Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “EVAPORATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Evaluation of The Risk of Solids Formation in the 2H Evaporator System

Savannah River Remediation (SRR) Tank Farm Engineering requested technical assistance from the Savannah River National Laboratory (SRNL) to troubleshoot recent and rapid plugging of the 2H Evaporator gravity drain line (GDL) to the Evaporator Drop Tank (currently Tank 38) with unwanted solids of unknown composition and to evaluate the risk of solids formation in the 2H Evaporator system moving forward. The GDL to Tank 38 recently plugged twice within hours of startup, resulting in a one-month shutdown both times. SRNL was asked to simulate current and historic (2016 to 2017) aqueous feed chemistries in the Evaporator Feed Tank (currently Tank 43) using the OLI Systems software to determine the mass of precipitated salts that would be expected to form under 2H Evaporator operating conditions for a range of concentration factors (i.e., evaporator overhead-to-feed volume ratio). A recommended evaporator concentration factor was determined based on the current Tank 43 feed composition to minimize solids formation and extend the time between shutdowns. Current and historic (2016 to 2017) aqueous chemistries in Tank 38 were also evaluated for completeness.

42 ENGINEERING↗
DOE OSTI2013

Upward-facing Lithium Flash Evaporator for NSTX-U

NSTX plasma performance has been significantly enhanced by lithium conditioning [1]. To date, the lower divertor and passive plates have been conditioned by downward facing lithium evaporators (LITER) as appropriate for lower null plasmas. The higher power operation expected from NSTX-U requires double null plasma operation in order to distribute the heat flux between the upper and lower divertors making it desirable to coat the upper divertor region with Li as well. An upward aiming LITER (U-LITER) is presently under development and will be inserted into NSTX-U using a horizontal probe drive located in a 6" upper midplane port. In the retracted position the evaporator will be loaded with up to 300 mg of Li granules utilizing one of the calibrated NSTX Li powder droppers[2]. The evaporator will then be inserted into the vessel in a location within the shadow of the RF limiters and will remain in the vessel during the discharge. About 10 seconds before a discharge, it will be rapidly heated and the lithium completely evaporated onto the upper divertor, thus avoiding the complication of a shutter that prevents evaporation during the shot when the diagnostic shutters are open. The minimal time interval between the evaporation and the start of the discharge will avoid the passivation of the lithium by residual gases and enable the study of the conditioning effects of un-passivated Li surfaces [3]. Two methods are being investigated to accomplish the rapid (few second) heating of the lithium. A resistive method relies on passing a large current through a Li filled crucible. A second method requires using a 3 kW e-beam gun to heat the Li. In this paper the evaporator systems will be described and the pros and cons of each heating method will be discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Impact of post-rainfall evaporation from porous roof tiles on building cooling load in subtropical China

Rainfall occurs frequently in subtropical regions of China, with the subsequent water evaporation from building roofs impacting the thermal performance and the energy consumption of buildings. In this paper, we proposed a novel simulation method using actual meteorological data to evaluate this impact. New features were developed in EnergyPlus to enable the simulation: (1) an evaporation latent heat flux source term was added to the heat balance equation of the external surface and (2) algorithms for the evaporative cooling module (ECM) were developed and implemented into EnergyPlus. The ECM experimental results showed good agreement with the simulated results. The ECM was used to assess the impact of evaporation from porous roof tiles on the cooling load of a one-floor building in subtropical China. The results show that the evaporation process decreased the maximal values of the external and internal roof surface temperatures by up to 6.4 °C and 3.2 °C, respectively, while the lower internal surface temperature decreased the room accumulated cooling load by up to 14.8% during the hot summer period. Lastly, the enhanced EnergyPlus capability can be used to evaluate the evaporative cooling performance of roofs with water-storage mediums, as well as to quantify their impact on building cooling loads.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

On falling film evaporator – A review of mechanisms and critical assessment of correlation on a horizontal tube bundle with updated development

