Hongzhi Xu^1,2, Jian Wang^1,3, Shuxia Li^1,*, Fengrui Zhao¹, Chengwen Wang¹, Yang Guo¹

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.3, pp. 505-523, 2024, DOI:10.32604/fdmp.2023.030604

Abstract Natural gas hydrate (NGH) is generally produced and accumulated together with the underlying conventional gas. Therefore, optimizing the production technology of these two gases should be seen as a relevant way to effectively reduce the exploitation cost of the gas hydrate. In this study, three types of models accounting for the coexistence of these gases are considered. Type A considers the upper hydrate-bearing layer (HBL) adjacent to the lower conventional gas layer (CGL); with the Type B a permeable interlayer exists between the upper HBL and the lower CGL; with the type C there is an impermeable interlayer between the… More >

Jiangshuai Wang^1,*, Chuchu Cai¹, Pan Fu^2,3, Jun Li^4,5, Hongwei Yang⁴, Song Deng¹

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.3, pp. 537-546, 2024, DOI:10.32604/fdmp.2023.030430

Abstract Multi-gradient drilling is a new offshore drilling method. The accurate calculation of the related wellbore temperature is of great significance for the prediction of the gas hydrate formation area and the precise control of the wellbore pressure. In this study, a new heat transfer model is proposed by which the variable mass flow is properly taken into account. Using this model, the effects of the main factors influencing the wellbore temperature are analyzed. The results indicate that at the position where the separation injection device is installed, the temperature increase of the fluid in the drill pipe is mitigated due… More >

Md Nahin Mahmood^*, Boyun Guo

Energy Engineering, Vol.120, No.12, pp. 2707-2720, 2023, DOI:10.32604/ee.2023.042996

Abstract The energy industry faces a significant challenge in extracting natural gas from offshore natural gas hydrate (NGH) reservoirs, primarily due to the low productivity of wells and the high operational costs involved. The present study offers an assessment of the feasibility of utilizing geothermal energy to augment the production of natural gas from offshore gas hydrate reservoirs through the implementation of the methane-CO₂ swapping technique. The present study expands the research scope of the authors beyond their previous publication, which exclusively examined the generation of methane from marine gas hydrates. Specifically, the current investigation explores the feasibility of utilizing the… More >

Xincan Song^1,3,4, Lin Wang^1,3,4,*, Cheng Yu^1,2, Jiaxin Chen^1,3,4, Linjie Ma^1,3,4

Energy Engineering, Vol.120, No.8, pp. 1837-1852, 2023, DOI:10.32604/ee.2023.027637

Abstract The coupled formation of wax crystals and hydrates is a critical issue for the safety of deep-sea oil and gas exploration and subsea transport pipeline flow. Therefore, this paper conducts an experimental study on the characteristics of methane hydrate formation in a water-in-oil (W/O) system with different wax crystal contents and explores the influence of different initial experimental pressures on the induction period and maximum rate of hydrate formation. The wavelet function was introduced to process the reaction rate and calculate the maximum speed of hydrate formation. Notably, the higher the pressure, the smaller the maximum rate of hydrate formation.… More >

Waleed Awadalseed¹, Honghua Zhao¹, Hemei Sun², Ming Huang³, Cong Liu^4,*

Journal of Renewable Materials, Vol.11, No.4, pp. 1911-1935, 2023, DOI:10.32604/jrm.2023.025100

Abstract This study examined the effects of using bagasse ash in replacement of ordinary Portland cement (OPC) in the treatment of expansive soils. The study concentrated on the compaction characteristics, volume change, compressive strength, splitting tensile strength, microstructure, California bearing ratio (CBR) value, and shear wave velocity of expansive soils treated with cement. Different bagasse ash replacement ratios were used to create soil samples. At varying curing times of 7, 14, and 28 days, standard compaction tests, unconfined compressive strength tests, CBR tests, Brazilian split tensile testing, and bender element (BE) tests were carried out. According to X-ray diffraction (XRD) investigations,… More >

