Dynamics Of Bubble Growth Research Articles

Potential response of single successive constant-current-driven electrolytic hydrogen bubbles spatially separated from the electrode

The presence of bubbles in gas-evolving electrolytic processes can heavily alter the mass transport of gaseous products and can induce severe overpotential penalties at the electrode through the action of bubble coverage (hyperpolarization) and electrolyte constriction (Ohmic shielding). However, bubble formation can also alleviate the overpotential by lowering the concentration of dissolved gas in the vicinity of the electrode. In this study, we investigate the latter by considering the growth of successive hydrogen bubbles driven by a constant current in alkaline-water electrolysis and their impact on the half-cell potential in the absence of hyperpolarization. The bubbles nucleate on a hydrophobic cavity surrounded by a ring microelectrode which remains free of bubble coverage. The dynamics of bubble growth does not adhere to one particular scaling law in time, but undergoes a smooth transition from pressure-driven towards supply-limited growth. The contributions of the different bubble-induced phenomena leading to the rich behaviour of the periodic fluctuations of the overpotential are identified throughout the different stages of the bubble lifetime, and the influence of bubble size and applied current on the concentration and Ohmic overpotential components is quantified. We find that the efficiency of gas absorption, and hence the concentration-lowering effect, increases with increasing bubble size and also with increasing current. However, the concentration-lowering effect is always eventually countered and overcome by the effect of Ohmic shielding as the bubble size outgrows and eclipses the electrode ring beneath.

Bubble-growth regime for confined foams: Comparison between N2–CO2/foam and CO2/foam stabilized by silica nanoparticles

The use of foam technology in Pre-Salt reservoirs is a potential solution to control gas mobility in highly heterogeneous reservoirs. However, achieving stable CO2-foams under reservoir conditions can be challenging since high solubility in water of supercritical CO2 enhances coarsening and coalescence of bubbles. Coarsening is the evolution of foam structure with time due to gas diffusion between bubbles. In this phenomenon, gas normally diffuses from smaller to larger bubbles, which for confined foam is relevant because this ends up decreasing the number of bubbles in a determined area/volume of the pore space (foam texture). When foam texture coarsens, gas mobility control is impaired, and it can also affect foam rheology. Therefore, it is important to characterize bubble growth kinetics to compare strategies to reduce coarsening and investigate their impact on gas mobility reduction due to foam injection. In a previous work, we reported the use of nanoparticles and a CO2/N2 gas mixture as strategies for improving gas mobility of CO2-foams formed with a zwitterionic surfactant in a micromodel experiment. The present study focuses on quantitatively assessing the bubble growth regime related to coarsening for these two strategies. Indeed, bubble growth is a key parameter for population balance mathematical models that simulate CO2-foams in porous media. Image analysis was used to characterize the foam texture by calculating the bubble density and bubble size distribution of the foam confined in dead-end pores areas of the micromodel. Our results showed that, the number of trapped bubbles was twice as high for the foam formed with the gas mixture compared to those containing nanoparticles, and this higher bubble density was correlated with the higher pressure drop observed for this system, indicating lower gas mobility. The coarsening rates obtained by analyzing the change in trapped bubble area with time of CO2-foam containing nanoparticles (0.25 μm2 s−1) was in the same order of magnitude compared to that obtained by a CO2/N2 gas mixture-foam (0.44 μm2 s−1), under the same high-pressure high-temperature (HPHT) conditions. These results meant that both strategies were able to stabilize the weak foam formed between zwitterionic surfactant and CO2, and that the initial foam texture determined resistance to flow. The semi-automatic algorithm successfully identified the bubbles trapped within the system during the period of analysis, which allowed us not to add dyes that could change interfacial behavior at the water-gas interface. The novel results that evaluate the coarsening rate for CO2-foam under HPHT conditions can positively impact the estimation of foam destruction parameters for population balance models for more representative reservoir conditions of trapped gas. Our findings fill part of the gap in terms of evaluation of coarsening rate under more representative reservoir conditions, improving the understanding of kinetics of foam destruction. This information is relevant for establishing a correct range of the destruction term for populational balance models. Moreover, our results reveal that the type of strategy chosen to delay coarsening can significantly impact gas mobility reduction and that using nanoparticles impacted significantly interfacial properties of the formed foam.

