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The performance of an ejector refrigeration cycle is investigated both theoretically and experimentally. By applying the equations for the conservation of mass, energy, and momentum as well as that for the exergy balance, for each component in the cycle, a new two-dimensional thermodynamic model is developed. The influence of flow viscosity is taken into account by assuming a two-dimensional flow near the ejector inner wall. Results indicate that the cycle coefficient of performance decreases with increasing generator temperature and the second law efficiency increases with increasing evaporator temperature and/or decreasing generator temperature. It is found that the maximum relative error occurred in calculating the entrainment ratio is 7.52%. Exergy analysis revealed that the ejector has almost the highest contribution in the total exergy destruction. In addition, increasing the evaporator temperature from 2 to 15.5 C results in a decrease in ejector exergy destruction by up to 8%.

In this paper, dynamic behavior of a vapor bubble inside a narrow channel filled with a viscous liquid has been studied numerically. The boundary integral equation method (BIEM) and the procedure of viscous correction of viscous potential flow (VCVPF) have been employed for obtaining the vapor bubble profiles during its pulsations inside the narrow channel filled with a viscous liquid. In the present paper a new method has been proposed for considering the effects of viscosity in a viscous liquid flow in the framework of the Green's integral formula together with the modified form of unsteady Bernoulli equation. The reported experimental and numerical results of the problem under investigation have been used for verification of the results of the present work. Numerical results show that, by increasing the viscosity of liquid around the vapor bubble, the bubble lifetime increases. Numerical results also indicate that for Reynolds numbers with the order of 3 (10 ) O , the viscosity effects are extremely reduced. Furthermore, the dynamic behavior of the bubble in water and oil is investigated at different Reynolds numbers and at different so-called dimensionless channel radii. KeywordsBubble dynamics, boundary element method, viscous pressure correction, narrow channel, viscous potential flow 30 computational uid dynamics. His interest extends to the field of droplet management, fluid flow in porous media (oil recovery enhancement), and impinging jets. Professor Shervani-Tabar has published more than 45 publications.

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