High Mass Flux Research Articles

Experimental and numerical study on the heat transfer to supercritical water in an inclined smooth tube

Heat transfer to supercritical water in a smooth tube with an inclined angle of 25° was investigated experimentally and numerically. Experimental results show that the increase of mass flux improves the heat transfer. As the pressure increases, influence of physical property variation to the heat transfer becomes gentle. Thereby, the increase of pressure reduces the heat transfer under an enhanced condition. Dimensionless buoyancy parameters Grq*/Grqth and Gr‾/Re2.7 are compared on the basis of experimental results. The evaluated result shows that Grq*/Grqth is applicable to the inclined tube flow. Base on the supercritical data, a new heat transfer correlation is proposed. Numerical analysis was completed with the shear stress transport k-ω model. Corresponding results show that the influence of variable mass flux and pressure on supercritical heat transfer is realized by changing radial distributing characteristics of turbulence and physical property. The increase of mass flux improves the radial turbulence and heat-absorbing capacity of the boundary fluid, so the supercritical heat transfer is enhanced. At a low mass flux condition where heat transfer reduction occurs, the increase of pressure improves the heat transfer. At a high mass flux condition where heat transfer enhancement occurs, the increase of pressure reduces the heat transfer. Influence of natural convection caused by the buoyancy leads to the occurrence of heat transfer disparity between top and bottom sides of the inclined tube. The increase of mass flux weakens the influence of natural convection and improves local heat transfer at the top side. At the low mass flux condition, the increase of pressure conducts the same effect with the increase of mass flux. At the high mass flux condition, the increase of pressure reduces the local heat transfer at the top side.

A Comparative Study on the Condensation Heat Transfer of R-513A as an Alternative to R-134a

This paper presents the two-phase condensation heat transfer and pressure drop characteristics of R-513A as an alternative refrigerant to R-134a in a 9.52-mm OD horizontal microfin copper tube. The test facility had a straight, horizontal test section with an active length of 2.0 m and was cooled by cold water circulated in a surrounding annular space. The annular-side heat transfer coefficients were obtained using the Wilson plot method. The average heat transfer coefficient and pressure drop data are presented at the condensation temperature of 35 °C in the range of 100–440 kg·m−2·s−1 mass flux. The test data of R-513A are compared with those of R-134a, R-1234yf, and R-1234ze(E). The average condensation heat transfer coefficients of the R-513A and R-1234ze(E) refrigerants were similar to R-134a at the lower mass flux (100~150 kg·m−2·s−1), while they were up to 10% higher than R-134a as the mass flux increased. The pressure drop of R-513A was similar to R-1234yf and 10% lower than that of R-134a at the higher mass flux. The R-1234ze(E) pressure drops were 20 % higher compared to those of R-134a at the higher mass flux.

Experimental investigation of refrigerant condensation in circular and square micro- and mini- channels

Microchannel condensers have the potential to improve system level efficiency by increasing the heat transfer coefficient because of the small hydraulic diameters. In addition, they offer a high surface area-to-volume ratio, reducing the overall system size and fluid inventory. Understanding condensation in microchannels is essential for efficient component design, especially with the need for new low Global Warming Potential (GWP) working fluids. Condensation of refrigerants R134a, R245fa and R1234ze(E) in circular (Dh = 1.55 mm) and square (Dh = 0.98 mm) microchannels over a range of mass fluxes (50 < G < 200 kg m−2 s−1), saturation temperatures (30 < Tsat< 50°C), and wall subcooling (1.7 < ΔT < 5K) is investigated in this study. It is found that at high mass fluxes (G ≥ 150 kg m−2 s−1), R245fa has a higher heat transfer coefficient and pressure gradient than both R1234ze(E) and R134a, which have comparable heat transfer coefficients at similar conditions. In the circular channel, for a mass flux range of 50 < G < 150 kg m−2 s−1 and Tsat = 30°C, the heat transfer coefficients for R245fa, R134a, and R1234ze(E) varied between 2.3 and 6.7 kW m−2 K−1, 2.5 and 4.7 kW m−2 K−1, and 2.2 and 5.4 kW m−2 K−1, respectively.