Numerical simulation of polymethyl‐methacrylate supercritical fluid foaming process: Bubble growth dynamics

AbstractControl of cell structure is an important factor of fabricating polymer foam, which is related to technological design and product performance. In this article, a multibubble growth model of polymethyl‐methacrylate (PMMA) is established based on supercritical fluid foaming method and fluid simulation, aiming to analyze and predict the effects of foaming conditions (foaming temperature and foaming pressure) on the cell structures of PMMA foams. The bubble growth process is endothermic, resulting in a drop of temperature in PMMA/CO2 system, a decrease in diffusion coefficient and an increase in surface tension and viscosity, thereby preventing bubble growth. The pressure in the outer cells decreases faster than the pressure in the inner cells, causing the outer cells preferentially grow and deform, and will limit the growth of the inner cells. An empirical formula for the average cell size and foaming conditions is obtained.

Mechanical controls on methane bubble solute exchange within muddy aquatic sediments and its growth characteristics

Methane (CH4) bubbles in muddy aquatic sediments threaten climate sustainability and sediment mechanical stability. Mechanical response of muddy sediment to bubble growth is described by Linear Elastic Fracture Mechanics (LEFM). Minor roles of mechanical sediment characteristics in CH4 bubble solute supply and growth rates, were quantified by preceding studies, compared to biogeochemical controls. We investigate them using a coupled single-bubble mechanical/reaction-transport numerical and analytical models. We demonstrate that inner pressure of the growing bubble at fracturing, concentration at its surface, bubble size and spatial location, are uniquely defined by the Fracture Toughness of muddy sediment. However, a temporal evolution of the bubble inner pressure at expansion between the fracturing events depends on the Young's modulus. Fracture Toughness and Young's modulus thus play complementary, spatial and temporal, roles in the bubble inner pressure evolution. The proportionality suggested by LEFM manages the bubble solute exchange and growth rates. Higher Fracture Toughness controls development of longer flatter bubbles in the deeper sediments. A substantial role of the mechanical muddy sediment characteristics in the CH4 bubble growth dynamics and solute exchange is demonstrated, comparable to the role of the biogeochemical controls. Their contributions to development of no-growth and competitive bubble growth conditions, affecting a gas dynamics at a macro-scale, are discussed.

Theoretical Analysis of Pressure Relaxation Time in N-Dimensional Thermally-Limited Bubble Dynamics in Fe3O4/Water Nanofluids

The present manuscript is devoted to study the theoretical analysis of pressure relaxation time (PRT) of N-dimensional spherical bubble dynamics immersed in Fe3O4/H2O nanofluid. The mathematical model consists of mass equation in N-dimensions nanofluids, thermal and physical properties of Fe3O4/H2O-nanoparticles (NPs), and PRT in N-dimensions nanofluids. The proposed model of PRT is studied theoretically and solved analytically by using the modified Plesset and Zwick (MPZ) technique taking into account, through the relaxed model with unequal pressure of the thermally-limited bubble dynamics and non-steady pressure field concerning the collapsing and growing of bubble dynamics. Additionally, the PRT is estimated in an N-dimensional vapour bubble under influence of the thermophysical properties of particles nanofluids. Furthermore, The current research also looks at the elements that influence the dynamics of vapour bubble growth in N-dimensions nanofluids. Our results show that the appearance of volume concentration NPs and NPs diameter can significantly decrease the PRT but N-dimensions increases the PRT on thermally-limit bubble dynamics in nanofluids. Additionally, the good agreement are illustrated, for bubble growth in the N-dimensional of Fe3O4/H2O nanofluid with the current model and previous works using theoretical data appropriate for values of N-dimensions “N” at N = 3, 5, 7.

