Jiayu Zhang, Zhenyang Li, Xinli Zhang^*

Journal of Renewable Materials, Vol.10, No.11, pp. 2871-2881, 2022, DOI:10.32604/jrm.2022.019373 - 29 June 2022

Abstract Geopolymers are inorganic aluminosilicate materials, which have been a great research interest as a material for sustainable development. However, they possess relatively low toughness properties similar to brittle solids. The limitation may be altered by fiber reinforcement to improve their strength and toughness. This research describes the synthesis of bamboo shaving (BS) reinforced geopolymer composites and the characterization of their mechanical properties. The effect of BS content (0–2 wt. %) on the physical and mechanical properties and microstructure of metakaolin based geopolymer paste were investigated. The workability, setting time, bulk density, apparent porosity, thermal conductivity,… More >

John Paul¹, K. Kadirgama¹, M. Samykano^2,*, R. Saidur³, A. K. Pandey³, R. V. Mohan⁴

Energy Engineering, Vol.119, No.4, pp. 1299-1325, 2022, DOI:10.32604/ee.2022.019172 - 23 May 2022

Abstract

Buildings contribute to 33% of total global energy consumption, which corresponds to 38% of greenhouse gas emissions. Enhancing building’s energy efficiency remains predominant in mitigating global warming. Advancements in thermal energy storage (TES) techniques using phase change material (PCM) have gained much attention among researchers, primarily to minimize energy consumption and to promote the use of renewable energy sources. PCM technology stays as the most promising technology for developing high-performance and energy-efficient buildings. The major drawback of PCM is its poor thermal conductivity which limits its potential use which could be resolved by dispersing conductive nanofillers.

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Nikola Vavřínová^*, Kateřina Stejskalová, Jiří Teslík, Kateřina Kubenková, Jiří Majer

Journal of Renewable Materials, Vol.10, No.7, pp. 1859-1873, 2022, DOI:10.32604/jrm.2022.018908 - 08 March 2022

Abstract This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards. This composite material is made of gypsum and reinforcing natural fibers. The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum. From this composite material, high-strength plasterboards could then be produced, which meet the higher demands of users than conventional gypsum plasterboards. For their production, natural waste materials would be used efficiently. As part of… More >

Dadang Mohamad^1,*, Mohammed Abed Jawad², John William Grimaldo Guerrero³, Tonton Taufik Rachman⁴, Huynh Tan Hoi⁵, Albert Kh. Shaikhlislamov⁶, Mustafa M. Kadhim⁷, Saif Yaseen Hasan⁸, A. Surendar⁹

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 851-866, 2022, DOI:10.32604/fdmp.2022.019485 - 22 February 2022

Abstract

Further development in the field of geothermal energy require reliable reference data on the thermophysical properties of geothermal waters, namely, on the thermal conductivity and viscosity of aqueous salt solutions at temperatures of 293–473 K, pressures Ps = 100 MPa, and concentrations of 0–25 wt.%. Given the lack of data and models, especially for the dynamic viscosity of aqueous salt solutions at a pressure of above 40 MPa, generalized formulas are presented here, by which these gaps can be filled. The article presents a generalized formula for obtaining reliable data on the thermal conductivity of water

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Yuling Zhai^*, Long Li, Zihao Xuan, Mingyan Ma, Hua Wang

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 629-646, 2022, DOI:10.32604/fdmp.2022.017485 - 22 February 2022

Abstract The thermo-physical properties of nanofluids are highly dependent on the used base fluid. This study explores the influence of the mixing ratio on the thermal conductivity and viscosity of ZnO-CuO/EG (ethylene glycol)-W (water) hybrid nanofluids with mass concentration and temperatures in the ranges 1-5 wt.% and 25-60°C, respectively. The characteristics and stability of these mixtures were estimated by TEM (transmission electron microscopy), visual observation, and absorbance tests. The results show that 120 min of sonication and the addition of PVP (polyvinyl pyrrolidone) surfactant can prevent sedimentation for a period reaching up to 20 days. The… More >

