Parallel Microchannels Research Articles

Pulse electroosmotic flow of Newtonian fluids in parallel plate microchannels under triangular and half-sinusoidal pulse electric fields

Unlike the conventional electroosmotic flow (EOF) driven by direct current and alternating current electric fields, this study investigates the pulse EOF of Newtonian fluids through a parallel plate microchannel actuated by pulse electric fields. Specifically, the pulses considered encompass triangular and half-sinusoidal pulse waves. By applying the Laplace transform method and the residual theorem, the analytical solutions for the velocity and volumetric flow rate of the pulse EOF associated with these two pulse waves are derived, respectively. The influence of pulse width a¯ and electrokinetic width K on velocity is further considered, while the volumetric flow rate as a function of time t¯ and electrokinetic width K is examined separately. A comparison of the volumetric flow rates related to these two pulse waves under varying parameters is also conducted. The research findings indicate that irrespective of the pulse wave, a broader pulse width results in a prolonged period and increased amplitude of the velocity profile. Elevating the electrokinetic width yields higher near-wall velocities, with negligible effect on near-center velocities. It is noteworthy that regardless of the electrokinetic width, the near-wall velocity exceeds that of the near-center during the first half-cycle, while the situation reverses during the second half-cycle. The volumetric flow rate varies periodically with time, initially surging rapidly with electrokinetic width before gradually stabilizing at a constant level. More interestingly, independent of pulse width and electrokinetic width, the volumetric flow rates linked to the half-sinusoidal pulse wave consistently surpass those of the triangular pulse wave. For any pulse width, the volumetric flow rates corresponding to the two pulse waves grow with higher electrokinetic widths, especially prominent at alternating intervals of the two half-cycles within a complete cycle. These findings have important implications for improving the design and optimization of microfluidic devices in engineering and biomedical applications utilizing pulse EOF.

Two-Layer Electroosmotic Flow in a Parallel Plate Microchannel with Sinusoidal Corrugation

This study investigates the electroosmotic flow (EOF) of a two-layer Newtonian fluid system in a parallel plate microchannel with sinusoidal corrugated walls. The upper fluid is conducting, while the lower fluid is nonconducting. This analysis is performed under the Debye–Hückel approximation, utilizing perturbation expansion and the separation of variables. The potential distribution, velocity field, and the dependence of average velocity on roughness are derived. It is observed that the velocity distribution w(x, y), is significantly influenced by the phase difference θ between the corrugations on the upper and lower walls. The velocity w(x, y) decreases with an increase in the viscosity ratio μr of the bottom to top fluid, and w(x, y) is directly proportional to the dimensionless pressure gradient G and the zeta potential ratio ζ. The variation of the average velocity increment (roughness function) u2m related to wall roughness tends to decrease with the increase of the corrugation wave number λ, the electrokinetic width K, the depth ratio hr of the bottom to top fluid, the zeta potential ratio ζ and the dimensionless pressure gradient G; and increases with the increase of the viscosity ratio μr of the bottom to top fluid. Furthermore, the effect of uI2m is smaller than that of uII2m.

An Experimental Investigation of Pressure Drop in Two-Phase Flow during the Condensation of R410A within Parallel Microchannels

In this study, the flow condensation of R-410A within 18 square microchannels arranged horizontally in parallel was experimentally investigated. All components of pressure drop, including expansion, contraction, deceleration, and friction, were quantified specifically for microchannels. The test conditions included saturation temperature, vapor quality, and mass flux, ranging from 18.86 to 24.22 bar, 0.09 to 0.92, and 200 to 445 kg/m2·s, respectively. The frictional pressure loss made up approximately 92.89% of the overall pressure reduction. The findings demonstrate that the pressure drop rises with higher mass flux and a lower saturation temperature. By comparing with correlations and semi-empirical models outlined in the literature across various scales, specimen types, and refrigerant media, correlations developed for two-phase adiabatic flows in multi-channel configurations can effectively predict the pressure drop in microchannel condensation processes. The model introduced by Sakamatapan and Wongwises demonstrated the highest predictive accuracy, with a mean absolute deviation of 8.4%.

