Using silicagel industrial wastes to synthesize polyethylene glycol/silica-hydroxyl form-stable phase change materials for thermal energy storage applications

Polyethylene glycol form-stable phase change materials (PEG FSPCMs) have received much attention in recent years for thermal energy storage applications due to their remarkable thermal properties. However, the conventional synthesis of PEG FSPCMs usually employed chemical grade regents as starting materials, which is unlikely suitable for large-scale industrial preparation of PCMs. In the present work, silicagel industrial wastes were employed as starting materials for the first time to synthesize a polyethylene glycol/silica-hydroxyl compound (PEG/SHC) form-stable phase change material using a facile sol-gel method. The morphology and chemical compatibility were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The thermal energy storage performance was evaluated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermal constants analysis, respectively. The results indicated that the PEG was encapsulated in the SHC matrix through a physical interaction, and the weight fraction of PEG in the FSPCM could be as high as 80% with no significant leaking liquid observed. The thermal energy storage capacity in this FSPCM was found to be (59.38-132.4) J/g and (63.56-133.4) J/g in the melting and crystallization process, respectively, as the loaded PEG weight fraction ranging from 50% to 80%. The thermal conductivity of the FSPCM enhanced by the SHC matrix was determined to be as high as 30% compared with that of the pure PEG. Additionally, the FSPCM synthesized in this method could maintain a stable thermal property during the heating/cooling cycles. On the basis of these results, it was demonstrated that the sol-gel method developed in this work could not only obtain PEG based FSPCMs with good performance for thermal energy storage, but also propose an effective way of producing economic benefits by reusing silicagel industrial wastes

Intestinal disease of scattered mirror carp Cyprinus carpio caused by Thelohanellus kitauei and notes on the morphology and phylogeny of the myxosporean from Sichuan Province, southwest China

The mass mortality of pond-reared scattered mirror carp, Cyprinus carpio, caused by Thelohanellus kitauei, occurred at fish farms in Sichuan Province, southwest China. Morphological and molecular analyses were supplemented with histological evaluation of infected tissues to better understand the route of infection and the pathological effects of T. kitauei on the fish host. The intestine of the diseased host was full of large cysts of the myxosporean. The cysts range from 2 cm to 3.6 cm in diameter. Histopathology indicated that T. kitauei first invaded the submucosa of the host intestine and then moved into the mucosa layers with the development of their spores, finally entering into the enteric cavity of the hosts after the disruption of mucosa layers. The pyriform spores of T. kitauei were surrounded by the transparent spore sheath, measuring 25.98 mu m +/- 0.95 mu m in body length, 8.72 mu m +/- 0.51 mu m in body width, and 7.86 mu m +/- 0.26 mu m in body thickness. The single polar capsule was pyriform, measuring 14.73 mu m +/- 0.92 mu m in length and 6.82 mu m +/- 0.45 mu m in width, with eight to 10 turns of filament coils winding inside. Phylogenetic analysis based on the 18S small-subunit ribosomal DNA sequences indicated that minimal genetic differences were present between T. kitauei samples from South Korea and from China. Close affinity was found between the genus Thelohanellus and Myxobolus. Additionally, two polar capsule nuclei were found at the anterior end of the single polar capsule in spores of T. kitauei stained with hematoxylin and eosin, which suggested the separation of the genus Thelohanellus from Myxobolus.</p

Thermal analysis and heat capacity study of polyethylene glycol (PEG) phase change materials for thermal energy storage applications

Phase change materials (PCMs) generally offer high latent heats for a wide range of thermal energy storage technologies. As typical organic PCMs, polyethylene glycol (PEG) has been widely studied due to their high latent enthalpy, non-toxic and non-corrosive natures. However, the thermal properties especially the heat capacities of PEG, which would play a vital role in theoretically and technically investigating PCM thermal performance, have never been studied in a wide temperature region. Herein, we reported the heat capacities of PEG samples with the molar massvarying from 1000 to 20,000 for the first time in the temperature range from (1.9 to 400) K using a combination method of Physical Property Measurement System (PPMS) and differential scanning calorimeter (DSC). Furthermore, the standard molar heat capacity, entropy and enthalpy at 298.15 K and 0.1 MPa were calculated based on the heat capacity curve fitting. Meanwhile, the phase transition temperature and enthalpy, thermal conductivity and thermal stability of these PEG samples were measured using various thermal analysis methods, and these thermal properties were also compared with the previous results. (C) 2018 Published by Elsevier Ltd

