Spray Evaporation Research Articles

Spray evaporation characteristics of isopropanol-butanol-ethanol (IBE)/diesel blends in a constant volume chamber

As an intermediate fermentation product of butanol, isopropanol-butanol-ethanol (IBE) can be used as an alternative fuel for diesel directly to reduce the separation and purification costs during the butanol fermentation process. However, how the properties of IBE affect the spray evaporation characteristics of diesel is rarely studied. In this regard, IBE was blended into diesel at various volumetric ratios and then tested in a constant volume chamber using Mie scattering method. The experimental results show that after blending IBE into diesel, the spray evaporation characteristics improve noticeably. The more IBE blended into diesel, the shorter liquid spray penetration and smaller spray area are. However, the reduction of the liquid spray penetration and spray area are not linear, they exhibit a huge drop when the IBE to diesel ratio increases from 60% to 80% in volume. With more IBE blended into diesel, the time for the spray to reach the stable stage decreases. Results also show that the ambient temperature has great effects on both the spray evaporation of pure diesel and IBE/diesel blends. As the ambient temperature rises, their spray jets become smaller, and the corresponding liquid spray penetration become shorter. That means elevate the ambient temperature can further improve the spray evaporation of IBE/diesel blends.

Large Eddy Simulation of a Reacting Kerosene Spray in Hot Vitiated Cross-Flow

The evaporation and combustion characteristics of a kerosene spray injected perpendicularly into a cross-flow of high-temperature vitiated air is investigated. This fundamental flow configuration has wider implications for the future development of ultra-low emission aeronautical combustors, particularly with respect to technologies involving MILD combustion. Large eddy simulations with a Eulerian–Lagrangian framework are performed to investigate the spray evolution and the characteristics of the reaction zone for a range of conditions. For the closure of turbulence-chemistry interactions at the sub-grid scales, a transported probability density function approach solved by the Eulerian stochastic fields method is applied. A configuration based on the use of airblast atomisation is assessed first and compared with experimental observations. The effect of the atomiser air-to-liquid mass flow ratio is studied in greater detail, both in terms of the resulting gas-phase properties and the droplet evaporation process. Then, the effect of ambient pressure on the global spray flame behaviour is examined. For this part of the study, no atomising air is included in the simulation to separate the effects of ambient pressure on the spray from the interaction with the air jet. Analysis of the flame and spray properties at cross-flow operating pressures of 1 atm, 2 bar and 4 bar highlights the strong coupling between the reacting flow and droplet evaporation characteristics, which are highly affected by the penetration of the spray into a flow field characterised by relatively large gradients of temperature. The results reported in this work provide fundamental understanding for the development of novel low-emission combustion technologies and demonstrate the feasibility of applying large eddy simulation with detailed chemistry for the investigation of reacting aviation fuel sprays in hot vitiated cross-flow.

Dissolution enhancement of Enzalutamide by solid dispersion approach

Enzalutamide (ENZ) is a BCS class II, fast crystallizing, a hydrophobic compound that has solubility limited absorption in vivo. Ternary solid dispersion of Enzalutamide was prepared with water-soluble polymers Soluplus (SOL) and Poloxamer P 188 (POL) by solvent evaporation spray drying technique. Initially, different ratios of Soluplus: Poloxamer and solvents were used to prepare Ternary solid dispersions of Enzalutamide and evaluated for the dissolution enhancement property. The prepared solid dispersion was characterized by FTIR spectroscopy, Differential scanning calorimetry (DSC), X-ray diffraction (XRD) analysis, Scanning electron microscopy (SEM), Particle size distribution (PSD) by Malvern and Physico-chemical analysis. FTIR spectroscopy shows that there was no interaction between the ENZ and polymers. DSC and XRD analysis show that conversion to amorphous form of ENZ in ternary SD, which enhances the dissolution rate. In vitro dissolution studies and Ex-vivo intestinal absorption studies clearly show that the prepared solid dispersion enhanced the dissolution and ex-vivo intestinal absorption of ENZ compared with pure ENZ.