Experimental Study on Film Cooling Effectiveness of Blade With Chevron-Shaped Holes Under Wake Influence

Abstract Gas turbines have been widely used. With the continuous improvement of the performance of gas turbines, the turbine inlet temperature has greatly exceeded the heat-resistance limit of the turbine blade material, so advanced cooling technology is required. The film cooling effectiveness distribution over the blade under the effect of wake was obtained by the pressure-sensitive paint (PSP) technique. The test blade has five rows of chevron film holes on the pressure side, three rows of cylindrical film holes on the leading edge, and three rows of chevron film holes on the suction side. The mainstream Reynolds number is 130,000 based on the blade chord length, and the mainstream turbulence intensity is 2.7%. The upstream wake was simulated by the spoken-wheel type wake generator. The film cooling effectiveness was measured at three wake Strouhal numbers (0, 0.12, and 0.36) and three mass flux ratios (MFR1, MFR2, and MFR3). The results show that the increase of mass flux ratio leads to a decrease of the film cooling effectiveness on the suction surface. In the wake condition, the effect of mass flux ratio is weakened. Wake leads to a marked decrease of the film cooling effectiveness over most blade surface except for the surface near leading edge on the pressure surface. In the high mass flux ratio condition, the effect of wake on the film cooling effectiveness is weakened on the suction surface and strengthened on the pressure surface.

수평관 내 R-1234yf 응축 열전달 실험

Due to environmental problems around the world, HFC refrigerants have been used instead of CFC and HCFC refrigerants with high ODP in the field. But, these refrigerants are also subject to regulation due to their high GWP. Accordingly to cope with the phased regulatory planning of HFC refrigerants, related companies have developed HFO refrigerants with low GWP. Among HFO refrigerants, the working fluid R-1234yf (GWP:4) in this paper is similar in thermodynamic properties to R-134a (GWP:1300). The experiment results are summarized as follows. The condensation heat transfer coefficient of R-1234yf in the double tube heat exchanger increased with increasing mass flux and quality. The condensation heat transfer coefficient decreased with increasing saturation temperature, but at high mass flux and high quality, it had little effect on saturation temperature. As the temperature difference between the coolant and the refrigerant increased, the heat transfer coefficient tended to increase. The condensation heat transfer coefficient of R-1234yf is lower than that of R-134a in almost all quality. However, at low quality and low mass flux the condensation heat transfer coefficient of R-1234yf tended to be greater than R-134a. Due to the difference in refrigerant physical properties such as density, surface tension, and thermal conductivity of the two refrigerants. As a result, it is believed that this paper could be used as a foundation for the optimal design of condensers using R-1234yf.

Effect of wettability on flow boiling heat transfer in a microtube

As one of the main factors, surface wettability significantly affects flow boiling characteristics. In this study, the wettability effect in a microtube was presented by a numerical method. A gas-liquid phase-change model was adopted to research characteristics of two-phase flow and heat transfer. Three types of wettability surfaces (hydrophilic, hydrophobic, and gradient wettability) were explored under different mass fluxes with subcooling inlet and constant heat flux conditions. Numerical results indicate that the slug flow is absent near the outlet under a higher mass flux, mainly due to the backward movement of saturated nucleation boiling. Hence, better heat transfer performance is achieved on both hydrophilic and hydrophobic surfaces. Outstanding performance is exhibited on the hydrophilic surface, mainly in subcooling, bubbly, and confined bubble flow. Since the unstable interface fluctuation and the bubble sliding behavior, the hydrophobic surface's heat transfer performance is improved in the confined bubble and slug flow. As incorporating the contact angle continuous variation effect and the hydrophilic and hydrophobic surfaces' advantages, gradient wettability surface shows sound heat transfer performance in each flow region, especially in the slug flow where shorter bubbles and drastic fluctuation of unstable bubble interface appears. Based on the present investigation, the gradient wettability surface demonstrates considerable potential in equipment cooling applications by regulating the flow boiling characteristics and improving the performance.

Experimental investigation on flow oscillation of boiling two-phase flow in a single rod channel

Flow oscillation of two-phase flow has significant effect on the safety of relative industrial application, such as nuclear reactor. Oscillation of mass flux can induce undesirable such as boiling crisis. In this paper, a visual experimental study is carried out in a single rod channel to investigate the mechanism of flow oscillations. The system pressure is from 0.1 MPa to 1.0 MPa with different mass flux and inlet subcooling. According to the characteristics of the flow oscillation combined with bubble behavior, the flow oscillation is divided into slightly flow oscillation with high subcooled and high mass flux condition, boiling onset flow oscillation with bubbly flow and flow patterns transition oscillation with flow pattern transition. In this paper, the effect of thermal conditions on flow oscillation is also analyzed and discussed in detail.

