The present research aims to study the charge and discharge processes within a triplex-tube system. In this system, the water flows inside the outer and inner pipes and the annulus region is filled with RT82 as the phase change material (PCM). The aim of this investigation is to evaluate the effects of adding Al2O3 nanoparticles with concentration of 0 and 0.05 as well as influence of geometry, fin installation, and other influential factors on these processes. The simulations were performed using ANSYS Fluent 18.1 and verification with previous articles guaranteed the correctness of modeling. The flow was considered laminar and the Boussinesq approximation has been employed to the problem. Moreover, the stored energy was evaluated. The results suggest that the usage of nanoparticles leads to significant conduction enhancements and can reduce the solidification and melting time in system about 12 and 6.4%, respectively. Also, the fin installation results in decrement of solidification and melting time by 5 and 37.8%, respectively.

In present article, benefits of fins and dispersing nanomaterial were employed to achieve quickest solidification. Heat release process has been examined in various cases and RT35 has been utilized as PCM. With employ of gravity term, three main cases were scrutinized. The first case has no fins while two other cases have fins with different arrangement. Two finned tank have same volume of PCM and buoyancy force is the only factor which leads to different the performance of these cases. Copper oxide has been added in to paraffin to enhance the discharging rate because of greater conduction mode. Single phase mode for estimating nanomaterial effect helps to decline the computational price. Due to low concentration of CuO, the slip velocity between particles and PCM has been ignored. Verification with previous articlemade us confidence about the accuracy of modeling. With inclusion of nanomaterial in second case, the needed time changes from 19.16 min to 5.83 min. Also, augmenting phi from 0 to 0.05 for third case leads to change in discharging time from 19.45 min to 16.65 min. The solidification time for 2nd and 3rd cases with NEPCM reduces about 70.06% and 69.2% in comparison to first case, respectively. With augment of Ste. from 0.15 to 0.27 and 0.21 for second case with pure RT35, the time need for full discharging reduces about 44.4% and 28.9%, respectively. With progress of time, the mass of liquid phase reduces and subsequently lower amount of heat release will be achieved. Inclusion of nanomaterial results in lower amount of energy. Also, the second case has greater amount of energy than third case. (C) 2020 Elsevier B.V. All rights reserved.

In this attempt, the heat stored and released units with combination of copper oxide (CuO) nanoparticles and triangular fin on the process of charging and discharging in the triplex pipe has been scrutinized. The middle tube is full of RT35 and CuO was dispersed to enhance its conductivity. Water flows via the outer and inner tube. Impacts of combining nanoparticles and fin on the period of various times of the Phase Change Material (PCM) solidification and melting process were scrutinized. The outputs depicts that the existence of nanoparticles reduces the discharging process as well as melting phenomena. The results indicate that impose of triangular fins can enhance solidification rate about 40.75% and with inclusion of nanoparticles, solidification time declines about 44.88%. Temperature of PCM at end of discharging declines about 13.34% when phi = 0.02. As fraction of nanofluid augments, melting time declines from 5.616 min to 5.4 min. Temperature of PCM augments about 5.81% as time increases from 1 to 5 min for melting case. Stored energy is an increasing function of time during melting while augments of phi leads to reduction of this factor.

Current article presents a study on the solidification within triplex tube storage unit for analyzing the thermal treatments of PCM. H2O flows within the outer and inner pipes, in the meanwhile the middle pipe is filled with RT82 paraffin as PCM. The chief goal of this research is to investigate the effects of making the inner, outer or both of these pipes in heat exchanger wavy, and also investigate the enhancements which can be obtained by dispersing nanomaterial into the PCM. The stored energy amount and Tave of PCM during the freezing process in the TTHX containing pure PCM and NEPCM were compared. The results suggest that with the dispersion of nanomaterial, the heat transfer rate augments and the nanoparticles reduce the freezing time and making the pipes wavy can reduce the freezing time.

Nowadays, the rise in the human population and consequently increasing demand for energy in different fields, have caused serious trouble for societies. Increasing energy demand necessitates the need to produce more energy, thus, the consumption of fossil fuels that are a form of non-renewable energy will be increased. Phase change materials as environments for storing heat have wide applications in storing solar energy. This energy source is clean, inexhaustible, and accessible. Its usage by humans varies based on circumstances such as geographical conditions, terrain, time variations, and cloud cover. Current article reports a comprehensive overview of TES technologies using PCM throughout discharging and charging. The purpose of current research is to scrutinize the used techniques for augmenting performance of TES for non-power plants and PCM applications. In addition, heat transfer enhancement using extended surfaces, encapsulation, different ways of augmenting the thermal features, and applying of multiple PCMs were scrutinized. Furthermore, a brief discussion on the recent articles on various fluids and nanoparticles has been presented. The results show that the paraffin was the most used PCM in the studies, and the most common unit was shell and tube heat exchanger. Results also indicate that addition of longitudinal fin is the most popular technique in TES units.

In current modeling, solidification process within a three-dimensional triplex tube was numerically studied. In two sides, the cold water flow is used while the middle tube contains RT82. The purpose of the current article is investigating the impacts of using nanoparticles, fin, and the combination of both of them on thermal characteristics during solidification in an energy storage unit. Also, the amount of stored energy has been investigated over time, and the influences of temperature and water velocity were scrutinized. The results revealed some substantial improvements in the solidification rate by adding fins or nanoparticles. It was indicated that using a combination of these two heat transfer enhancement methods presents a better enhancement compared to when either of these two methods is employed alone.

Nanoparticle-enhanced phase change materials have engrossed augmenting consideration to remove the main limitation of PCMs in various industrial uses. Current article reports the use of PCMs as well as utilize of nanoparticles to intensify energy performance and effective thermal management. Overviews of recent work and developments in the use of NEPCMs have been presented. Nanoparticles are employed to expedite unsteady processes and improve performance. Usually, the amount of nanoparticles is <5% by weight. In this case, the impact of adding nanoparticles on PCMs was investigated. Outputs revel that dispersing nanoparticles to PCMs have greater charging and discharging rates than pure PCM. Besides, this way is more effective in improving the management of energy because of augmenting conduction mode and reduction of fusion heat.