MXene/rGO grafted sponge with an integrated hydrophobic structure towards light-driven phase change composites

While phase change materials (PCMs) have great potential for use in solar energy storage, they suffer from a lack of shape stability and energy conversion ability. In this study, proper amination of melamine sponge (MS) was designed to construct an integrated MXene and reduced graphene oxide (rGO) structure. The MXene/rGO layer is sufficiently robust to endure the capillary pressure caused by solvent evaporation during the airdrying process. In addition, the reduction of GO using oleylamine (OA) contributes to the protection of MXene from oxidation by preventing the surface of MXene nanosheets from being exposed to oxygen and moisture. The as-designed MXene/rGO sponges have been shown to effectively enhance the thermophysical and photo absorption properties of paraffin wax (PW) in the composite PCM. The composite with the highest amount of MXene/rGO maintained 93.3% of the latent heat of pure PW. The photothermal storage efficiency can reach as high as 93.0% at an MXene content of around 1%. A thermal conductivity enhancement of 66.9% can be achieved compared to the pure MS/PW composite. Therefore, this study presents a new approach for designing of high-performance phase change composites for waste-heat recovery and solar thermal energy storage applications.</p

Parametric study on the thermal performance enhancement of a thermosyphon heat pipe using covalent functionalized graphene nanofluids

Heat transfer characteristics of copper sintered heat pipe explored using a modified graphene nanoplatelets (GNP)-containing nanofluid with great dispersion stability as a novel working fluid. Firstly, a water dispersible GNP with specific desire was synthesized by the reaction of GNP sheets with the diazonium salt (DS) of sodium 4-aminoazobenzene-4-sulfonate. An X-ray photoelectron spectroscopy (XPS) test shown successful covalent functionalization of GNP using DS which provided special water dispersibility characteristics. The results indicate that the thermal conductivity enhancement was up to 17% by adding modified GNP sheets in the base fluid. It also, exhibited a maximum sedimentation of 16% after 840 hrs. Further research works were carried on thermal performance of heat pipe by varying nanofluid concentrations, filling ratio, input heating powers and inclination angles of heat pipes. The results proof that the maximum enhancements of the effective thermal conductivity and reduction in thermal resistance for purposed nanofluid atφ = 5% were 105% and 26.4%, respectively. Moreover, these good features of the GNP/DS nanofluid make it a very promising working fluid to enhance the thermal performance and efficiency of the current heat pipe systems

Product Benchmarking Using DFA and DFD Tools / Amir Reza Akhiani

Tight competition between manufacturers forces them to look for new ways to increase productivity and quality and hence reduce costs. These efforts have led researchers to develop methods such as the DFX Tools: Design for Manufacturing, Design for Assembly, Design for Disassembly, Design for Environment, Design for Recyclability, etc. In this research, Design for Assembly (DFA) and Design for Disassembly (DFD) methods are used to analyze and optimize an automotive product. DFA reduces time and cost through parts reduction, which simplifies assembly and increases reliability. DFD reduces cost by hastening the recycling or dismantling processes (direct effect) and decreases environmental impact and damage to the environment (indirect effect). Most big manufacturing companies such as Sony, Hitachi, Ford, and Chrysler have their own method for implementing DFA and DFD, which are developed for a specific product. One of the oldest and general methods for DFA and DFD is the Boothroyd Method. The main goal of this research is to optimize assembly of the rear light of Proton Waja cars through supply of the assembly data to the DFA and DFD software, and to implement the software’s recommendations into improving the initial design. When compared with the old design, the new design markedly improves assembly, as shown by the DFA index and cost breakdown graph. The software considers only the cost reduction that is due to parts reduction; costs of producing new parts such as molds for the plastic parts or stamping die for the metallic parts were not considered

Highly hydrophobic silanized melamine foam for facile and uniform assembly of graphene nanoplatelet towards efficient light-to-thermal energy storage

Solar-thermal technology based on phase change materials (PCMs) has received a lot of attention as a cost-effective and practical way to overcome solar energy intermittency. However, weak photothermal conversion ability and complex preparation processes have hindered the practical application of PCMs. In this work, a new approach for facile, uniform, and firm assembly of graphene nanoplatelet (GNP) through the reaction of graphene oxide (GO) with the silanized melamine foam (MF) is introduced. Here, the deposited amino siloxane layer not only promotes the adhesion and integrity of embedded GNP/GO nanosheets but also facilitates the synthetic route compared to the previous studies. Following the reduction of GO with oleylamine (OA), the hybrid GNP/rGO foams with an integrated network were obtained. The composite PCMs were prepared through the incorporation of paraffin wax (PW) into the hybrid structure. The high hydrophobicity and porosity of the GNP/rGO foams resulted in a high loading of paraffin wax (nearly 97 wt%) and thus large transition enthalpy of 182 J g-1. The GNP/rGO framework provided excellent solar-thermal storage efficiency of up to 92.2%. The PCM composite containing the highest content of GNP (6 wt%) revealed an enhanced thermal conductivity by 87% compared to the unmodified MF/PW composite

Parametric study on the thermal performance enhancement of a thermosyphon heat pipe using covalent functionalized graphene nanofluids

Heat transfer characteristics of copper sintered heat pipe explored using a modified graphene nanoplatelets (GNP)-containing nanofluid with great dispersion stability as a novel working fluid. Firstly, a water dispersible GNP with specific desire was synthesized by the reaction of GNP sheets with the diazonium salt (DS) of sodium 4-aminoazobenzene-4-sulfonate. An X-ray photoelectron spectroscopy (XPS) test shown successful covalent functionalization of GNP using DS which provided special water dispersibility characteristics. The results indicate that the thermal conductivity enhancement was up to 17% by adding modified GNP sheets in the base fluid. It also, exhibited a maximum sedimentation of 16% after 840 hrs. Further research works were carried on thermal performance of heat pipe by varying nanofluid concentrations, filling ratio, input heating powers and inclination angles of heat pipes. The results proof that the maximum enhancements of the effective thermal conductivity and reduction in thermal resistance for purposed nanofluid atφ = 5% were 105% and 26.4%, respectively. Moreover, these good features of the GNP/DS nanofluid make it a very promising working fluid to enhance the thermal performance and efficiency of the current heat pipe systems