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  • Open Access

    ARTICLE

    STUDY ON SUPERSONIC CONDENSATION AND INFLUENCING FACTORS OF NATURAL GAS WITH CARBON DIOXIDE

    Rongge Xiaoa,*, Shuaishuai Jina, Xin Fengb, Peng Zhangc, Zheng Daic

    Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-7, 2021, DOI:10.5098/hmt.16.25

    Abstract With the increasing production and use of natural gas, the supersonic nozzle has become focus of the impurity removal research. In this paper, the modified classical nucleation model is used as the condensation nucleation model, and the Gyarmathy growth model is selected as the droplet growth model. Based on the assumption of no phase slip and Eulerian two fluid model, the flow control equation of wet natural gas is established. By giving the selection criteria as a turbulence equation, the SRK real gas equation is used to carry out the corresponding numerical simulation. The required More >

  • Open Access

    ARTICLE

    A COMPARISON OF THE EQUILIBRIUM AND THE DROPLETS BASED NON-EQUILIBRIUM COMPRESSIBLE PHASE CHANGE SOLVERS FOR CONDENSATION OF CARBON DIOXIDE INSIDE NOZZLES

    Kapil Dev Choudhary, Shyam Sunder Yadav , Mani Sankar Dasgupta

    Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-10, 2021, DOI:10.5098/hmt.16.14

    Abstract In the current work, we simulate the condensation of supercritical CO2 during its high speed flow inside two different converging-diverging nozzles. We use the homogeneous equilibrium method and the classical nucleation theory based non-equilibrium phase change model for this purpose. The simulation results indicate significant influence of the nozzle inlet condition, nozzle shape and the fluid thermophysical behaviour on the nonequilibrium conditions prevailing inside the nozzles. We observe very low, ∼0.15 K, supercooling for the flow of CO2 inside the Claudio Lettieri nozzle compared to the supercooling of ∼3 K observed for the Berana nozzle. Very… More >

  • Open Access

    ARTICLE

    Numerical Analysis of Labyrinth Seal Performance for the Impeller Backface Cavity of a Supercritical CO2 Radial Inflow Turbine

    Jinguang Yang, Feng Zhao, Min Zhang*, Yan Liu, Xiaofang Wang

    CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.3, pp. 935-953, 2021, DOI:10.32604/cmes.2021.014176 - 19 February 2021

    Abstract For a radial inflow turbine (RIT), leakage flow in impeller backface cavity has critical impacts on aerodynamic performance of the RIT and axial force acting on the RIT impeller. In order to control this leakage flow, different types of labyrinth seals are numerically studied in this paper based on a supercritical carbon dioxide (S-CO2) RIT. The effects of seal clearance and cavity outlet pressure are first analyzed, and the impacts of seal design parameters, including height, number and shape of seal teeth, are evaluated. Results indicate that adding labyrinth seal can improve cavity pressure and hence More >

  • Open Access

    ARTICLE

    Microparticle Effect of Carbon Dioxide Hydrate Crystal Nucleus in Reaction Kettle

    Yujie Bai1,*, Youquan Huang3, Guangsheng Cao1, Xiaohan Nan1, Qingchao Cheng1, Lei Wang2, Tong Du4

    Journal of Renewable Materials, Vol.9, No.4, pp. 651-669, 2021, DOI:10.32604/jrm.2021.014479 - 01 February 2021

    Abstract This study analyzed the partial effect of carbon dioxide hydrate in reaction kettle experiments. The particle and bubble characteristics of the crystal nucleus during carbon dioxide hydrate decomposition were observed under the microscope. The results showed that in the temperature range of 0.5°C–3.5°C, the pressure range of 3 MPa– 5.5 MPa, phase characteristics in the reaction kettle changed in a complex fashion during carbon dioxide hydrate formation. During hydrate decomposition, numerous carbon dioxide bubbles were produced, mainly by precipitation at high temperatures or in the hydrate cage structure. The hydrate crystal nucleus initially exhibited fluidity More >

  • Open Access

    ARTICLE

    EFFECT OF RESIDUAL NON-CONDENSABLE GASES ON THE PERFORMANCE OF A CARBON DIOXIDE EVAPORATOR AND THE SYSTEM PERFORMANCE

    Jing Hua,* , Mingxing Dub

    Frontiers in Heat and Mass Transfer, Vol.14, pp. 1-7, 2020, DOI:10.5098/hmt.14.5

    Abstract Inert gases are conveniently used for leak detection. Relative to CO2, majority of the inert gases are non-condensable. It is of great significance to understand the effects of residual non-condensable gases on the performance of a refrigeration system. This paper investigates, both theoretically and experimentally, on the impact of residual non-condensable gases on the performance of a carbon dioxide (CO2) evaporator and the system performance. A theoretical analysis indicates that residual non-condensable gases can convert homogeneous nucleation into a heterogeneous nucleation process and accelerate phase change, thus, reducing superheat or incipient boiling temperature. To investigate the… More >

  • Open Access

    ARTICLE

    Applying ANN, ANFIS and LSSVM Models for Estimation of Acid Solvent Solubility in Supercritical CO2

