Heat Transfer In Channel Research Articles

Heat transfer in a non-uniform channel on MHD peristaltic flow of a fractional Jeffrey model via porous medium

Heat transfer in a non-uniform channel on MHD peristaltic flow of a fractional Jeffrey model via porous medium

Multiple aspects of heat generation/absorption on the hydromagnetic flow of Carreau nanofluids via nonuniform channels

The use of nanofluid technology as a working fluid in specific channels has significantly improved heat exchange rate in thermal engineering applications. In fact, nonuniform channels with converging or diverging nature offer special characteristics that encourage the most favorable usage, such as flow via nozzles, diffusers, and reducers in polymer processing and flow through canals and rivers. Therefore, we present a theoretical and mathematical insight into nanofluid heat transfer and flow dynamics in nonuniform channels utilizing non-Newtonian nanofluids. The impacts of heat absorption/generation and Joule heating in a magnetohydrodynamics (MHD) flow of Carreau nanofluids with viscous dissipation are addressed in this research. Brownian and thermophoresis diffusion are deliberated to investigate heat and mass transport mechanisms. The modeled flow equations are numerically handled using a built-in MATLAB code based on the finite difference approach (bvp4c) for velocity, temperature, and concentration fields. The consequences of the variable magnetic field, heat absorption/generation, and numerous physical parameters on the temperature and concentration field are surveyed. The results indicate that the increasing values of heat generation/absorption parameter and Eckert number significantly enhances the temperature profiles in convergent channel. In addition, a similar behavior is observed for higher Prandtl number. An assessment of solutions achieved in this article is made with existing data in the literature.

Melting heat transport in a mixed convective squeeze flow of a hybrid nanofluid with interfacial nanolayer effects

AbstractThe interfacial nanolayer effect on a mixed convection flow of single wall CNT (carbon nanotube) and CuO (cupric oxide) water based hybrid nanofluid inside a squeezed channel is studied. To maintain the flow, hybrid nanofluid under consideration is either squeezed or dilated in the parallel plate channel. Melting heat condition on one side of the channel is taken. Generalized thermophysical models which include the interfacial nanolayer effects are proposed for the hybrid nanofluid. Governing equations for the flow are tackled via similarity mappings and bvp4c technique. Statistical analysis revealed a strong significance of the interfacial ratio parameters with Nusselt numbers and skin friction coefficients at both ends of the channel. In case of squeezing flow, it is interestingly noted that the melting parameter uplifted the heat transfer rate, however reverse trend prevailed for dilating flow regime. Mixed convection parameter declined the rate of heat transfer in the squeezing channel, but elevated the coefficient of skin friction.

One-dimensional modelling and simulation of multiple solution characteristics of hydrocarbon fuel flow excursion in scramjet parallel cooling channels

To investigate flow excursion of hydrocarbon fuel in parallel cooling channels of the scramjet, one-dimensional steady-state model of hydrocarbon fuel flow and heat transfer in parallel channels is developed and validated. Flow excursion occurs in the negative slope region of the fuel hydrodynamic curve. Multiple solutions (stable and unstable ones) of flow and temperature distributions are presented. Further simulations are developed at the pressure of 2.2–7.0 MPa, heat flux of 0.5–3.0 MW/m2. Influencing factors such as back pressure, hot resistance, heat flux, thermal deviation and parallel channels number are studied. Higher back pressure affects the fuel properties and negative slope of hydrodynamic curve disappears, which restrains the flow excursion. Hot resistance presents a non-monotonic influence on flow excursion. Hot resistance that is too large or too small suppresses flow excursion. Higher heat flux magnifies the flow excursion amplitude and narrows the flow range of multiple solutions. When channel number increases, the feature of multiple solutions is much more complex and the flow excursion modes becomes tricky.

Asymmetric Method of Heat Transfer Intensification in Radial Channels of Gas Turbine Blades

Loop and semi-loop cooling schemes are widely used for the high-temperature gas turbine blades. In such schemes, the mid-chord airfoil parts are traditionally cooled by radial channels with ribbed walls. The blades with a small specific span, or “short” blades, have different heat flux amounts on pressure and suction sides, which results in a temperature difference in these sides of 100–150 °K. This difference causes thermal stresses and reduces the long-term strength margins. This paper presents a new method of heat transfer intensification in the ribbed radial cooling channels. The method is based on air streams’ injection through holes in the ribs that split channels. The streams are directed along the walls into the stagnation zones behind the ribs. The results of a 3D coolant flow simulation with ANSYS CFX code show the influence of the geometry parameters upon the channel heat transfer asymmetry. In the Reynolds number within a range of 6000–20,000, the method provides the heat transfer augmentation difference by up to 40% on the opposite channel walls. Test results presented in the criteria relations form allow for the calculation of mean the heat transfer coefficient along the channel length.

