Two-Dimensional model of a Delugeable Flat Bare Tube Air- Cooled Steam Condenser Bundle

摘要

In this paper, a two-dimensional model was developed for the numerical evaluation of the thermal performance of a delugeable flat tube bundle to be incorporated in the second stage of an induced draft hybrid (dry/wet) dephlegmator (HDWD) of a direct air-cooled steam condenser (ACSC). The heat and mass transfer analogy method of analysis was employed during the evaluation, and the governing differential equations were discretised into algebraic equations using linear upwind differencing scheme. The two-dimensional model’s accuracy was validated through a comparison of its solutions to one dimensional model solutions presented in Angula (2018), where the heat and mass transfer analogy, Merkel, and Poppe approaches were usedfor the analytical evaluation of the thermal performance of the same tube bundle. Satisfactory correlation between the one and two-dimensional results was reached. However, the heat transfer rates yielded from one-dimensional model were found to be slightly higher than that obtained from two-dimensional model with differences of 1.98%, 8.23%, and 10.79% for heat and mass transfer analogy, Merkel, and Poppe methods, respectively. The difference in air-side pressure drop obtained by all the methods was found to be insignificant. Furthermore, the identification of best configuration of a delugeable flat tube bundlefor the second stage of induced draft HDWD wascarried out, through the comparison study of its performance to that of round tube bundle. The performance of the round tube bundle was found to be 1.95 times, and 1.43 times of that of flat tube bundle, when both bundles operate as an evaporative and dry air-cooled condenser, respectively.