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71.
《International Journal of Hydrogen Energy》2020,45(1):958-971
A micro-combined cooling heating and power (CCHP) system integrated with geothermal-assisted methanol reforming and incorporating a proton exchange membrane fuel cell (PEMFC) stack is presented. The novel CCHP system consists of a geothermal-based methanol steam reforming subsystem, PEMFC, micro gas turbine and lithium bromide (LiBr) absorption chiller. Geothermal energy is used as a heat source to drive methanol steam reforming to produce hydrogen. The unreacted methanol and hydrogen are efficiently utilized via the gas turbine and PEMFC to generate electricity, respectively. For thermodynamic and economic analysis, the effects of the thermodynamic parameters (geothermal temperature and molar ratio of water to methanol) and economic factors (such as methanol price, hydrogen price and service life) on the proposed system performance are investigated. The results indicate that the ExUF (exergy utilization factor the exergy utilization factor), TPES (trigeneration primary energy saving) and energy efficiency of the novel system can be reached at 8.8%, 47.24% and 66.3%, respectively; the levelized cost of energy is 0.0422 $/kWh, and the annual total cost saving ratio can be reached at 20.9%, compared with the conventional system. The novel system achieves thermodynamic and economic potential, and provides an alternative and promising way for efficiently utilizing abundant geothermal energy and methanol resources. 相似文献
72.
73.
《International Journal of Hydrogen Energy》2020,45(28):14266-14280
Shale gas resources (SGR), as a representative of natural gas hydrate reservoirs, have been the main energy supply for the energy consumption currently. The multi-scale pore structure of shale, complicated seepage mechanisms, including Knudsen diffusion, matrix deformation, stress sensitivity, non-Darcy flow and spatial fracture network stimulated by hydraulic fracturing technology have posed huge challenges to an accurate prediction and assessment of shale gas recovery. A full understanding of gas seepage mechanism of shale gas is the critical and scientific issue to develop carbon hydrogen energy resources effectively. It is very urgent to establish a comprehensive mathematical model to analyze the productivity capacity through simultaneously considering various flow mechanisms and fractures network system. To fill this gap, this paper presents a comprehensive numerical model of hydraulic fracturing horizontal well with discrete fracture network where embedded discrete fracture model (EDFM) is employed to characterize the coupled phenomenon between discrete fracture network and fractured SGR. And then two numerical discretization methods, e.g., finite difference and finite-volume, are used to numerically discretize the equations, subsequently, the Newton-Raphson iterative method is adopted to obtain the final solutions. Finally, the sensitivity analysis experiments are employed to investigate the effects of the key parameters. The results can provide some certain guidance for the optimization of stimulated treatment in natural gas hydrate reservoirs. 相似文献
74.
《International Journal of Heat and Mass Transfer》1964,7(2):159-167
Electrokinetic-potential fluctations produced by a two-dimensional submerged water jet impinging on a plate have been measured. The potential fluctuations appear to be approximately proportional to the longitudinal-velocity fluctuations ux' in the neighborhood of the boundary.Normalized frequency distributions of potential-fluctuation measurements agree with velocityfluctuation data taken by Klebanoff and Laufer with a hot-wire anemometer at adimensionless distance y/δ ∼- 10−3 from the wall. Assumptions made concerning the relationship between potential and velocity fluctuations give a possible explanation of the change in the shape of the potential-fluctuation spectrum with the flow velocity and the electrical conductivity of the water. Further analysis is required to establish a definite relationship between electrokinetic-potential fluctuations and velocity fluctuations occurring near a solid boundary. 相似文献
75.
《Chemical engineering science》1970,25(5):761-768
Based upon the film theory, the approximate solutions for gas absorption accompanied by two consecutive chemical reactions of the forms γAA+γBB→γCC+ Product,γA′A′+γCC→γCC→γBB and γAA+γBB→γCC,γAA+γ′CC Product, are derived and compared with the numerical solutions. For the case of equal diffusivities, the approximate and numerical solutions agree with each other within a few per cent. 相似文献
76.
油气田CO2/H2S共存腐蚀与缓蚀技术研究进展 总被引：3，自引：0，他引：3
CO2/H2S是油气田采集、运输、处理过程中主要的腐蚀介质,由其引起的管道设备的腐蚀问题变得越来越严重,腐蚀和防腐已经成为研究热点。分别对近年来国内外开展的有关CO2和H2S共存腐蚀及缓蚀技术的研究进行综述。CO2/H2S共存腐蚀研究主要依靠试验手段,但目前的研究结果有很大的离散性,根据不同的试验条件会产生不同的研究结果。分压比是国内外大多数学者研究CO2/H2S腐蚀规律的切入点,但关于两者主导腐蚀的分压比界限划分现有研究存有争议。缓蚀技术研究讨论了缓蚀剂作用机理,评述了抑制CO2/H2S共存腐蚀常用的酰胺类、咪唑啉衍生物类、季铵盐类和Schiff碱类缓性剂在国内外的研究与应用现状,展望了这一领域的研究前景及发展方向。 相似文献
77.
The characteristics of a ceiling jet of an inclined tunnel in a fire will be studied and reported in this paper. Scale modeling experiments on a ceiling jet in a model tunnel of length 3.0 m, width 0.8 m and height 1.0 m inclined at different angles of 0°, 10°, 20° and 30° were carried out. Numerical studies by large eddy simulation were then performed. Both experimental observation and numerical simulation indicated that the characteristics of the temperature and velocity fields near the upper tunnel are different from those obtained using the empirical equations reported in the literature. Another set of empirical equations for gas temperature and flow velocity along the tunnel were fitted by experimental data. These derived empirical equations are useful for estimating the temperature and flow velocity patterns for the ceiling jet in an inclined tunnel with an angle within the range 0–30°. 相似文献
78.
79.
《Acta Metallurgica Materialia》1994,42(7):2493-2498
The diffusion coefficient of hydrogen in aluminium has been determined in the temperature range between 446 and 681 K by a glow discharge permeation method which enables us to extend the temperature range of measurements by enhancement of the permeation flux in spite of the small equilibrium solubility of hydrogen in solid aluminium. The temperature dependence of the diffusion coefficient of hydrogen in aluminium shows a linear Arrhenius relationship with the pre-exponential factor (6.1 ± 0.5) × 10−5 m2 s−1 and with the activation energy (54.8 ± 0.4) kJmol−1. These values are higher than those estimated by several previous authors with hydrogen evolution techniques in high temperature regions. However, the present values are well consistent with the results by Ishikawa and McLellan using an electrolytic permeation method around room temperature, suggesting that hydrogen atoms in aluminium diffuse by the interstitial mechanism in the whole temperature range. 相似文献
80.
《Materials Research Bulletin》2013,48(4):1477-1483
The graphite oxide was synthesized using the Hummers method, and then it was reduced by hydrazine hydrate to obtain graphene. It was characterized with UV (ultra violet), IR (infra red), XRD (X-ray diffraction) spectra and SEM (scanning electron microscope) images. The composite coating of Ni–graphene on mild steel specimens was obtained by the electrodeposition technique. The composite coating was subjected to various electrochemical tests to know its corrosion behavior and compared with pure Ni coating. The EIS (electrochemical impedance spectroscopy) was performed to confirm the corrosion resistance property. The composite film was studied by recording its XRD and SEM. The crystallite size, texture coefficients and hardness of coating was measured. 相似文献