Heat Transfer and Pressure Drops in a Helical Flow Channel Liquid/Solid Fluidized Bed

Industrial liquid/solid fluidized bed heat exchangers are commonly used with particle recycling systems to allow an increased superficial velocity and higher heat transfer rates. Here, experimental results are reported on a novel helical flow channel geometry for liquid/solid fluidized beds which allow higher heat transfer rates and reduced complexity by operating below the particle transport fluid velocity. This eliminates the complexity of particle recycle systems whilst still delivering a compact heat exchanger. The qualitative character of the fluidization was studied for a range of particle types and sizes under several inclinations of the helices and various hydraulic diameters. The best fluidization combinations were further studied to obtain heat transfer coefficients and pressure drops. Improvements over the heat exchange from a plain concentric tube in an annulus were obtained to the following degree: vertical fluidized bed, 27%; helical baffles, 34 to 54%; and fluidized bed with helical baffles, 69 to 89%.

Effects of Jet-to-Target Surface Spacing and Pin-Fin Height on Jet Impingement Heat Transfer in a Rectangular Channel

Abstract An experimental study was completed to quantify heat transfer enhancement, pressure loss, and crossflow effect within a channel of inline impinging jets. The jet diameter is 5.08 mm; the jet-to-jet spacings in the streamwise and spanwise directions are fixed at x/d = 11.1 and y/d = 5.9, respectively. The effect of jet-to-target surface spacing was considered with z/d = 3 and 6. For both jet-to-target surface spacings, smooth, short pin-finned, and long pin-finned target surfaces were investigated. Both roughened surfaces have a staggered array of 120 copper pin-fins. The pin-to-jet diameter ratio is fixed at D/d = 0.94. The pin height-to-jet diameter ratio for the short and long pins are H1/d = 1.5 and H2/d = 2.75, respectively. Regionally averaged heat transfer coefficient distributions were measured on the target surface, and these distributions were coupled with pressure measurements through the array. The heat transfer augmentation and pressure penalty were investigated over a range of jet Reynolds numbers (10k–70k). The results show high discharge coefficients for all the cases. The channels with the small jet-to-target surface spacing experience double the crossflow effect of the large spacing channels. The addition of surface roughness showed a negligible effect on the crossflow. The best heat transfer performance was observed in the narrow impingement channel with the long pins.

Second Law Analysis of MHD Forced Convective Nanoliquid Flow Through a Two-Dimensional Channel

Abstract The present study deals with fluid flow, heat transfer and entropy generation in a two-dimensional channel filled with Cu–water nanoliquid and containing a hot block. The nanoliquid flow is driven along the channel by a constant velocity and a cold temperature at the inlet, and the partially heated horizontal walls. The aim of this work is to study the influence of the most important parameters such as nanoparticle volume fraction (0%≤ϕ≤4%), nanoparticle diameter (5 nm≤dp≤55 nm), Reynolds number (50≤Re≤200), Hartmann number (0≤Ha≤90), magnetic field inclination angle (0≤γ≤π) and Brownian motion on the hydrodynamic and thermal characteristics and entropy generation. We used the lattice Boltzmann method (LBM: SRT-BGK model) to solve the continuity, momentum and energy equations. The obtained results show that the maximum value of the average Nusselt number is found for case (3) when the hot block is placed between the two hot walls. The minimum value is calculated for case (2) when the hot block is placed between the two insulated walls. The increase in Reynolds and Hartmann numbers enhances the heat transfer and the total entropy generation. In addition, the nanoparticle diameter increase reduces the heat transfer and the irreversibility, the impact of the magnetic field inclination angle on the heat transfer and the total entropy generation is investigated, and the Brownian motion enhances the heat transfer and the total entropy generation.