Optimization of the energy efficiency and reduction of the greenhouse gas emission for the heat pump system is imperative to meet the net-zero goals at 2050. Chillers with falling film evaporator design not only possess better system performance but also contain less refrigerant inventory. Hence, accurate prediction of the evaporator performance is pivotal especially when charged with low-GWP refrigerant. Here, the study reviews the correlations for falling film evaporator with a horizontal tube bundle configuration. The major efforts of this study include four tasks: (a) literature review of the experimental studies and available empirical correlations; (b) comprehensive discussion of the falling film evaporation heat transfer mechanism; (c) development of a new rationally based correlation based on available literature; and (d) comparison of different correlations based on the existing data. The collected data includes 4114 data points from 8 sources, 6 refrigerants (R-600a, R-290, R-245fa, R-134a, R-1234ze(E), R-123), 5 types of the tubes (Plain, Turbo-GII-HP, GEWA-B, Low-fin, High-Flux), liquid Weber number from 2.2 × 10 –6 to 0.7, imposed vapor Weber number from 0 to 37.2, heat flux from 2.5 to 151.5 kW/m 2 , and film Reynolds number from 1 to 3159.8. The new correlation gives a MAD of 28.3%, and an R 2 of 0.86. Yet, the developed correlation considers various heat transfer mechanisms, including the transition point from falling film evaporation to the nucleate boiling, local evaporation, dry-out, mist flow, imposed flow, and enhanced tube effects.

42 ENGINEERING↗
DOE OSTI2017

Technical Performance and Economic Evaluation of Evaporative and Membrane-Based Concentration for Biomass-Derived Sugars

Several conversion pathways of lignocellulosic biomass to advanced biofuels require or benefit from using concentrated sugar syrups of 600 g/L or greater. And while concentration may seem straightforward, thermal sugar degradation and energy efficiency remain major concerns. This study evaluated the trade-offs in product recovery, energy consumption, and economics between evaporative and membrane-based concentration methods. The degradation kinetics of xylose and glucose were characterized and applied to an evaporator process simulation. Though significant sugar loss was predicted for certain scenarios due to the Maillard reaction, industrially common falling-film plate evaporators offer short residence times (<5 min) and are expected to limit sugar losses. Membrane concentration experiments characterized flux and sugar rejection, but diminished flux occurred at >100 g/L. A second step using evaporation is necessary to achieve target concentrations. Techno-economic process model simulations evaluated the overall economics of concentrating a 35 g/L sugar stream to 600 g/L in a full-scale biorefinery. A two-step approach of preconcentrating using membranes and finishing with an evaporator consumed less energy than evaporation alone but was more expensive because of high capital expenses of the membrane units.

09 BIOMASS FUELS↗
DOE OSTI2024

Elucidating the Mechanism of Helium Evaporation from Liquid Water

Here, we investigate the evaporation of trace amounts of helium solvated in liquid water using molecular dynamics simulations and theory. Consistent with experimental observations, we find a super-Maxwellian distribution of kinetic energies of evaporated helium. This excess of kinetic energy over typical thermal expectations is explained by an effective continuum theory of evaporation based on a Fokker–Planck equation, parametrized molecularly by a potential of mean force and position-dependent friction. Using this description, we find that helium evaporation is strongly influenced by the friction near the interface, which is anomalously small near the Gibbs dividing surface due to the ability of the liquid–vapor interface to deform around the gas particle. Our reduced description provides a mechanistic interpretation of trace gas evaporation as the motion of an underdamped particle in a potential subject to a viscous environment that varies rapidly across the air–water interface. From it we predict the temperature dependence of the excess kinetic energy of evaporation, which is yet to be measured.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Insights Into the Aerodynamic Versus Radiometric Surface Temperature Debate in Thermal-Based Evaporation Modeling

