Date of Award

6-2020

Degree Name

Doctor of Philosophy

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Parviz Merati

Second Advisor

Dr. Tianshu Liu

Third Advisor

Dr. Christopher Cho

Fourth Advisor

Dr. Dewei Qi

Keywords

Evaporation, natural convection, free water surface, Sherwood Number, Rayleigh Number

Abstract

Evaporation of water can be considered an essential part of the hydrological cycle. It is important for many technological applications such as industrial cooling towers, air conditioning, solid material drying, distillation, and liquid film cooling. Moreover, the interfacial convection caused by the density gradient belongs to Rayleigh convection, which plays an important role in the evaporation process by means of intensifying heat and mass transfer, as in an isopropanol‒water system. In addition, natural convection, which can be defined as a buoyancy-driven flow, is important in astrophysics, geophysics, and numerous engineering applications such as solar energy systems, cooling of electrical equipment, ventilation, and passive cooling in nuclear power plants.

In the current work, an experimental study along with a numerical simulation investigation of free water surface evaporation in case of natural convection is carried out. First, an experiment is conducted to predict Sherwood‒Rayleigh correlation for free water surface evaporation in case of natural convection in the range of 1.4×109 a< 1.1×1011, which is based on measuring the room air temperature, the bulk water temperature, the surface temperature, the room relative humidity, and the mass loss due to evaporation. A second experiment is performed utilizing particle image velocimetry (PIV), to investigate the flow pattern in the case of a free surface undergoing evaporation. This investigation of flow pattern is conducted for the side and top of a water tank. In addition, numerical two-dimensional (2-D) and three-dimensional (3-D) simulations are carried out in order to study the flow pattern along with rise in temperature. As a part of the numerical simulation, a user-defined function (UDF) code is developed and compiled to investigate the surface evaporation. A comparison follows of the numerical simulation and experimental work. Finally, an experiment is implemented using stereo particle image velocimetry (SPIV) to calculate the third velocity component. Subsequently, the effect of the third component on the flow pattern and velocity magnitude is addressed and discussed.

Access Setting

Dissertation-Campus Only

Restricted to Campus until

6-30-2022

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