Inlet Flow Conditions Research Articles

Experimental study on fireproof of aviation lubrication oil tank

Abstract This paper presents an experimental study on the fireproof performance of aeroengine lubrication oil tanks. By constructing a simplified lubrication oil tank model and simulating the harsh operating conditions of engine fires, the oil tank was exposed to flames generated by a standard burner for testing. The study monitored and recorded key parameters such as temperature, pressure, flow rate, and phase changes within the tank. The results indicate significant differences in the temperature distribution characteristics of the tank walls under different inlet temperatures and flow conditions. In the rigorous 15-minute flame test, all tests successfully completed the fire verification process.

Preliminary Implementation of High-Resolution Multi-Scale coupling calculations for the entire pressure vessel based on OpenFOAM

Significant coupling effects exist among system components in nuclear pressure vessel. Due to the complex geometric structures, the nuclear industry primarily relies on system codes or sub-channel methods for core safety analysis. However, these methods suffer from low model accuracy and insufficient coupling capabilities. Additionally, the differences in model scales impede direct coupling analysis with the CFD calculations of the plenum system. To address these issues, this paper proposes a multi −scale coupling calculation method for the entire pressure vessel: For the plenum system, detailed CFD modeling is employed, while the core calculations are conducted using CorTAF, a high-resolution core Multiphysics-coupling analysis method developed by our team. A cross-resolution coupling model is utilized to integrate the two, achieving cross-resolution coupling simulations for the entire pressure vessel, encompassing both the plenum and core system. The above method was applied to the coupling calculations of a typical pressurized water reactor’s lower plenum and core, revealing detailed thermal–hydraulic phenomena under precise core flow inlet distribution conditions. The lateral flow at the core inlet exceeds 1 m/s, with the maximum and minimum fluid velocities in the subchannels deviating by up to 70 % from the average velocity of 2.42 m/s. The flow distribution only begins to stabilize after a height of 1.2 m in the core. The paper also includes inlet asymmetric flow reduction calculations. Overall, the method enables multi-scale and multi-physics coupling calculations, which provide significant reference value for improving the accuracy of current core safety analyses.

Pore-Scale multi-objective shape optimization of triply periodic minimal surface cellular architectures: Volumetric Nusselt number versus friction factor

Triply Periodic Minimal Surface (TPMS) cellular architectures, i.e., minimal surfaces that are periodic in three independent directions, have attracted interest in the engineering community for their potential in heat transfer applications with severe volume constraints due to their high surface-to-volume ratio, unique geometrical properties and smooth porous structure. Such performance can be conveniently controlled by tuning the TPMS unit type, relative density, and structural parameters. In this study, a multi-objective optimization process is carried out to investigate how pore-scale geometric characteristics affect the heat transfer performance of TPMS, and which combinations result in an optimal trade-off between heat dissipation capability and associated pressure drop in terms of the Nusselt number and friction factor. The analysis is performed using an in-house Genetic Algorithm routine that generates the structure, allowing for a wider and denser range of investigation, and incorporates a commercial finite element CFD software as a black box fitness function. Over 14,000 unique combinations between two heat transfer boundary conditions (constant wall heat flux, fixed wall temperature) and several flow inlet conditions are investigated. The optimization achieved an increase in performance of up to 245 % in terms of volumetric Nusselt number, which was accompanied, however, by a significant, although reasonable, increase in friction factor values. The results also show specific trends among the geometric characteristics studied, which are then contextualized through the use of CFD analysis. Finally, empirical correlations are derived to cluster the non-dominated solutions obtained, enabling the reader to choose the best cellular TPMS structure by selecting the desired level of trade-off between convection heat transfer and flow resistance.

Microscale heat transfer and phase change mechanisms of carbon dioxide at near-critical conditions

