Investigate the Impact of Dimple Size and Distribution on the Hydrothermal Performance of Dimpled Heat Exchanger Tubes

In this study,the primary objective was to enhance the hydrothermal performance of a dimpled tube by addressing areas with low heat transfer compared to other regions.To accomplish this,a comprehensive numerical investigation was conducted using ANSYS Fluent 2022 R1 software,focusing on different diameters of dimples along the pipe’s length and the distribution of dimples in both in-line and staggered arrangements.The simulations utilized the finite elementmethod to address turbulent flowwithin the tube by solving partial differential equations,encompassing Re numbers spanning from 3000 to 8000.The study specifically examined single-phase flow conditions,with water utilized as the cooling fluid.The results of the investigation indicated that increasing the Reynolds number resulted in higher average Nusselt numbers,pressure drops,the overall performance criterion,and a reduction in average thermal resistance across all models analyzed.Notably,both proposedmodels demonstrated improved heat transfer when compared to the conventional model.Out of all the models evaluated,the tube featuring staggered dimples(Model B)demonstrated the most notable improvement in the Nu number.It exhibited an enhancement of approximately twice the value compared to the conventional model.The mean thermal resistance for the tube with dimples in the staggered arrangement(Model B)is 0.0057 k/W,compared to 0.0118 k/W for the traditional model.The maximum overall performance criterion for Model-A-and Model-Bis 1.22 and 1.33,respectively.

Investigation the Influence of Phase Change Material Amount on a Hot-Water Stratification in Charging ode

Among the various techniques for enhancing the storage and consumption of energy in a thermal energy storage system,the establishment of thermal stratification in a hot-water container is an effective technology.The current study aims to assess the performance of the thermal stratification for hot-water containers using(ANSYS Fluent)R.1.0,2022,through the study of the impact of different numbers of paraffin-filled containers,namely 3,5,and 7,that are equivalent to 5,7,and 9 kg of paraffin,respectively.To validate the present numerical model,a comparison between the current study results and the experimental findings from the literature was conducted,and the results demonstrated that there was a good approval between these results.The results of this study depict that the profile temperature at the outlet of the container indicates an enhancement in the Richardson number and stratification number by 37.9%and 45.8%,respectively,when the charging process is finished.Furthermore,increasing the number of paraffin-filled containers from 5 to 9 results in a 29.9%improvement in charging efficiency,resulting in an improvement in storage efficiency.Finally,the results have proven that the 3D CFD approach is a highly beneficial tool to assess the effect of PCM mass on stratification performance in a hot-water container.