In this work, the melting process of phase change material (PCM) in double tube heat exchangers was investigated and evaluated through the use of different combinations (1, 2, 3% Nano-Enhanced PCM and 1, 3, 5% Nano-HTF) of GQD, as well as SWCNT nanoparticles and PCM (RT82). In this study, the effect of three different methods, namely the dispersion of nanoparticles in PCM (nano-enhanced PCM), the dispersion of nanoparticles in HTF (nano-HTF), and the simultaneous dispersion of nanoparticles in PCM and HTF (nano-enhanced PCM, nano-HTF) concerning the nanoparticles participation in the thermal energy storage system in a double tube heat exchanger was evaluated. Other effective factors, such as the inlet fluid temperature, different Reynolds numbers, fin as well as new parameter of pipe, and fin thickness were also evaluated. The results showed that the highest effect of different parameters on the PCM melting process was related to the 1% nano-HTF and 3% nano-enhanced PCM nanoparticles of SWCNT, which decreased the PCM melting rate by about 39%. The evaluation of the effect of pipe and fan thickness also showed that the melting rate improved by 31% through reducing the thickness of the HTF fin and pipe. In general, the current study followed two purposes first, to examine three methods of the dispersion of nanoparticles in the thermal energy storage system; second, to reduce the thickness of the tube and fin. Findings of the study yielded positive results.

In this paper we consider the Horava–Lifshitz background and obtain the massless fermion quasinormal modes. In that case we use the Newman–Penrose formalism and the massless Dirac equation to calculate the radial and angular parts of equations. The wave function and corresponding modes can be obtained using the factorization method.

The integration of photovoltaic/thermal (PV/T) systems with nanofluids presents a promising avenue for enhancing sustainable energy solution. This study investigates the performance of such systems through experimental analysis and computational fluid dynamics (CFD) simulations. Nanofluids, engineered colloidal suspensions of nanoparticles in base fluids, are employed to enhance heat transfer within the PV/T system. The experimental setup involves measuring electrical output, thermal efficiency, and overall system performance under varying conditions. Additionally, CFD simulations are conducted to model fluid flow and heat transfer dynamics within the PV/T collector integrated with nanofluids. The results from both experimental and simulation studies provide insights into the synergitic effects of nanofluids on enhancing energy conversion efficiency and thermal management of the PV/T system. The research contributes to the development of sustainable energy solutions by demonstrating the potential of nanofluid-enhanced PV/T systems in improving energy conversion efficiency and thermal management for various environmental conditions.

The use of solar dish concentrators for harnessing solar energy is an established technology in the Realm of renewable energy solutions. This study presents a comprehensive Computational Fluid Dynamics (CFD) simulation to analyze the performance of a solar dish concentrator equipped with different cavity receivers. The aim is to optimize the thermal efficiency and energy absorption capabilities of the system. Various geometries of cavity receivers, including cylindrical, cubical, and hemispherical shapes, are evaluated under identical operational conditions. The simulations consider factors such as incident solar radiation, heat losses, temperature distribution, and fluid flow dynamics within the cavity. Results indicate significant variations in thermal performance based on the cavity design, with certain geometries exhibiting superior heat retention and minimal thermal losses. This research provides critical insights into the design and optimization of cavity receivers, contributing to the advancement of high-efficiency solar dish concentrator systems. The findings are expected to aid in the development of more efficient solar energy harvesting technologies, promoting sustainable energy solutions.