Performance Prediction of a Model Rotary Air Preheater Through Porous Media Approach

Abstract

Rotary regenerative heat exchangers or rotary regenerators are used for various heat recovery applications in order to fulfill the energy requirements. Rotary air preheater is a rotary regenerative heat exchanger which is widely used in thermal power plants to recover heat energy from exhaust flue gases. Several numerical works are being carried out to improve the performance and reduce the cost of the rotary air preheater. However, the accurate modeling of the internal structure of the matrix demands a lot of CPU power and is a big challenge for researchers. To overcome this problem, the rotary matrix of the preheater can be modeled using a porous media approach. But a thorough investigation is required to evaluate its performance. In this work, rotary air preheater simulations were carried out by applying a porous media approach. The effects of different operating conditions, such as speed of rotor, the mass flowrate of incoming fluids, material of matrix, and inlet temperature of hot fluid on the performance of rotary air preheater were investigated. Simulation results were validated with the results obtained from the experimentation performed in-house. The effect of fluid flowrates on pressure drop was also studied. It has been observed that the rotational speed of the rotor significantly affects the performance of the preheater, while the inlet temperature of hot fluid has a negligible effect on performance.