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Search Results (19)
  • Open Access

    ARTICLE

    HYDROTHERMAL CHARACTERISTICS OF WATER FLOW INTO A DIMPLED TUBE HEAT EXCHANGER: A PARAMETRIC STUDY

    Mousa Aqeel Ali*, Saad Najeeb Shehab

    Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-10, 2022, DOI:10.5098/hmt.19.39

    Abstract In this study, the hydrothermal water flow characteristics using a dimpled inner tube heat exchanger are investigated experimentally and numerically. A numerical analysis has performed on two types of dimpled tubes (In-lined and staggered distributions) for two distribution angles 60o and 90o , and two dimple diameters(4 mm and 6 mm) with constant pitch ratio (X/d=8). In experimental part, a staggered arrangement dimpled inner tube distribution with angle 60o , dimple diameter of 6 mm and constant pitch ratio (X/d=8)is used as well as plain tube. The results illustrate that the heat transfer as Nusselt number for case of staggered… More >

  • Open Access

    ARTICLE

    Two-Step Preparation of Hierarchical Porous Carbon Materials Derived from Tannin for Use as an Electrode Material for Supercapacitors

    Jianping Deng1, Qianqian Zhang1, Yuling Lan1, Lingcong Luo1, Zimin Dai1, Zhonghang Lin1, Zhixin Lu1, Jiancheng Yuan1, Yiqi Fu1, Lu Luo2,*, Weigang Zhao1,*

    Journal of Renewable Materials, Vol.11, No.6, pp. 2631-2646, 2023, DOI:10.32604/jrm.2023.027163

    Abstract The development and utilization of biomass and agroforestry processing byproducts for high-value applications have been an important topic in the field of renewable materials research. Based on this, a two-step microwave hydrothermal pre-carbonization and KOH activation method was proposed to synthesize tannin-based activated carbons with a high specific surface area, hierarchical pore structure, and good electrochemical performance. The microstructure, texture properties, and physicochemical characteristics were investigated. The results show that the prepared tannin-based activated carbons presented a hierarchical pore structure (micro- and mesopores) with a specific surface area as high as 997.46 m3 g−1 . The electrochemical analysis shows that… More > Graphic Abstract

    Two-Step Preparation of Hierarchical Porous Carbon Materials Derived from Tannin for Use as an Electrode Material for Supercapacitors

  • Open Access

    ARTICLE

    Green Hydrothermal Synthesis and Applications of Sorbus pohuashanensis/Aronia melanocarpa Extracts Functionalized-Au/Ag/AuAg Nanoparticles

    Jin Huang1,2,#, Jixiang Sun1,3,4,#, Kai Shao1,3,4, Yamei Lin1,3,4, Zhiguo Liu1,3,4,*, Yujie Fu1, Liqiang Mu2,*

    Journal of Renewable Materials, Vol.11, No.4, pp. 1807-1821, 2023, DOI:10.32604/jrm.2023.023721

    Abstract Nanoparticles (NPs) have already been widely used in catalysis, antibacterial and coating fields. Compared with the traditional toxic and harmful reducing reagents, green synthesis of NPs by using plant extracts is not only environmental-friendly and cost-effective but also conducive to the multi-level and efficient utilization of wild plant resources. In this study, the aqueous extracts from Sorbus pohuashanensis (SP) and Aronia melanocarpa (AM) fruits were used as the reducing and protective reagents for synthesizing Au/AgNPs, with the characteristics of originality operation and high repeatability. The SP/AM fruit extracts functionalized Au/AgNPs were characterized by UV-vis spectroscopy (UV-vis), transmission electron microscopy (TEM),… More > Graphic Abstract

    Green Hydrothermal Synthesis and Applications of <i>Sorbus pohuashanensis</i>/<i>Aronia melanocarpa</i> Extracts Functionalized-Au/Ag/AuAg Nanoparticles

  • Open Access

    ARTICLE

    Effects of Hydrothermal Environment on the Deformation of the Thin Bamboo Bundle Veneer Laminated Composites

    Ge Wang, Linbi Chen, Haiying Zhou*, Shanyu Han, Fuming Chen*

    Journal of Renewable Materials, Vol.11, No.3, pp. 1499-1511, 2023, DOI:10.32604/jrm.2022.025130

    Abstract To overcome warping in thin bamboo bundle veneer laminated composites (TBLC), their hydrothermal deformation characteristics were systematically investigated in this study. It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment, which increased their warpage. TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature. The warpage of Type E increased by 155.88% and 66.67% in the width and diagonal directions, respectively, when the temperature increased from 25 C to 100 C. The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability. We revealed that… More >

  • Open Access

    REVIEW

    Hydrochar Pelletization towards Solid Biofuel from Biowaste Hydrothermal Carbonization

    Ao Li, Kai Jin, Jinrui Qin, Zhaowei Huang, Yu Liu, Rui Chen, Tengfei Wang*, Junmin Chen*

    Journal of Renewable Materials, Vol.11, No.1, pp. 411-422, 2023, DOI:10.32604/jrm.2022.024889

    Abstract Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to fact that moisture involved can be directly used as reaction media under subcritical-water region. With this, value-added utilization of hydrochar as solid fuel with high carbon and energy density is one of the important pathways for biomass conversion. In this review, the dewatering properties of hydrochar after the hydrothermal carbonization of biowaste, coalification degree with elemental composition and evolution, pelletization of hydrochar to enhance the mechanical properties and density, coupled with the combustion properties of hydrochar biofuel were discussed with various biomass and carbonization parameters. Potential applications for… More > Graphic Abstract