Flow-through microfluidic relative permittivity sensor using highly-doped silicon sidewall electrodes

Abstract This paper reports a flow-through sensor for the real-time measurement of the relative permittivity of a flowing fluid. The proposed sensor contains multiple parallel microchannels. Each channel acts as a parallel plate capacitor in which the electrodes are isolated from the fluid. This approach results in a low pressure drop and high sensitivity while the internal volume is only 50 nl. The fabrication technology allows for controllable scaling of the channel geometry. Equally deep microchannels with widths varying between 5 µm and 50 μ m are fabricated. The fabrication technology is compatible with other flow-through sensors, enabling further on-chip integration. The sensor has been characterised using 10 different fluids with relative permittivity values ranging from 1 to 80—including water and water-containing mixtures—at a measurement frequency of 300 kHz. The results show an accuracy within 3% of full scale and the repeated measurements with nitrogen and water show standard deviations of 1.20 and 1.03, respectively.

Non-uniform maldistribution of boiling flow in two parallel microchannels with entry effects

Abstract Current theoretical studies of parallel channel instability are restricted to the full development assumption, and the entry effect of the existing developmental stage in miniaturized heat dissipation scenarios is not taken into consideration, leading to some deviations in the predicted results of the stability in practical applications. Using a kinetic model of phase transition and pressure drop, we study microchannels with an L/D ratio of 50 and a hydraulic diameter of 200 μm. The significant influence of the entry effect during both the development and fully developed stages is revealed by our results, which demonstrates a narrowing of the overall flow discrepancy and, consequently, an enhancement in the system’s stability. Particularly, the mitigating effect of the entry effect on the flow instability and maldistribution within the parallel channels was gradually enhanced when the qin increased from 20 W/cm2 to 100 W/cm2.

Numerical and experimental study on manifold-distributed jet microchannel with micro-pin-fins

Traditional parallel microchannels are inadequate for managing the thermal requirements of newer, large-area and high-heat-flux chips. This inadequacy arises from its high flow resistance and poor temperature uniformity. Therefore, A novel manifold microchannel heat sink combining manifold inlet/outlet structures, distributed array jets, and micro pin-fins is introduced. Numerical simulations and experimental methods were employed to investigate the flow and heat transfer performance of the heat sink. Experimental results show that, with an average heat flux density exceeding 330 W/cm2 and a total power of 2500 W, the average chip temperature remains below 70 °C, ensuring efficient heat dissipation. Secondary impingement occurs at sufficiently low jet chamber heights, resulting in an increase of 3 times in the average Nusselt number for a smooth base plate. For the micro-pin-finned surface, it is shown that the presence of micro-pin-fins is not necessarily conducive to heat transfer enhancement. A critical volume fraction of micro-pin-fins (critical fin-ratio) exists where the obstructive effect and enhancement effect balance each other out. This value is influenced by multiple parameters. Finally, a novel relationship for predicting the average Nusselt number of jet impingement was proposed, with an average absolute error of less than 15 %. This series of investigations addresses the existing gaps in research on manifold-distributed array jet heat sinks and provides a meticulous theoretical foundation for the design and optimization of heat sinks facing the high-power chips.

High-Efficiency Condensation Heat Transfer Interfaces Based on Superwetting Copper Microgroove/Nanocone Structure.

Utilizing superhydrophobic micro/nanostructures to enhance condensation heat transfer (CHT) of copper surfaces has attracted intensive interest in recent years due to its significance in multiple industrial fields including nuclear power generation, thermal management, water harvesting, and desalination. However, superhydrophobic surfaces have instability risk caused by microcavity defect-induced vapor penetration and/or hydrophobic chemistry destruction. Here, we report a superwetting copper hierarchical microgroove/nanocone (MGNC) structure strategy that can realize high-efficiency CHT over a whole range of surface subcooling. By regulating groove width, fin width, groove depth, and nanostructure growth time, we obtain the optimal MGNC structure, where the CHT coefficient is 121% and 107% higher than that of hydrophilic flat surfaces at surface subcooling of 2 and 15 K, respectively. Such remarkable enhancement can be ascribed to the synergy of three interface effects: more nucleation sites for phase-change energy exchanging, thinner condensate films for reducing thermal resistance, and parallel microchannels for timely drainage. Compared with superhydrophobic strategies, our strategy not only can be mass-producible but also has other inherent advantages: no microcavity-induced performance failure risk as well as being free of chemistry modification, which makes the fabrication process simpler and more economic. Hierarchical micropillar/nanocone structure is also fabricated as the contrast sample for highlighting the superiority of the superwetting MGNC structure in enhancing CHT. This work not only enriches research systems of superwettability surfaces but also helps develop high-performance chips' cooling devices and explore more potential applications.

