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  • Open Access

    ARTICLE

    Comparison and Analysis of Heat Transfer and Inflow Rate for Supercritical Carbon Dioxide Based on Different Tubes

    Huda Adel Hassan Ali, Ameer Abed Jaddoa*, Jafaar Mohamme Daif

    Frontiers in Heat and Mass Transfer, Vol.21, pp. 443-465, 2023, DOI:10.32604/fhmt.2023.042288

    Abstract This paper is twofold. First, the effect of non-linear thermophysical property variation was presented using supercritical carbon dioxide (SCO2) around the thermodynamic pivotal point. The second part exhibits an experimental examination of the heat transfer (HT) behaviour of SCO2 in a helical tube with a hydraulic diameter of 2 mm at different mass fluxes (MF), heat fluxes (HF), and pressures (P). The experiments were carried out based on various pressures, mass fluxes, and heat fluxes for both scenarios. CO2 was cooled in a 2 mm diameter serpentine tube made of copper material. The experimental results showed that HT degradation could… More >

  • Open Access

    ARTICLE

    HEAT TRANSFER ENHANCEMENT OF HEAT EXCHANGER INSERTED TWISTED PLATES FOR CARBON DIOXIDE GAS

    Makoto Shibahara*

    Frontiers in Heat and Mass Transfer, Vol.6, pp. 1-4, 2015, DOI:10.5098/hmt.6.9

    Abstract Overall heat transfer coefficients of the heat exchanger inserted twisted plates for CO2 were measured. The overall heat transfer coefficients increased with mass flow rates of water at the same Reynolds number in the experiment. It is considered that the helically twisting fluid motions in the twisted heat exchanger were contributed to the heat transfer enhancements. More >

  • Open Access

    ARTICLE

    Numerical-Experimental Analysis of the Coal Fracture Formation Mechanism Induced by Liquid CO2 Explosion

    Yun Lei1,2,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.12, pp. 3021-3032, 2023, DOI:10.32604/fdmp.2023.029570

    Abstract The highly inefficient simultaneous extraction of coal and gas from low-permeability and high-gas coal seams in deep mines is a major problem often restricting the sustainable development of coal industry. A possible way to solve this problem under deep and complex geological conditions is represented by the technology based on the phase-change induced explosion of liquid carbon dioxide. In this work, the mechanism of formation of the coal mass fracture circle resulting from the gas cracking process is theoretically analyzed. Numerical simulations show that a blasting crushing zone with a radius of 1.0 m is formed around the blasting hole.… More >

  • Open Access

    ARTICLE

    Optimisation Strategy of Carbon Dioxide Methanation Technology Based on Microbial Electrolysis Cells

    Qifen Li, Xiaoxiao Yan*, Yongwen Yang, Liting Zhang, Yuanbo Hou

    Journal of Renewable Materials, Vol.11, No.7, pp. 3177-3191, 2023, DOI:10.32604/jrm.2023.027749

    Abstract Microbial Electrolytic Cell (MEC) is an electrochemical reaction device that uses electrical energy as an energy input and microorganisms as catalysts to produce fuels and chemicals. The regenerative electrochemical system is a MEC improvement system for methane gas produced by biological carbon sequestration technology using renewable energy sources to provide a voltage environment. In response to the influence of fluctuating disturbances of renewable electricity and the long system start-up time, this paper analyzes the characteristics of two strategies, regulating voltage parameter changes and activated sludge pretreatment, on the methane production efficiency of the renewable gas electrochemical system. In this system,… 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 influence of residual non-condensable… More >

  • 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 supersonic nozzle structure and grid… 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 high nucleation rate (∼… More >

  • Open Access

    REVIEW

    Recycling Carbon Resources from Waste PET to Reduce Carbon Dioxide Emission: Carbonization Technology Review and Perspective

    Xing Zhou1,2,5,6,*, Qi Wang1, Sai Feng1, Jingrui Deng1, Keming Zhu1, Yun Xing1,3, Xiaolian Meng3, Xiaojun Wang4, Lu Li5,6

    Journal of Renewable Materials, Vol.11, No.5, pp. 2085-2108, 2023, DOI:10.32604/jrm.2023.025032

    Abstract Greenhouse gas emissions from waste plastics have caused global warming all over the world, which has been a central threat to the ecological environment for humans, flora and fauna. Among waste plastics, waste polyethylene terephthalate (PET) is attractive due to its excellent stability and degradation-resistant. Therefore, merging China’s carbon peak and carbon neutrality goals would be beneficial. In this review, we summarize the current state-of-the-art of carbon emission decrease from a multi-scale perspective technologically. We suggest that the carbon peak for waste PET can be achieved by employing the closed-loop supply chain, including recycling, biomass utilization, carbon capture and utilization.… More > Graphic Abstract

    Recycling Carbon Resources from Waste PET to Reduce Carbon Dioxide Emission: Carbonization Technology Review and Perspective

  • Open Access

    ARTICLE

    Title Supersonic Condensation and Separation Characteristics of CO2-Rich Natural Gas under Different Pressures

    Yong Zheng1, Lei Zhao1, Yujiang Wang1, Feng Chang1, Weijia Dong2,*, Xinying Liu2, Yunfei Li2, Xiaohan Zhang2, Ziyuan Zhao3

    Energy Engineering, Vol.120, No.2, pp. 529-540, 2023, DOI:10.32604/ee.2023.022765

    Abstract Supersonic separation technology is a new natural gas sweetening method for the treatment of natural gas with high CO2 (carbon dioxide) content. The structures of the Laval nozzle and the supersonic separator were designed, and the mathematical models of supersonic condensation and swirling separation for CO2-CH4 mixture gas were established. The supersonic condensation characteristics of CO2 in natural gas and the separation characteristics of condensed droplets under different inlet pressures were studied. The results show that higher inlet pressure results in a larger droplet radius and higher liquid phase mass fraction; additionally, the influence of centrifugal force is more pronounced,… More >

  • Open Access

    ARTICLE

    Optimization of a Single Flash Geothermal Power Plant Powered by a Trans-Critical Carbon Dioxide Cycle Using Genetic Algorithm and Nelder-Mead Simplex Method

    Yashar Aryanfar1,*, Jorge Luis García Alcaraz2

    Energy Engineering, Vol.120, No.2, pp. 263-275, 2023, DOI:10.32604/ee.2023.022587

    Abstract The usage of renewable energies, including geothermal energy, is expanding rapidly worldwide. The low efficiency of geothermal cycles has consistently highlighted the importance of recovering heat loss for these cycles. This paper proposes a combined power generation cycle (single flash geothermal cycle with trans-critical CO2 cycle) and simulates in the EES (Engineering Equation Solver) software. The results show that the design parameters of the proposed system are significantly improved compared to the BASIC single flash cycle. Then, the proposed approach is optimized using the genetic algorithm and the Nelder-Mead Simplex method. Separator pressure, steam turbine output pressure, and CO2 turbine… More > Graphic Abstract

    Optimization of a Single Flash Geothermal Power Plant Powered by a Trans-Critical Carbon Dioxide Cycle Using Genetic Algorithm and Nelder-Mead Simplex Method

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