    Hydrochar Pelletization towards Solid Biofuel from Biowaste Hydrothermal Carbonization

  • Open Access

    ARTICLE

    Tunable Luminescence Properties and Elucidating the Electronic Structures of Single-Phase Spherical BaWO4: Dy3+, Tm3+, Eu3+ Phosphors for Warm-White-Lighting

    Zun Bi1,2,3, Ke Jia1,2,3, Yunfei Liu1,2,3,*, Yinong Lyu1,2,3,*

    Journal of Renewable Materials, Vol.10, No.2, pp. 431-451, 2022, DOI:10.32604/jrm.2022.016735

    Abstract A series of uniform single-phase spherical BaWO4: Dy3+, Tm3+, Eu3+ phosphors were prepared via a microwave hydrothermal method by using trisodium citrate dehydrate as surfactant. The phase structure, morphology and photoluminescence properties were measured by powder X-ray diffraction, scanning electron microscope and fluorescence spectrometer, respectively. The results show that uniform spherical microcrystals with diameters in the range of 2–4 μm are obtained. And the phase and morphology of samples are not significantly changed by doping rare earth (RE3+) ions. Under the excitation wavelength of 356 and 365 nm, the samples BaWO4: 0.03Dy3+, yTm3+ can emit cold white light. In order to… More >

  • Open Access

    ARTICLE

    Experimental Investigation on Hydrophobic Behavior of Carbon Spheres Coated Surface Made from Microplastics

    Peng Liu, Bin Bai, Cui Wang, Yunan Chen, Zhiwei Ge, Wenwen Wei, Hui Jin*

    Journal of Renewable Materials, Vol.9, No.12, pp. 2159-2174, 2021, DOI:10.32604/jrm.2021.016166

    Abstract In this paper, a simple method to plate a hydrophobic coating on the inner surface of a small-scaled tube was proposed, where the coating consisted of carbon microspheres. Three common plastics polystyrene, polycarbonate and polyethylene were used as the feedstocks to be processed in supercritical water in a quartz tubular reactor. After reaction, the contact angle of droplet on the inner surface of the quartz tube was turned out to be over 100°, significantly larger than that of the blank tube 54°. When processing polystyrene in the 750C supercritical water for 10 min, the largest contact angle was obtained, up… More > Graphic Abstract

    Experimental Investigation on Hydrophobic Behavior of Carbon Spheres Coated Surface Made from Microplastics

  • Open Access

    ARTICLE

    Zeolite A Synthesized from Geothermal Waste Using Conventional and Microwave Heating for the Hydrothermal Treatment

    Sulardjaka Sulardjaka1,*, Sri Nugroho1, Norman Iskandar1, Agus P. Adi1, Deni F. Fitriyana2

    FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.2, pp. 385-395, 2021, DOI:10.32604/fdmp.2021.011784

    Abstract Zeolite A has been successfully synthesized from geothermal waste with natrium aluminate and natrium silicate using conventional (C-H) and microwave heating (M-H) for the hydrothermal treatment. The products obtained for different aging times have been characterized using X-Ray Diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). It is shown that with the M-H process, zeolite can be formed at relatively low temperature (100°C) in a relatively short time (40 min). The crystallization of zeolite A has been found to be generally promoted by an increase of aging and synthesis time; however, it has also been observed… More >

  • Open Access

    ARTICLE

    Simulating the Turbulent Hydrothermal Behavior of Oil/MWCNT Nanofluid in a Solar Channel Heat Exchanger Equipped with Vortex Generators

    Rachid Maouedj1, Younes Menni2, Mustafa Inc3,4,*, Yu-Ming Chu5,6,*, Houari Ameur7, Giulio Lorenzini8

    CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.3, pp. 855-889, 2021, DOI:10.32604/cmes.2021.014524

    Abstract Re-engineering the channel heat exchangers (CHEs) is the goal of many recent studies, due to their great importance in the scope of energy transport in various industrial and environmental fields. Changing the internal geometry of the CHEs by using extended surfaces, i.e., VGs (vortex generators), is the most common technique to enhance the efficiency of heat exchangers. This work aims to develop a new design of solar collectors to improve the overall energy efficiency. The study presents a new channel design by introducing VGs. The FVM (finite volume method) was adopted as a numerical technique to solve the problem, with… More >

  • Open Access

    ARTICLE

    CFD-Based Simulation and Analysis of Hydrothermal Aspects in Solar Channel Heat Exchangers with Various Designed Vortex Generators

    Mohamed Salmi1,2, Younes Menni3, Ali J. Chamkha4,5,*, Houari Ameur6, Rachid Maouedj7, Ahmed Youcef7

    CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.1, pp. 147-173, 2021, DOI:10.32604/cmes.2021.012839

    Abstract The hydrothermal behavior of air inside a solar channel heat exchanger equipped with various shaped ribs is analyzed numerically. The bottom wall of the exchanger is kept adiabatic, while a constant value of the temperature is set at the upper wall. The duct is equipped with a flat rectangular fin on the upper wall and an upstream V-shaped baffle on the lower wall. Furthermore, five hot wall-attached rib shapes are considered: trapezoidal, square, triangular pointing upstream (type I), triangular pointing downstream (type II), and equilateral-triangular (type III) cross sections. Effects of the flow rates are also inspected for various Reynolds… More >

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