Impacts of preferential vaporization on flashback behaviors of multi-component liquid fuels

Liquid transportation fuels are composed of a wide range of molecular structures and weights, therefore exhibiting a relatively large distillation temperature range. When fuel chemical properties change along with the distillation temperature curve, preferential vaporization effects could play a role in near-limit combustion behaviors. The objective of this study is to experimentally evaluate the role of preferential vaporization on flame flashback behaviors. A unique spray burner is developed to control the extent of fuel spray vaporization by adjusting flow rates and/or the spray injection location from the burner exit. Spray characteristics are comprehensively determined using Phase Doppler Particle Analyzer. Two binary component mixtures are formulated (n-octane/iso-cetane and iso-octane/n-hexadecane) to exhibit common combustion behaviors in the fully vaporized condition but have considerably different preferential vaporization characteristics. Identical flashback behaviors of two mixtures are observed for fully pre-vaporized conditions by setting the burner temperature at 700 K, including both propagation- and ignition-driven flashback behaviors. Partially vaporized conditions are investigated at two global equivalence ratios (1.0 and 1.4) by setting the burner temperature at 450 K. The flashback behaviors for both global equivalence ratio conditions are found to be affected by the preferential vaporization characteristics represented by laminar flame speeds of the vaporized fuel mixture composition. The relative significance of local flow perturbation induced by instantaneous fuel droplet evaporation near the flame surface has been also investigated by analyzing planar laser-induced fluorescence images, as well as considering the changes of Markstein length with the extent of fuel vaporization. Finally, the relative contributions of local laminar flame speed representing local fuel vapor deposit, local flow perturbation, and preferential vaporization are evaluated through feature sensitivity analyses.

Experimental study on the treatment of desulfurization wastewater from coal-fired power plant by spray evaporation.

In this study, a pilot-scale evaporation tower system was built to treat the desulfurization wastewater by spray evaporation. The distribution characteristics of Cl- in the wastewater evaporation process were investigated. Besides, the morphology and physicochemical property of solid evaporation products from desulfurization wastewater were analyzed. In addition, the emission characteristics of fine particulates were evaluated. The results indicated that the increase of salt content in desulfurization wastewater increased the mass concentrations of Cl- in three phases, but the proportions of it remained almost unchanged, which were about 10%, 55%, and 35% in the gas phase, outlet solid phase, and bottom solid phase respectively. The increase of flue gas temperature can improve the content of Cl- in the gas phase, while the increase of wastewater pH inhibited the formation of gaseous HCl. The solid evaporation products from desulfurization wastewater had a prismatic crystal structure, which mainly included the sulfate and chloride salts, and the main elements including O, Na, Mg, S, Cl, K, and Ca. Besides, the peak values of particle size distribution in the bottom solid phase and outlet solid phase were 7.67 and 0.32μm, respectively. For the particulate matters in flue gas, the spray evaporation of desulfurization wastewater can reduce the particle concentration, promote particle agglomeration, reduce the number concentration of fine particles, and improve the removal effect of PM10. When the inlet particle concentration was 7.62g/m3, it can reduce the particle concentration at the tower outlet to 4.59g/m3 and reduce the number and mass concentrations of PM10 after ESP by about 43.8% and 36.8%.

Numerical Simulation of Multi-Nozzle Droplet Evaporation Characteristics for Desulfurization Wastewater

Spraying flue gas desulfurization wastewater into flue ducts is an emerging technology that is receiving extensive attention in thermal power plants. In order to study the evaporative performance of wastewater-atomizing droplets under variable working conditions, a combined Euler–Lagrange model was developed to demonstrate the thermal behavior of FGD wastewater spray evaporation in flue gas. The effects of several control factors under various operating conditions were numerically determined and validated against experimental data. Due to the complicated parameters and various other conditions, a least-square support vector machine (LSSVM) model relying on numerical results was used to anticipate the evaporation rate of the droplets. We prove that the LSSVM model has high prediction accuracy for the evaporation rate at different cross-sections of flue under a different operating situation. The conclusion is that for the sake of improving the quality of evaporation, the spacing between two adjacent nozzles should be increased while increasing the flow rate. However, using a higher flue gas temperature, higher initial temperature and smaller diameter of droplets can shorten the time and distance of complete evaporation. In summary, this research analysis can be used effectively to determine the design of the FGD wastewater flue gas evaporative process in thermal power plants.