Bing Liu¹, Yikun Chen¹, Huachen Liu¹, Qiao Wu¹, Minghui Wang¹, Jianlong Wan^2,*

Energy Engineering, Vol.119, No.2, pp. 815-826, 2022, DOI:10.32604/ee.2022.017988 - 24 January 2022

Abstract The operating range of the flow rate or flow velocity for the micro-jet flame is quite wide, which can be used as the heat source. In order to optimize the micro-jet tube combustor in terms of the solid material, the present paper numerically investigates the impact of thermal conductivity (λ_s) on the operating limit of micro-jet flame. Unexpectedly, the non-monotonic blow-off limits with the increase of λ_s is found, and the corresponding generation mechanisms are analyzed in terms of the thermal coupling effect, flow field, and strain effect. At first, the lower preheating temperature of the More >

Kang Liu, Yanqiao Wang^*

CMES-Computer Modeling in Engineering & Sciences, Vol.131, No.1, pp. 119-135, 2022, DOI:10.32604/cmes.2022.018134 - 24 January 2022

Abstract Soil slope stability in seasonally frozen regions is a challenging problem for geotechnical engineers. The freeze-thaw process of soil slope caused by the temperature fluctuation increases the difficulty in predicting the slope stability because the soil property is influenced by the freeze-thaw cycle. In addition, the frozen soil, which has ice crystal, ice lens and experienced freeze-thaw process, could present stronger heterogeneity. Previous research has not investigated the combined effect of soil heterogeneity and freeze-thaw cycle. This paper studies the influence of soil heterogeneity on the stability of frozen soil slope under freeze-thaw cycles. The… More >

Muhammad Sami Rashad¹, Haihu Liu^1,*, Shan Ali Khan²

CMES-Computer Modeling in Engineering & Sciences, Vol.130, No.1, pp. 233-254, 2022, DOI:10.32604/cmes.2022.017277 - 29 November 2021

Abstract A mathematical modeling is explored to scrutinize the unsteady stagnation point flow of Oldroyd-B nanofluid under the thermal conductivity and solutal diffusivity with bioconvection mechanism. Impacts of Joule heating and Arrhenius activation energy including convective boundary conditions are studied, and the specified surface temperature and constant temperature of wall (CTW) are discussed. The consequences of thermal conductivity and diffusivity are also taken into account. The flow is generated through stretchable disk geometry, and the behavior of non-linear thermal radiation is incorporated in energy equation. The partial differential equations governing the fluid flow in the structure… More >

Kafel Azeez Mohammed^a,*, Ahmed Mustaffa Saleem^b , Zain alabdeen H. Obaid^a

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-8, 2021, DOI:10.5098/hmt.16.20

Abstract Numerical investigation is performed for the determination of Nusselt number of ZnO, TiO₂ and SiO₂ nanoparticles dispersed in 60% ethylene glycol and 40% water inside inclined cylinder for adiabatic and isothermal process. The present study was conducted for both the constant heat flux (10,000 W/m²) and constant wall temperature (313.15 K) boundary conditions. At the inlet, the uniform axial velocity and initial temperature (293 K) were assumed. The results show the change of average Nusselt number at Reynolds number (400), Rayleigh number (10⁶) and volume fraction percentage (2%). From results for adiabatic process when increasing the slop More >

F. S. Bayones¹, S. M. Abo-Dahab^2,*, Ahmed E. Abouelregal³, A. Al-Mullise¹, S. Abdel-Khalek^1,4, E. M. Khalil^1,5

CMC-Computers, Materials & Continua, Vol.67, No.3, pp. 2899-2913, 2021, DOI:10.32604/cmc.2021.012583 - 01 March 2021

Abstract The present paper paper, we estimate the theory of thermoelasticity a thin slim strip under the variable thermal conductivity in the fractional-order form is solved. Thermal stress theory considering the equation of heat conduction based on the time-fractional derivative of Caputo of order α is applied to obtain a solution. We assumed that the strip surface is to be free from traction and impacted by a thermal shock. The transform of Laplace (LT) and numerical inversion techniques of Laplace were considered for solving the governing basic equations. The inverse of the LT was applied in More >