Global evaporation monitoring from Earth observation thermal infrared satellite missions is historically challenged due to the unavailability of any direct measurements of aerodynamic temperature. State-of-the-art one-source evaporation models use remotely sensed radiometric surface temperature as a substitute for the aerodynamic temperature and apply empirical corrections to accommodate for their inequality. This introduces substantial uncertainty in operational drought mapping over complex landscapes. By employing a non-parametric model, we show that evaporation can be directly retrieved from thermal satellite data without the need of any empirical correction. Independent evaluation of evaporation in a broad spectrum of biome and aridity yielded statistically significant results when compared with eddy covariance observations. While our simplified model provides a new perspective to advance spatio-temporal evaporation mapping from any thermal remote sensing mission, the direct retrieval of aerodynamic temperature also generates the highly required insight on the critical role of biophysical interactions in global evaporation research.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Microphysics Dominates Sub‐Cloud Rain Evaporation in Trade Cumuli Over Barbados

This study investigates the microphysical and thermodynamic influences on North Atlantic trade-cumulus rain evaporation in the sub-cloud layer over Barbados from January to November 2020. Using radar observations and a 1-D model, the results reveal that microphysical properties, namely geometric mean diameter (D g ) and raindrop concentration, primarily control evaporation processes under conditions of limited thermodynamic variability. Thermodynamic factors like cloud base height and relative humidity exert a smaller influence due to their narrow observed ranges. Small D g leads to rapid increases in rain evaporation fraction (REF), as small drops evaporate completely, while larger D g yields slower, more gradual REF changes. Frequent weak-rain cases reduce the mean evaporation flux, whereas infrequent intense-rain events substantially enhance it. These findings highlight the pivotal role of microphysical variability in shaping sub-cloud evaporation in this trade cumulus regime, while thermodynamic effects may be more important in other environments.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

A comparative study of the electrical properties of Pd/ZnO Schottky contacts fabricated using electron beam deposition and resistive/thermal evaporation techniques

A systematic investigation to check the quality of Pd Schottky contacts deposited on ZnO has been performed on electron beam (e-beam) deposited and resistively/thermally evaporated samples using current-voltage, IV, and conventional deep level transient spectroscopy (DLTS) measurements. Room temperature IV measurements reveal the dominance of pure thermionic emission on the resistively evaporated contacts, while the e-beam deposited contacts show the dominance of generation recombination at low voltages, <0.30 V, and the dominance of pure thermionic emission at high voltages, greater than 0.30 V. The resistively evaporated contacts have very low reverse currents of the order of 10{sup -10} A at a reverse voltage of 1.0 V whereas the e-beam deposited contacts have reverse currents of the order of 10{sup -6} A at 1.0 V. Average ideality factors have been determined as (1.43 {+-} 0.01) and (1.66 {+-} 0.02) for the resistively evaporated contacts and e-beam deposited contacts, respectively. The IV barrier heights have been calculated as (0.721 {+-} 0.002) eV and (0.624 {+-} 0.005) eV for the resistively evaporated and e-beam deposited contacts, respectively. Conventional DLTS measurements reveal the presence of three prominent defects in both the resistive and e-beam contacts. Two extra peaks with energy levels of 0.60 and 0.81 eV below the conduction band minimum have been observed in the e-beam deposited contacts. These have been explained as contributing to the generation recombination current that dominates at low voltages and high leakage currents. Based on the reverse current at 1.0 V, the degree of rectification, the dominant current transport mechanism and the observed defects, we conclude that the resistive evaporation technique yields better quality Schottky contacts for use in solar cells and ultraviolet detectors compared to the e-beam deposition technique. The 0.60 eV has been identified as possibly related to the unoccupied level for the doubly charged oxygen vacancy, V{sub o}{sup 2+}.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Applicability of post-ionization theory to laser-assisted field evaporation of magnetite