Vapor Flux on Bumpy Surfaces: Condensation and Transpiration on Leaves

Drop condensation and evaporation as a result of the gradient in vapor concentration are important in both engineering and natural systems. One of the interesting natural examples is transpiration on plant leaves. Most of the water in the inner space of the leaves escapes through stomata, whose rate depends on the surface topography and a difference in vapor concentrations inside and just outside of the leaves. Previous research on the vapor flux on various surfaces has focused on numerically solving the vapor diffusion equation or using scaling arguments based on a simple solution with a flat surface. In this present work, we present and discuss simple analytical solutions on various 2D surface shapes (e.g., semicylinder, semiellipse, hair). The method of solving the diffusion equation is to use the complex potential theory, which provides analytical solutions for vapor concentration and flux. We find that a high mass flux of vapor is formed near the top of the microstructures while a low mass flux is developed near the stomata at the leaf surface. Such a low vapor flux near the stomata may affect transpiration in two ways. First, condensed droplets on the stomata will not grow due to a low mass flux of vapor, which will not inhibit the gas exchange through the stomatal opening. Second, the low mass flux from the atmosphere will facilitate the release of highly concentrated vapor from the substomatal space.

Design aspects of forced circulation evaporators of high salty water from the view point of scale formation

In this paper, dryout phenomenon was studied for vertical tubes working at the operating condition of forced circulation evaporator in zero liquid discharge systems to find the maximum allowable value of temperature difference between evaporator effects in which scale formation and fouling do not occur. Eulerian two-fluid approach coupled with Rensselaer Polytechnic Institute wall boiling model was used to simulate upward flow subcooled boiling. Critical near-wall void fraction was used as the criterion of dryout. The value of the critical temperature difference was investigated for 36 cases. Values varied from 4.8 to 10.7 °C for different amounts of tube length, tube diameter and mass flux. In addition, the effect of tube length, tube diameter and mass flux on critical temperature difference was analyzed. The results showed that critical temperature difference decreased approximately linearly with an increase in tube length. Furthermore, the value of critical temperature difference decreased with the increase in tube diameter and decrease in mass flux and the effect of tube diameter is more significant at higher mass fluxes.

On the Use of a Buoyancy Parameter for Distinguishing Deteriorated From Normal Heat Transfer in Upward Flows at Supercritical Pressures

Abstract An extensive analysis of two versions of a buoyancy parameter as supercritical heat transfer deterioration (DHT) identifiers was conducted for large databases obtained in carbon dioxide flowing through three electrically heated tubes with internal diameters equal to 4.6, 8.0, and 22.0 mm and in Refrigerant R134a through an 8.0 mm tube. For the first time, buoyancy parameter profiles along each tube were considered for wide ranges of closely incremented operating conditions. The occurrence of DHT in each test section was first assessed confidently by observation of wall temperature profiles and comparison of measurements with wall temperature predictions of a correlation for normal heat transfer (NHT). The objective of this work was to determine whether a universal buoyancy parameter threshold could be used as a means for identifying DHT in a test section. It was found that correction factors were required for both parameters to account for an observed shift of the threshold for DHT occurrence, as the mass flux was changed. The resulting threshold for one of the buoyancy parameters identified correctly DHT for cases having a mass flux up to a certain value, but failed to do so for cases with a higher mass flux.

Flow boiling pressure drop characteristics in a multi-microchannel heat sink

We make an effort in this study to experimentally investigate the flow boiling pressure drop characteristics in a multi-microchannel heat sink. For the multi-microchannel heat sink, 27 parallel microfluidic channels are considered. Microchannels are fabricated on the copper block and have a hydraulic diameter of 421 µm and length of 40 mm. We perform experiments considering the refrigerant, considered the working fluid in this study. A high mass flux (G ∼ 400 kg/m2 s–1200 kg/m2 s) for a range of wall heat flux (q′′ ∼ 10 kW/m2–170 kW/m2) and varying degrees of saturation temperature (Tsat ∼ 13 °C, 18 °C, and 23 °C) are considered for the experiments. We demonstrate the correlative effect of the total pressure drop on the two-phase flow pattern in the channel. By depicting the interplay between the total pressure drop (∆p) and the frictional pressure gradient, we show that the frictional pressure gradient increases with the increasing mass flux while it decreases with the increasing degree of saturation temperature. We show the significant impact of the heat flux and saturation temperature on the frictional pressure gradient. In addition, we develop a new correlation for the pressure drop characteristics taking the interference effect of the frictional pressure drop in the multi-microchannel heat sink. The inferences of this experimental study will have far-ranging consequences for the design of heat exchangers, leading to the optimization of microscale thermal management equipment.