Belén Begines, Francisca Zamora, M. Violante de Paz, Isaac Roffé, Manuel Mancera, Juan A. Galbis^*

Journal of Renewable Materials, Vol.1, No.3, pp. 212-221, 2013, DOI:10.7569/JRM.2013.634119

Abstract A batch of linear [m,n]-type sugar-based polyureas was synthesized by polyaddition reaction in solution from hexamethylene diisocyanate or 4,4’-methylene-bis(phenyl isocyanate) with the acyclic 2,3,4-tri-O-methyl-1,5- diamino-alditols having L-arabino, or xylo confi guration or the bicyclic 1,6-diamino-1,6-dideoxy-2,4:3,5-diO-methylene-D-glucitol. The polymers were obtained in good yields and fair molecular weights. All these polyureas were semicrystalline materials showing well-defi ned melting transition within the 86−171°C range, with T_g s being dependent on the aliphatic or aromatic nature of the diisocyanate used, and on the cyclic or acyclic chemical structure of the sugar moiety. They were found to be stable up to around 240°C, decomposing at… More >

Xiwen Shao¹, Dongsheng Gai¹, Dapeng Gao¹, Yanqiu Geng^1,*, Liying Guo^1,2,*

Phyton-International Journal of Experimental Botany, Vol.91, No.4, pp. 745-759, 2022, DOI:10.32604/phyton.2022.018933

Abstract The aim of this study was to investigate carbohydrate metabolism in rice seedlings subjected to salt-alkaline stress. Two relatively salt-alkaline tolerant (Changbai 9) and sensitive (Jinongda 138) rice cultivars, grown hydroponically, were subjected to salt-alkaline stress via 50 mM of salt-alkaline solution. The carbohydrate content and the activities of metabolism-related enzymes in the leaves and roots were investigated. The results showed that the contents of sucrose, fructose, and glucose in the leaves and roots increased under salt-alkaline stress. Starch content increased in the leaves but decreased in the roots under salt-alkaline stress. The activities of sucrose-phosphate synthase, sucrose synthase, amylase,… More >

Zaibo Zhou¹, Juanhong Liu^1,2,3,*, Kun Luo¹, Aixiang Wu^1,3, Hongjiang Wang^1,3

Journal of Renewable Materials, Vol.10, No.2, pp. 373-384, 2022, DOI:10.32604/jrm.2022.016380

Abstract In order to reduce the influence of impurities in hemihydrate phosphogypsum(HPG) on the environment and improve the workability of HPG, the effects of the content of quicklime and types of biopolymer (hydroxypropyl methylcellulose, xanthan gum, sodium polyacrylate(PAANa)) on the compressive strength, softening coefficient and ultrasonic velocity of HPG were evaluated. When the content of quicklime was 1.5% and the content of PAANa was 0.2%, HPG had the best mechanical properties and workability, its water retention rate can be increased by 5.8%, and unconfined compressive strength of 3 days increased by 10.3% and 7 days increased by 13.1%. Through the analysis… More > Graphic Abstract

Ruma Arora Soni^1,*, K. Sudhakar^1,3,4,*, R. S. Rana²

Energy Engineering, Vol.118, No.4, pp. 1045-1056, 2021, DOI:10.32604/EE.2021.016082

Abstract Spirulina is a sort of algae that grows in both fresh and seawater. It is considered the Earth’s most nutritionally dense food. Certain claims about Spirulina’s beneficial health properties are attributed to the relatively high protein content of the cells. Spirulina’s lipid, fatty acid profile, and biochemical composition have received little attention. The purpose of this study is to investigate the nature and decomposition of spirulina biomass at various temperatures. In the present investigation, Fourier transforms infrared spectroscopy, thermogravimetric analysis, and elemental analysis were used to study spirulina biomass biochemical characteristics. The optimal content of spirulina protein, lipid, and the… More >

Yujie Bai^1,*, 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

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 in the reaction. However, as… More >