Analysis of the mean Fe ion charge state from laser-assisted field evaporation of magnetite (Fe3O4) reveals unexpected trends as a function of laser pulse energy that break from conventional post-ionization theory for metals. For Fe ions evaporated from magnetite, the effects of post-ionization are partially offset by the increased prevalence of direct evaporation into higher charge states with increasing laser pulse energy. Therefore the final charge state is related to both the field strength and the laser pulse energy, despite those variables themselves being intertwined when analyzing at a constant detection rate. Comparison of data collected at different base temperatures also show that the increased prevalence of Fe2+ at higher laser energies is possibly not a direct thermal effect. Conversely, the ratio of 16O+:16O2+ is well-correlated with field strength and unaffected by laser pulse energy on its own, making it a better overall indicator of the field evaporation conditions than the mean Fe charge state. Plotting the normalized field strength versus laser pulse energy also elucidates a non-linear dependence, in agreement with previous observations on semiconductors, that suggests a field-dependent laser absorption efficiency. Together these observations demonstrate that the field evaporation process for laser-pulsed oxides exhibits fundamental differences from metallic specimens that cannot be completely explained by post-ionization theory. Further theoretical studies, combined with detailed analytical observations, are required to understand fully the field evaporation process of non-metallic samples.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2013

Analysis Of 2h-Evaporator Scale Wall [HTF-13-82] And Pot Bottom [HTF-13-77] Samples

Savannah River Remediation (SRR) is planning to remove a buildup of sodium aluminosilicate scale from the 2H-evaporator pot by loading and soaking the pot with heated 1.5 M nitric acid solution. Sampling and analysis of the scale material has been performed so that uranium and plutonium isotopic analysis can be input into a Nuclear Criticality Safety Assessment (NCSA) for scale removal by chemical cleaning. Historically, since the operation of the Defense Waste Processing Facility (DWPF), silicon in the DWPF recycle stream combines with aluminum in the typical tank farm supernate to form sodium aluminosilicate scale mineral deposits in the 2Hevaporator pot and gravity drain line. The 2H-evaporator scale samples analyzed by Savannah River National Laboratory (SRNL) came from the bottom cone sections of the 2H-evaporator pot [Sample HTF-13-77] and the wall 2H-evaporator [sample HTF-13-82]. X-ray diffraction analysis (XRD) confirmed that both the 2H-evaporator pot scale and the wall samples consist of nitrated cancrinite (a crystalline sodium aluminosilicate solid) and clarkeite (a uranium oxy-hydroxide mineral). On “as received” basis, the bottom pot section scale sample contained an average of 2.59E+00 ± 1.40E-01 wt % total uranium with a U-235 enrichment of 6.12E-01 ± 1.48E-02 %, while the wall sample contained an average of 4.03E+00 ± 9.79E-01 wt % total uranium with a U-235 enrichment of 6.03E-01% ± 1.66E-02 wt %. The bottom pot section scale sample analyses results for Pu-238, Pu-239, and Pu-241 are 3.16E- 05 ± 5.40E-06 wt %, 3.28E-04 ± 1.45E-05 wt %, and <8.80E-07 wt %, respectively. The evaporator wall scale samples analysis values for Pu-238, Pu-239, and Pu-241 averages 3.74E-05 ± 6.01E-06 wt %, 4.38E-04 ± 5.08E-05 wt %, and <1.38E-06 wt %, respectively. The Pu-241 analyses results, as presented, are upper limit values. These results are provided so that SRR can calculate the equivalent uranium-235 concentrations for the NCSA. Results confirm that the uranium contained in the scale remains depleted with respect to natural uranium. SRNL did not calculate an equivalent U-235 enrichment, which takes into account other fissionable isotopes U-233, Pu-239 and Pu-241. The applicable method for calculation of equivalent U-235 will be determined in the NCSA.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Preparation and evaporation of Hanford Waste treatment plant direct feed low activity waste effluent management facility simulant

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Melter Off-Gas Condensate, LMOGC) from the off-gas system. The baseline plan for disposition of this stream during full WTP operations is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation, and recycled to the LAW vitrification facility. However, during the Direct Feed LAW (DFLAW) scenario, planned disposition of this stream involves concentrating the condensate in a new evaporator at the Effluent Management Facility (EMF) and returning it to the LAW melter. The LMOGC stream will contain components, e.g. halides and sulfates, that are volatile at melter temperatures, have limited solubility in glass waste forms, and present a material corrosion concern. Because this stream will recycle within WTP, these components are expected to accumulate in the LMOGC stream, exacerbating their impact on the number of LAW glass containers that must be produced. Diverting the stream reduces the halides and sulfates in the glass and is a key objective of this program. In order to determine the disposition path, it is key to experimentally determine the fate of contaminants. To do this, testing is needed to account for the buffering chemistry of the components, determine the achievable evaporation end point, identify insoluble solids that form, determine the formation and distribution of key regulatoryimpacting constituents, and generate an aqueous stream that can be used in testing of the subsequent immobilization step. This overall program examines the potential treatment and immobilization of the LMOGC stream to enable alternative disposal. The objective of this task was to (1) prepare a simulant of the LAW Melter Off-gas Condensate expected during DFLAW operations, (2) demonstrate evaporation in order to predict the final composition of the effluents from the EMF evaporator to aid in planning for their disposition, and (3) generate concentrated evaporator bottoms for use in immobilization testing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Laser heating and evaporation of a single droplet