Effect of channel width on the sedimentation modes of a cold elliptical particle in hot narrow channels

Many natural and industrial processes involve transport of solid particles. This research reports sedimentation modes of a single cold elliptical particle with an aspect ratio of 2 in narrow hot channels. Prior research on settling of non-isothermal elliptical particles was limited to wide vertical channels. A cold particle with constant non-dimensional temperature of T p ∗ = 0 and an initial orientation of θ 0 = π / 3 between its major axis and horizontal axis is released in a hot fluid. Fluid Prandtl number is 7, and its initial temperature is T f , 0 ∗ = 1 . Simulations are based on an in-house lattice-Boltzmann solver with two distribution functions for fluid flow and heat transfer and using Boussinesq approximation in low density variations. In total, 120 simulations in five channel widths have been run, with enough time for the particle to reach a distinct sedimentation/rising pattern. Effects of channel width ( L = 12 A / 13 − 38 A / 13 ), where A is ellipse major diameter, the Grashof number ( Gr = 100 − 1000 ), and particle-to-fluid density ratio ( ρ r = 1 . 0003 − 1 . 3 ) have been studied. Channel width, gravity and heat transfer have been discovered to cause the particle to travel up or down. Seven sedimentation modes have been observed including i) horizontal at centerline, ii) inclined off-center, iii) vertical at center, iv) oscillatory motion around centerline, v) tumbling off-center, vi) horizontal fluttering at centerline, and vii) inclined off-center with oscillations. Three of these patterns (iii, iv, vii) are peculiar to narrow channels, and have not previously been observed for cold elliptic particles in wide channels ( L = 52 A / 13 ). Moreover, the particle has been seen to move upward rather downward in the narrowest channel for small particle-to-fluid density ratios. • Sedimentation modes of a cold elliptical particle in hot narrow channels are studied. • In total seven settling modes are observed; three of them are new and unique to narrow channels. • Grashof and Archimedes number and channel width have significant influence on the sedimentation pattern. • In narrow channels, wall and heat transfer effect are stronger than in wide channels and can even push the particle upward by overcoming the gravity. • Sedimentation velocity of the particle has been seen to be lower in narrow channels compared to wider ones.

Thermal Conductivity of Solid Triphenyl Phosphite

The thermal conductivity, κ, of solid triphenyl phosphite was measured by using the transient hot-wire method, and its temperature and pressure dependencies were analyzed to understand heat transfer processes in the solid polymorphic phases, as well as in the glass and the exotic glacial state. Phase transformations and the structural order of the phases are discussed, and a transitional pressure-temperature diagram of triphenyl phosphite is presented. The thermal conductivity of both the crystalline and disordered states is described within the theory of two-channel heat transfer by phonons and diffusons in dielectric solids. In the glass and glacial states, the weakly temperature-dependent (glass-like) κ is described well by the term associated with heat conduction of diffusons only, and it can be represented by an Arrhenius-type function. In the crystal phases, the strongly temperature-dependent (crystal-like) κ associated with heat transfer by phonons is weakened by significant heat transfer by diffusons, and the extent of the two contributions is reflected in the temperature dependence of κ. We find that the contribution of diffusons in the crystal phases depends on pressure in the same way as that in amorphous states, thus indicating that the same mechanism is responsible for this channel of heat transfer in crystals and amorphous states.

Thermally conductive MWCNTs/Fe3O4/Ti3C2T MXene multi-layer films for broadband electromagnetic interference shielding

• MWCNTs/Fe 3 O 4 /Ti 3 C 2 T x MXene composite film with multi-layer architecture was fabricated by a facile method. • The obtained composite film exhibited high comprehensive performance, including high thermal conduction property and broadband EMI shielding property. • The EMI shielding mechanism of the composite film was comprehensively disclosed. The Ti 3 C 2 T x MXene is thought to be a promising candidate for next-generation electromagnetic interference (EMI) shielding materials. However, its broadband shielding capability and thermal conduction performance are insufficient to meet the growing demands. Herein, we reported a layer-by-layer composite film composed of Ti 3 C 2 T x MXene, multi-walled carbon nanotubes (MWCNTs), and Fe 3 O 4 nanoparticles. Benefitting from the architecture and the synergistic effect of components, the obtained composite film exhibited high comprehensive performance. Specifically, the introduction of Fe 3 O 4 magnetic nanoparticles effectively reduced the impedance mismatch between the composite film and air and enhanced the magnetic loss of the composite film. The layered structure prolonged the transmission path of electromagnetic waves inside the composite film and constructed a rich conductive network, causing interfacial polarization and ohmic loss. The results indicated that the composite film (52 μm) delivered a high EMI shielding effectiveness of 49 dB in the frequency range from X-band to K u -band. Furthermore, the MWCNTs layers in the composite films provided numerous heat transfer channels, reducing phonon scattering during heat transfer and resulting in a maximum thermal conductivity of 8.241 W/(m K).

