Mechanical model development of rolling bearing-rotor systems: A review

Global warming has been a major concern, and the amount of CO2 released to the atmosphere keeps increasing due to overuse of the earth's fossil fuel reserves. Overpopulation and lack of comprehensive energy management add to the problem. New and renewable energy sources are still expensive or in the conceptual phase. The organic Rankine cycle (ORC) seems to be a viable option to address these issues by reusing waste and low-grade heat that would otherwise be released into the environment. Many ORC power plants are already in commercial use. Since the introduction of the basic ORC (BORC), there have been many revolutionary ideas to optimize the performance of power generators, but they have not been experimentally tested extensively. This study focuses on zeotropic refrigerant mixtures made of two or three refrigerants instead of a single working fluid. The main advantages of this system are increased exergy efficiency and decreased irreversibility in the evaporator and condenser, where the isothermal phase change of pure refrigerant would not match the temperature profile of the heat source and heat sink. Published experimental studies on this topic are extremely rare. This study discusses almost all the articles on this subject, the proposed mixtures, and the conclusions.

Investigation of organic Rankine cycles with zeotropic mixtures as a working fluid: Advantages and issues

Performance of geothermal energy extraction in a horizontal well by using CO2 as the working fluid

Wave propagation in viscoelastic single walled carbon nanotubes is investigated by accounting for the simultaneous effects of the nonlocal constant and the material length scale parameter. To this end, thin shell theory is used to model the viscoelastic single walled carbon nanotubes, and the nonlocal strain gradient theory is used to account for the effects of the nonlocal constant and the material length scale parameter. The Kelvin–Voigt model is used to model the viscoelastic property, and the governing equations are derived through Hamilton’s principle. The viscoelastic single walled carbon nanotube medium is modeled as visco-Pasternak. The results demonstrate that viscoelastic single walled carbon nanotube rigidity is higher in the strain gradient theory and lower in the nonlocal theory in comparison to that in the classical theory. Also, the size effects, nanotube radius, circumferential wavenumber, nanotube damping coefficient, and foundation damping coefficient exert considerable effects on viscoelastic single walled carbon nanotube phase velocity.

Wave propagation in viscoelastic thin cylindrical nanoshell resting on a visco-Pasternak foundation based on nonlocal strain gradient theory

Geothermal energy extraction in CO2 rich basin using abandoned horizontal wells

Determination of optimum geothermal Rankine cycle parameters utilizing coaxial heat exchanger

Dynamic analysis of a high speed rotor-bearing system

Vibration analysis of functionally graded carbon nanotube-reinforced composite nanoplates using Mindlin’s strain gradient theory

http://scientiairanica.sharif.edu/article_4325_d313774daf8501654bc29e2d6b681c1b.pdf

Free Vibration Analysis of Rotating Functionally Graded Annular Disc of Variable Thickness Using Generalized Differential Quadrature Method

Elastic stress analysis of rotating variable thickness annular disk made of functionally graded material (FGM) is presented. Elasticity modulus, density, and thickness of the disk are assumed to vary radially according to a power-law function. Radial stress, circumferential stress, and radial deformation of the rotating FG annular disk of variable thickness with clamped-clamped (C-C), clamped-free (C-F), and free-free (F-F) boundary conditions are obtained using the numerical finite difference method, and the effects of the graded index, thickness variation, and rotating speed on the stresses and deformation are evaluated. It is shown that using FG material could decrease the value of radial stress and increase the radial displacement in a rotating thin disk. It is also demonstrated that increasing the rotating speed can strongly increase the stress in the FG annular disk.

/pdf/elastic-stress-analysis-of-rotating-functionally-graded-540laz63p4.pdf

Behrooz Shahriari

Papers

Determination of optimum geothermal Rankine cycle parameters utilizing coaxial heat exchanger

Dynamic analysis of a high speed rotor-bearing system

Vibration analysis of functionally graded carbon nanotube-reinforced composite nanoplates using Mindlin’s strain gradient theory

Free Vibration Analysis of Rotating Functionally Graded Annular Disc of Variable Thickness Using Generalized Differential Quadrature Method

Elastic Stress Analysis of Rotating Functionally Graded Annular Disk of Variable Thickness Using Finite Difference Method