Bubbles and atom clusters in rock melts: A chicken and egg problem

Bubble and crystal nucleation and growth dynamics play a vital function in determining the eruptive behaviour of a magma. Investigating the initial stages of bubble nucleation and crystallization processes, including their rate and relative timing, can thus give us insight into the eruption parameters of magmas including their rheology. Although many experiments and numerical simulations of decompression-induced vesicle nucleation in magmas have been carried out, the mechanisms of bubble nucleation remain poorly understood. It is widely accepted that there are two ways bubbles can form: either by homogeneous nucleation within a melt, or by heterogeneous nucleation on a surface, interface, or particle. It has been tentatively suggested that what had been interpreted as homogeneous nucleation in magmas was instead heterogeneous nucleation on the surface of elusive nano- or micro-scale crystals present throughout the melt. Herein, we have conducted an experiment whereby bubble nucleation is induced in a synthetic andesitic glass sample using radiation damage from a focused ion beam (FIB) to investigate the initial stages of bubble nucleation. Scanning transmission electron microscopy, electron energy-loss spectroscopy and atom probe tomography (APT) data reveal sub-nanometer scale chemical heterogeneities in the form of Fe-, Na-, and/or Ca-rich clusters at the bubble-glass interface of the newly created bubbles. Comparatively, specimens prepared by cryogenic FIB, in which bubble nucleation is suppressed, are without bubbles; however, APT data shows similar chemical heterogeneities suggesting these clusters existed within the synthetic glass prior to bubble formation. Based on these observations, our data demonstrate the existence of nanoscale chemical heterogeneities within a synthetic silicate glass and at bubble-glass interfaces. Although our experiments do not replicate the conditions of natural processes, our results contribute to the hypothesis that previously described homogeneous nucleation may be re-interpreted as a variety of heterogeneous nucleation. These findings highlight the need to revise the commonly used definition of homogeneous nucleation among magma scientists.

Morphological and textural analysis of basaltic pyroclasts (Atexcac maar, central Mexico): Implications for fragmentation and conduit processes

Atexcac is a maar volcano, which forms part of the monogenetic volcanic field of the Serdán-Oriental Basin, in the eastern sector of the Mexican Volcanic Belt. This volcanic landform was originated by a combination of phreatic, magmatic and phreatomagmatic explosive eruptions. During the formation of the distinct depositional facies, fluctuations in the water availability of the local aquifer, as well as in the magma flux, were probably responsible for the different mechanisms of magmatic and phreatomagmatic fragmentation and the production of the two main populations of fragments (breccia and cross-bedded deposits particles), whose morphological features, allow us to infer the dominant regime (brittle or ductile), fragmentation mechanism (magmatic or phreatomagmatic) and conditions of bubble growth dynamics and fragmentation processes during the ascent of magma through the conduit. We conclude that the breccia particles were derived from dominant magmatic explosions while the cross-bedded deposits particles are thought to be generated from explosive phreatomagmatic events. 3D imaging based on high-precision X-ray microtomography was used to determine the vesicularity of juvenile fragments of the Atexcac maar. Calculated vesicularity index, vesicle number density (VND) and vesicle morphology indicate important processes of coalescence of gas bubbles, during the ascent of the magma. VND's Atexcac clasts suggests vesicle mechanisms similar to medium-intensity eruptions, reported in the literature. The elongated and polylobular vesicle morphology of the Atexcac clasts reveals early acceleration of magma and subsequent coalescence events at most stages of gas bubble growth.

Numerical modelling of acoustic cavitation threshold in water with non-condensable bubble nuclei

Numerical modelling of acoustic cavitation threshold in water is presented taking into account non-condensable bubble nuclei, which are composed of water vapor and non-condensable air. The cavitation bubble growth and collapse dynamics are modeled by solving the Rayleigh-Plesset or Keller-Miksis equation, which is combined with the energy equations for both the bubble and liquid domains, and directly evaluating the phase-change rate from the liquid and bubble side temperature gradients. The present work focuses on elucidating acoustic cavitation in water with a wide range of cavitation thresholds (0.02–30 MPa) reported in the literature. Computations for different nucleus sizes and acoustic frequencies are performed to investigate their effects on bubble growth and cavitation threshold. The numerical predictions are observed to be comparable to the experimental data in the previous works and show that the cavitation threshold in water has a wide range depending on the bubble nucleus size.

Dynamics of bubble growth under a heated substrate

This paper investigates the growth dynamics of a vapor-gas bubble pressed against a heating plate by the buoyancy force. The shadow method was used to capture images, which were then automatically processed to calculate the size of the bubble. As expected, the bubble dynamics significantly depends on the heating power. It was found that the ratio of bubble diameter to bubble height increases as it grows.

Dynamics of bubble growth during boiling at microgravity

The purpose of this investigation is to study the mechanisms of boiling heat transfer in microgravity conditions. The RUBI (Reference mUltiscale Boiling Investigation) is an experiment where the basic phenomena of boiling heat transfer processes on a heated surface are investigated on the ISS (International Space Station). The special focus is paid to the coupling of macroscopic bubble dynamics from nucleation, growth and detachment combined with the microscopic phenomena in the thin films and micro layers on the heater, underneath the boiling bubbles. The image treatment program has been developed in order to extract the bubble volume as well as the contact angle from the experimental images. The first data of the bubble growth dynamics have been obtained and analysed.