A thermally-driven seawater desalination system: Proof of concept and vision for future sustainability

Since the 1970s, commercial-scale thermally-driven seawater desalination plants have been powered by low-grade energy sources, drawn either with low-pressure bled-steam from steam turbines or the solar renewable energy harvested that are supplied at relatively low temperatures. Despite the increasing trend of seawater reverse osmosis plants, the role of thermal desalination methods (such as multi-stage flashing and multi-effect distillation) in GCC countries is still relevant in the Arabian Gulf, arising from higher salinity, the frequent algae blooms of seawater and their ability to utilize low temperature heat sources. Given the urgent need for lowering both the capital and operating costs of all processes within the desalination industry and better thermodynamic adaptation of low-grade heat input from renewable sources, the present paper addresses the abovementioned issues by investigating the direct contact spray evaporation and condensation (DCSEC) method. A DCSEC system comprises only hollow chambers (devoid of membranes or tubes, minimal use of chemical and maintenance) where vapor generation (flashing) utilizes the enthalpy difference between the sprayed feed seawater and the saturated vapor enthalpy of the vessels. Concomitantly, vapor is condensed with spray droplets of cooler water (potable) in adjacent condenser vessels, employing a simple design concept. We present detailed design and real seawater experiments data of a DCSEC system for the first time. The water production cost is calculated as $0.52/m 3 , which is one of the lowest figures reported compared to commercial processes presented by Global Water Intelligence.

Modeling of spray flame in gas turbine combustors with LES and FGM

A large eddy simulation formulation was proposed for spray combustion in gas turbine combustion chambers, using a FGM combustion model coupled with detailed chemical reaction mechanisms. The solver was developed using the open-source toolkit—OpenFOAM. The two-way coupling between spray particles and gas field was modeled by a Eulerian–Lagrangian method. The enthalpy loss resulting from spray evaporation was also considered in the FGM combustion model. The solver was first validated against the experimental data of a model combustion chamber. The predictions of mean and fluctuation velocities were in good agreement with the experimental values for both cold and reacting flows, and the flame shapes were also nicely reproduced. It was revealed that there existed local extinctions at the swirler exit, leading to a lift-off flame. The validated solver was then applied to a realistic combustor of an aeroengine. It was found that different from the diffusive nature of the flame in the model combustor, the spray combustion in the realistic combustor is of partially premixed nature. The predicted pressure loss and the exit temperature profile agreed rather well with the measurements, demonstrating the capability of the present solver to simulate realistic combustors with complex geometries.

Improving quantification of hydrogen peroxide by synchrotron vacuum ultraviolet photoionization mass spectrometry

Hydrogen peroxide (H2O2) plays a key role in the autoxidation of fuels related to ignition in compression engines, and in the degradation of volatile organic compounds (VOC) in the atmospheric autoxidation. Advanced synchrotron vacuum ultraviolet radiation photoionization mass spectrometry (SVUV-PIMS) is widely used for in-situ analysis of H2O2 in the gas phase autoxidation process. However, considerable uncertainty has been observed in the quantification of H2O2 by SVUV-PIMS. This work improves the quantification of H2O2 by re-evaluating its photoionization cross section (PICS). Spray vaporization, combined with a low pressure flow reactor, was used to minimize decomposition and wall loss of H2O2 in the PICS measurement. It was found that the PICS of H2O2 obtained here was lower than that reported in the literature by a factor of two. Adopting this newly obtained PICS significantly improved quantification of H2O2, and will prove valuable in evaluating the reaction kinetics of H2O2 and the development of combustion and atmospheric autoxidation models.

Experimental Investigation on Spray Evaporation and Dispersion Characteristics of Impinged Biodiesel-Butanol Blends

Abstract The objective of the investigation is to explore the spray evaporation and dispersion characteristics of impinged biodiesel-butanol blends at various n-butanol ratios (0, 10%, 30%, 50%) and ambient conditions. A total of 180 experimental cases were performed in a constant-volume combustion chamber. The liquid- and vapor-phase sprays were captured by backlight imaging technique and Schlieren imaging technique, respectively. Several macroscopic parameters were measured and discussed, including impinged spray structure, width, height, and area. Some novel parameters are derived to analyze spray evaporation and dispersion. Results show that biodiesel blended with 30% n-butanol transits better from liquid-phase to vapor-phase compared with other blends, displaying rapid liquid-phase evaporation an steady vapor-phase dispersion. After wall impingement, an increase in the ambient pressure or temperature hinders the liquid-phase dispersion in the vertical direction significantly, leading to a rapid decrease in the height of the impinged spray. The vapor-phase diffusion rate in the horizontal direction is about four times the rate in the vertical direction, and the rate ratio is slightly affected by ambient conditions and injection pressure. Compared with the free jet, the impinged spray is not beneficial for liquid-phase evaporation and vapor-phase dispersion, presenting larger liquid-phase area and smaller vapor-phase area. However, impinged biodiesel blended with 30% n-butanol displays better spray evaporation and dispersion.