Flexible and Biocompatible Silk Fiber-Based Composite Phase Change Material for Personal Thermal Management

Phase change materials (PCMs) are regarded as an effective passive personal thermal management strategy. However, the preparation of flexible and biocompatible PCMs remains a great challenge. In this study, a silk fiber (SF)-based composite PCM for wearable personal thermal management was prepared using renewable natural silkworm cocoons and biocompatible capric acid (CA). The SF/CA composite PCM is flexible, biocompatible, and dyeable. The results show that the SF and CA are physically bonded, and the crystal structure of CA is not influenced by SF. The melting phase change enthalpy and temperature of the SF/CA composite PCM are 123.4 J/g and 30.6 °C, respectively. It has excellent shape stability, thermal stability, and cycling stability. Particularly, the SF/CA composite PCM has excellent performance for wearable personal thermal management under three scenarios including variable temperature mode, isothermal mode, and light irradiation mode. It can also reduce the temperature fluctuation of the human body in a hot or cold environment. Therefore, the SF/CA composite PCM has bright application prospects for wearable personal thermal management in hot and cold environments

Heat capacities of some sugar alcohols as phase change materials for thermal energy storage applications

In recent years, sugar alcohols have attracted much attention due to their remarkable phase change properties for thermal energy storage applications. The thermodynamic properties especially the heat capacities would play a crucial role in theoretically and technically investigating the energy storage performance for sugar alcohols. However, as far as we known, the heat capacities of sugar alcohols have never been studied in a wide temperature region. In this study, we have measured the heat capacities of six sugar alcohols of D-mannitol, Myo-Inositol, xylitol, D-arabinitol, L-arabinitol and erythritol in the temperature range from T = (1.9 to 550) K for the first time using a combination of Physical Property Measurement System and differential scanning calorimeter. Based on the heat capacity curve fitting, the standard molar heat capacity, entropy and enthalpy at 298.15 K and 0.1 MPa, and melting temperature and transition enthalpy in the solid-liquid phase transition region were consequently obtained for these sugar alcohols. Moreover, the heat capacity and phase transition properties obtained in this work were also compared with previous results reported in literature. (C) 2017 Elsevier Ltd

Flexible and Biocompatible Silk Fiber-Based Composite Phase Change Material for Personal Thermal Management

Phase change materials (PCMs) are regarded as an effective passive personal thermal management strategy. However, the preparation of flexible and biocompatible PCMs remains a great challenge. In this study, a silk fiber (SF)-based composite PCM for wearable personal thermal management was prepared using renewable natural silkworm cocoons and biocompatible capric acid (CA). The SF/CA composite PCM is flexible, biocompatible, and dyeable. The results show that the SF and CA are physically bonded, and the crystal structure of CA is not influenced by SF. The melting phase change enthalpy and temperature of the SF/CA composite PCM are 123.4 J/g and 30.6 °C, respectively. It has excellent shape stability, thermal stability, and cycling stability. Particularly, the SF/CA composite PCM has excellent performance for wearable personal thermal management under three scenarios including variable temperature mode, isothermal mode, and light irradiation mode. It can also reduce the temperature fluctuation of the human body in a hot or cold environment. Therefore, the SF/CA composite PCM has bright application prospects for wearable personal thermal management in hot and cold environments

Porous Carbon-Based Phase Change Material Host Matrix from Semicoking Wastewater

The capture and storage of solar energy using phase change materials (PCMs) are very important for cost-effective energy management. However, their low thermal conductivity and liquid phase leakage pose persistent challenges for effectively harvesting thermal energy with PCMs. Herein, using semicoking wastewater-derived phenolic resin (SWPR) as the carbon source and potassium hydroxide as activator, hierarchical porous carbon (HPC) materials with abundant porous structures were synthesized to confine the PCM. The HPCs generated microporous and mesoporous layered cavities that provided more space as well as capillary adsorption and physical interaction for PCM storage. Shape-stable phase change composites (PCCs) were then fabricated by vacuum impregnation of the HPCs with paraffin wax to address the problems of low thermal conductivity and liquid melt leakage. The PCCs exhibited high energy storage densities of up to 84.07 J g–1, dimensional stability, excellent thermal cycle stability, and the phase transition enthalpy of around 80.25 J g–1 after 500 heating–cooling cycles. The carbon support increased the thermal conductivity of the optimum PCC by 166% compared to that of pure paraffin wax. This study provides a cost-effective and environmentally friendly method for shape-stable PCMs based on waste-derived porous carbon materials with potential applications in solar–thermal energy storage