Electrochemical Impedance Spectroscopy-Based Microfluidic Biosensor Using Cell-Imprinted Polymers for Bacteria Detection.

The rapid and sensitive detection of bacterial contaminants using low-cost and portable point-of-need (PoN) biosensors has gained significant interest in water quality monitoring. Cell-imprinted polymers (CIPs) are emerging as effective and inexpensive materials for bacterial detection as they provide specific binding sites designed to capture whole bacterial cells, especially when integrated into PoN microfluidic devices. However, improving the sensitivity and detection limits of these sensors remains challenging. In this study, we integrated CIP-functionalized stainless steel microwires (CIP-MWs) into a microfluidic device for the impedimetric detection of E. coli bacteria. The sensor featured two parallel microchannels with three-electrode configurations that allowed simultaneous control and electrochemical impedance spectroscopy (EIS) measurements. A CIP-MW and a non-imprinted polymer (NIP)-MW suspended perpendicular to the microchannels served as the working electrodes in the test and control channels, respectively. Electrochemical spectra were fitted with equivalent electrical circuits, and the charge transfer resistances of both cells were measured before and after incubation with target bacteria. The charge transfer resistance of the CIP-MWs after 30 min of incubation with bacteria was increased. By normalizing the change in charge transfer resistance and analyzing the dose-response curve for bacterial concentrations ranging from 0 to 107 CFU/mL, we determined the limits of detection and quantification as 2 × 102 CFU/mL and 1.4 × 104 CFU/mL, respectively. The sensor demonstrated a dynamic range of 102 to 107 CFU/mL, where bacterial counts were statistically distinguishable. The proposed sensor offers a sensitive, cost-effective, durable, and rapid solution for on-site identification of waterborne pathogens.

Arrangement and feedback effects of droplet swarms in a parallel microchannel device

Droplet swarms are the dominant form of highly dispersed microdroplets in cavities. During the self-assembly of droplet swarms, the continuous phase is inclined to flow along the path of the minimum resistance, while the arrangement of the droplet swarms seeks to minimize the potential energy, and the two mechanisms compromise in competition. In this paper, the ability of droplet swarms to timely adjust the morphology is measured by the ratio of the average flow rate of the two-phase flow to that of the droplet swarms, thereby clarifying the dominant mechanism of the arrangement of droplet swarms. The arrangement of droplet swarms dominated by different mechanisms and their distribution are introduced, and the prediction method for the arrangement of droplet swarms is proposed. The mechanism underlying the breakup of the microdroplets in the cavity is elucidated, and three modes of the breakup in the cavity are introduced. Furthermore, a resistance model for the microdevice is established to quantify the fluctuations of pressure difference and flow rate resulting from the formation of droplet swarms. The feedback effects of droplet swarms on the uniformity of droplet formation and flow patterns are analyzed, revealing the ideal flow range for the formation of highly dispersed droplets in microchannels. This paper elucidates the arrangement and the feedback effects of droplet swarms, which will guide the application of microdevices in reaction and mass transfer processes.

On the analysis of static thermal instabilities occurring in two-phase flow systems

In this study, we investigate a novel type of static thermal instability that occurs in two-phase flow systems. The instability is theoretically and experimentally confirmed to occur for flow boiling micro-channel scenarios and flow condensing scenarios. The theory presented is independent of the evaporator geometry as well as flow boiling/condensing situations. A stability criteria is derived using a Reynolds Transport approach applied to the evaporator of a two-phase pumped loop (TPPL) system. The theory is then validated experimentally using a TPPL containing a parallel micro-channel evaporator. The instability is confirmed with pressure, temperature, and void fraction measurements acquired at the exit of the evaporator. The findings reveal that static thermal instabilities can arise when simultaneous heat addition and reduction in system saturation temperature occurs (or vice versa). The implications of the thermal instability result in dramatic changes in evaporator heat flux, as well as a flow transition from stratified laminar flow to vigorous turbulent flow with high void fractions. By identifying the additional instability mechanisms, this work contributes to enhancing system reliability and predictability of TPPL systems.