Flow Regime Transition in the Post-CHF Flow Regimes under Subcooled and Low-quality Conditions

Post critical heat flux (post-CHF) heat transfer may occur during loss of coolant accidents (LOCAs) in water-cooled nuclear reactors when makeup water quenches the uncovered portion of fuel rods in the reactor cores. Post-CHF flow regimes include inverted annular film boiling (IAFB), dispersed flow film boiling (DFFB), and a transition regime between these two, i.e., inverted slug film boiling (ISFB) for low mass fluxes or agitated inverted annular film boiling (AIAFB) for high mass fluxes. Flow regime transition is important for modeling heat transfer characteristics in the post-CHF flow regimes. Breakup of the liquid core in the IAFB regime represents the flow regime transition from the IAFB to ISFB/AIAFB regimes. This paper first presents a literature review of previous experimental and theoretical studies of the mechanisms of breakup of the liquid core in the IAFB regime and flow regime transition in the post-CHF regimes. To physically explain the breakup of the liquid core in the IAFB regime, the Weber number is calculated from the experimental data obtained from steady-state post-CHF experiments at subcooled and low-quality conditions and a critical Weber number is obtained to describe the flow regime transition from the IAFB to ISFB/AIAFB regimes. Parametric effects of the inlet subcooling, mass flux, and system pressure on the critical Weber number are then studied, based on which a new correlation for the critical Weber number is proposed to predict the flow regime transition from the IAFB to ISFB/AIAFB regimes. Due to the different flow patterns in the transition regime, i.e., ISFB and AIAFB respectively for low and high mass fluxes, the heat transfer characteristics show different trends. The indication of the flow regime transition from the IAFB to ISFB/AIAFB regimes by the critical Weber number criterion matches well with the trend of the wall heat transfer coefficient.

Effects of vegetation pattern and of biochar and powdery soil amendments on soil loss by wind in a semi‐arid region

AbstractDust emission from wind erosion is a widespread phenomenon in arid and semi‐arid areas having considerable implications for ecosystems and human well‐being. However, few studies have examined the efficiency of biochar amended to soil on wind erosion control. Aimed at studying the effect of biochar on resistance of soils against wind erosion, a wind tunnel experiment was conducted. We tested (a) soils amended with hard waste walnut wood biochar and soft maize cob biochar, and (b) soils amended with powdery waste wood and powdery maize cob, and compared them with (c) non‐treated soil, in their susceptibility to wind erosion and also the additional effect of various patterns of vegetation cover. Amending soil with biochar and powdery material did significantly increase their resilience to wind erosion because of increased soil aggregation. In comparison with the non‐treated control, the mass flux of un‐vegetated soil reduced from 4.42 to 1.86 g m−2 s−1 for the waste walnut wood biochar, from 4.28 to 1.50 g m−2 s−1 for maize cob biochar, from 4.11 to 1.44 g m−2 s−1 for powdery maize cob and from 3.97 to 1.14 g m−2 s−1 for powdery waste walnut wood. When combining amendments with vegetation, there was still a substantial improvement, though the soil treatments responded differently in terms of soil loss to different vegetation patterns. A single row vegetation pattern had the highest mass flux, while a zigzag vegetation pattern had the lowest. In conclusion, waste wood or maize cobs, whether applied as biochar or as powdery material, are able to fix soil and reduce wind erosion.

Two-phase flow boiling in a microfluidic channel at high mass flux

We report the experimental investigations of two-phase flow boiling heat transfer characteristics of a refrigerant in a microfluidic channel at a high mass flux (more than 1000 kg/m2 s). We investigate the heat transfer coefficients at a heat flux range of 7.63 kW/m2–49.46 kW/m2, mass flux range of 600 kg/m2 s–1400 kg/m2 s (high mass flux), and saturation temperature range of 23 °C–31 °C. We propose the new two-phase flow boiling heat transfer correlation of a refrigerant, which is used as the working fluid for the present experiments, at the microfluidic scale. We experimentally establish the functional relationship of two-phase flow boiling heat transfer correlation of the refrigerant during flow boiling in a rectangular microchannel with the Reynolds number, the boiling number, and the Weber number. We believe that the inferences of this study may provide a design basis for the micro-heat exchanger, typically used for thermal management in electronic devices, micro-electro-mechanical systems, and electric vehicle battery cooling system.