Recent studies highlight the potential benefits of two-phase carbon dioxide (CO2) systems operating near their thermodynamic critical point. Significant heat transfer coefficients and resistance to critical heat flux from improved vapor phase properties can enable heat transfer and reliability enhancements. However, the physical mechanisms of phase change that govern heat transfer behavior in the near-critical regime of reduced pressures (0.85<PR<1, where PR=P/Pcrit) are not well understood. In the present study, subcooled microscale (hydraulic diameter, Dh=500μm) flow boiling experiments are conducted to elucidate the heat transfer behavior near the critical point and the underlying mechanisms that influence it. Experimental data reveals a deviation from the trends predicted by the Cheng correlation (Cheng, L et al., 2008, “New prediction methods for CO2 evaporation inside tubes: Part II—An updated general flow boiling heat transfer model based on flow patterns.” Int. J. Heat Mass Transfer), in particular, displaying a decreasing peak heat transfer coefficient as pressure increases. Heat transfer in the near-critical regime can be further partitioned into two regions: near-critical boiling (0.85<PR<0.96) that exhibits heat transfer highly dependent on surface temperature, and supercritical-like behavior (0.96<PR<1) exhibiting a strong heat transfer dependence on mass flux. High-speed side-view flow visualization reveals the dominant nucleation mechanism (heterogeneous or homogeneous) governs the heat transfer behavior and is adequately predicted using flow inlet conditions. The present study provides a method for predicting nucleation behavior, which, in turn, facilitates the prediction of heat transfer near the critical point. The continuous alteration of heat transfer in the near-critical regime as a function of PR is underscored by this mechanistic insight, bridging the gap between typical flow boiling (PR<0.85) and supercritical heat transfer (PR>1).

Improvement of macroscopic turbulence model for subchannel analysis in the rod bundle array

The PRIUS program was established to generate an experimental database for the 6 × 4 and 12 × 6 rod bundle geometry. The database will be used to address the subchannel and CFD code analysis required for modeling and validation. This is necessary because Small Break Loss of Coolant Accident (SBLOCA) and Intermediate Break Loss of Coolant Accident (IBLOCA) present three-dimensional phenomena in the core due to the radial power profile, crossflow, and diffusion-dispersion. Therefore, specific experimental programs are required, especially during core reflooding, to investigate the large-scale three-dimensional effects. However, validating each sensitive model of the code separately in the presence of 3D effects is not possible due to the inability to implement instrumentation at high pressure and temperature steam-water flow conditions. The PRIUS test program uses a single-phase flow test to simulate a non-homogeneous velocity distribution and provide information on crossflow with radial mixing effects between subchannels. The CUPID code, which uses a macroscopic turbulence model, has been validated using the PRIUS-II experimental database. Existing macroscopic turbulence models were also validated for their prediction capabilities with different inlet flow conditions. However, the validation revealed significant errors in the shear region between subchannels. An improved macroscopic turbulence model showed promising results in predicting turbulence kinetic energy in porous media analysis.

Effect of gas turbulence in quartz-enhanced photoacoustic spectroscopy: A comprehensive flow field analysis

Here we present a computational and experimental fluid dynamics study for the characterization of the flow field within the gas chamber of a Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) sensor, at different flow rates at the inlet of the chamber. The transition from laminar to turbulent regime is ruled both by the inlet flow conditions and dimension of the gas chamber. The study shows how the distribution of the flow field in the chamber can influence the QEPAS sensor sensitivity, at different operating pressures. When turbulences and eddies are generated within the gas chamber, the efficiency of photoacoustic generation is significantly altered.

Flow dynamics studies in the NETmix reactor for a large range of flowrate ratios between feed streams

The mixing dynamics that occur inside the NETmix reactor have been previously thoroughly studied for equal feed streams distributed through the inlets. To broaden the applicability of this static mixer, this work intends to expand the knowledge of the mixing dynamics mechanisms for cases where dissimilar inlet flowrates are imposed. Computational Fluid Dynamics (CFD) tools were used to simulate flow dynamics experiments in a reduced NETmix geometry for different inlet flowrate ratios. The simulation results show that this reactor can attain the desirable condition of similar outlet flowrates for several dissimilar inlet flow conditions. A flow dynamics analysis enabled the determination of the natural frequency of oscillation of the flow and related it to the volume of the chambers occupied by vortices. Finally, the velocity fluctuations at the centre of NETmix chambers were characterised in terms of the intensity of turbulence.

