In this study, the effect of using louvered strip inserts in heat exchangers on flow and transfer characteristics is numerically investigated. The continuity, momentum, and energy equations have been solved using a finite volume method. The wall of the tube is heated wi More
In this study, the effect of using louvered strip inserts in heat exchangers on flow and transfer characteristics is numerically investigated. The continuity, momentum, and energy equations have been solved using a finite volume method. The wall of the tube is heated with a uniform heat flux boundary condition. This paper uses a louvered strip insert arrangement (forward) with a Reynolds number of 10,000. The effects of louvered strip slant angle of and pitch of 50 mm were used for Al2O3 nanoparticles with different volume fractions in the range of 1% to 4% and different nanoparticle diameters in the range of 20 nm to 50 nm, mixed in a base fluid (water) is used. The comparison of numerical analysis results with existing equations has shown a good convergence. The numerical results reveal that the Nusselt number has increased with decreasing the nanoparticle diameter. The results indicate a slight change in the skin friction coefficient when nanoparticle diameters of Al2O3 nanofluid are varied. The Nusselt number increases with increasing nanoparticle volume fraction of Al2O3 /water nanofluid, while it is found that pure water has the lowest Nusselt number value. Also, the nanofluid has reduced the wall's temperature more than the base fluids (water), which indicates the advantage of using nanofluids in improving the system's thermal performance.
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Drilling mud is one of the most important and basic requirements for drilling oil and gas wells. Optimization of drilling fluid properties leads to reduce drilling time and costs. Water-based drilling mud is one type of drilling fluid that is mainly used in drilling wel More
Drilling mud is one of the most important and basic requirements for drilling oil and gas wells. Optimization of drilling fluid properties leads to reduce drilling time and costs. Water-based drilling mud is one type of drilling fluid that is mainly used in drilling wells due to its environmental compatibility. In this research, in order to increase the efficiency of this type of drilling fluid, graphene and silicon oxide nanoparticles in equal weight ratio in water-based drilling mud have been used. This study investigates the effect of different concentrations (0.25, 0.5, 0.75 and 1% volume fraction) of these nanoparticles on different properties of drilling fluid such as plastic viscosity, yield point, gel strength of 10 minutes and 10 seconds, circulation loss of the samples and the coefficient of thermal conductivity are discussed. All rheological properties tests are performed according to the standard (API RP 13B). The transient hot wire method has been used to determine the thermal conductivity of the fluid. The results show that the increase of nanoparticles has a significant effect on the rheological and thermo-physical properties of water-based drilling mud and reduces plastic viscosity (15%), decreases circulation loss of the samples (25%) and gel strength and also increases the thermal conductivity by 16% in the volume fraction of 1%.
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Cooling is one of the most important challenges in saving energy and increasing the productivity of many industries. The first serious obstacle in compressing and making heat transfer devices more efficient is the weak properties of heat transfer fluids. The energy effi More
Cooling is one of the most important challenges in saving energy and increasing the productivity of many industries. The first serious obstacle in compressing and making heat transfer devices more efficient is the weak properties of heat transfer fluids. The energy efficiency of heat transfer equipment depends on the heat flux changes created in them. The use of common fluids such as water and ethylene glycol as cooling fluids in the cooling system of various heat transfer devices is not the answer to the removal of very high heat flux (tens of megawatts per square meter). Today, nanofluids are made as new heat transfer fluids by adding nanoparticles to fluids that have low heat transfer and by creating changes in the density, specific heat and viscosity of these fluids in order to increase thermal conductivity and improve heat transfer performance. In this research, the results of laboratory research on heat transfer in nanofluids under laminar, turbulent flows and pool boiling are discussed and investigated.
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Energy saving is one of the challenges of today. In recent years, growing concerns about the environmental impacts of energy consumption and global warming has doubled the importance of this issue. Meanwhile energy consumption in construction sector is so high that savi More
Energy saving is one of the challenges of today. In recent years, growing concerns about the environmental impacts of energy consumption and global warming has doubled the importance of this issue. Meanwhile energy consumption in construction sector is so high that saving even as little as possible in this section will have significant effect on efficiency rate of no renewable sources. Accurate measurement of thermal conductivity has an important role in determining the calculations of cooling and heating loads of buildings according to different climates. Considering multiple relevant parameters in energy consumption with no application of simulating tools cannot permit reasonable decisions on designing building parts. In this research, the annual energy consumption of an office building located in the climate of Yazd city has been simulated and compared by Design Builder.
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