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 > Graphic Abstract

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 >

Yun Lei^1,2,*

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 >

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 >

Jing Hu^a,* , Mingxing Du^b

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 >

Rongge Xiao^a,*, Shuaishuai Jin^a, Xin Feng^b, Peng Zhang^c, Zheng Dai^c

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 >

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 >

Xing Zhou^1,2,5,6,*, Qi Wang¹, Sai Feng¹, Jingrui Deng¹, Keming Zhu¹, Yun Xing^1,3, Xiaolian Meng³, Xiaojun Wang⁴, Lu Li^5,6

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

Yong Zheng¹, Lei Zhao¹, Yujiang Wang¹, Feng Chang¹, Weijia Dong^2,*, 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 >

Yashar Aryanfar^1,*, 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