The effect of buoyancy driven convection on the growth and dissolution of bubbles on electrodes

Enhancing the efficiency of water electrolysis, which can be severely impacted by the nucleation and growth of bubbles, is key in the energy transition. In this combined experimental and numerical study, in-situ bubble evolution and dissolution processes are imaged and compared to numerical simulations employing the immersed boundary method. We find that it is crucial to include solutal driven natural convection in order to represent the experimentally observed bubble behaviour even though such effects have commonly been neglected in modelling efforts so far. We reveal how the convective patterns depend on current densities and bubble spacings, leading to distinctively different bubble growth and shrinkage dynamics. Bubbles are seen to promote the convective instability if their spacing is large (≥4 mm for the present conditions), whereas the onset of convection is delayed if the inter-bubble distance is smaller. Our approach and our results can help devise efficient mass transfer solutions for gas evolving electrodes.

Positron beam studies on the irradiation response of FeCrCoNi upon He ion implantation

Positron beam-based Doppler broadening results on He ion-implanted FeCrCoNi show distinct changes in defect-sensitive S-parameter corresponding to the formation of helium-vacancy complexes, nucleation/ growth of helium bubbles, and finally the helium bubble rupture, with isochronal annealing. Data analyses of the positron beam-based ratio curves provide clear information on the kinetics of bubble growth and rupture. The difference data in S-parameter (ΔS), which corresponds to the bubble growth, displays a maximum at 1123 K, with annealing temperature. Comparing the ΔS value to that reported for nickel, it is concluded that FeCrCoNi has higher bubble growth resistance than nickel.

A seamless multiscale operator neural network for inferring bubble dynamics

Modelling multiscale systems from nanoscale to macroscale requires the use of atomistic and continuum methods and, correspondingly, different computer codes. Here, we develop a seamless method based on DeepONet, which is a composite deep neural network (a branch and a trunk network) for regressing operators. In particular, we consider bubble growth dynamics, and we model tiny bubbles of initial size from 100 nm to 10 $\mathrm {\mu }\textrm {m}$ , modelled by the Rayleigh–Plesset equation in the continuum regime above 1 $\mathrm {\mu }\textrm {m}$ and the dissipative particle dynamics method for bubbles below 1 $\mathrm {\mu }\textrm {m}$ in the atomistic regime. After an offline training based on data from both regimes, DeepONet can make accurate predictions of bubble growth on-the-fly (within a fraction of a second) across four orders of magnitude difference in spatial scales and two orders of magnitude in temporal scales. The framework of DeepONet is general and can be used for unifying physical models of different scales in diverse multiscale applications.

Thermophysical bubble dynamics in N-dimensional Al2O3/H2O nanofluid between two-phase turbulent flow

The purpose of this work is to apply a new method for the growth behavior of bubble dynamics in N-dimensional turbulent Al2O3/H2O-nanofluid for bubble dynamics applications in polymers and climate change models under the influence of surface tension and viscosity. This paper also investigates the factors affecting the dynamics of vapor bubble growth in N-dimensions for turbulent nanofluid. The turbulent flow of the nanofluid in N-dimensions in this study is examined at Re ranging from 3000 to 5000, and concentration from 4 to 6%. The theoretical analysis is conducted using the MPZ technique considering the initial time of bubble growth. The obtained results reveals that the radius of the bubble is proportional to the thermal diffusivity and inversely proportional to the surface tension, viscosity, critical bubble radius, concentration rate of Al2O3-nanoparticles, and initial void fraction. We also found that the growth of the vapor bubble in a nanofluid turbulent flow is less than that of the Newtonian fluid. To the best of our knowledge, the efficient utilization of N-dimensional turbulent Al2O3 nanoparticles in bubble dynamics leads to more reduction for bubble growth process than other previous models. Additionally, the stability analysis is examined via phase plane algorithm with nonlinear ODEs.

Operator learning for predicting multiscale bubble growth dynamics.