Interstage transmission and differential analysis of pressure fluctuations in multistage centrifugal pump-as-turbine

Pumps as turbines (PATs) are used in petroleum and chemical industries to recover high-pressure residual energy. Multistage PATs allow for a wider energy recovery interval and wider range of applications. However, because multistage centrifugal pumps were not originally designed for turbine conditions, complex pressure fluctuations occur, impacting the stable operation and performance of multistage PAT. Pressure fluctuation is essentially a wave, and by analogy with the wave intensity definition, pressure fluctuations were quantified using the pressure wave energy flow density, and the pressure fluctuation patterns at different stages were investigated. The findings reveal significant differences in the intensity of pressure fluctuations at different locations within the multistage PAT. Specifically, the pressure fluctuation intensity is significantly higher from the second to the final stage, compared to the first stage. The difference in inlet flow conditions is the main reason for this difference in pressure fluctuations between stages. The inlet inflow from the second to the final stage is subject to rotational effects that exacerbate the difference in pressure fluctuation intensity between stages. Pressure fluctuations are found to be negatively related to the distance from the source of fluctuations and positively related to the flow state. Different flow conditions and interaction regions of the impeller affect the distribution of pressure fluctuation intensity and the distribution of pressure fluctuation energy across different frequency domains within the guide vanes. The main source of fluctuations in the shaft frequency and four times the shaft frequency is the impeller inlet interaction region, whereas the fluctuations in the blade passing frequency originate from the impeller outlet interaction region. This paper provides a reference for improving the stable operation of multistage PATs.

High fidelity core flow measurement experiment for an advanced research reactor using a real scale mockup

Owing to spatial effects and vortex flow, flow in research reactors that use plate-type fuels can be maldistributed to the parallel channels of the core, which significantly impacts the reactor safety. In this study, the core flow of an advanced research reactor was measured in a real-scale facility under various hydraulic conditions. For flow measurement, integrated pressure lines were embedded in the mockups of 22 fuel assemblies and six fission molybdenum assemblies. Each assembly mockup was individually calibrated to obtain the relationship between the pressure drop and flow rate. Real-scale facility, which implements the characteristics of the hydraulic conditions in research reactors, was then used to evaluate the assembly-to-assembly flow distribution under normal operating condition, a partially withdrawn condition for the follower fuel assemblies, no flow for the pool water management system, and 1:1.5 asymmetric inlet flow condition. As a parallel channel system, core flow distribution was analyzed with conventional header design approach. Taking into account the measuring uncertainty, the core flow was uniformly distributed within 5 % under all conditions. This was mainly because the core flow resistance was sufficiently high and the vortex flow was minimized by the perforated plate.

Equations and methodologies of inlet drainage system discharge coefficients: A review

Abstract Accurate determination of grate inlet discharge coefficients is crucial in reducing modeling uncertainties and mitigating urban flooding hazards. This review critically examines the methods, equations, and recommendations for determining the weir/orifice discharge coefficients, based on the inlet parameters and flow conditions. Reviewing previous studies for inlets showed that the discharge coefficient of rectangular inlets under subcritical flow ranges from 0.53 to 0.6 for weirs and from 0.4 to 0.46 for orifices, while in grated circular inlets, it falls between 0.115 and 0.372 for weirs and between 0.349 and 2.038 for orifices. For circular non-grated inlets under subcritical flow, the weir and orifice coefficients are in the range of 0.493–0.587 and 0.159–0.174, respectively. However, the orifice discharge coefficients of grated and non-grated inlets with unknown Froude number range between 0.14–0.39 and 0.677–0.82, respectively. For supercritical flow, the weir and orifice discharge coefficients of grated and non-grated rectangular inlets are 0.03–0.47 and 1.67–2.68, respectively. Previous studies showed that it is recommended to correlate the discharge coefficients with the approaching flow and Froude number under subcritical and supercritical flows, respectively. Yet, additional studies are recommended for a better understanding of the limits and parameters governing the flow transitional stage between weir and orifice and between subcritical and supercritical conditions. Moreover, further research is required to determine the weir and orifice discharge coefficients of circular inlets under supercritical flow as well as the orifice discharge coefficient range of rectangular non-grated inlets under subcritical flow. Finally, it is recommended to increase the road surface roughness to reduce Froude number, and thereby, increase discharge coefficients of street inlets. The aim of this review is to help inlet designers and authorities promote sustainable cities with resilient urban drainage systems and reduce the environmental, economic, health, and social impacts of urban drainage failure.

