scholarly journals Propagation Characteristics of Supercritical Carbon Dioxide Induced Fractures under True Tri-Axial Stresses

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4229 ◽  
Author(s):  
Yi Hu ◽  
Feng Liu ◽  
Yuqiang Hu ◽  
Yong Kang ◽  
Hao Chen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
In Situ Stress ◽  
Breakdown Pressure ◽  
Ae Energy ◽  
Induced Fractures ◽  
Supercritical Carbon

Supercritical carbon dioxide (SC-CO2) fracturing is a non-aqueous fracturing technology, which has attracted considerable attention on exploiting shale gas. In this study, shale specimens and artificial sandstone specimens were used to conduct SC-CO2 fracturing and water fracturing experiments to investigate the characteristics of SC-CO2 induced fractures. An acoustic emission (AE) monitoring device was employed to monitor the AE energy release rate during the experiment. The experiment results indicate that the breakdown pressure of SC-CO2 fracturing is lower than that of water fracturing under the same conditions, and the AE energy release rate of SC-CO2 fracturing is 1–2 orders of magnitude higher than that of water fracturing. In artificial sandstone, which is homogeneous, the main fracture mainly propagates along the directions perpendicular to the minimum principal stress, no matter if using SC-CO2 or water as the fracturing fluid, but in shale with weak structural planes, the propagation direction of the fracture is controlled by the combined effect of a weak structural plane and in-situ stress.

scholarly journals Effect of pressure of supercritical carbon dioxide on morphology of wool fibers during dyeing process

2015 ◽  
Vol 19 (4) ◽  
pp. 1297-1300 ◽  
Author(s):  
Lai-Jiu Zheng ◽  
Peng-Peng Yin ◽  
Fang Ye ◽  
Wei Ju ◽  
Jun Yan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Release Rate ◽  
Surface Brightness ◽  
Color Difference ◽  
Effect Of Pressure ◽  
Pressure Release ◽  
Dyeing Process ◽  
Wool Fibers ◽  
Supercritical Carbon

In this paper, the effect of pressure release rate on dyeing of wool fibers was studied in the supercritical carbon dioxide dyeing. Surface morphology, chemical composition and color difference at different pressure release rates were investigated by employing scanning electron microscope, color matching, and measuring instrument. Experiment data reveal that wool fibers are easy to be damaged with increasing pressure release rate. Fiber?s surface brightness varies also with the pressure release rate. The phenomena are theoretically explained using Bernoulli's principle.

Response Surface Modeling of Drug-Loaded Micelles Prepared Through Supercritical Carbon Dioxide Evaporation Method Using Box-Behnken Experimental Design

2019 ◽  
Vol 19 (6) ◽  
pp. 3616-3620 ◽  
Author(s):  
Zhen Jiao ◽  
Xianjun Zha ◽  
Ziyi Wang ◽  
Xiudong Wang ◽  
Wenjing Fan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Response Surface ◽  
Release Rate ◽  
Volume Ratio ◽  
Spherical Shape ◽  
Entrapment Efficiency ◽  
Evaporation Method ◽  
Supercritical Carbon

The nanoscale drug-loaded micelles can be prepared by the supercritical carbon dioxide evaporation method. Here, response surface methodology is used to optimize this process. The effects of pressure, ScCO2 release rate and the volume ratio of water against ScCO2 on the drug entrapment efficiency (EE) of the obtained micelles are discussed in detail. The obtained second-order polynomial equation can successfully predict the drug EE of the drug-loaded micelles. The maximum EE can reach 70.1% under optimal conditions in which the pressure is 12.27 MPa, the release rate is 10 L min−1 and the volume ratio of water against ScCO2 is 3.67:1. The prepared micelles exhibit a narrow size distribution and relatively regularly spherical shape. In vitro drug release study reveals that the release of paclitaxel from the micelles is slow and sustained.

Calculating Energy Release Rate as a Function of Crack Length Using a Multiple-Step Crack Closure Technique in Tire Finite Element Models

2018 ◽  
Vol 46 (3) ◽  
pp. 130-152
Author(s):  
Dennis S. Kelliher
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Crack Closure ◽  
Release Rate ◽  
Fatigue Behavior ◽  
Three Dimensions ◽  
Quantitative Prediction ◽  
Closure Technique

ABSTRACT When performing predictive durability analyses on tires using finite element methods, it is generally recognized that energy release rate (ERR) is the best measure by which to characterize the fatigue behavior of rubber. By addressing actual cracks in a simulation geometry, ERR provides a more appropriate durability criterion than the strain energy density (SED) of geometries without cracks. If determined as a function of crack length and loading history, and augmented with material crack growth properties, ERR allows for a quantitative prediction of fatigue life. Complications arise, however, from extra steps required to implement the calculation of ERR within the analysis process. This article presents an overview and some details of a method to perform such analyses. The method involves a preprocessing step that automates the creation of a ribbon crack within an axisymmetric-geometry finite element model at a predetermined location. After inflating and expanding to three dimensions to fully load the tire against a surface, full ribbon sections of the crack are then incrementally closed through multiple solution steps, finally achieving complete closure. A postprocessing step is developed to determine ERR as a function of crack length from this enforced crack closure technique. This includes an innovative approach to calculating ERR as the crack length approaches zero.

Sign in / Sign up

Export Citation Format

Share Document