that influences work safety during shield tunneling processes. In recent years, the number of accidents caused by the failure of shield grease during shield tunnel construction has gradually increased. Taking Foshan Metro Line 2 accident as the research background, this study adopts the indoor model test and Ansys computational fluid dynamics (CFD) to estimate the grease sealing performance under the influence of environmental factors. The results indicate that, temperature increase, seawater, and sand mixing will greatly weaken the sealing performance of grease. In fact, the grease viscosity has been greatly weakened due to environmental factors. Using the numerical model, a simulation study was carried out on the sealing performance of the shield tail under the conditions of different grease viscosity and length of grease cavity. Grease viscosity and length of grease cavity have a linear positive relationship with the time of initial water leakage. Finally, a grease sealing performance evaluation model is proposed. Based on the above research results, the environmental impact coefficient k can be determined. The results of this study can be beneficial in both the selection and evaluation of the shield tail grease.

Numerical and computational fluid dynamics analysis of airflow in the air intake manifold of a 1.8L engine with respect to different intake velocity

The intake air manifold is a vital part of any internal combustion engine. The main purpose of the air intake manifold is to provide sufficient air to each cylinder and also equal distribution of air flow for each runner. The air needed to be distributed evenly within the runners, to achieve the maximum efficiency and performance of the engine. The present study is performed on the air intake manifold used over a 1.8-liter Dual Overhead Cam Engine (DOHC) in-Line16-valve 4-cylinder engine (2015 Model). The main objective of this study is to perform computational fluid dynamics (CFD) analysis using Ansys – Fluent package. The analysis is performed using steady-state and transient conditions. The simulations are performed by varying the air intake velocity, also the effect of each runner with references to the time (Transient). The mathematical calculation is performed to having different boundary conditions to enhancing the analysis. The results obtained for the outlet velocity using mathematical calculation 113m/sec and that of simulation is 79m/sec. This paper mainly focuses on the flow simulation study of the air-intake manifold using Ansys CFD Fluent for the four outlet runners with regards to the different inlet velocity. Furthermore, the study is incorporated by the mesh resolution method by using three different values such as (0, 4 and 7). This method can be adopted for any air-intake system and a comparative study can be performed.

Heat transfer modeling of shrimp in tunnel type individual quick freezing system

AbstractCryogenic freezers are commonly used for quick freezing of high‐value food products at a lower temperature. These freezers offer improved overall product quality and reduced dehydration and drip losses. An accurate prediction of heat transfer during the food freezing process is useful in deciding proper production, design, handling procedure, and amount of cryogen required. In this study, computational fluid dynamics (CFD) was used for numerical modeling of heat transfer phenomena in a freezing system during individual quick freezing (IQF) of shrimp. The residence time of shrimp in the developed IQF tunnel freezer was determined using modified Plank's equation and verified by experimentations. Modeling was done in two zones of the freezer: (i) Precooling zone containing cold liquid nitrogen (LN2) vapors that were utilized for precooling of incoming shrimp and (ii) freezing zone where LN2 was sprayed on shrimp before exiting freezer. Simulations of heat transfer in shrimp were performed using the Ansys CFD software at seven different locations of the IQF tunnel freezer. Results revealed that the core temperature of shrimp decreased from 304.5 K to 263 K as it passes through the freezer. In general, as compared to other segments of shrimp, core temperature of shrimp was the highest while the top portion was minimal. Dynamics of velocity distribution, thermal profile, and spray modeling results of cryogen in the freezer supported simulation model of shrimp. Overall, numerical modeling results are consistent (≤5% variation) with experimental values.Practical ApplicationsThe cryogenic freezer is widely preferred to obtain a superior quality of frozen food products owing to minimal defects (cracking and break down), drip loss, and freezing time compared to traditional mechanical freezers. The inefficient utilization of cryogen and handling issues results in a higher cost of food products frozen with IQF technology. Thus, an insight into heat transfer phenomena in cryogenic freezers may lead to improvement in the design, efficient utilization of cryogen, reduction of freezing time, and improvement in overall product quality. In conclusion, these would aid in reducing the cost of the technology.

Review on Condenser Heat Transfer of Computational FluidDynamic System Using ANSYS

Condenser is a high pressure side heat exchanger in which heated vapor enters and gets converted into liquid form by condensation process. In the condenser coil, gaseous substance is condensed into liquid by transferring latent heat content present in it to the surrounding. In the whole process, mode of heat transfer is conduction in condenser coil and forced convection between refrigerant and condenser. Any refrigeration system's backbone is comprised of condensers. It aids in the transfer of heat from the refrigerant to the universal sink, which is the atmosphere. The latent heat of the refrigerant is lost in the condenser. At the entry of the condenser, vapours from the compressor enter, and during the length of the condenser, the vapours are converted to liquid form, resulting in refrigerant in the form of saturated or even sub-cooled liquid form at the condenser's exit. In several sectors of chemical and petroleum engineering, computational fluid dynamics (CFD) is a common tool for simulating flow systems. As a branch of fluid mechanics, computational fluid dynamics (CFD) is an appropriate tool for investigating and modelling the ANSYS Program. The applicability of CFD studies for simulating the ANSYS Program was reviewed in this work. Ansys CFD is one of the industry's most powerful simulation packages

Constructal design of two-phase stacked microchannel heat exchangers for cooling at high heat flux

Constructal design of high heat flux two-stacked horizontal microchannel heat sinks are presented for cooling of electronic devices. Using ANSYS Computational Fluid Dynamics (CFD) code for subcooled nucleate boiling, fixed volume constraints were invoked for the heat sinks and microchannels to achieve optimal flow velocities and pressure drops at global minimum thermal resistances of the microchannel heat sinks; this is in line with constructal design principle. Validation of the CFD code was done by comparing its results with those of experimental data in the open literature. The closeness of the two results showed the CFD code to be accurate in predicting subcooled flow boiling for cooling of microelectronic devices. Heat fluxes of 1100 and 1200 W/cm2 (1.1 × 107 W/m2 and 1.2 × 107 W/m2) were used in the simulations and optimizations. The thermal resistance, pumping power and Bejan number were based on microchannels that an optimal heat sink of 1 cm width could accommodate. The thermal resistances and base temperatures for optimal microchannel heat sinks at these high heat fluxes (the focus of the study) are low; the pumping power requirements are also low, which show that they are useable in the cooling of electronic devices and other similar applications. Also, this is an indication that optimal two-stacked microchannel heat sinks operating in subcooled flow boiling could be considered as a viable alternative in the cooling of electronics. Optimal two-stacked microchannel heat sink operating at 1200 W/cm2 and in counterflow and parallel flow arrangements, was used for the critical heat flux study and the results show that both have good CHF performance, although counterflow arrangement was better.