Effect of liquid nitrogen cooling on mechanical characteristics and fracture morphology of layer coal under Brazilian splitting test

2022 ◽  
Vol 151 ◽  
pp. 105026
Author(s):  
Peng Hou ◽  
Yi Xue ◽  
Feng Gao ◽  
Fakai Dou ◽  
Shanjie Su ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Mechanical Characteristics ◽  
Fracture Morphology ◽  
Splitting Test ◽  
Liquid Nitrogen Cooling ◽  
Brazilian Splitting

scholarly journals Effect of liquid nitrogen cooling on the permeability and mechanical characteristics of anisotropic shale

2018 ◽  
Vol 9 (1) ◽  
pp. 111-124 ◽  
Author(s):  
Long Jiang ◽  
Yuanfang Cheng ◽  
Zhongying Han ◽  
Qi Gao ◽  
Chuanliang Yan ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Mechanical Characteristics ◽  
Liquid Nitrogen Cooling

Numerical Thermal Simulation of Cryogenic Power Modules Under Liquid Nitrogen Cooling

2005 ◽  
Vol 128 (3) ◽  
pp. 267-272 ◽  
Author(s):  
Hua Ye ◽  
Harry Efstathiadis ◽  
Pradeep Haldar
Keyword(s):  
Liquid Nitrogen ◽  
Electrical Current ◽  
Oxide Semiconductor ◽  
Junction Temperature ◽  
Electronic Systems ◽  
Power Module ◽  
Power Modules ◽  
Allowable Range ◽  
Liquid Nitrogen Cooling ◽  
Thermal Simulations

Understanding the thermal performance of power modules under liquid nitrogen cooling is important for the design of cryogenic power electronic systems. When the power device is conducting electrical current, heat is generated due to Joule heating. The heat needs to be efficiently dissipated to the ambient in order to keep the temperature of the device within the allowable range; on the other hand, it would be advantageous to boost the current levels in the power devices to the highest possible level. Projecting the junction temperature of the power module during cryogenic operation is a crucial step in designing the system. In this paper, we present the thermal simulations of two different types of power metal-oxide semiconductor field effect transistor modules used to build a cryogenic inverter under liquid nitrogen pool cooling and discussed their implications on the design of the system.

scholarly journals The effect of liquid nitrogen cooling on coal cracking and mechanical properties

2018 ◽  
Vol 36 (6) ◽  
pp. 1609-1628 ◽  
Author(s):  
Chengzheng Cai ◽  
Feng Gao ◽  
Yugui Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Acoustic Emission ◽  
Liquid Nitrogen ◽  
Wave Velocity ◽  
Count Rate ◽  
Initial State ◽  
Nitrogen Injection ◽  
Strength Tests ◽  
Liquid Nitrogen Cooling

Liquid nitrogen is a type of super-cryogenic fluid, which can cause the reservoir temperature to decrease significantly and thereby induce formation rock damage and cracking when it is injected into the wellbore as fracturing fluid. An experimental set-up was designed to monitor the acoustic emission signals of coal during its contact with cryogenic liquid nitrogen. Ultrasonic and tensile strength tests were then performed to investigate the effect of liquid nitrogen cooling on coal cracking and the changes in mechanical properties thereof. The results showed that acoustic emission phenomena occurred immediately as the coal sample came into contact with liquid nitrogen. This indicated that evident damage and cracking were induced by liquid nitrogen cooling. During liquid nitrogen injection, the ring-down count rate was high, and the cumulative ring-down counts also increased rapidly. Both the ring-down count rate and the cumulative ring-down counts during liquid nitrogen injection were much greater than those in the post-injection period. Liquid nitrogen cooling caused the micro-fissures inside the coal to expand, leading to a decrease in wave velocity and the deterioration in mechanical strength. The wave velocity, which was measured as soon as the sample was removed from the liquid nitrogen (i.e. the wave velocity was recorded in the cooling state), decreased by 14.46% on average. As the cryogenic samples recovered to room temperature, this value increased to 18.69%. In tensile strength tests, the tensile strengths of samples in cooling and cool-treated states were (on average) 17.39 and 31.43% less than those in initial state. These indicated that both during the cooling and heating processes, damage and cracking were generated within these coal samples, resulting in the acoustic emission phenomenon as well as the decrease in wave velocity and tensile strength.

Analysis of the Crack Fracture Morphology of the Asphalt Mixture under Tensile Stress Effects

2011 ◽  
Vol 250-253 ◽  
pp. 3533-3537 ◽  
Author(s):  
Li Hua Zhao ◽  
Jing Yun Chen ◽  
Sheng Wu Wang
Keyword(s):  
Brittle Fracture ◽  
Fracture Surface ◽  
Tensile Stress ◽  
Mechanical Characteristics ◽  
Asphalt Mixture ◽  
Fracture Morphology ◽  
Microscopic Mechanism ◽  
Interface Zone ◽  
Stress Effects ◽  
Bending Fracture

Through studying the bending fracture and cleavage fracture of the asphalt mixture within the different temperature condition, confirming that the temperature influences the microscopic mechanism of mixture cracking: the fracture is relatively flat with low temperture, the destruction of the asphalt mixture is also mainly result of the brittle fracture; As the temperature rise, fracture surface becomes coarse, some part show large plastic elapse deformation. Adding fiber can reduce thickness of the asphalt membrane, improve the bonding strength of asphalt mastic, and greatly increase the ratio of the aggregate fracture and interface zone fracture, so as to enhance the asphalt mixture crack-resistance. The fracture morphology of asphalt mixture has a better reflection for its mechanical characteristics.

Influence of cryogenic liquid nitrogen cooling and thermal shocks on petro-physical and morphological characteristics of Eagle Ford shale

2021 ◽  
pp. 104313
Author(s):  
Khalil Rehman Memon ◽  
Muhammad Ali ◽  
Faisal Ur Rahman Awan ◽  
Aftab Ahmed Mahesar ◽  
Ghazanfer Raza Abbasi ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Morphological Characteristics ◽  
Cryogenic Liquid ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Liquid Nitrogen Cooling ◽  
Thermal Shocks

scholarly journals Analysis and optimization of cooling channels performances for industrial extrusion dies

2021 ◽  
Author(s):  
Riccardo Pelacci ◽  
Marco Negozio ◽  
Barbara Reggiani ◽  
Lorenzo Donati ◽  
Luca Tomesani
Keyword(s):  
Liquid Nitrogen ◽  
Numerical Models ◽  
Extrusion Process ◽  
Die Design ◽  
Design Stage ◽  
Fe Model ◽  
Cooling Efficiency ◽  
Channel Design ◽  
Liquid Nitrogen Cooling ◽  
Experimental Trials

Liquid nitrogen cooling is widely used in the extrusion industrial practice in order to increase the production rate, to reduce the die temperature and to avoid defects on the profile exit surfaces resulting from an excessive heating. However, the efficiency of the cooling is deeply affected by position and design of the liquid nitrogen channel so that numerical modelling is gaining an increasing industrial interest in relation to the possibility offered to optimize the channel design without expensive and time-consuming experimental trials. In this work, a numerical FE model developed within COMSOL Multiphysics® is proposed and validated against experimental trials performed in industrial environment. The model combines the 3D simulation of the extrusion process with a 1D model of the cooling channel thus allowing the testing of a number of different solutions at the die design stage. The global aim of this work is the assessment of the liquid nitrogen cooling efficiency in the extrusion of an industrial aluminum profile and the proof of the potentials offered by numerical models to get an optimized channel design in terms of cooling efficiency, die thermal balancing and reduction of liquid nitrogen consumption.

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