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Evaluation of equilibrium and non-equilibrium evaporation models for many-droplet gas-liquid flow simulations

Miller, R. S. and Harstad, K. and Bellan, J. (1998) Evaluation of equilibrium and non-equilibrium evaporation models for many-droplet gas-liquid flow simulations. International Journal of Multiphase Flow, 24 (6). pp. 1025-1055. ISSN 0301-9322. https://resolver.caltech.edu/CaltechAUTHORS:20171019-110525024

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Abstract

A variety of liquid droplet evaporation models, including both classical equilibrium and non-equilibrium Langmuir–Knudsen formulations, are evaluated through comparisons with experiments with particular emphasis on computationally efficient procedures for gas–liquid flow simulations. The models considered are those used in droplet laden flow calculations such as direct numerical simulations for which large numbers of individual (isolated) droplet solutions are obtained. Diameter and temperature evolution predictions are made for single-component droplets of benzene, decane, heptane, hexane and water with relatively large initial sizes ∼1 mm vaporizing in convective air flows. All of the models perform nearly identically for low evaporation rates at gas temperatures significantly lower than the boiling temperature. For gas temperatures at and above the boiling point, large deviations are found between the various model predictions. The simulated results reveal that non-equilibrium effects become significant when the initial droplet diameter is <50 μm and that these effects are enhanced with increasing slip velocity. It is additionally observed that constant properties can be used throughout each simulation if both the gas and vapor values are calculated at either the wet-bulb or boiling temperature. The models based on the Langmuir–Knudsen law and a corrected (for evaporation effects) analytical heat transfer expression derived from the quasi-steady gas phase assumption are shown to agree most favorably with a wide variety of experimental results. Since the experimental droplet sizes are all much larger than the limit for non-equilibrium effects to be important, for these conditions the most crucial aspect of the current Langmuir–Knudsen models is the corrected analytical form for the heat transfer expression as compared to empirical relations used in the remaining models.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/S0301-9322(98)00028-7DOIArticle
http://www.sciencedirect.com/science/article/pii/S0301932298000287?via%3DihubPublisherArticle
Additional Information:© 1998 Elsevier Science Ltd. Received 28 July 1997, Revised 7 May 1998, Available online 5 January 1999. This research was conducted at the California Institute of Technology’s Jet Propulsion Laboratory (JPL) and sponsored by General Electric (GE) through the Air Force Office of Scientific Research (AFOSR) Focused Research Initiative program with Dr David Burrus from GE serving as contract monitor. Computational resources were provided by the super computing facility at JPL.
Funders:
Funding AgencyGrant Number
JPL/CaltechUNSPECIFIED
General ElectricUNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Subject Keywords:condensation; droplet; evaporation; non-euilibrium; spray
Issue or Number:6
Record Number:CaltechAUTHORS:20171019-110525024
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20171019-110525024
Official Citation:R.S. Miller, K. Harstad, J. Bellan, Evaluation of equilibrium and non-equilibrium evaporation models for many-droplet gas-liquid flow simulations, In International Journal of Multiphase Flow, Volume 24, Issue 6, 1998, Pages 1025-1055, ISSN 0301-9322, https://doi.org/10.1016/S0301-9322(98)00028-7. (http://www.sciencedirect.com/science/article/pii/S0301932298000287)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:82496
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Oct 2017 18:09
Last Modified:03 Oct 2019 18:55

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