The laser technology is being abundantly studied for controlled energy deposition for a range of applications in aerodynamic flow control, material processing, ignition, and combustion. The absorption of laser radiation by liquid droplets affects further propagation of laser in the atmosphere and causes bleaching of suspended droplets while the ignition and combustion characteristics in combustors are influenced by the evaporation rate of the sprayed fuel. In this work, we present a multi-dimensional mathematical model built on OpenFOAM for laser heating and evaporation of a single droplet in the diffusion dominated regime taking into account absorption of the laser radiation, evaporation process and vapor flow dynamics. The developed solver is validated against available experimental and numerical data for the ethanol and water droplet heating and evaporation. For continuous heating the peak temperature is established by the balance of cooling, evaporation and heating and results in high temperature for larger droplets. It has been shown that for heating by a single laser pulse the maximum temperature of droplets depends only on the peak intensity of the laser radiation. Furthermore, for the peak irradiance close to the transition to the boiling regime, temporal dynamics of the droplet temperature is independent of the droplet size. With proper normalization of time, the dynamics of the droplet shrinkage and cooling is shown to be independent of droplet sizes and peak laser intensities. The influence of cooling and evaporation processes on droplet heating was found to be controlled by the pulse repetition rate for repeated pulse operation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

The influence of land cover on surface energy partitioning and evaporative fraction regimes in the U.S. Southern Great Plains

Land-atmosphere interactions are important to climate prediction, but the underlying effects of surface forcing of the atmosphere are not well understood. In the U.S. Southern Great Plains, grassland/pasture and winter wheat are the dominant land covers but have distinct growing periods that may differently influence land-atmosphere coupling during spring and summer. Variables that influence surface flux partitioning can change seasonally, depending on the state of local vegetation. We use surface observations from multiple sites in the U.S. Department of Energy Atmospheric Radiation Measurement Southern Great Plains Climate Research Facility and statistical modeling at a paired grassland/agricultural site within this facility to quantify land cover influence on surface energy balance and variables controlling evaporative fraction (latent heat flux normalized by the sum of sensible and latent heat fluxes). We demonstrate that the radiative balance and evaporative fraction are closely related to green leaf area at both winter wheat and grassland/pasture sites and that the early summer harvest of winter wheat abruptly shifts the relationship between evaporative fraction and surface state variables. Prior to harvest, evaporative fraction of winter wheat is strongly influenced by leaf area and soil-atmosphere temperature differences. After harvest, variations in soil moisture have a stronger effect on evaporative fraction. Finally, this is in contrast with grassland/pasture sites, where variation in green leaf area has a large influence on evaporative fraction throughout spring and summer, and changes in soil-atmosphere temperature difference and soil moisture are of relatively minor importance.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Global variation of transpiration and soil evaporation and the role of their major climate drivers