Thermal Management and Optimization of Automotive Film Capacitors based on Parallel Microchannel Cooling Plates

Abstract The automotive film capacitors (AFCs) stand as a widely employed components in electric vehicles. Yet, a notable concern arises with the potential for excessive ripple current, which can prompt self-heating in the AFC and diminish its reliability. Therefore, it becomes crucial to conduct thermal management and effective heat dissipation design for the AFC to ensure its optimal performance. In this study, considering the trend toward integrated and lightweight motor controllers, a parallel microchannel cooling plate (PMCP) is designed at the bottom of the AFC. Through optimization, the thermal performance of the AFC and the overall cooling performance of the PMCP are enhanced. The AFC thermal model is established and the calculation method for equivalent thermal properties of the film capacitor core is described. A conjugate heat transfer simulation model for the AFC and the PMCP is created by FLUENT and validated through two experimental tests. Additionally, based on an optimal Latin Hypercube Sample size, the accuracy of five fitting models is compared and the non-dominated sorting genetic algorithm II (NSGA-II) for optimization is employed. The results indicate that the error between the simulation method and the two experiments is within 5 %. The application of the PMCP effectively redistributes the hottest region of the AFC to the outer housing, reducing the maximum AFC temperature by 10.90 °C. Among the five fitting models, the RSM (Response Surface Model) proved to be the most accurate. The optimized PMCP enhances the overall cooling performance by 10.32 %, and increases the maximum withstand ripple current of the AFC by 43.83 %.

Modified Splitting Distributor for Enhanced Flow Uniformity in Parallel Microchannels: An Experimental Study on the Effect of Fluid Properties

Modified Splitting Distributor for Enhanced Flow Uniformity in Parallel Microchannels: An Experimental Study on the Effect of Fluid Properties

PC12 differentiation to neuron cells activated by a low-level laser at 660 nm on UV pre-treated CR-39 scaffolds with parallel microchannels.

The lack of regeneration of injured neurons in the central and peripheral neural system leads to the failure of damaged tissue repair in patients. While there is no definitive cure for most neurodegenerative diseases, new therapeutic methods that cause the proliferation and differentiation of neurons are of interest. Challenges such as the inability of neuronal cells to proliferate after injury, the lack of a stimulus for initial stimulation, and the presence of the microenvironment around CNS neurons contain several inhibitory factors that prevent neuron regeneration, thus, creating a structure similar to the extracellular matrix helps the cell proliferation in current treatment. A rapid method of neuron-like cell differentiation of PC12 cells is introduced here based on a novel synthetic scaffold. Initially, poly allyldiglycol carbonate (CR-39) substrate is textured under a high dose of ArF UV excimer laser (1000 shot, 300 mJ/pulse equivalent to 300 J/cm2 at 193 nm) to create superficial periodic parallel microchannels with the micrometer spacing and sub-micron width. Ultraviolet treated CR-39 (UT CR-39) provides a suitable scaffold to speed up the transformation/differentiation of PC12 cells. The latter is pheochromocytoma of the rat adrenal medulla as an embryonic origin from the neural crest usually exposed to the nerve growth factor (NGF). In fact, PC12 cells are seeded on the microchannels and simultaneously are stimulated by coherent red photons at 660 nm within the therapeutic window. The UT CR-39 scaffold undergoes extra improvement of ∼ 30% after 12 minutes of laser activation regarding the photo-biomodulation (PBM) mechanism. The cell activation due to the coherent photons also gives rise to enhanced proliferation/differentiation. Here, PC12 cells are efficiently differentiated into neurons according to immunocytochemistry (ICC) and Western Blot verification tests based on MAP2 and synapsin-1 protein expression. In general, UT CR-39 acts as a superior bed to elevate the population of neuron-like cells up to threefold against those of untreated (control)ones. We conclude that the surface cross-linking due to UV exposure and subsequent induced hydrophilicity notably contribute to the neuron-like cell differentiation of PC12 without adding NGF.

Mass transfer of gas–liquid two‐phase flow in asymmetric parallel microchannels with liquid feed splitting

AbstractDue to size limitations, the gas–liquid absorption capacity of a single microchannel is limited, making it difficult to achieve large‐scale CO2 capture. Therefore, the parallel microchannels combining the advantages of high efficiency and large throughput stand out. However, when the operating condition is high gas–liquid flow rate ratio, the liquid phase between bubbles almost disappears after multiple distributions, which affects the amount of gas–liquid absorption. In this study, the numbering‐up of the asymmetric parallel microchannels in the gas–liquid absorption process was investigated by splitting the liquid feed stream in two. The flow patterns under different operating conditions were obtained. The flow and distribution of gas–liquid two‐phase flow were investigated, and the reason of the distribution deterioration caused by appearance of long slug bubbles was explained by the pressure drop distribution. The total liquid mass transfer coefficient and bubble residence time were derived and obtained, and the mass transfer was further discussed.