Experimental Study on Heat Transfer and Flow Characteristics in Subcooled Flow Boiling in a Microchannel

The current study presents an experimental investigation of heat transfer and flow characteristic for subcooled flow boiling of deionized water in the microchannel heat sink. The test section consisted of a single microchannel having 300μm wide nominal dimensions and 300μm height (hydraulic diameter of 300μm). The test section formed of oxygen-free copper with 72mm length and 12mm width. Experimental operation conditions spanned the heat flux (78-800) kW/m2, mass flux (1700 and 2100) kg/m2.s at 31˚C subcooled inlet temperature. The boiling heat transfer coefficient is measured and compared with existing correlations. Also, the experimental pressure drop is measured and compared with microscale pressure drop correlations. The results showed that higher mass flux leads to higher boiling heat transfer coefficient, and the dominant mechanism is convective boiling. Also, the experimental pressure drop decrease with increasing heat flux in a single-phase region while it increases in a two-phase region. Comparing the experimental results in the experimental condition range, showed that an existing correlation provides a satisfactory prediction of heat transfer coefficient and pressure drop.

Flow boiling heat transfer characteristics of R245fa refrigerant in a plate heat exchanger

Plate heat exchangers (PHEs) are used extensively in industrial applications and, owing to their compactness, and higher thermal efficiency, they are keys component of organic Rankine cycle (ORC) application. This study presents the experimental heat transfer characteristics during flow boiling of R245fa refrigerant with a commercial working fluid used in ORCs; inside brazed plate heat exchanger with chevron angle of 65 degree. The flow boiling heat transfer characteristics were measured with varying saturation temperatures, mass flux and heat flux, which range from 55.5 °C-61.8 °C, 15.5-17.4 kg m−2 s−1, and 6400-10120 W m−2, respectively. The experimental results showed that flow boiling heat transfer coefficient is dependent upon the heat flux and mass flux. The results showed that the heat transfer coefficient increases with the increase of heat flux, and then starts to decrease due to local dry out. However, at low mass flux, locally triggering dry out was more prominent than that high mass flux. The heat transfer coefficient showed to be sensitive to the change in the saturation temperature. Moreover, flow boiling heat transfer coefficient showed a linear relationship with mass flux of the refrigerant.

Experimental study of heat transfer coefficient, pressure drop and flow pattern of R1234yf condensing flow in inclined plain tubes

The purpose of the present study is to investigate the condensation heat transfer coefficient, pressure drop and flow pattern characteristics of R1234yf refrigerant in an inclined plain tube with an internal diameter of 8.3 mm. Experiments are conducted at four mass fluxes of 80, 160, 240 and 320 kg/m2s, mean vapor qualities in the range of 0.12 to 0.75, saturation temperature of 25 °C, and for tubes with inclination angles in the range of -90° (vertically downwards) to +90° (vertically upwards). The effects of different parameters such as mass flux, mean vapor quality, and the inclination angle of the tube on flow pattern, condensation heat transfer coefficient, and pressure drop are investigated. According to the results, it is found that inclination angle significantly influenced the flow pattern. Furthermore, it is observed that generally, increasing vapor quality and mass flux, enhances the heat transfer coefficient for all the inclination angles. At low mass fluxes or low vapor qualities, the highest heat transfer coefficient occurs in the tube with the inclination angle of -30°, while at higher mass fluxes or higher vapor qualities, the effect of inclination angle on heat transfer is negligible. With increasing the vapor quality, total pressure drop increases for tubes with the negative or zero angles, while it generally decreases, for the tubes with positive angles. In addition, total pressure drop increases with increasing mass flux at constant vapor quality for all the inclination angles. Experimental results of this study are also compared with the existing correlations in literature that predict the amount of heat transfer coefficient and frictional pressure drop. Finally, based on the present data, a new correlation is developed and suggested to predict the flow condensation heat transfer coefficient in inclined plain tubes.

