Power plants production’s growth capacity has led to increased concerns about efficiency and reliability of steam turbines. Its components are prone to cracking and failure caused by creep and fatigue. The present work used Ansys® and nCode GlyphWorks® package to predict tensions and deformations. The methodology used allows calculate the level of structural damage caused to each work cycle. Analysis of the application of a chemical process on the rotor to improve failure resistance influenced the component life, avoiding corrosion fatigue. To create residual stresses on the surface of material was used Shot peening process. Thermal analysis results show that the rotor supports approximately 3.18 × 104 cycles, obtaining a maximum error of 12.5% compared to experimental reference. The shot peening process increased the rotor life by about 3000 h (10.5%) and changes in the heat treatment microstructure increased by 9.6% in number of cycles.
This paper outlines the application of a numerical procedure to compute the LMTD correction factor for one tube pass and one shell pass, namely 1-1, shell-and-tube heat exchangers. Although the procedure was applied for this specific arrangement, it can easily be applied to different heat exchanger arrangements. The numerical methodology is based on an association of ε-NTU and LMTD approaches introduced by Kays and London (1998). Unlike other shell-and-tube heat exchanger arrangements, such as one tube pass and two shell pass, no available analytical expression in closed form is available in the literature. Hence, the presented numerical procedure is applied to determine the LMTD correction factor for 1-1 shell-and-tube heat exchangers and numerical results were obtained by increasing the number of baffles (1, 3, 7, 9, 19 and 49), in order to analyze the obtained results. Finally, charts for the LMTD correction factor is presented as a function of two dimensionless parameters, namely P and R.
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