Two-phase Simulation of Nanofluid in a Heat Exchanger in Turbulent Flow Regime

Turbulent forced convection of different nanofluids consisting of -Al2O3/water and CuO/water in a concentric double tube heat exchanger has been investigated numerically using two-phase approach. Nanofluids that are used as coolants flowing in the inner tube while hot pure water flows in outer tube. The study was conducted for Reynolds numbers ranging from 20,000 to 50,000 and nanoparticles volume fractions of 2, 3, 4 and 6 percent. The three-dimensional governing equations are discretized using the finite volume approach. Although, two different nanoparticles have almost the same thermal conductivity but using CuO/water nanofluid showing better enhancement in heat transfer that proves thermal conductivity is not the only reason of enhancing heat transfer. Also, CuO/water showing bigger shear stress in comparison of -Al2O3/water nanofluid. As a result, nanofluids show higher overall heat transfer coefficient in comparison of pure water

Two-phase Simulation of Nanofluid in a Heat Exchanger in Turbulent Flow Regime

Turbulent forced convection of different nanofluids consisting of -Al2O3/water and CuO/water in a concentric double tube heat exchanger has been investigated numerically using two-phase approach. Nanofluids that are used as coolants flowing in the inner tube while hot pure water flows in outer tube. The study was conducted for Reynolds numbers ranging from 20,000 to 50,000 and nanoparticles volume fractions of 2, 3, 4 and 6 percent. The three-dimensional governing equations are discretized using the finite volume approach. Although, two different nanoparticles have almost the same thermal conductivity but using CuO/water nanofluid showing better enhancement in heat transfer that proves thermal conductivity is not the only reason of enhancing heat transfer. Also, CuO/water showing bigger shear stress in comparison of -Al2O3/water nanofluid. As a result, nanofluids show higher overall heat transfer coefficient in comparison of pure water

Two-phase Simulation of Nanofluid in a Heat Exchanger in Turbulent Flow Regime

Turbulent forced convection of different nanofluids consisting of -Al2O3/water and CuO/water in a concentric double tube heat exchanger has been investigated numerically using two-phase approach. Nanofluids that are used as coolants flowing in the inner tube while hot pure water flows in outer tube. The study was conducted for Reynolds numbers ranging from 20,000 to 50,000 and nanoparticles volume fractions of 2, 3, 4 and 6 percent. The three-dimensional governing equations are discretized using the finite volume approach. Although, two different nanoparticles have almost the same thermal conductivity but using CuO/water nanofluid showing better enhancement in heat transfer that proves thermal conductivity is not the only reason of enhancing heat transfer. Also, CuO/water showing bigger shear stress in comparison of -Al2O3/water nanofluid. As a result, nanofluids show higher overall heat transfer coefficient in comparison of pure water

Laminar dissipative flow in a porous channel bounded by isothermal parallel plates

The effects of viscous dissipation on thermal entrance heat transfer in a parallel plate channel filled with a saturated porous medium, is investigated analytically on the basis of a Darcy model. The case of isothermal boundary is treated. The local and the bulk temperature distribution along with the Nusselt number in the thermal entrance region were found. The fully developed Nusselt number, independent of the Brinkman number, is found to be 6. It is observed that neglecting the effects of viscous dissipation would lead to the well-known case of internal flows, with Nusselt number equal to 4.93. A finite difference numerical solution is also utilized. It is seen that the results of these two methods, analytical and numerical, are in good agreement

Multiobjective Optimization of Irreversible Thermal Engine Using Mutable Smart Bee Algorithm

A new method called mutable smart bee (MSB) algorithm proposed for cooperative optimizing of the maximum power output (MPO) and minimum entropy generation (MEG) of an Atkinson cycle as a multiobjective, multi-modal mechanical problem. This method utilizes mutable smart bee instead of classical bees. The results have been checked with some of the most common optimizing algorithms like Karaboga’s original artificial bee colony, bees algorithm (BA), improved particle swarm optimization (IPSO), Lukasik firefly algorithm (LFFA), and self-adaptive penalty function genetic algorithm (SAPF-GA). According to obtained results, it can be concluded that Mutable Smart Bee (MSB) is capable to maintain its historical memory for the location and quality of food sources and also a little chance of mutation is considered for this bee. These features were found as strong elements for mining data in constraint areas and the results will prove this claim

Comparison between the volumetric flow rate and pressure distribution for different kinds of sliding thrust bearing

In this paper a hydrodynamic journal sliding bearing, forming with two nonparallel surfaces that the lower surface moves with a unidirectional velocity and the upper surface is stationary shaped with exponential geometry is verified mathematically. The values of volumetric flow rate and distribution of pressure for incompressible lubricant flow between two supports in several conditions of velocity with different variables are determined. The results indicate that by increasing the amount of constant (m), the maximum oil pressure in the bearing will face an extreme decrease, and also by increasing the α coefficient, the rate of volumetric flow rate will decrease

CFD simulation of airflow behavior and particle transport and deposition in different breathing conditions through the realistic model of human airways

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