Electro-Osmotic Flow and Mass Transfer through a Rough Microchannel with a Modulated Charged Surface.

In this paper, we investigate the electro-osmotic flow (EOF) and mass transfer of a Newtonian fluid propelled by a pressure gradient and alternating current (AC) electric field in a parallel microchannel with sinusoidal roughness and modulated charged surfaces. The two-wall roughness is described by in-phase or out-of-phase sine functions with a small amplitude δ. By employing the method of perturbation expansion, the semi-analytical solutions of the Poisson-Boltzmann (P-B) equation based on the Debye-Hückel approximation and the modified Navier-Stokes (N-S) equation are obtained. The numerical solution of the concentration equation is obtained by the finite difference method. The effects of sinusoidal roughness, modulated charged surface, and the AC electric field on the potential field, velocity field, and concentration field are discussed. Under the influence of the modulated charged surface and sinusoidal roughness, vortices are generated. The velocity oscillates due to the effect of the AC electric field. The results indicate that solute diffusion becomes enhanced when the oscillation Reynolds number is below a specific critical value, and it slows down when the oscillation Reynolds number exceeds this critical value.

Thermally developing streaming potential-mediated pressure-driven flow of Phan–Thien–Tanner fluid in a microchannel

In this study, we have conducted a semi-analytical investigation into the streaming potential-mediated pressure-driven flow of hydrodynamically fully developed and thermally developing viscoelastic fluid in a parallel plate microchannel. We have utilized a simplified Phan–Thien–Tanner model to describe the rheology of the viscoelastic fluid. Our approach delved into the full Poisson–Boltzmann equation, deriving exact analytical solutions for the electrostatic potential distribution and velocity profile. Furthermore, we concurrently derived semi-analytical solutions for the temperature distribution and Nusselt number, accounting for the effects of heat generation from viscous dissipation and Joule heating in thermally developing flows. We have demonstrated that an increase in the degree of surface charge triggers the streaming potential field, while the volumetric flow rate escalates with the viscoelastic parameter εWik¯2. Moreover, we have observed that the magnitude of the dimensionless temperature decreases with increasing values of the effective Joule heating parameter Speff. Our analysis reveals that the streaming potential effect hampers fluid flow, resulting in an increase in the bulk fluid temperature and consequently reducing the heat transfer rate. We observe that the magnitude of the Nusselt number decreases with increasing Speff. The entropy generation analysis reveals that increasing the Peclet number amplifies flow and temperature gradients, leading to higher fluid irreversibility in microchannels. The Bejan number experiences a significant decrease across the channel, reaching its minimum at a specific axial location before stabilizing further downstream. We find that heat transfer irreversibility predominantly influences system irreversibility, except for the Brinkmann number Br = 0.01, where convective heat transfer dominates at the entrance region, transitioning to friction losses beyond the thermal entry zone.

Machine learning-based thermal performance study of microchannel heat sink under non-uniform heat load conditions

The parallel microchannel heat sink stands as a pivotal solution in managing high heat flux electronics due to its efficient heat transfer characteristics and ease of manufacturing. While numerous studies have explored the thermal performance and flow characteristics of microchannel heat sinks, most have focused on uniform heat loads or relied heavily on numerical methods. This study presents an experimental system tailored to generate data for analyzing the thermal performance of microchannel heat sinks under various conditions. Leveraging this dataset, four distinct machine learning models Artificial Neural Network (ANN), XGBoost, LightGBM, and K-nearest neighbor (KNN) were trained using 22 input features, totalling 560 data points categorised into geometry parameters, heating patterns, and boundary conditions details. The models were tasked with predicting six response variables: the average base temperature of the heat sink, temperature change (ΔT), hotspot temperature, heat transfer coefficient (h), Nusselt number (Nu), and thermal resistance (Rth). Among the four machine learning models, XGBoost exhibited a good predictive accuracy of an average R2 value of 0.98 and MAE values of 2.1 across all responses. Furthermore, the study delved into the impact of varying input features on prediction accuracy, revealing a consistent enhancement in accuracy with the inclusion of more features across all models.