Comparison of RANS and LES turbulent flow models in a real stenosis

This study focuses on the performance of various turbulence models in predicting hemodynamic variables within a patient-specific geometry of the Brachiocephalic trunk exhibiting a severe stenosis. Numerical simulations employing Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models were conducted, comparing four RANS with two LES models. Results indicated significant differences in turbulent structures between RANS and LES models, with the k-ω RANS model closely approximating LES throughout the cardiac cycle. The velocity and Turbulent Kinetic Energy (TKE) results were consistent in the stenosis region due to the proximity to the inlet and plug flow conditions. However, notable disparities were observed in bifurcation and outlet regions. Time-Averaged Wall Shear Stress (TAWSS) comparisons revealed that the k-ω-based models provided closer agreement with LES, particularly in atherosclerosis-prone areas. The study highlights the limitations and strengths of each turbulence model, emphasizing the importance of model selection in simulating complex cardiovascular conditions. While RANS models demonstrated computational efficiency, their accuracy varied across regions. The effectiveness of the k-ω model in capturing the intricacies of such a complex flow field suggests its potential as a reliable and accurate tool for simulating physiological conditions with strong curvature and advanced stenosis.

Experimental investigation of two-phase flow development through two-stage orifices

In this study, the effect of flow development length on two-stage flow orifices at an intermittent flow condition was investigated. Experiments were carried out for two-stage orifices with area ratio of 0.25–0.14 and with 1, 3, and 5D spacing between orifices. Also, experiments were carried out on single-stage orifices of the same area ratios under the same inlet flow conditions. The data suggested that restricting the flow in stages, with the smaller area of the restriction in the final stage, reduced the flow separation, enhance the mixing and improve flow development downstream as the spacing increased. Also, the total pressure drop of the two-stage orifice found to decrease as the spacing decreased especially at low gas superficial velocity. Finally, a new approach to correlate the total pressure drop was proposed and successfully implemented in order to determine the pressure drop multiplier of two-stage orifice with varying spacing.

Predicting the Performance of Turbine Exhaust Diffuser-Collector Systems Across the Operating Range: Comparison of Lattice-Boltzmann Method Simulations With Experiments

Abstract The predictive capability of the lattice-Boltzmann very large eddy simulation (LBM-VLES) methodology was evaluated for industrial gas turbine exhaust diffuser-collector applications. The effort focused on evaluating the accuracy of performance predictions against experimental rig data gathered at engine representative conditions including the Reynolds number, Mach number, and inlet flow conditions. The performance prediction capability of LBM-VLES simulations was also compared against Reynolds-averaged Navier–Stokes (RANS) simulations. Evaluations were completed for two distinct exhaust rig geometries at conditions indicative of their respective design points, and the performance prediction capability was also evaluated at conditions depicting two off-design cases. The off-design conditions were represented by an increase in inlet swirl angle and associated incidence on the diffuser struts. Overall, the authors found that LBM-VLES simulations were a suitable approach for predicting the performance of gas turbine exhaust diffuser-collector systems at both on- and off-design conditions. The LBM-VLES simulation accuracy was substantially better than that achieved by RANS simulations, with 66% lower RMS pressure recovery error between computational fluid dynamics (CFD) and experiments for the four cases studied, and an 89% reduction in error for the furthest off-design case. The computational cost of the transient LBM-VLES simulations was roughly the same as the RANS simulations performed using best practices for that solver.

Numerical simulation of gas-solid flow in a cyclone separator with additional inlet

In this study, an additional inlet was added to the gas-solid cyclone separator to enhance the separation efficiency. Four different heights were tested, including 0.95D, 1.4D, 1.5D, and 1.95D (D is the diameter of the cylindrical section). The investigation involved two inlet flow conditions: increasing and dividing the inlet flow rate. The finite volume method and Reynolds stress turbulence model were used to solve the averaged Navier–Stokes equations, whereas the Eulerian–Lagrangian approach and discrete phase model (DPM) were applied to track particles with a uniform diameter of 0.5–1.8 microns as the discrete phase. Owing to the low Stokes number and small and low-volume-fraction particles, a one-way coupling method was employed between air and the particles. The addition of an additional inlet reduced the static pressure in the center and downstream areas and increased the reverse flow velocity at the end of the cyclone. The installation of an additional inlet at 0.95D had the most positive effect on the separation efficiency, with an increase of 28.8% in the increasing flow rate case and 19.6% in the dividing flow rate case compared with the cyclone without an additional inlet. Furthermore, the increase in the separation efficiency of the submicron particles was greater than that of the larger particles in both flow distribution cases.