Double-Layer MWCNTs@HPPS Photothermal Paper for Water Purification with Strong Acid-Alkali Corrosion Resistance.

Solar-driven interfacial evaporation technology has been identified as a promising method to relieve the global water crisis, and it is particularly important to design an ideal structure of the solar thermal conversion evaporation device. In this paper, hydrophilic polyphenylene sulfide (HPPS) paper with loose structure and appropriate water transmission performance was designed as the based-material, and multi-walled carbon nanotubes (MWCNTs) layer with excellent photothermal conversion performance was constructed to realize the high-efficiency solar-driven evaporation. Under tail swabbing mode, the cold evaporation surface on the back of the evaporator greatly improved the evaporation rate, cut off the heat transfer channel to bulk water, and achieved the maximum evaporation rate of 1.23 L/m2·h. Ethyl cellulose (EC) was introduced to adjust the water supply performance of HPPS layer, and a large specific surface area of cold evaporation was obtained, thus improving the water evaporation rate. In the simulation experiment of seawater desalination and dye wastewater treatment, it showed good water purification capacity and acid/alkali-resistance, which had great practical application significance.

Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method

A two-dimensional rectangular domain is considered with a discrete arrangement at equal distances from copper metal foam in a solar air heater (SAH). The local thermal non-equilibrium model is used for the analysis of heat transfer in a single-pass rectangular channel of SAH for different mass flow rates ranging from 0.03 to 0.05 kg/s at 850 W/m2 heat flux. Three different pores per inch (PPI) and porosities of copper metal foam with three different discrete thicknesses at equal distances are studied numerically. This paper evaluates the performance of SAH with 10 PPI 0.8769 porosity, 20 PPI 0.8567 porosity, and 30 PPI 0.92 porosity at 22 mm, 44 mm, and 88 mm thicknesses. The Nusselt number for 22 mm, 44 mm, and 88 mm thicknesses is 157.64%, 183.31%, and 218.60%, respectively, higher than the empty channel. The performance factor for 22 mm thick metal foam is 5.02% and 16.61% higher than for 44 mm and 88 mm thick metal foam, respectively. Hence, it is found that metal foam can be an excellent option for heat transfer enhancement in SAH, if it is designed properly.

The experimental research on subcooled flow boiling in vertical narrow rectangular channels with relatively Wide-Ranged parameters

A series of tests are performed for subcooled boiling heat transfer characteristics of water in narrow rectangular channels. The channel sizes are 50mm×3mm×1000mm, 60mm×3mm×1000mm and 50mm×2mm×1000mm. The test matrix covers a relative wide range of conditional parameters with a mass flux range of 2003000kg/m2∙s, a system pressure range of 0.25.5MPa and an inlet subcooling of 20100K. The images of bubble behaviors are caught by high-speed camera. The images analysis and sensitive study on each parameter of boiling incipience and subcooled boiling heat transfer characteristics are carried out. The effect of forced convection could not be neglected in wall temperature of ONB prediction. Subcooled boiling heat transfer capacity gets enhanced by bubble sliding. According to the force balance analysis and bubble behavior photograph, flow condition is the main factor to promote bubble departure. To consider the appearance of confined bubble in narrow rectangular channel, the particular confined aspect ratio number α∗ is proposed. By measuring α∗, the effect of geometric characteristic on subcooled boiling heat transfer could be known. The new correlation for ONB prediction and subcooled boiling heat transfer in narrow rectangular channel is developed within the deviation of ±20%. In particular, the ONB prediction correlation shows good performance in prediction based on the database from other literatures.