Simulating and predicting multiscale problems that couple multiple physics and dynamics across many orders of spatiotemporal scales is a great challenge that has not been investigated systematically by deep neural networks (DNNs). Herein, we develop a framework based on operator regression, the so-called deep operator network (DeepONet), with the long-term objective to simplify multiscale modeling by avoiding the fragile and time-consuming "hand-shaking" interface algorithms for stitching together heterogeneous descriptions of multiscale phenomena. To this end, as a first step, we investigate if a DeepONet can learn the dynamics of different scale regimes, one at the deterministic macroscale and the other at the stochastic microscale regime with inherent thermal fluctuations. Specifically, we test the effectiveness and accuracy of the DeepONet in predicting multirate bubble growth dynamics, which is described by a Rayleigh-Plesset (R-P) equation at the macroscale and modeled as a stochastic nucleation and cavitation process at the microscale by dissipative particle dynamics (DPD). First, we generate data using the R-P equation for multirate bubble growth dynamics caused by randomly time-varying liquid pressures drawn from Gaussian random fields (GRFs). Our results show that properly trained DeepONets can accurately predict the macroscale bubble growth dynamics and can outperform long short-term memory networks. We also demonstrate that the DeepONet can extrapolate accurately outside the input distribution using only very few new measurements. Subsequently, we train the DeepONet with DPD data corresponding to stochastic bubble growth dynamics. Although the DPD data are noisy and we only collect sparse data points on the trajectories, the trained DeepONet model is able to predict accurately the mean bubble dynamics for time-varying GRF pressures. Taken together, our findings demonstrate that DeepONets can be employed to unify the macroscale and microscale models of the multirate bubble growth problem, hence providing new insight into the role of operator regression via DNNs in tackling realistic multiscale problems and in simplifying modeling with heterogeneous descriptions.

Kinetic study of electrochemically produced hydrogen bubbles on Pt electrodes with tailored geometries

Understanding bubbles evolution kinetics on electrodes with varied geometries is of fundamental importance for advanced electrodes design in gas evolution reaction. In this work, the evolution kinetics of electro-generated hydrogen bubbles are recorded in situ on three (i.e. smooth, nanoporous, and nanoarray) Pt electrodes to identify the geometry dependence. The bubble radius shows a time-dependent growth kinetic, which is tightly-connected to the electrode geometry. Among the three electrodes, the smooth one shows a typical time coefficient of 0.5, in consistence with reported values; the nanoporous one shows a time coefficient of 0.47, less than the classic one (0.5); while the nanoarray one exhibits fastest bubble growth kinetics with a time coefficient higher than 0.5 (0.54). Moreover, the nanoarray electrode has the smallest bubble detachment size and the largest growth coefficient (23.3) of all three electrodes. Based on the experimental results, a growth model combined direct bottom- injection with micro-convection is proposed to illustrate the surface geometry dependent coefficients, i.e., the relationship between geometry and bubble evolution kinetics. The direct injection of generated gas molecules from the bottom of bubbles at the three phase boundaries are believed the key to tailor the bubble wetting states and thus determine the bubble evolution kinetics.

Growth and Collapse Dynamics of a Vapor Bubble near or at a Wall

This study investigated the dynamics of vapor bubble growth and collapse for a laser-induced bubble. The smoothed particle hydrodynamics (SPH) method was utilized, considering the liquid and vapor phases as the van der Waals (VDW) fluid and the solid wall as a boundary. We compared our numerical results with analytical solutions of bubble density distribution and radius curve slope near a wall and the experimental bubble shape at a wall, which all obtained a fairly good agreement. After validation, nine cases with varying heating distances (L2 to L4) or liquid heights (h2 to h10) were simulated to reproduce bubbles near or at a wall. Average bubble radius, density, vapor mass, velocity, pressure, and temperature during growth and collapse were tracked. A new recognition method based on bubble density was recommended to distinguish the three substages of bubble growth: (a) inertia-controlled, (b) transition, and (c) thermally controlled. A new precollapse substage (Stage (d)) was revealed between the three growth stages and collapse stage (Stage (e)). These five stages were explained from the out-sync between the bubble radius change rate and vapor mass change rate. Further discussions focused on the occurrence of secondary bubbles, shockwave impact on the wall, system entropy change, and energy conversion. The main differences between bubbles near and at the wall were finally concluded.