Research on the thermal and flow characteristics of novel micro-channel PV/T collectors

A novel micro-channel PV photothermal collector is investigated, comprising of PV cells and collectors. Its distinctive feature lies in the flow mode of its micro-channels. The novel micro-channel investigated in this study is composed of multiple drums, allowing for a non-parallel flow configuration. This distributional flow pattern facilitates enhanced contact between the water flow and the heat transfer surface, thereby resulting in significantly improved heat transfer efficiency. Characteristics and flow properties are studied to enhance the thermoelectric performance and broaden the application scope of PV photothermal collector technology. This study focuses on parallel micro-channels and three-passes micro-channels for comparison, employing ANSYS FLUENT to simulate electrical and thermal efficiencies, temperature distribution, velocity field, and pressure field under typical operating conditions. The validity of the model is verified by comparing it with experimental panel surface temperature data. Within this framework, various inlet flow conditions are examined to investigate the collector's temperature profile, standard deviation of temperature distribution, pressure drops, and maxi-mum velocity. Results indicate that under specific circumstances, the heat collection performance of parallel micro-channel PV photothermal collectors is inferior to that of three-passes micro-channel counterparts. Both types exhibit reduced efficiency during winter conditions, however, three-passes micro-channels experience a more significant decline at 22.4%, compared to 19.7% for parallel micro-channels. In terms of flow resistance characteristics, parallel micro-channels demonstrate advantages in terms of pressure drops over three-passes configurations as they exhibit nearly 3935 Pa lower values under certain conditions. Regarding temperature uniformity in PV-photothermal systems, parallel micro-channel collectors outperform their three-passes counterparts.

Research on Micro-Turbine Operating State Characterization Based on Bearing Vibration Signals Analysis

An air flow-driven micro-turbine, widely used in air-condition control systems in aircraft cabins, train coaches, etc., exhibits complex vibration behaviors under stable or unstable inlet flow conditions, and especially has a certain correlation with speeds. In this paper, the vibration responses of the micro-turbine undergoing stable and unstable inlet flows measured on a test rig are analyzed and compared by using different signal processing methods, which include time and frequency domain methods, and statistical and nonlinear methods. First, the test rig system of the airflow-driven micro-turbine, the instrument system and four typical experimental cases are introduced. Then the measured vibration signals are analyzed and compared by time domain characteristic parameters (peak-to-peak value, RMS value and kurtosis value), statistical parameters (auto-correlation and BDS), and amplitude spectra in the frequency domain, statistic spectrum indicators (SSI) based on Welch's periodogram of power spectra, and the spectra of selected IMF components based on Hilbert-Huang Transform (HHT). In particular, some nonlinear feature analyzing methods, including Pseudo-Poincare mapping diagrams and Lempel-Ziv(LZ) complexity, are also used for analyzing measured vibration responses. The obtained results using the above multiple methods are compared and show that, when the inlet flow of the turbine fluctuates significantly, the nonlinear characteristics of the turbine bearings are significantly higher than those of the relatively stable inlet flow and speed conditions. Under these circumstances, commonly used time-frequency analysis methods cannot characterize the different speed operating state of the turbine, and LZ-Complexity and other nonlinear characterization methods should be used to better understand the characteristics of different speeds under unstable conditions.This study provides references for the aerodynamic stability monitoring of the micro-turbine and its design improvement.

Unsteady conjugate heat transfer simulation of wall heat loads for rotating detonation combustor

Rotating detonation engines (RDEs) are the most promising pressure-gain combustion devices, but their long-duration operations are hindered by the harsh thermal environment inside the chamber. This study analyzes the instantaneous and average heat loads on chamber walls of RDEs based on the newly developed unsteady conjugate heat transfer (CHT) OpenFOAM solver named multiRegionBYRFoam. To enhance accuracy in predicting heat transfer characteristics compared to decoupled simulations focusing solely on fluid or solid behavior, three-dimensional CHT simulations are conducted for a premixed H2/air annular RDE coupling the detonation simulation with heat conduction in both inner and outer chamber walls. The transient time evolutions of wall heat flux in RDEs are numerically captured for the first time and agree well with experiments. The calculated peak wall heat flux is 1.98 MW/m2 at the inner wall and 2.63 MW/m2 at the outer wall when a single detonation wave propagates with a mass flow rate of 0.227 kg/s. By investigating the influence of inlet flow conditions and detonation modes, valuable guidelines on designing efficient thermal management systems for RDEs are obtained: larger mass flow rates and multi-wave modes result in higher average wall heat flux; the heat flux at the outer wall exceeds that at the inner wall while both walls require effective cooling for gas turbine engines with a rotating detonation combustor. Furthermore, a novel heat transfer model for RDEs is proposed based on a thermal operation map depicting total heat transfer rates to describe the nonlinear impact of mass flow rate and number of detonation waves, which can be employed to predict total wall heat loads under specific operation conditions of RDE.