Experimental investigation in the local heat transfer of supercritical carbon dioxide in the uniformly heated horizontal miniature tubes

This study experimentally investigated the local heat transfer characteristics of supercritical carbon dioxide, which was uniformly heated in horizontal circular smooth tubes with inner diameters of 1.0 mm, 0.75 mm and 0.5 mm. The experimental results illustrated heat transfer enhancement with an increase in fluid temperature before the pseudocritical point and a decline in heat transfer just after the pseudocritical point. Subsequently, the heat transfer coefficient increased again when the fluid temperature was sufficiently higher than the pseudocritical value due to the enhancement of turbulence resulting from the decrease in viscosity. In addition, the parametric effects of outlet pressure, heat flux, mass flux, inlet temperature, and tube diameter on local heat transfer were investigated. The system demonstrated the optimal heat flux with the highest thermal performance when the outlet fluid condition was close to the corresponding pseudocritical point, at which both the specific heat and Prandtl number attained peak values. With other parameters fixed, the system with a higher mass flux, lower inlet temperature, or smaller diameter exhibited higher heat transfer performance. A new empirical correlation developed on the basis of the experimental data can reasonably predict the local Nusselt number of supercritical carbon dioxide along the flow path in uniformly heated horizontal tubes.

Numerical Study on the Gravity Effect on Heat Transfer of Supercritical CO2 in a Vertical Tube

The effects of gravity on the heat transfer performance of supercritical CO2 flowing within a vertical tube with a diameter of 4.75 mm are numerically studied in this paper. The main objectives are to comprehensively investigate the action of gravity and buoyancy on the supercritical heat transfer. An effective numerical method, which employs a modified Shear Stress Transfer k-ω model (SST k-ω), is applied at various gravity conditions. It is found that, for both upward and downward flows, the heat transfer of supercritical CO2 is improved with increased gravity magnitude. The effect of gravity on heat transfer are more pronounced under a low mass flux condition than that under a high mass flux condition and it is closely related to the variations of thermal properties. For the upward flow, the increased gravity magnitude accelerates the near wall fluid and creates a classic “M-shaped” radial velocity distribution. For the downward flow, the increased gravity magnitude decelerates the near wall fluid and creates a parabola-like radial velocity distribution. On one hand, the turbulent kinetic energies of both the upward and downward flows are enhanced as the gravity magnitude increases, which benefits heat transfer dominated by turbulent eddy diffusion. On the other hand, high-density fluid with high thermal conductivity occupies the near wall region as the gravity magnitude increases, which benefits heat transfer dominated by molecular diffusion. The results might provide some instructive advice to improve the design and operation safety of heat exchanger at various gravity conditions.

Elucidating the Impact of Flow on Material-Sensitive Critical Heat Flux and Boiling Heat Transfer Coefficients: An Experimental Study with Various Materials

Steady-state internal flow boiling critical heat flux (CHF) experiments were carried out at 10℃ inlet subcooling and atmospheric pressure (84 kPa at an altitude of about 5300 feet) with mass flux ranging from 200 to 2,000 kg/m2-s on seven tube materials, including the accident-tolerant fuel cladding candidate FeCrAl (C26M) alloy. At a relatively low flow rate, the sensitivity of CHF to different materials was appreciable (the average difference among the tested materials was 19% at 200 kg/m2-s). As the absolute CHF differences stayed constant for higher flow rates, the increased flow rate led to reduced relative CHF differences among the tested materials (average relative difference of 15% at 1,000 kg/m2-s). FeCrAl alloy claddings that were oxidized under simulated Light Water Reactor (LWR) conditions yielded CHF comparable to as-received FeCrAl alloy cladding, with less than 1.8% difference. Experimental CHF results imply marginal material sensitivity impacts on the departure from nucleate boiling ratio in steady-state nuclear reactor cores. Yet, for accident progression analysis, material sensitivity may hold importance, as boiling behavior variation at low mass flux is appreciable. Macroscopic material parameters (surface wettability, surface roughness, and thermal properties) do not provide a suitable explanation for observed material-sensitive CHFs. Yet, surface roughness and thermal effusivity revealed power and linear relations, respectively, to the nucleate boiling heat transfer coefficients at low mass flux. At high mass flux, material sensitivity on nucleate boiling heat transfer significantly decreased due to the increased shear stress on boiling surface overwhelming material-related boiling implications.