NUMERICAL AND EXPERIMENTAL INVESTIGATIONOF STEAM FILM CONDENSATION ON A VERTICAL TUBE
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Abstract
Film condensation of steam on a vertical tube is investigated numerically and experimentally,
in the present work. A mathematical model was set based on the basic conservation laws of mass
and energy, Nusselts analysis of film condensation, and empirical equations available in the
literature. Then, a simulation program in FORTRAN language was developed which simulates the
film condensation of steam on a vertical tube. A complete steam tables subprogram was also
developed and incorporated with the main program. The experimental work was carried out using a
steam condensation test bench. The inlet and outlet cooling water temperatures, steam temperature
and pressure, tube surface temperature at center, and cooling water flow rate are recorded during
each experimental test run. The inlet cooling water temperature, steam temperature, and cooling
water flow rate are used as an input for the numerical program, then the program calculates tube
surface temperature distribution, cooling water temperature distribution, local heat transfer rate,
local condensation heat transfer coefficient, condensate boundary layer thickness distribution, total
heat transfer rate, and average condensation heat transfer coefficient. The effect of various
parameters on the condensation heat transfer coefficient, such as steam temperature, steam-surface
temperature difference, and the presence of non-condensable gas were investigated and reported
graphically. It was found that increasing (steam-surface) temperature difference while keeping the
steam temperature constant results in an increase in condensate boundary layer thickness, which in
turn causes a decrease in condensation heat transfer coefficient. On the other hand, increasing steam
temperature and keeping the (steam-surface) temperature difference constant leads to an increase in
condensation heat transfer coefficient. In addition, the presence of non-condensable gas with
different concentrations was also investigated and it was shown that it causes a noticeable reduction
in the average condensation heat transfer coefficient. An equation for calculating average
condensation heat transfer coefficient on a vertical tube was also developed. The experimental data
obtained from the test runs were compared with numerical results and showed good agreement.
Thus, it can be concluded that the present computational program is suitable for simulating steam
condensation on a vertical tube.
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