Study on orientation and number of water spray nozzles for scientific experimental application

In dry climates, evaporative cooling techniques are frequently used in place of air-conditioners to increase energy efficiency and reduce installation costs. An evaporative nozzle is a type of evaporative cooling technique. Evaporative nozzle spraying is a technique that is used in a variety of applications, including cooling and humidification. The performance of evaporative spray nozzles with a number ranging from 2 to 8 nozzles has been examined in terms of nozzle combinations, orientations (horizontal and vertical), and Reynolds numbers ranging from 13000 to 83000. In general, the results show that relative humidity is inversely proportional to the Reynolds number. Furthermore, the nozzle numbers are proportional to the relative humidity. As the number of nozzles in a vertical arrangement increases from 2 to 8, the relative humidity rises to 90%. For 8 spray nozzles, the vertical arrangement produces 7.4% higher outlet relative humidity than the horizontal arrangement. The current investigation’s highest relative humidity is 90%, which occurs for 8 nozzles in the vertical direction at Reynolds number 13300. Moreover, the horizontal and vertical correlations were developed to predict the outlet relative humidity with respect to the nozzle orientation.

Vitrification by Transient Vacuum Flashing Spray Cooling of Liquid Nitrogen

BACKGROUND: The transient vacuum flashing spray cooling of liquid nitrogen (LN2 ) on a microstructured surface can provide ultra-fast cooling rate and may improve cell survival rates. OBJECTIVE: To utilize flashing spray cooling of LN2 instead of film boiling to improve further cell vitrification. METHOD: This study analyzed the effects of the three key parameters (flow rate of liquid nitrogen, ambient pressure, and spray distance) on the cooling process by experimentation. RESULTS: The experimental results showed that the vacuum flashing spray cooling of LN2 can gain higher cooling rates than that achieved by film boiling in conventional vitrification methods. The three parameters all affected the vacuum flash evaporation spray cooling of LN2, and their effect trends were not monotonous but followed a parabolic trend that increased and then decreased. That is, the three parameters all have optimum values to the cooling process. CONCLUSION: Vacuum flash evaporation spray cooling can develop the ultra-fast cooling rates needed to enhance cell vitrification.

Modeling Investigation of Liquid Oxygen Flashing Spray with CFD

Injection of cryogenic propellants (e.g. liquid oxygen) into low-pressure environment (e.g. upper-stage rocket engine) may trigger flashing phenomenon, which severely affects the propellants’ mixing and combustion. In order to unveil the characteristics of flashing sprays, numerical models of flashing sprays were developed and validated. First, a developed model based on Adachi-correlation was employed for the flashing spray simulation. The results show good agreements with the experiments, both for the flashing spray morphology and temperature distribution. In the near-injector region, the flashing evaporation dominates the spray vaporization with the evaporation mass flow rate of about 2 orders of magnitude higher than that by the other heat transfers, whereas downstream the injector, the external heat transfer (i.e. heat conduction and convection) does. Furthermore, a new flashing spray model based on the nucleate boiling theory was proposed, which shows an improved agreement of the droplet temperature between the simulation and test data.

Computational Investigations of Spray Atomization and Evaporation Under Cold-Start Conditions of a Diesel Engine