Lattice Boltzmann study of bubble dynamics and heat transfer on a hybrid rough surface with a cavity-pillar structure

In this work, a two-dimensional phase-change lattice Boltzmann model is used to investigate the pool boiling from a hybrid rough surface with a single cavity and one or two pillars on the superheated plate for an entire ebullition cycle. The bubble growth and departure dynamics on the hybrid pillared cavity surfaces, namely a single-pillared cavity surface (a surface with one cavity and one neighbouring pillar) and a double-pillared cavity surface (a surface with one cavity and one pillar on its both sides), are also compared with a simple cavity surface (a surface with only one cavity). The results showed that the incorporation of the pillar to the simple cavity surface increases the surface area and distance between the pinning locations of the three-phase contact line (TCL), and thus, enhances the bubble departure diameter and heat flux. It is found that bubble departure diameter and heat flux increase with cavity-pillar spacing up to a certain value, in this case sp∗ = 0.50, beyond which they start to decease and approach the simple cavity surface case at sp∗ = 1.0, while the opposite trend is observed for bubble departure frequency. The bubble departure diameter, frequency and heat flux also increase with pillar width. Compared to uniformly hydrophilic surfaces, the mixed wettability surfaces exhibit large heat flux with relatively small increase in bubble departure diameter.

Post-fragmentation vesiculation timescales in hydrous rhyolitic bombs from Chaitén volcano

Bubble nucleation and growth dynamics exert a primary control on the explosivity of volcanic eruptions. Numerous theoretical and experimental studies aim to capture the complex process of melt vesiculation, whereas textural studies use vesicle populations to reconstruct magma behaviour. However, post-fragmentation vesiculation in rhyolitic bombs can create final quenched bubble (vesicle) textures that are not representative of the nature of fragmenting magma within the conduit. To examine bubble growth in hydrous rhyolitic bombs, we have used heated stage microscopy to directly observe vesiculation of a Chaitén rhyolite melt (with an initial dissolved water content of ~0.95 wt %) at atmospheric pressure and magmatic temperatures upon reheating. Thin wafers of obsidian were held from 5 min up to two days in the heated stage at temperatures between 575 °C and 875 °C. We found that bubble growth rates, measured through changes in bubble diameter, increased with both temperature and bubble size. The average growth rate at the highest temperature of 875 °C is ~1.27 μm s−1, which is substantially faster than the lowest detected growth rate of ~0.02 μm s−1 at 725 °C; below this temperature no growth was observed. Average growth rate Vr follows an exponential relationship with temperature, T and inferred melt viscosity η, where Vr = 5.57×10−7e0.016T and Vr = 3270e−1.117η. Several stages of evolving bubble morphology were directly observed, including initial relaxation of deformed bubbles into spheres, extensive growth of spheres, and, at higher temperatures, close packing and foam formation. Bubble deformation due to bubble-bubble interaction and coalescence was observed in most experiments. We use our simple, experimentally-determined relationship between melt viscosity and bubble growth rates to model post-fragmentation vesicle growth in a cooling 1 m-diameter rhyolitic bomb. The results, which indicate negligible vesicle growth within 2–3 cm of the bomb surface, correspond well with the observed dense margin thickness of a Chaitén bomb of comparable dimensions. The experiments described can be used to effectively reconstruct the post-fragmentation vesiculation history of bombs through simple analytical expressions which provide a useful tool for aiding in the interpretation of pumiceous endmember textures in hydrous rhyolitic bombs.

Effect of heated surface inclination on the growth dynamics and detachment of a vapor bubble, a numerical study

Nucleate boiling is an important part of the pool boiling phenomenon which occurs in various processes involving heat transfer, such as, steam production, chemical processes, etc. The inclination of the heated surface, where bubbles nucleates, significantly affects the bubble growth dynamics as well as the heat transfer rate from the microlayer underneath the bubble during the nucleate boiling. In this study, the effect of the surface inclination on the bubble growth and detachment during the nucleate boiling is investigated numerically. For this purpose, the proposed model of Lay and Dhir for the microlayer is modified to include the effect of the inclination of the heated surface. The resulting equations are solved numerically, and the effect of varying the inclination of the heated surface on the bubble growth and heat transfer is investigated. The results show that the largest bubble size and the highest heat transfer from the heated surface occur when the inclination of the heated surface is 30°; while, the smallest bubble size and the lowest heat transfer from the heated surface are observed for the horizontal surface. Furthermore, the total heat transfer from the inclined surface during the bubble growth increases up to 32% compared to that for the horizontal surface.