Accelerated thermal cycling test of microencapsulated paraffin wax/polyaniline made by simple preparation method for solar thermal energy storage

Microencapsulated paraffin wax/polyaniline was prepared using a simple in situ polymerization technique, and its performance characteristics were investigated. Weight losses of samples were determined by Thermal Gravimetry Analysis (TGA). The microencapsulated samples with 23% and 49% paraffin showed less decomposition after 330 °C than with higher percentage of paraffin. These samples were then subjected to a thermal cycling test. Thermal properties of microencapsulated paraffin wax were evaluated by Differential Scanning Calorimeter (DSC). Structure stability and compatibility of core and coating materials were also tested by Fourier transform infrared spectrophotometer (FTIR), and the surface morphology of the samples are shown by Field Emission Scanning Electron Microscopy (FESEM). It has been found that the microencapsulated paraffin waxes show little change in the latent heat of fusion and melting temperature after one thousand thermal recycles. Besides, the chemical characteristics and structural profile remained constant after one thousand thermal cycling tests. Therefore, microencapsulated paraffin wax/polyaniline is a stable material that can be used for thermal energy storage systems.Mahyar Silakhori, Mohammad Sajad Naghavi, Hendrik Simon Cornelis Metselaar, Teuku Meurah Indra Mahlia, Hadi Fauzi, and Mohammad Mehral

The attentive focus on T cell-mediated autoimmune pathogenesis of psoriasis, lichen planus and vitiligo

T cell-mediated autoimmune skin diseases develop as a result of the aberrant immune response to the skin cells with T cells playing a central role. These chronic inflammatory skin diseases encompass various types including psoriasis, lichen planus and vitiligo. These diseases show similarities in their immune-pathophysiology. In the last decade, immunomodulating agents have been very successful in the management of these diseases thanks to a better understanding of the pathophysiology. In this review, we will discuss the immunopathogenic mechanisms and highlight the role of T lymphocytes in psoriasis, lichen planus and vitiligo. This study could provide new insights into a better understanding of targeted therapeutic pathways and biological therapies. © 2020 The Scandinavian Foundation for Immunolog

Facile preparation of carbon microcapsules containing phase-change material with enhanced thermal properties.

This study describes the hydrothermal synthesis of a novel carbon/palmitic acid (PA) microencapsulated phase change material (MEPCM). The field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) images confirm that spherical capsules of uniform size were formed with a mean diameter of 6.42 μm. The melting and freezing temperature were found to be slightly lower than those of pure PA with little undercooling. The composite retained 75% of the latent heat of pure PA. Thermal stability of the MEPCM was found to be better than that of pure PA. The thermal conductivity of MEPCM was increased by as much as 41% at 30°C. Due to its good thermal properties and chemical and mechanical stability, the carbon/PA MEPCM displays a good potential for thermal energy storage systems

Preparation of nitrogen-doped graphene/palmitic acid shape stabilized composite phase change material with remarkable thermal properties for thermal energy storage

Palmitic acid (PA) is one of the main phase change materials (PCMs) for medium temperature thermal energy storage systems. In order to stabilize the shape and enhance the thermal conductivity of PA, the effects of adding nitrogen-doped graphene (NDG) as a carbon nanofiller were examined experimentally. NDG was dispersed in liquid PA at various mass fractions (1-5 wt%) using high power ultrasonication. The dropping point test shows that there was clearly no liquid leakage through the phase change process at the operating temperature range of the composite PCMs. The thermal stability and thermal properties of composite PCM were investigated with a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), respectively. The thermal conductivity of the PA/NDG composite was determined by the laser flash method. The thermal conductivity at 35 degrees C increased by more than 500% for the highest loading of NDG (5 wt%). The electrical conductivity of composite PCMs was increased significantly by using NDG. The thermal cycling test proved that the PA/NDG composites PCMs had good thermal reliability and chemical durability after 1000 cycles of melting and freezing. The thermal effusivity of the PA/NDG composite PCMs was larger than that of pure PA, which is advantageous for latent heat thermal energy storage (LHTES). (C) 2014 Elsevier Ltd. All rights reserved

Dynamic response of ladder track rested on stochastic foundation under oscillating moving load

The ladder track is a new type of an elastically supported vibration-reduction track system that has been applied to several urban railways. This paper is devoted to the investigation of dynamic behavior of a ladder track under an oscillating moving load. The track is represented by an infinite Timoshenko beam supported by a random elastic foundation. In this regard, equations of motion for the ladder track are developed in a moving frame of reference. In continuation, by employing perturbation theory and contour integration, the response of the ladder track is obtained analytically and its results are verified using the stochastic finite element method. Finally, using the verified model, a series of sensitivity analyses are accomplished on effecting parameters including velocity and load frequency

Accelerated Thermal Cycling Test of Microencapsulated Paraffin Wax/Polyaniline Made by Simple Preparation Method for Solar Thermal Energy Storage.

Microencapsulated paraffin wax/polyaniline was prepared using a simple in situ polymerization technique, and its performance characteristics were investigated. Weight losses of samples were determined by Thermal Gravimetry Analysis (TGA). The microencapsulated samples with 23% and 49% paraffin showed less decomposition after 330 °C than with higher percentage of paraffin. These samples were then subjected to a thermal cycling test. Thermal properties of microencapsulated paraffin wax were evaluated by Differential Scanning Calorimeter (DSC). Structure stability and compatibility of core and coating materials were also tested by Fourier transform infrared spectrophotometer (FTIR), and the surface morphology of the samples are shown by Field Emission Scanning Electron Microscopy (FESEM). It has been found that the microencapsulated paraffin waxes show little change in the latent heat of fusion and melting temperature after one thousand thermal recycles. Besides, the chemical characteristics and structural profile remained constant after one thousand thermal cycling tests. Therefore, microencapsulated paraffin wax/polyaniline is a stable material that can be used for thermal energy storage systems

Full-spectrum volumetric solar thermal conversion via graphene/silver hybrid plasmonic nanofluids

The wide-spread adoption of solar thermal absorbers is currently hampered by their low absorption efficiencies and their high capital cost. As a result, a number of initiatives, including direct absorption solar collectors (DASC), are currently underway to improve the absorber efficiencies. In this regard, this study focused on application of hybrid nanofluids containing reduced graphene oxides decorated with silver nanoparticles in volumetric solar absorbers. Their superior solar absorptance and thermal conductivity is based on the plasmonic effect of the nanoparticles and high thermal conductivity of graphene nanosheets, respectively. Several parameters such as mass concentration of graphene nanosheets and Ag decoration contents were studied that could affect the thermal and optical properties of the nanofluids. The results indicated that the prepared nanofluids can be employed for direct absorption solar collectors over a short period of solar irradiation time, even at a low illumination intensity of one sun. A collector efficiency of 77% is achievable at low concentration of 40 ppm owing to the enhanced light absorption of graphene at the excitation wavelength. These findings therefore suggest that this solution can contribute to the final goal of utilizing nanofluids for efficient solar thermal energy harvesting.Energy TechnologyMicro and Nano Engineerin

Theoretical model of an evacuated tube heat pipe solar collector integrated with phase change material

Abstract not availableM.S. Naghavi, K.S. Ong, I.A. Badruddin, M. Mehrali, M. Silakhori, H.S.C. Metselaa