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Summary: The usage of phase change materials (PCMs) in thermal energy storage (TES) systems has been a promising approach in recent years. An accurate estimation of their thermophysical properties is a key factor in their optimal and efficient performance in TES systems. In this study, aluminum oxide (Al2O3) and copper (Cu) nanoparticles were incorporated in paraffin wax as a PCM to enhance its thermophysical properties. The effects of the nanoparticle type, mass fraction, and its size on the specific heat, density, thermal conductivity, and TES density of the nanocomposites, were investigated. A field emission scanning electron microscope (FESEM) was used to study their morphology. The experiments were based on three factors, nanoparticle type (Al2O3 and Cu), nanoparticle mass fraction (1%, 3%, and 6%), and nanoparticle size (30, 70, and 110 nm), while pure paraffin wax was applied as the control sample. The addition of nanoparticles to paraffin has been proven to be a promising technique. The results showed that the specific heat changes of the NePCMs have not been influenced by the factors under consideration. Also, higher mass fractions and smaller sizes of nanoparticles resulted in higher densities in NePCMs. Moreover, the thermal energy storage density of NePCMs increased at higher loading and smaller size of the nanoparticles. The improvement in thermal conductivity is especially significant if the smallest nanoparticle size with mass fractions of 3% and 6% is used. An improvement in thermal conductivity of up to 72% has been achieved at a mass fraction of 6% of 30 nm copper nanoparticles. Finally, the NePCM containing 6% mass fraction and 30 nm size of the nanoparticle (A6S and C6S) were selected as optimal NePCMs. [ABSTRACT FROM AUTHOR]

Summary: People in the Middle East are facing the problem of freshwater shortages. This problem is more intense for a remote region, which has no access to the power grid. The use of seawater desalination technology integrated with the generated energy unit by renewable energy sources could help overcome this problem. In this study, we refer a seawater reverse osmosis desalination (SWROD) plant with a capacity of 1.5 m3/h used on Larak Island, Iran. Moreover, for producing fresh water and meet the load demand of the SWROD plant, three different stand‐alone hybrid renewable energy systems (SAHRES), namely wind turbine (WT)/photovoltaic (PV)/battery bank storage (BBS), PV/BBS, and WT/BBS are modeled and investigated. The optimization problem was coded in MATLAB software. Furthermore, the optimized results were obtained by the division algorithm (DA). The DA has been developed to solve the sizing problem of three SAHRES configurations by considering the object function's constraints. These results show that this improved algorithm has been simpler, more precise, faster, and more flexible than a genetic algorithm (GA) in solving problems. Moreover, the minimum total life cycle cost (TLCC = 243 763$), with minimum loss of power supply probability (LPSP = 0%) and maximum reliability, was related to the WT/PV/BBS configuration. WT/PV/BBS is also the best configuration to use less battery as a backup unit (69 units). The batteries in this configuration have a longer life cycle (maximum average of annual battery charge level) than two other configurations (93.86%). Moreover, the optimized results have shown that utilizing the configuration of WT/PV/BBS could lead to attaining a cost‐effective and green (without environmental pollution) SAHRES, with high reliability for remote areas, with appropriate potential of wind and solar irradiance. [ABSTRACT FROM AUTHOR]