Estimation of the Evaporation Rate of an Isolated Water Microdroplet Subjected to Infrared Radiative Heating

• Author / Creator

  Ferraz Albani, Luis A

• A combined numerical-experimental investigation was performed to study the influence of infrared radiation on the evaporation of a single-component droplet in the range between 10 and 50 micrometers, under different environmental conditions of relative humidity and temperature of air. A numerical model that predicts the evolution of the droplet size with respect to time was developed under the assumptions of steady state evaporation, spherical symmetry, no relative velocity between the droplet and the surroundings, constant material properties, and no temperature gradient inside the droplet. Numerical simulations were generated to obtain plots of droplet diameter with respect to time for droplets with an initial diameter of 50 micrometers under four different conditions of relative humidity (i.e., 0%, 30%, 60%, and 90%), two different air temperatures (i.e., 20 °C and 60 °C), and various radiation intensities (i.e., 0 to 10000 milliwatts per millimeters squared). Experiments were performed using an opto-mechanical rig capable of generating a monodispersed vertical chain of droplets inside a glass flow tube with various conditions of relative humidity and air temperature, in which the size of the droplets was measured using shadowgraphy. The droplet images were collected and processed using a 12X microscopic optical system and commercial software, respectively. An infrared laser beam with a wavelength of 2.8 micrometers was generated and aligned with the vertical droplet chain in order to provide the system with high amounts of infrared radiation at a
  wavelength in which the liquid water has a high absorptivity. The experimental and numerical results showed good agreement in all cases. It was determined that at elevated magnitudes of incident infrared radiation the evaporation rate of water droplets increases substantially and high amount of vapor content in the surrounding air becomes inconsequential.

• Subjects / Keywords

  • Radiation
  • Evaporation
  • Droplets

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3397J

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.