Although global variation in actual evapotranspiration has been widely investigated, it remains unclear how its two major components, transpiration and soil evaporation, are driven by climate drivers across global land surface. This paper uses a well-validated, process-based model that estimates transpiration and soil evaporation, and for the first time investigates and quantifies how the main global drivers, associated to vegetation process and the water and energy cycle, drive the spatiotemporal variation of the two components. The results show that transpiration and soil evaporation dominate the variance of actual evapotranspiration in wet and dry regions, respectively. Dry southern hemisphere from 13°S to 27°S is highlighted since it contributes to 21% global soil evaporation variance, with only 11% global land area. In wet regions, particularly in the humid tropics, there are strong correlations between transpiration, actual evapotranspiration, and potential evapotranspiration, with precipitation playing a relatively minor role, and available radiative energy is the major contributor to the interannual variability in transpiration and actual evapotranspiration in Amazonia. Conversely in dry regions, there are strong correlations between soil evaporation, actual evapotranspiration, and precipitation. Lastly, our findings highlight that ecohydrological links are highly related to climate regimes, and the small region such as Australia has important contribution to interannual variation in global soil evaporation and evapotranspiration, and anthropogenic activities strongly influence the variances in irrigation regions

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Elimination of inter-discharge helium glow discharge cleaning with lithium evaporation in NSTX

Operation in the National Spherical Torus Experiment (NSTX) typically used either periodic boronization and inter-shot helium glow discharge cleaning (HeGDC), or inter-shot lithium evaporation without boronization, and initially with inter-shot HeGDC. To assess the viability of operation without HeGDC, dedicated experiments were conducted in which Li evaporation was used while systematically shrinking the HeGDC between shots from the standard 10 min to zero (10 → 6.5 → 4 → 0). Good shot reproducibility without HeGDC was achieved with lithium evaporations of 100 mg or higher; evaporations of 200–300 mg typically resulted in very low ELM frequency or ELM-free operation, reduced wall fueling, and improved energy confinement. The use of HeGDC before lithium evaporation modestly reduced D α in the outer scrape-off layer, but not at the strike point. Pedestal electron and ion temperature also improved modestly, suggesting that HeGDC prior to lithium evaporation is a useful tool for experiments that seek to maximize plasma performance.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Nanoscale Measurement of Laser-Induced Temperature Rise and Field Evaporation Effects in CdTe and GaN

The measurement of laser-induced temperature change and its influence on the field evaporation behavior in nanoscale CdTe and GaN specimens was assessed through systematic studies using laser pulsed atom probe tomography. For CdTe, the laser was shown to induce a linear thermal response in the material. Using the determined relationships, a phase map of the field evaporation behavior was created. This shows that at high base temperatures, high laser energies, or low fields, significant Cd sublimation occurs, leading to apparently Te-rich measured compositions. In contrast, the highest fields result in simultaneous evaporation of multiple Te species, leading to apparently Cd-rich measured compositions. For GaN, increasing laser energy reduced the applied bias necessary for a given detection rate, whereas base temperature changes produced no significant effect on the evaporation behavior, indicative of a largely athermal evaporation mechanism. Similarly, the laser energy and bias affected the measured compositions, whereas the base temperature did not. Additionally, the field evaporation behavior in GaN appears unusual in that there is a strong crystallographic dependence resulting in a nonuniform field being maintained across the apex of the specimen. Furthermore, these methods are useful beyond atom probe analyses for elucidating information about bonding and optoelectronic properties

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Surprising Effects of Hydrochloric Acid on the Water Evaporation Coefficient Observed by Raman Thermometry

© 2017 American Chemical Society. The kinetics and energetics of cloud droplet and aerosol formation in the atmosphere are strongly influenced by the evaporation and condensation rates of water, yet the magnitude and mechanism of evaporation remains incompletely characterized. Of particular import (and controversy) is the nature of interfacial water pH and its potential effects on evaporation rate and environmental reactivity. We have used Raman thermometry measurements of freely evaporating microdroplets to determine evaporation coefficients (Î) for two different hydrochloric acid solutions, both of which result in a significant deviation from Îwater. At 95% confidence, we find the evaporation coefficient for 1.0 M HCl to be 0.24 ± 0.04, a â-60% decrease relative to pure water, and for 0.1 M HCl to be 0.91 ± 0.08, a â-45% increase relative to pure water. These results suggest a large perturbation in the surface structure induced by either hydronium ions adsorbing to the water surface or by the presence of a Cl-···H3O+ ion-pair moiety in the interfacial region.

Rizzuto, Anthony M↗