    Amin Bemani1, Alireza Baghban2, Shahaboddin Shamshirband3, 4, *, Amir Mosavi5, 6, 7, Peter Csiba7, Annamaria R. Varkonyi-Koczy5, 7

    CMC-Computers, Materials & Continua, Vol.63, No.3, pp. 1175-1204, 2020, DOI:10.32604/cmc.2020.07723 - 30 April 2020

    Abstract In the present work, a novel machine learning computational investigation is carried out to accurately predict the solubility of different acids in supercritical carbon dioxide. Four different machine learning algorithms of radial basis function, multi-layer perceptron (MLP), artificial neural networks (ANN), least squares support vector machine (LSSVM) and adaptive neuro-fuzzy inference system (ANFIS) are used to model the solubility of different acids in carbon dioxide based on the temperature, pressure, hydrogen number, carbon number, molecular weight, and the dissociation constant of acid. To evaluate the proposed models, different graphical and statistical analyses, along with novel More >

  • Open Access

    ARTICLE

    Numerical Study on Rock Breaking Mechanism of Supercritical CO2 Jet Based on Smoothed Particle Hydrodynamics

    Xiaofeng Yang1, *, Yanhong Li1, Aiguo Nie1, Sheng Zhi2, Liyuan Liu3

    CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.3, pp. 1141-1157, 2020, DOI:10.32604/cmes.2020.08538 - 01 March 2020

    Abstract Supercritical carbon dioxide (Sc-CO2) jet rock breaking is a nonlinear impact dynamics problem involving many factors. Considering the complexity of the physical properties of the Sc-CO2 jet and the mesh distortion problem in dealing with large deformation problems using the finite element method, the smoothed particle hydrodynamics (SPH) method is used to simulate and analyze the rock breaking process by Sc-CO2 jet based on the derivation of the jet velocity-density evolution mathematical model. The results indicate that there exisits an optimal rock breaking temperature by Sc-CO2. The volume and length of the rock fracture increase with the… More >

  • Open Access

    ABSTRACT

    Comparative Study on Dry Reforming of Methane Over Co-M (M=Ce, Fe, Zr) Catalysts Supported on N-Doped Activated Carbon

    Yinghui Sun1, Guojie Zhang1,2,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.1, pp. 105-105, 2019, DOI:10.32604/icces.2019.05173

    Abstract A series of Co-M (M = Ce, Fe, Zr) binary oxides supported on N-doped catalysts were prepared by impregnation methods and tested for DRM reaction. Moreover, the influence of Co and Ce atomic contents in the catalysts on DRM performance was investigated. Significant enhancement of activity performance over Ce promoted 3Co-1Ce/AC-N catalyst was observed. Compared with Fe and Zr, the catalyst with 1/4 mol% of Ce showed the highest activity and was higher than the supported Co catalyst. The calcined and spent catalysts were characterized by XPS, H2-TPR, TEM and EDX mapping studies. The characterization results… More >

  • Open Access

    ARTICLE

    Supercritical Carbon Dioxide Treated Kenaf Bast Pulp Fiber Reinforcement in Epoxy Composite

    N. A. Sri Aprilia1, M. S. Nurul Atiqah2, Zhari Ismail3, C. Y. Loo2, Chaturbhuj K. Saurabh2, Rudi Dungani4, Abdul Khalil H.P.S2*

    Journal of Renewable Materials, Vol.5, No.5, pp. 380-387, 2017, DOI:10.7569/JRM.2017.634130

    Abstract Due to environmental concerns, green composites have become a highly researched material. In the present study, kenaf fiber was used as reinforcement in epoxy-based composite with weight fraction ranges from 0, 5, 10, and 15% (w/w of resin). The ratio of epoxy to hardener was 65:32.5. Prior to incorporation, kenaf bast fiber underwent Soda-AQ pulping followed by total chlorine-free bleaching (OAZP sequence). The obtained pulp was then subjected to supercritical carbon dioxide extraction (SCE) treatment. It was observed that epoxy composite with 10% of fiber loading demonstrated the highest mechanical properties with a tensile strength More >

  • Open Access

    ARTICLE

    Chitin Preparation by Demineralizing Deproteinized Lobster Shells with CO2 and a Cationite

    Miguel Ángel Ramírez1, Patricia González2, Juan Reinerio Fagundo2, Margaret Suarez3, Clara Melian3, Tania Rodríguez1, Carlos Peniche4*

    Journal of Renewable Materials, Vol.5, No.1, pp. 30-37, 2017, DOI:10.7569/JRM.2016.634121

    Abstract The inorganic components of crustacean shells are usually removed using HCl solutions. This provokes undesirable modifications in the extracted chitin. In the present procedure, deproteinized lobster shells were demineralized with CO2 and a cationic resin (cationite). The resulting chitin (CHI-CO2) is compared in terms of degree of acetylation (DA), crystallinity index (CrI) and thermal stability with chitins obtained by demineralization procedures with HCl (CHI-HCl) and ethylenediaminetetraacetic acid (CHI-EDTA). The ash content of chitins demineralized with CO2 was similar to that of chitins prepared using HCl or EDTA. However, the resultant DA and CrI of CHI-HCl More >

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