Numerical simulation of rotary regenerative air preheater (Ljungstrom) in steam power plant with the aim of optimizing of thermal performance

Rotary Regenerative Air Preheater (RRAPH) is one of the main equipments for energy recovery in the steam power plants. In this study, air preheater of the Bisotoun Power Plant of Kerrmanshah has been investigated with the aim of optimizing its thermal performance. So, with Computational Fluid Dynamics (CFD), three-dimensional simulation of the rotary air preheater has performed to solve the continuity, momentum and energy equations in porous medium by using moving refrence frame (MRF) method. The results showed acceptable accuracy in comparison with the experimental results which is achieved from the power plant data. In this research, the effect of rotational speed on the efficiency of air preheater in different loads and mass flow rates for both without and with leakage conditions has investigated. The results showed that the impact of the rotational speed on the performance of RRAPH is noticeable in the range of 0.5 to 4 rpm, and after this increase in speed does not have a significant effect on efficiency. The present study also showed that leakage has a significant effect on reduction of the efficiency of the RRAPH in all loads and rotational speeds. In the following, the effect of matrix material change on the efficiency of RRAPH has investigated. According to the results, for both without and with leakage, the best thermal performance is related to the stainless steel, which has the least thermal diffusivity, also the least thermal performance is related to the copper, which has the highest thermal diffusivity.