CFD analysis of Al_(2)O_(3)-syltherm oil nanofluid on parabolic trough solar

In this paper,in order to improve the performance of a linear parabolic collector,the thermal effects of using Al_(2)O_(3)-syltherm oil nanofluid with different concentrations and new flange-shaped turbulators are investigated.The simulation was performed by ANSYS-FLUENT-18.2 commercial software using Realizable k-εtwo-equation turbulence model.In accordance with the results,it was realized that increasing the volume fraction of nanoparticles(to 5%)and number of turbulators causes the heat transfer coefficient(h)of the fluid to elevate and ultimately the uniform temperature is created in the absorber.For instance,at a flow rate of 4.5kg/s and an inlet temperature of 350 K,the value of h increases by about 8.5%by changing the number of turbulators from 10 to 15 sets.On the other hand,the results indicate that by changing the arrangement of the turbulators,the heat transfer efficiency of the collector can be increased by 5%for 350 K,3.5%for 450 K and 1%for 550 K inlet temperature.

Computer simulation of Cu:AlOOH/water in a microchannel heat sink using a porous media technique and solved by numerical analysis AGM and FEM

Extensive improvements in small-scale thermal systems in electronic circuits,automotive industries,and microcomputers conduct the study of microsystems as essential.Flow and thermic field characteristics of the coherent nanofluid-guided microchannel heat sink are described in this perusal.The porous media approximate was used to search the heat distribution in the expanded sheet and Cu:γ-AlOOH/water.A hybrid blend of Boehme copper and aluminum nanoparticles is evaluated to have a cooling effect on the microchannel heat sink.By using Akbari Ganji and finite element methods,linear and non-linear differential equations as well as simple dimensionless equations have been analyzed.The purpose of this study is to investigate the fluid and thermal parameters of copper hybrid solution added to water,such as Nusselt number and Darcy number so that we can reach the best cooling of the fluid.Also,by installing a piece of fin on the wall of the heat sink,the coefficient of conductive heat transfer and displacement heat transfer with the surrounding air fluid increases,and the efficiency of the system increases.The overall results show that expanding values on the NP(series heat transfer fluid system maximizes performance with temperatures)volume division of copper,as well as boehmite alumina particles,lead to a decrease within the stream velocity of the Cu:AlOOH/water.Increasing the volume fraction of nanoparticles in the hybrid mixture decreases the temperature of the solid surface and the hybrid nanofluid.The Brownian movement improves as the volume percentage of nanoparticles in the hybrid mixture grows,spreading the heat across the environment.As a result,heat transmission rates rise.As the Darcy number increases,the thermal field for solid sections and Cu:AlOOH/water improves.

Improving energy storage by PCM using hybrid nanofluid[(SWCNTs-CuO)/H_(2)O]and a helical(spiral)coil:Hybrid passive techniques

The aim of this study is the numerical analysis of the melting process of the phase change material(PCM)in a spiral coil.The space between the inner tube and outer shell is filled with RT-50 as PCM.Moreover,the hybrid nanofluid(with a carbon component)flows through the inner tube.The novelty of this work is to use different configurations of fin and different percentage of hybrid nanoparticles(SWCNTs-Cu O)on the PCM melting process.In the numerical model created by ANSYS-Fluent,the effect of various inlet temperatures is investigated.The results indicate that the extended surface created by extra fin has a dominant effect on melting time,so by adding the third fin,the melting time is reduced by 39.24%.The next most influential factor in PCM melting is the inlet temperature of the working fluid,so that 10°C increment of temperature result in the PCM melting time decreased by 35.41%.

Design and implementation of a new portable hybrid solar atmospheric water-generation system

During recent years,atmospheric water generation(AWG)has garnered significant attention among researchers as a viable solution to the water-scarcity problem.Generally,AWG requires dehumidification,which includes two main principles of refrigeration and sorption.Among refrigeration methods,thermoelectric coolers are suitable and,among sorption methods,it is best to utilize desiccant materials with high sorption capacity and low heat generation.In the present study,a portable hybrid/integrated solar AWG system was designed and tested under realistic conditions of Babol,Iran(36.5387°N,52.6765°E)over four typical summer days between 14 and 31 August 2021.Two models(Models A and B)were designed and evaluated.Temperature,relative humidity,solar irradiance and water-production data were recorded to assess the system performance(i.e.the ratio between the generated water and consumed power in ml/W.hour)and economically analyse the system.Based on the results acquired,the maximum water production in the proposed configuration(acquired from Model B)was 2.12 l/m^(2).day at an average relative humidity and a temperature of 52%and 36°C,respectively.The desired AWG system had a system performance of 0.19 ml/W.hour,annual water production of 774.4 l/m^(2),production cost of 0.0246$/l/m^(2)and a payback period of 1.19 years.

Analytical investigation of laminar flow through expanding or contracting gaps with porous walls

Laminar,isothermal,incompressible and viscous flow in a rectangular domain bounded by two moving porous walls,w hich enable the fuid to enter or exit during successive expansions or contractions is investigated analytically using optimal homotopy asymptotic method(OHAM).OHAM is a powerful method for solving nonlinear problems without depending to the small parameter.The concept of this method is briefly introduced,and it's application for this problem is studied.Then,the results are compared with numerical results and the validity of these methods is shown.After this verification,we analyze the effects of some physical applicable parameters to show the efficiency of OHAM for this type of problems.Graphical results are presented to investigate the influence of the non-dimensional wall dilation rate(a)and pemeation Reynolds number(Re)on the velocity,normal pressure distribution and wall shear stress.The present problem for slowly expanding or contracting walls with weak permeability is a simple model for the transport of biological fuids through contracting or expanding vessels.