COMPUTATIONAL MODELING FOR THE PERFORMANCE PREDICTION OF QUAD-SECTOR ROTARY AIR PREHEATER AND COMPARATIVE STUDY WITH TRI-SECTOR AND BI-SECTOR ROTARY AIR PREHEATERS

Abstract

Rotary air preheaters are mainly used to improve the economy of a steam power plant by preheating the air with the help of hot flue gases from the boiler. Modern steam power plants are preferring tri-sector and quad-sector rotary air preheaters over bi-sector due to their better performance and lower leakage. In the present work, thermal behavior of a quad-sector rotary air preheater is the focus using computational fluid dynamics. The porous media approach is used for numerical simulation assuming local thermal equilibrium condition between fluid and solid. The performance of the air preheater is accessed by effectiveness and pressure drop. Porosity is estimated for four different cell shapes, which are used in the rotary preheater core for numerical investigation. The study reveals that the core consisting of a triangular cell has the highest effectiveness. The effect of porosity on performance is also investigated for various cell shapes. The effect of important operating parameters, such as rotor speed, aspect ratio, and mass flow rate of fluids on the effectiveness, as well as pressure drop is investigated for a quad-sector rotary air preheater. The study ends with a comparative performance analysis between bi-, tri-, and quad-sector rotary air preheaters. The performance of quad-sector air preheater is found to be better than other two preheaters in terms of effectiveness, whereas its pressure drop is maximum.