Heat Transfer and Friction in a Rectangular Channel With Varying Numbers of Walls Roughened With 90-Deg Transverse or 45-Deg V-Shaped Ribs

Abstract An experimental investigation was performed to measure the regionally averaged heat transfer distributions and friction factors for fully developed turbulent flow in a rectangular channel with a width-to-height aspect ratio (AR = 3). Data for transverse 90-deg and 45-deg V-shaped, carbon steel ribs placed on one, two, or four sides of the channel were reported for a Reynolds number range (Re = 5,000–60,000). The pitch-to-rib height ratio (P/e) was set at 10 while the rib height-to-channel hydraulic diameter (e/Dh) is 0.041. This corresponds to a roughness Reynolds number range (e+=25−500). For both rib configurations, results show the highest thermal performance was achieved in the channels with four-ribbed wall followed by the two and one-ribbed wall channels, respectively. Using the law of the wall similarity, friction roughness functions (R) and heat transfer roughness functions (G) were developed based on four-sided friction and heat transfer data. Moreover, friction and heat transfer data of similar rib designs were obtained from literature and correlated to the corresponding friction and heat transfer roughness functions. Covering a wide range of roughness Reynolds numbers, more robust heat transfer and friction correlations were developed which can be used by designers to accurately predict both heat transfer and friction in ribbed channels with different numbers of ribbed walls. Using these correlations, one can predict the measured friction and heat transfer data of this study with maximum errors of 9% and 7%, respectively.

Thermal Visualization and Performance Analysis in a Channel Installing Transverse Baffles with Square Wings

The experimental examination of local heat transfer, thermal intensification, friction factors, and thermal performance factors (TPF) in a rectangular channel with square-winged transverse baffles (SW-TB) are presented in this paper. The purpose of this study is to modify the typical transverse baffles (TB) into square-winged transverse baffles (SW-TB) in order to improve the thermal performance and heat transfer rate of the channel. The effects of SW-TBs with various wing attack angles and Reynolds numbers on the heat transfer performance characteristics were examined using a thermochromic liquid crystal sheet. In the experiments, the SW-TBs were attached to the bottom wall of the channel, which had an aspect ratio (W:H) of 3.75:1. The SW-TBs had a width (w) of 150 mm, a square perforated cross-sectional area (a × b) of 8 × 8 mm2, and attack angles (θ) of 0° (solid transverse-baffle), 22.5°, 45°, 67.5°, and 90°. The bottom wall of the channel was evenly heated, while the other walls were insulated. The temperature contours on the heated surface were plotted using temperatures obtained through using the thermochromic liquid crystal (TLC) image-processing method. Experimental results revealed that the SW-TBs created multiple impinging jets, apart from the recirculation. At the proper attack angles (θ = 22.5° and 45°), the SW-TBs offered greater heat transfer rates and caused lower friction losses, resulting in higher TPFs than the solid transverse baffles. In the current work, channels where the SW-TBs display a θ = 45° presented the greatest TPF, as high as 1.26. The multiple impinging jets issuing by the SW-TBs suppressed the size of the recirculation flow and allowed better contact between the fluid flow and channel wall.

Blood-based hybrid nanofluid flow through converging/diverging channel with multiple slips effect: a development of Jeffery-Hamel problem

PurposeThe purpose of this paper is to study and analyze the converging/diverging channel flow and heat transfer with the multiple slips effect, which is a development of the Jeffery–Hamel problem using the mass-based hybrid nanofluid algorithm. Whereas transferring biological liquid by arteries is a vital issue, mathematical modeling of hybrid nanofluid flow containing titanium dioxide and silver as nanoparticles and blood as base liquid through a converging/diverging duct, which can be a useful analysis for the fields of drug delivery, has been investigated.Design/methodology/approachThe present approach is based on the Tiwari–Das nanofluid method. In this modeling, the volume fraction of nanoparticles is replaced with nanoparticles masses. The partial differential equations of the mass, momentum and energy conservations are changed to the system of ordinary differential equations through the similarity solution method. The final governing equations are solved by Runge–Kutta–Fehlberg procedure and shooting method.FindingsThe effect of emerging parameters on the temperature, the velocity, the Nusselt number and the skin friction have been analyzed by graphical and tabular reports. It is observed that the opposition to hybrid nanofluid flow in the attendance of particles of nonspherical shapes is more enhanced than those in the attendance of particles of spherical shapes. This issue demonstrates that the rheology of a hybrid nanofluid is dependent on the shape of particles. Besides, backflow regimes form in the divergent channel for high values of Reynolds number, m2 and a. Indeed, this modeling for the hybrid nanofluid can be useful in different technologies and industries such as biological ones. It is worth mentioning that the excellent achievement of the mass-based algorithm for heat transfer and hybrid nanofluid flow is the most important success of this study.Originality/valueThe main originality is related to the development of the Jeffery–Hamel problem using the mass-based hybrid nanofluid algorithm. This new mass-based method is a single-phase hybrid nanofluid approach that the inputs are masses of nanoparticles and base liquid. Besides, considering the multiple slips effect and also pure blood as base fluid in this problem are also new.