Abstract Unburnt hydrocarbon emissions and combustion instability are severe issues in diesel engines during cold starting. This simulation study aims to provide insights for improving the cold-start issues of diesel engines. Computational analysis of the diesel spray and evolution of plumes from a 7-hole injector was done in a constant volume quiescent spray chamber for analyzing the effect of fuel temperature. This study was based on a comprehensive numerical analysis using CONVERGE computational fluid dynamics (CFD) software, where an Eulerian–Lagrangian approach was adopted in a large eddy simulation (LES) framework. Diesel engine-like cold-start conditions were replicated by reducing the fuel temperatures to 250 K to simulate freezing conditions outside. This computational study compares fuel sprays at 250 K with 312 K into a relatively colder ambient temperature of 626 K vis-a-vis high-temperature diesel engine-like ambient conditions with ambient temperature to 961 K to investigate the degree of spray characteristics improvements due to increased fuel temperature. The predicted liquid spray penetration obtained by simulations agreed well with the experimental data for fuel temperatures injected into the ambient at cold (626 K) and hot (961 K) engine-like ambient conditions. The available empirical relations justify the simulation results of this study. Results showed that fuel and ambient temperatures significantly affected the spray atomization and evaporation characteristics. A higher reduction in liquid penetration length was found with increasing fuel temperature at hot ambient conditions. Increasing ambient temperature also improved the evaporation characteristics of the spray droplets. Vapor formation for the same increase in fuel temperature was higher at hot ambient temperature than the cold. Fuel temperature had a major role in the spray atomization process, whereas the ambient temperature affected the spray evaporation process. However, fuel and ambient temperatures had only a minor effect on the distribution of total kinetic energy (TKE). Among all test conditions, a fuel temperature of 312 K sprayed in hot ambient conditions showed superior fuel spray atomization and evaporation. Hence, to tackle the cold-start of diesel engines, measures taken to increase the fuel and ambient temperatures simultaneously proved to be useful.

Experimental study on liquid nitrogen flash evaporation spray on super-hydrophilic microstructured surface

Flash evaporation spray is an efficient heat transfer method. Changes in the microstructure and wettability of the cooling surface have important effects on its heat transfer. In this paper, four kinds of cooling surfaces, including a smooth copper surface, a square-column microstructured surface, a superhydrophilic smooth surface, and a superhydrophilic square-column surface, were prepared by chemical corrosion and laser etching. Using liquid nitrogen as the cooling medium, we conducted transient flash evaporation spray experiments on these four types of cooling surfaces. The experimental results show that surface superhydrophilic treatment can substantially enhance the flash evaporation spray of liquid nitrogen. It can more than double the cooling rate for both smooth copper surfaces and square-column microstructured surfaces. In addition, the combination of a microcolumn structure and superhydrophilicity on the cooling surface can provide double reinforcement for the liquid nitrogen flash evaporation spray. Its average cooling rate can reach 131,046 °C/min, and the maximum heat flux is 173 W/cm2. This study sheds some lights on heat transfer mechanism of superhydrophilic microstructure on the flash evaporation spray and contributes to the development of a new method for cell vitrification.

Calculation of Flow Field and Vibration Analysis of Heat Exchanging Tube in Low Temperature Multi-effect Seawater Desalination Evaporator

Abstract In this paper, a 1000t/d low-temperature multi-effect seawater desalination pilot plant (MED) is taken as the research object, a multi-phase flow (VOF) model is selected to describe the shell side flow field of the evaporator, and the overall direct simulation of the flow field on the shell side of MED is carried out by using the fluid mechanics calculation software Fluent. The vapor velocity field distribution around the evaporator tube bundle is obtained by calculation under stable test conditions. The influence of seawater spray density and evaporation temperature on flow field distribution and the vibration of tube bundle under different working conditions are researched. Research result shows that the spray density has little effect on steam velocity, but the maximum steam velocity is significantly affected by evaporation capacity of seawater. At the same time, when the evaporation capacity reaches a certain value, the phenomenon of flow resonance will occur in some areas of the evaporator, which will cause damage to the heat exchange tube bundle.

A numerical study on fuel film and emissions formations during cold start in a diesel engine using an improved spray-wall impingement model

