(Dr. Said Abdek-Khalik, advisor)
"An Experimental and Numerical Investigation of Evaporating Water Sprays Injected into Flowing Superheated Steam"
The objective of this research was to experimentally and numerically examine the various heat, mass, and momentum transport processes taking place in a steam conditioning system. A large-scale test facility was constructed within the low-pressure turbine extraction steam system of the University of North Carolina – Chapel Hill Cogeneration Plant. Before distribution to the academic and medical facilities on campus, the steam temperature needed to be reduced to more acceptable levels. To accomplish this, sub-cooled water was injected into the flowing superheated steam via a series of spray nozzles placed radially across the 30” diameter steam line. Temperature, pressure, and mass flow data were collected and analyzed to determine the extent of vaporization, droplet fall-out, and thermal stratification at two different axial and 48 radial locations along the downstream pipe. Experiments were conducted utilizing different control schemes, nozzle configurations, and steam flow conditions to determine the influence of various design and operational parameters on system performance including the creation of highly stratified steam flows in large diameter pipelines.
The experimental data were compared with predictions of the SteamCFD computer code developed at Georgia Tech. This code is based on mechanistic, transient, three-dimensional, two-fluid representation of the conservation equations. Computational and experimental thermal profiles were compared for each of the individual data sets. Based on this comparison, modifications in the system’s design and instrumentation were recommended to reduce the extent of thermal stratification and improve the vaporization performance.