Mixed convection heat transfer of Cu-water nanofluid in an arc cavity with non-uniform heating has been numerically studied. The top flat moving wall is isothermally cooled at Tc and moved with a constant velocity. While the heated arc stationary wall of the cavity is maintained at a hot temperature Th. FORTRAN code is used to solve the mass, momentum, and energy equations in dimensionless form with suitable boundary conditions. In this study, the Reynolds number changed from 1 to 2000, and the Rayleigh number changed from 0 to 10
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. Also, the range of nanoparticles volume fraction extends from ϕ = 0 to 0.07. Stream vorticity method selected for the discretization of flow and energy equations. The present results are compared with the previous results for the validation part, where the results found a good agreement with the others works. The isotherms are regulated near the arc-shape wall causing a steep temperature gradient at these regions and the local and average heat transfer rate increases with increased volume fraction or Reynolds number or Rayleigh number. Finally, Correlation equations of the average Nusselt number from numerical results are presented.
Numerical study of mixed convection heat transfer in multi-Lid driven concentric trapezoidal annulus filled with H2O-Cu-Al2O3 hybrid nanofluid has been investigated. Three cases for multi-Lid driven have been studied: single lid-driven, double lid-driven move in the same direction, double lid-driven move in the opposite direction. The lid-driven walls move with a constant speed with constant cold temperature TC and the other inclined walls are insulated while the inner trapezoidal cylinder heated at constant temperature Th. Finite volume method used to solve the continuity, momentum, and energy equations by SIMPLE algorithm. The results validated by comparing with previous study with a good agreement of accuracy. The working fluids was: water with hybrid nanoparticles (volume fraction ϕ = 0 to 10%). The Richardson numbers changed from 0.01 to 10, to cover all convection heat transfer modes, and aspect ratios were 0.5 and 1. The results show that, the opposing flow produced highest maximum stream function. Moreover, in aiding flow (case 2) produced a heat transfer coefficient on the top and bottom walls of outer cylinder higher than that produced by the opposing flow (case 3). Generally, the skin friction increases with increase in the volume fraction of nanoparticles due to increasing the viscosity of fluid causes increase in shear stress and leads to increasing the pressure drop. Additionally, the aiding flow produced fiction factor higher than the opposing flow.
One of the appealing technologies that contributes to raising the energy storage density is latent heat thermal energy storage. The heat of fusion is isothermally stored at a temperature representing the temperature at which a phase-change material transitions between phases. The current research provides a review of how phase transition materials are used in melting and solidification. Generally, the range of working temperature extends from -20 °C to 200 °C for solidification and melting applications. The first range (-20 to 5 °C) is employed for commercial and domestic refrigeration. The second range (5 to 40 °C) is utilized to lower the energy requirements for air-conditioning applications. The applications includes in third range (40 to 82 °C) are solar collector and heating of water. Applications of absorption cooling, waste electricity generations, and heat recovery are operated at high temperature range (82 to180 °C). There are various types of PCMs for all the above temperature ranges. The present review paper will discuss the application field, Geometry, PCM type, heat transfer augmentation technique and their effects on the performance. The conclusions are mentioned to give more insight about the PCM behavior in various applications.
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