Harnessing oscillatory fluid behaviour to improve debris wash-out in ureteroscopy

In ureteroscopy, a common method for kidney stone removal, a ureteroscope is inserted into the patient’s kidney, through which working tools such as a laser are inserted. During the procedure, the renal space proximal to the scope tip is irrigated with fluid in order to clear stone particles and debris. However, even with continual fluid flow into and out of the kidney, stone dust may become trapped in vortical structures, significantly impairing the operating clinician’s field of view. Key to overcoming this challenge is a clear understanding of the flow patterns within an irrigated kidney calyx, and a modelling framework that enables to interrogate how different flow conditions impact on the wash-out time of debris. Previous theoretical studies have uncovered the interplay between fluid structure, in particular the presence of vortical regions, and dust washout, but only in a regime of steady inlet flow conditions. In this paper we model a kidney calyx in an idealised 2D cavity geometry, in which we investigate the presence and potential disturbance of vortical structures due to an oscillatory inlet condition, and the impact on dust washout, modelled as a passive tracer in the flow. By varying the flow amplitude and frequency at the inlet, we uncover a delicate relationship with vortex size and vortex disturbance, and we demonstrate the potential for significant decrease in wash-out time with low-frequency high-amplitude conditions. We then compare this result to the commonly used practice of flushing, a discrete and temporary increase in flow, and we also demonstrate the qualitative robustness of our findings to changes in cavity geometry.

Determination of Time Constant of Temperature Sensors and its Application in Aero Gas Turbine Engines

Temperature sensors are widely used in aero gas turbine engines for measurement of air and gas temperature at various locations starting from inlet of fan to exhaust gas from the nozzle. Thermocouples are one of the most widely used sensors for the above purpose. Time constant of thermocouple is a key parameter in the selection of sensor for a particular application. Even though time constant is available for standard stand alone thermocouple configurations, it varies widely based on many physical parameters and inlet flow conditions inside a gas turbine engine. Experimental determination of time constant of stand alone thermocouples with step input is carried out for various thermocouple configurations and a Fibre Bragg Grating sensor using a dry block calibrator with hot air as medium. Two different methods are used to determine the time constant of thermocouple sensors. Further determination of time constant of thermocouple assembled in a rake and tested in real time situation in aero gas turbine engine is carried out. A comparative study reveals that many parameters are involved which influence the value of time constant under different input conditions. Finally the selection of sensors is carried out based on the measurement requirements.

Optimization of Flow Channel Design with Porous Medium Layers in a Proton Exchange Membrane Electrolyzer Cell

This study aims to optimize the flow channel design for a proton exchange membrane electrolyzer cell (PEMEC) to minimize the pressure drop across the cell. The pattern of parallel flow channels is considered with a dual-porous layer structure sandwiched between the flow channel plate and the catalyst layer. Four geometric factors are considered in the optimization analysis, including the width of the flow channel, the depth of the flow channel, the particle diameter of the large-pore porous layer, and the particle diameter of the small-pore porous layer. Computational fluid dynamics (CFD) is used to simulate the flow field, and based on the results of the CFD simulation, the Taguchi method is employed to analyze the optimal flow channel design. The importance of the factors is further analyzed by the analysis of variance (ANOVA) method. Three inlet velocities are assigned in the Taguchi analysis, which are 0.01, 0.1332, and 0.532 m/s, and then an orthogonal array is constructed and analyzed for each inlet flow condition. It is found that the optimal combination of the factors is the depth of the flow channel 1 mm, the width of the flow channel 3 mm, the particle diameter of the large-pore porous layer 0.212 mm, and the particle diameter of the small-pore porous layer 0.002 mm. The pressure drop across the PEMEC is minimized at the condition with the optimal combination of the factors. The ANOVA analysis shows that the depth of the flow channel exhibits the most significant impact on the pressure drop, while the other factors play minor roles only.