CFD-based simulation of heat transfer in a rectangular channel

Heat transfer is an important phenomenon in the industrial sector. Thus, the simulation is made to compute the distribution of heat in a rectangular channel in this paper. A heated rod is inserted at the center of the rectangular channel. The fluid flowing in the rectangular channel is considered to be a viscous fluid. Navier–Stokes equations of motion for laminar flow are used. The medium for the fluid motion is considered to be a porous medium. Heat transfer is computed for nonlinear two-dimensional incompressible and unsteady flows. The Fourier’s law of heat conduction is used for the transmission of heat in the rectangular channel. The Finite Element Method (FEM) is applied to the solution of the problem. For different values of the permeability parameter, Prandtl number and Rayleigh number, the graphic solution for the velocity and temperature fields is shown.

A novel approach for suppressing flow maldistribution in mini-channel heat exchangers

Mini-channel heat exchangers are extensively used to achieve heat dissipation with high heat flux, while the problem of flow maldistribution seriously impairs the thermal efficiency and operational reliability of heat exchangers. In this paper, the flow distribution characteristics of mini-channel heat exchangers with the conventional manifold model are numerically studied, and the influence of flow maldistribution on heat transfer is analyzed. To suppress the problem of flow maldistribution, an innovative approach for improving fluid uniformity by the built-in spiral baffle in the inlet manifold is proposed, and the effects of spiral baffles with different pitches and radii on flow distribution are discussed. Besides, the heat transfer characteristics and pressure drop under different manifold models are also compared. Finally, the variable-pitch spiral baffle is introduced to realize the stepped regulation of flow distribution. The results show that the conventional manifold model has serious flow maldistribution and causes the deterioration of heat transfer in front-end channels, especially at high Reynolds numbers. The improved manifold model greatly improves the uniformity of the fluid and temperature distribution inside mini-channel heat exchangers on the premise of sacrificing a small amount of pressure drop. The optimal pitch and radius of the spiral baffle are 20 mm and 9 mm respectively, and the flow maldistribution in almost all channels is controlled within the range of ±15% at this case. In addition, the variable-pitch spiral baffle further improves the flow uniformity of the mini-channel heat exchanger, and shows better overall performance than the equal-pitch spiral baffle.

Predictive method for flow condensation heat transfer in plain channels

The flow condensation heat transfer (FCHT) in plain channels has a variety of applications in many industrial sectors, and thus it is important to predict FCHT coefficients accurately. This paper compiled a large compound FCHT database containing 5607 data points and 30 fluids and presented a strategy for developing a new correlation of FCHT coefficients. The parameter range of the database is the hydraulic diameter D = 0.493–20 mm, vapor quality x = 0.003–0.992, mass flux G = 24–1533 kg/m2 s, heat flux q = 2.9–422 kW/m2, reduced pressure pr = 0.04–0.95, liquid Prandtl number Prl = 1.7–8.5, liquid Reynolds number Rel = 11.6–5.3 × 104, and gas Reynolds number Reg = 75.1–9.1 × 105. Based on the database and strategy, a new general correlation with substantially better accuracy was developed, which is applicable to plain channels of various sizes and a broad operational parameter range. It predicts the database with a mean absolute deviation (MAD) of 14.1%, while the best existing ΔT-independent correlation predicts the database with an MAD of 20.2%. The applicability of the new and 38 existing correlations to individual fluids was assessed. The new correlation performs best for 8 of the 14 fluids that have more than 50 data points in the entire database, while the most accurate existing one performs best only for 2 of them. The Fang number Fa plays an important role in the new correlation, implying that it relates to the fundamental mechanisms of both boiling and condensation heat transfer.