The movement of three-phase contact line which formed in the oil-water-solid three-phase area is of great importance in a number of applications, such as oil recovery, groundwater remediation, decontamination and dein...
The movement of three-phase contact line which formed in the oil-water-solid three-phase area is of great importance in a number of applications, such as oil recovery, groundwater remediation, decontamination and deinking The process of oil droplets/film migration and detachment, which are controlled by the moving contact line, has shown its great significance in oil *** are various factors which can drive the contact line to move, such as pressure and electrical driving ***, which will generate a velocity gradient for the flow near the *** this paper, we dedicate to investigate the moving rule of contact line under a velocity gradient from molecular dynamics (MD) insights.
A lab experiment was carried out to study the effects of pipe flow rate, particle concentration and pipe inner diameter ratio on proppant erosion of the reducing wall in hydraulic fracturing. The results show that the...
A lab experiment was carried out to study the effects of pipe flow rate, particle concentration and pipe inner diameter ratio on proppant erosion of the reducing wall in hydraulic fracturing. The results show that the erosion rate and erosion distribution are different not only in radial direction but also in circumferential direction of the sample. The upper part of sample always has a minimum erosion rate and erosion area. Besides, the erosion rate of reducing wall is most affected by fluid flow velocity, and the erosion area is most sensitive to the change in the diameter ratio. Meanwhile, the erosion rate of reducing wall in crosslinked fracturing fluid is mainly determined by the fluid flowing state due to the high viscosity of the liquid. In general, the increase in flow velocity and diameter ratio not only cause the expansion of erosion-affected flow region in sudden contraction section, but also lead to more particles impact the wall.
Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is...
Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is widespread but scattered, and the pressure, flow-rate and nitrogen content of CBM feed vary significantly. The skid-mounted liquefaction device is suggested as an efficient and economical way to recover methane. Turbo-expander is one of the most important parts which generates the cooling capacity for the cryogenic liquefaction system. Using turbo-expander, more cooling capacity and higher liquefied fraction can be achieved. In this study, skid-mounted CBM liquefaction processes based on Claude cycle are established. Cryogenic turbo-expander with high expansion ratio is employed to improve the efficiency of CBM liquefaction process. The unit power consumption per liquefaction mole flow-rate for CBM feed gas is used as the object function for process optimization, compressor discharge pressure, flow ratio of feed gas to turbo-expander and nitrogen friction are analyzed, and optimum operation range of the liquefaction processes are obtained.
In this study, the mechanisms that cause heat split, a specific phenomenon in dual-cooled annular fuel elements, were investigated. On the basis of thermal resistance analysis, the developing process of heat split phe...
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In this study, the mechanisms that cause heat split, a specific phenomenon in dual-cooled annular fuel elements, were investigated. On the basis of thermal resistance analysis, the developing process of heat split phenomenon was summarized. It was found that thermal expansion, fuel densification, swelling, creep, relocation and fission gas release are the original parameters driving the development of heat split. Due to these factors, thermal resistances for heat flux to internal and external channels change with the operating time, which results in heat split. Furthermore, the theoretical simulation on heat split was performed by FROBA-ANNULAR, which is a coupled thermal–mechanical analysis code for dual-cooled annular fuel elements. key parameters at different burnup stages, including gap size, gap conductance, temperature profile, coolant flux and heat flux were obtained. The calculation result shows that the fraction of heat flux to the internal cooling channel experiences complicated variation at the range of 32.9–39.7%. In addition, it was found that heat split does not match with the coolant split, especially at the lower burnup stage. Asymmetric heat transfer occurred because of the imbalance between heat split and coolant split, resulting in a substantial asymmetric temperature profile. Furthermore, heat split exerts an influence on DBNRs of inner and outer channels, although the computational values were still within the allowable limits.
Laser-induced breakdown spectroscopy(LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental *** has been extensively studied and developed due to the non-contact,fast...
Laser-induced breakdown spectroscopy(LIBS) is an analytical detection technique based on atomic emission spectroscopy to measure the elemental *** has been extensively studied and developed due to the non-contact,fast response,high sensitivity,real-time and multi-elemental detection *** development and applications of LIBS technique in Asia are summarized and discussed in this review *** researchers in Asia work on different aspects of the LIBS study in fundamentals,data processing and modeling,applications and *** to the current research status,the challenges,opportunities and further development of LIBS technique in Asia are also evaluated to promote LIBS research and its applications.
Rapid detection of coal and fly ash is significant to improve the efficiency of thermal power plants and reduce environmental pollution. Given its fast response, high sensitivity, real-time, and noncontact features, l...
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Rapid detection of coal and fly ash is significant to improve the efficiency of thermal power plants and reduce environmental pollution. Given its fast response, high sensitivity, real-time, and noncontact features, laser-induced breakdown spectroscopy (LIBS) has a great potential for online measurement in these applications. The direct measurement of particles and gases using LIBS has been studied, and the method has been shown to be effective for this application.
Differential pressure fluctuation is an inherent physical phenomenon in gas-liquid two-phase flow, which can be used to measure the quality and the whole flowrate. In order to study the influence of differential press...
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A 3-D measuring method for particle movement was established by using a single-lens dual-camera system. The light through an object-space telecentric lens was split half-and-half by a beam splitter and then are receiv...
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ISBN:
(纸本)9781509018185
A 3-D measuring method for particle movement was established by using a single-lens dual-camera system. The light through an object-space telecentric lens was split half-and-half by a beam splitter and then are received by two CCD industrial cameras, respectively. These two image sensors have different distances from the telecentric lens. As for the same imaging particle, two images with different degrees of defocus will be captured. These two images were used to solve the ambiguous problem of 3-D particle positions. Combining with the PTV technology and the single-frame and multiple-exposure imaging method, the system can determine the magnitude and direction of 3-D velocity. The feasibility was then proved by experiments.
In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2 droplets in t...
In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2 droplets in the high-speed gas flow is the critical process that determines the cooling rate, cooling capacity and the safe operation of the down-stream compressor. In this study, a numerical model of droplet motion and evaporation in high-speed gas flow is developed and verified against experimental data. The droplet evaporation rate, diameter and velocity are obtained during the evaporation process under different gas temperatures and flow velocities. The results show that the gas temperature has dominant influence on the droplet evaporation rate. High flow speed can increase droplet evaporation effectively at the beginning process. Evaporation of droplets with different diameters follows a similar trend. The absolute evaporation rate increases with the increase of droplet diameter while the relative evaporation amount is highest for the smallest droplet due to its high area-volume ratio. This numerical study provides insight for understanding the evaporation of LN2 droplets in high-speed gas flow and useful guidelines for the design of LN2 spray cooling.
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