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The improvement of heat transfer and energy storage are crucial tasks in many renewable energy applications. The thermal and hydrodynamic performances of a nano-encapsulated phase change material (NEPCM) suspension are investigated under a mixed convective heat transfer regime inside a trapezoidal enclosure. As the host fluid and dispersed NEPCM particles circulate in the enclosure, the nanoparticle cores absorb/release heat and undergo a phase transition process, enhancing heat transfer. The governing equations were scaled into a general non-dimensional format and then solved by the finite element method. The influence of nanoparticles fusion temperature and concentration, as well as the wavy wall characteristics and Richardson number, was addressed on heat transfer. A suitable fusion temperature of the nanoparticles can boost the heat transfer rate by 8%. Furthermore, by employing 5% NEPCM particles at a dimensionless fusion temperature of 0.1, the Nusselt number achieved was 9.05. This marks a significant 37% rise when contrasted with a base fluid, which only had a Nusselt number of 5.7. [ABSTRACT FROM AUTHOR]

Novel designs have been proposed for the phase change material (PCM) heat sink of concentrated photovoltaic (CPV) cells to enhance both convective and conductive heat transfer mechanisms. Trapezoid (with two different thickness ratios) and zigzag geometry designs are suggested for the CPV-heat sink. To enhance the performance, two improving treatments have also been presented for the proposed trapezoid phase change material heat sink, (i) using a baffle and (ii) using two small triangle fins. A set of energy, exergy, economics, and environmental analyses has been established by computational fluid dynamics simulation to compare the performance of the proposed heat sinks with the conventional foamed and finned rectangular heat sinks. The results reveal that a trapezoid heat sink with two small triangle fins reduces the average concentrated photovoltaic temperature by 22 °C, the complete melting time of the phase change material by 1800s (50% reduction), and increases the absorbed heat by 3.13 kJ (7.43% increment), the exergy efficiency by 2.22% (23.9% increment), the generated electricity by 10.55%, and CO2 emission reduction by 10.75% compared to the concentrated photovoltaic with the simple rectangular heat sink. These results of the trapezoid heat sink are very similar to the rectangular heat sink with four long fins but with almost 74.3% lower levelized copper cost. [ABSTRACT FROM AUTHOR]

An automobile radiator incorporated with novel Hybrid Nano-Phase Change Material (HyN-PCM) cooler was fabricated and experimentally analyzed using novel Hybrid Nano-coolant (HyNc). Graphene nano-platelets (GnP) and multi-walled carbon nano-tubes (MWCNT) nano-particles were selected and taken in 50:50 ratio for hybrid nano-particle preparation. Non-covalent method was adopted to prepare both HyNc and HyN-PCM. Nano-coolants were prepared for dissimilar volume proportion from 0.1 to 0.5% in five stages. HyN-PCM was prepared for 1% mass fraction of nano-particles. Experiments were carried out for dissimilar coolant flow rates (CFR) varying from 20 g s−1 to 100 g s−1 in five stages and inlet temperatures of 50 °C and 70 °C. Constant air velocity of 5 m s−1 is maintained for all experiments. The experiments were conducted and compared between two methods: (i) radiator and (ii) radiator with PCM cooler. The thermal conductivity (TC) of the prepared HyNc enhances to 59%, when compared with base coolant. At 70 °C inlet temperature and 0.5% volume proportion, the highest convective heat transfer coefficient (CHTC) and overall heat transfer coefficient (OHTC) improvement was found as ~ 75% and ~ 125%. The highest effectiveness of the radiator with HyN-PCM cooler is increased up to ~ 1%, when compared with radiator without cooler. Therefore, it is recommended to install the PCM cooler for peak load conditions. Twenty-five percent pressure drop increment was observed, at low operating temperatures. Because of the enriched heat transport performance, the implementation of HyN-PCM cooler is recommended, and the prepared HyNc is to be an alternate for the prevailing coolants.Graphical abstract: An automobile radiator incorporated with novel Hybrid Nano-Phase Change Material (HyN-PCM) cooler was fabricated and experimentally analyzed using novel Hybrid Nano-coolant (HyNc). Graphene nano-platelets (GnP) and multi-walled carbon nano-tubes (MWCNT) nano-particles were selected and taken in 50:50 ratio for hybrid nano-particle preparation. Non-covalent method was adopted to prepare both HyNc and HyN-PCM. Nano-coolants were prepared for dissimilar volume proportion from 0.1 to 0.5% in five stages. HyN-PCM was prepared for 1% mass fraction of nano-particles. Experiments were carried out for dissimilar coolant flow rates (CFR) varying from 20 g s−1 to 100 g s−1 in five stages and inlet temperatures of 50 °C and 70 °C. Constant air velocity of 5 m s−1 is maintained for all experiments. The experiments were conducted and compared between two methods: (i) radiator and (ii) radiator with PCM cooler. The thermal conductivity (TC) of the prepared HyNc enhances to 59%, when compared with base coolant. At 70 °C inlet temperature and 0.5% volume proportion, the highest convective heat transfer coefficient (CHTC) and overall heat transfer coefficient (OHTC) improvement was found as ~ 75% and ~ 125%. The highest effectiveness of the radiator with HyN-PCM cooler is increased up to ~ 1%, when compared with radiator without cooler. Therefore, it is recommended to install the PCM cooler for peak load conditions. Twenty-five percent pressure drop increment was observed, at low operating temperatures. Because of the enriched heat transport performance, the implementation of HyN-PCM cooler is recommended, and the prepared HyNc is to be an alternate for the prevailing coolants. [ABSTRACT FROM AUTHOR]