فهرست مطالب navid freidoonimehr

In this paper, parametric analysis and optimization of the transcritical ejector refrigeration cycle using different working fluids have been proposed which can be employed in the parts of solar energy processes. The main advantages of using ejector in the refrigeration cycles, which often use instead of the compressor, are simplicity in construction and maintenance, high reliability and low cost. In this study, the transcritical ejector refrigeration cycle is modelled using EES software and the effects of different parameters such as temperature and pressure of different parts of cycle on the coefficient of performance and entrainment ratio are investigated. In continued, the coefficient of performance of the transcritical ejector refrigeration cycle for four different working fluids is optimized using the combination the Artificial Neural Network and Particle Swarm Optimization algorithm.

The main propose of the present article is to study the second law of thermodynamics over a stretching permeable surface in the presence of the uniform vertical magnetic field in the slip nano-fluid regime. In this study, four types of nanoparticles i.e. Copper , Copper oxide , Aluminum oxide , and Titanium dioxide and also water as the base fluid are considered. Entropy generation equations, for the first time in this problem, are derived as a function of velocity and temperature gradients. Velocity profile as well as temperature distribution and averaged entropy generation are obtained using Homotopy Analysis Method (HAM). An excellent agreement exists between the present result and the other researchers’ result. The obtained result of present study presents that by decreasing magnetic parameter, nanoparticle volume fraction parameter, suction parameter, Reynolds number, Brinkman number, and Hartmann number as well as increasing the slip velocity parameter, the generated entropy reduces.

The main purpose of this study is to present dual solutions for the problem of magneto-hydrodynamic Jeffery–Hamel nano-fluid flow in non-parallel walls. To do so, we employ a new analytical technique, Predictor Homotopy Analysis Method (PHAM). This effective method is capable to calculate all branches of the multiple solutions simultaneously. Moreover, comparison of the PHAM results with numerical results obtained by the shooting method coupled with a Runge-Kutta integration method illustrates the high accuracy for this technique. For the current problem, it is found that the multiple (dual) solutions exist for some values of governing parameters especially for the convergent channel cases (α = -1). The fluid in the non-parallel walls, divergent and convergent channels, is the drinking water containing different nanoparticles; Copper oxide (CuO), Copper (Cu) and Silver (Ag). The effects of nanoparticle volume fraction parameter (φ), Reynolds number (Re), magnetic parameter (Mn), and angle of the channel (α) as well as different types of nanoparticles on the flow characteristics are discussed.

Present article provides an analytical investigation of the fluid flow and heat and mass transfer for the steady laminar MHD three-dimensional nano-fluid flow over a bi-directional stretching sheet with convective surface boundary condition using Optimal Homotopy analysis method (OHAM). In contrast to the conventional no-slip condition at the surface, Navier's slip condition has been applied. This paper contains two-component four-equation nonhomogeneous equilibrium model that incorporates the effects of Brownian diffusion and thermophoresis simultaneously. The governing partial differential equations (PDEs) are transformed into a highly nonlinear coupled ordinary differential equations (ODEs) consist of the momentum, energy and concentration equations via appropriate similarity transformations. The current OHAM solution demonstrates very good correlation with those of the previously published studies in the especial cases. The influences of different flow physical parameters on all fluid velocity components, temperature distribution and concentration as well as the skin friction coefficients in x and y directions, local Nusselt number and local Sherwood number are tabulated graphically and discussed in details. This study specifies that nano particles in the base fluid offer a potential in increasing the convective heat transfer performance of various liquids. The results show that wall temperature gradient decreases with an increase in thermophoresis parameter or a decrease in Brownian motion parameter. Further, local Sherwood number is inversely proportional to the thermophoresis parameter and also directly proportional to the Brownian motion parameter.