Understanding the physical process such as fuel film formation during cold start is essential to reduce engine emissions. In this study, an improved spray-wall impingement model was applied to the cold-start simulation of a diesel engine. The fuel film and emissions formations during cold start were studied in depth. The effects of injection strategies were investigated by the use of various designed injection schemes. The results showed that a certain amount of fuel film is deposited on the wall surface due to the poor spray evaporation caused by the adverse thermal atmosphere in the cylinder. The low combustion temperature, insufficient oxygen, and the deposited fuel film are the primary causes for high HC, CO and soot emissions. The NOx emissions are relatively low because of low combustion temperature and oxygen content. A double injection strategy can reduce the deposited and remaining fuel film by 13% due to improved mixing, which benefits the reduction of HC and CO emissions, while it has a negligible effect on NOx and soot emissions. The percentage of first injected fuel has little impact on the amount of the remaining fuel film and emissions in the studied range. Increasing engine speed can inhibit the formations of fuel film, HC, CO, and soot emissions, which is due to the improved fuel evaporation, better flow motion, and thermal environment in the cylinder. Double injection allows a smaller amount of injected fuel to obtain a stable ignition. Decreasing the injected fuel mass can suppress the formation of fuel film and improve mixing, thus reducing HC, CO, and soot emissions. This work expands the application scenarios of the newly developed spray-wall impingement model. The new model has been successfully applied to investigate the cold start process of diesel engines in detail. The results provide insights into the fuel film formation and its effect on emissions, which can guide the development of a cold-start emission control strategy.

Response of spray number density and evaporation rate to velocity oscillations

A theoretical investigation of the effect of gas velocity oscillations on droplet number density and evaporation rate is presented. Oscillations in gas velocity cause a number density wave, i.e. an inhomogeneous, unsteady variation of droplet concentration. The number density wave, as it propagates downstream at the mean flow speed, causes modulation of the local evaporation rate, creating a vapour wave with corresponding oscillations in equivalence ratio. The present work devises an analytical formulation of these processes. Firstly, the response of a population of droplets to oscillations in the gas velocity is modelled in terms of a number density wave. Secondly, the formulation is extended to incorporate droplet evaporation, such that an analytical expression for the evaporation rate modulation is obtained. Subsequently, the droplet 1D convection-diffusion transport equation with the calculated evaporation source term is solved using an appropriate Green’s function to determine the resulting equivalence ratio perturbations. The dynamic response of equivalence ratio fluctuations to velocity oscillations is finally characterized in terms of a frequency-dependent transfer function. The aforementioned analytical approach relies on a number of simplifying approximations, nevertheless it was validated with good agreement against 1D Euler-Lagrange CFD simulations.

Numerical simulation of water spray evaporation in a turbulent air flow

Water spray evaporation in a hot air flow is a common process for many industrial applications. Spray nozzles should be well adjusted and distributed specifically to achieve efficient evaporation. The present study addressed simulation of the process within the Eulerian-Lagrangian workframe with k-∈ turbulence model. Simulation was carried out via OpenFOAM and postprocessed with ParaView. SprayFOAM solver was used to obtain a solution for 2D and 3D representations of the wind tunnel. Custom JANAF-based approximations were introduced for thermophysical properties of working mediums (air and water vapor). Obtained results were accurate enough to validate the presented model against adopted experimental data. Drift eliminator was modelled with virtual interfaces (baffles), which were tested in two scenarios: accumulating and removing droplets from the computational domain.

Visualization and image analysis of droplet puffing and micro-explosion in spray-flame synthesis of iron oxide nanoparticles

Combusting metal precursor-laden droplets, required in spray-flame synthesis of nanomaterials, are known to undergo a rapid and disruptive disintegration, i.e., puffing and micro-explosion. In this work, imaging with high spatiotemporal resolution and image-analysis routines were developed to investigate droplet disruption in spray-flame synthesis of metal oxides. Droplet shadowgraphs were imaged on a high-speed camera. The solvent was a mixture of 35 vol% ethanol and 65 vol% 2-ethylhexanoic acid which (in some cases) was mixed with a 0.2 mol/l iron(III) nitrate nonahydrate precursor. Photometric and morphological processing identified in-focus features, estimated their size, velocity, and circularity, and discriminated regular, spherical droplets from disrupting ones. While solely regular droplets were found in the spray flame of pure solvent, with the precursor/solvent mixture, disrupting droplets were found in addition to the regular droplets. Disruption events were phenomenologically classified into puffing, comprising droplet deformation and local eruption, and micro-explosion, the violent disintegration of the droplet into multiple fragments. Puffing was found to occur much more frequently than micro-explosions. Disrupting droplets had a 32% smaller Sauter mean diameter than regular droplets, indicating that disruptions are beneficial for rapid spray evaporation. At 40 and 50 mm heights above the burner, about 8 and 6%, respectively, of the in-focus droplets are disrupting per millimeter axial distance. Thus, throughout their lifetime in the spray flame, all precursor-laden droplets are expected to experience disruption.Graphical abstract