3-D numerical simulation of forced convection heat transfer in microscale rectangular channels for low GWP refrigerants

This study presents a numerical evaluation of the performance of low Global Warning Potential (GWP) refrigerants R600a, R290, R1270, and R134a in heat dissipation by forced convection in a microchannel heat sink. The heat sink comprises 50 parallel microchannels with a cross-sectional area equal to 123 × 494 [µm2]. The differential equations describing the physical behavior interaction between the refrigerant and the copper matrix are solved using the finite volume method and the SIMPLEC coupling algorithm. The numerical model is used to predict fluid mechanics and heat transfer for single-phase laminar conditions including the friction factor, the Nusselt number and the average wall temperatures, as well as the whole performance of the microchannel heat sink. The accuracy of the numerical model is validated by comparing the performance of R600a with experimental data, resulting in deviations within the range of the uncertainty of each parameter. The evaluation of the performance of different refrigerants reveals that the friction factor and Nusselt number are significantly influenced by the microchannel geometry and thermal conditions, exhibiting unique yet similar trends for different refrigerants. Furthermore, the analysis of the average wall temperature in the microchannels demonstrates that the hydrocarbon-based refrigerants effectively reduce the temperature of the copper matrix compared to R134a, suggesting a superior performance in the dissipation of heat flux under single-phase laminar conditions.

A fully developed viscous electrically conducting fluid through infinitely parallel porous plates

AbstractThe current article deals with the steady behavior of a fully developed viscous electrically conducting and compressible Jeffrey fluid via infinitely parallel porous vertical microchannel in the sight of a transverse magnetic field. The fluid flow problem is modeled using Napier–Stokes and energy conservation equations. To analyze the problem, the leading equations are reformulated into dimensionless forms. These dimensionless transformed equations are described by nonlinear‐coupled ordinary differential equations and are eliminated utilizing the shooting method based on the fourth‐order Runge–Kutta technique through the boundary conditions; this represent slip velocity and temperature‐jump situations on the fluid–fence interface. The model equations are numerically solved with MATLAB's built‐in routine “bvp4c.” The behavior of Jeffrey fluid is described through graphs. The significance of model parameters is scrutinized and discussed in detail through graphs. Various significant impacts are examined in these simulations, such as radiation, magnetic field and viscous dissipation. Furthermore, the essential results of this investigation are the effects illustrated graphically and discussed quantitatively concerning various influencing parameters corresponding to the magnetic parameter, interaction parameter, buoyancy parameter, Darcy parameter, wall ambient temperature ratio, and the fluid‐wall relationship. We noticed that both walls are heated, that is, the velocity decreases with a rising Jeffrey parameter.

Subcooled flow boiling in multiple parallel rectangular micro-channel heat sink: Development of heat transfer correlation

This study experimentally evaluated and presented the heat transfer performance of FC-72 flow boiling in a rectangular micro-channel heat sink under subcooled conditions. The hydraulic diameter of the rectangular micro-channel under investigation is 666 µm, and the heat sink has twenty-four parallel mico-channels machined on an oxygen-free copper block. The width and height of the rectangular micro-channel are 400 µm and 2000 µm, respectively. The experimented mass flux and fluid inlet temperature to the heat sink range between 103–1026 kg/m2s and 20–50℃, respectively. Furthermore, a consolidated subcooled flow boiling database is developed by using the FC-72 flow boiling data of the present experimental study and the subcooled flow boiling database with four different micro-channel heat sinks with HFE-7100 as the coolant by Lee and Mudawar (2008). Nine prominent predictive heat transfer correlations for subcooled flow boiling are methodically assessed and contrasted against the combined database comprising 631 data points. The evaluation resulted in significant variations in the predictions by the correlations with the current consolidated database. The conventional correlations in the literature for flow boiling under subcooled conditions are inadequate for foreseeing the heat transfer during subcooled flow boiling in the micro-channel heat sink as they are developed based on conventional tubes and annuli with channel hydraulic diameters greater than 3 mm. A new subcooled flow boiling heat transfer correlation rooted in dimensionless group terms is then developed from the consolidated database. Compared to prior correlations, better predictive performance is observed for the new subcooled flow boiling correlation against the consolidated database. The newly developed correlation has a mean absolute error of 21.9%, with 74.9% of data points forecasted within ±30%.