scholarly journals Numerical Investigation of the Transient Behavior of a Hot Gas Duct under Rapid Depressurization

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
JingBao Liu ◽  
ShengYao Jiang ◽  
Tao Ma ◽  
RiQiang Duan
Keyword(s):  
High Temperature ◽  
Numerical Investigation ◽  
Structural Integrity ◽  
Transient Behavior ◽  
Pressure Differential ◽  
Key Factors ◽  
Pressure Transient ◽  
Hot Gas ◽  
Large Pressure ◽  
Decisive Parameter

A hot gas duct is an indispensable component for the nuclear-process heat applications of the Very-High-Temperature Reactor (VHTR), which has to fulfill three requirements: to withstand high temperature, high pressure, and large pressure transient. In this paper, numerical investigation of pressure transient is performed for a hot gas duct under rapid depressurization. System depressurization imposes an imploding pressure differential on the internal structural elements of a hot gas duct, the structural integrity of which is susceptible to being damaged. Pressure differential and its imposed duration, which are two key factors to evaluate the damage severity of a hot gas duct under depressurization, are examined in regard to depressurization rate and insulation packing tightness. It is revealed that depressurization rate is a decisive parameter for controlling the pressure differential and its duration, whereas insulating-packing tightness has little effect on them.

Numerical Investigation of Thermo-Mechanical Behaviour of Ball Grid Array Solder Joint at High Temperature Excursion

2011 ◽  
Vol 367 ◽  
pp. 287-292 ◽  
Author(s):  
E.H. Amalu ◽  
N.N. Ekere ◽  
R.S. Bhatti ◽  
S. Mallik ◽  
G. Takyi ◽  
...  
Keyword(s):  
High Temperature ◽  
Solder Joint ◽  
Numerical Investigation ◽  
High Temperatures ◽  
Structural Integrity ◽  
Mechanical Response ◽  
Coefficient Of Thermal Expansion ◽  
Electronic Systems ◽  
Bonded Materials ◽  
Transient Thermal

The solder joints of surface mount components (SMCs) experience thermal degradation culminating in creep and plastic shear strain deformation when subjected to cyclic temperature load over time. Degradation at the joints is due to thermal stress induced by the incompatible, differential and nonlinear expansion mismatch of the different bonded materials in the assembly. The stress magnitude influences the strain behaviour. Plastic strain response of solder joint is critical at the materials interface at the lower part of the joint due to the occurrence of wider variation in the coefficient of thermal expansion of the bonded materials and this may lead to static structural failure. The life expectancy of electronic components reduces exponentially as the operating temperature increases thus making reliability a key concern for electronic systems operating at high temperatures and in harsh environments. This paper reports on the numerical investigation of thermo-mechanical response of a critical BGA joint especially the character of plastic deformation of SnPb solder used in forming the joint as well as the joint’s high temperature reliability. The analysis uses a 3-D models to predict the effect of the transient thermal load on the static structural integrity of a single BGA joint. In this study, the base diameter of solder ball (interface between the PCB, copper pad and the solder) experienced higher damage than the top diameter interconnects. The paper provides a simplified methodology to study the reliability of BGA solder joint at high temperatures excursion.

Numerical investigation on thermohydraulic performance of high temperature hydrogen in twisted rod channels

2021 ◽  
Vol 161 ◽  
pp. 108434
Author(s):  
Yuliang Fang ◽  
Hao Qin ◽  
Chenglong Wang ◽  
Lei Zhou ◽  
Jing Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Numerical Investigation

Comparison of the Limit Loads Between Defected Pressure Pipes With an Internal Pit and an External Pit at High Temperature

2013 ◽  
Author(s):  
Changyu Zhou ◽  
Bo Wang ◽  
Zhigang Sun ◽  
Jilin Xue ◽  
Xiaohua He
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Structural Integrity ◽  
Load Condition ◽  
Relative Length ◽  
Limit Load ◽  
Relative Depth ◽  
Corrosive Media ◽  
Pressure Pipe ◽  
Pressure Pipes

High temperature pressure pipes are widely used in power stations, nuclear power plants, and petroleum refinery, which always bear combined effects of high temperature, high pressure, and corrosive media, so the local pits are the most common volume defects in pressure pipe. Due to various reasons, the defects usually appear on the internal or external wall of pipe. In this paper, the dimensions of a defect were characterized as three dimensionless factors: relative depth, relative gradient and relative length. The main objects of study were the pipe with an internal pit and pipe with an external pit. Orthogonal array testing of three factors at four different levels was applied to analyze the sequence of the influence of three parameters. In present study, when the maximum principal strain nearby the location of the defects reaches 2%, the corresponding load is defined as the limit load, which is classified as two kinds of load type: limit pressure and limit bending moment. According to this strain criterion and isochronous stress strain data of P91 steel, the limit load of high temperature pipe with a local pit was determined by using ABAQUS. And in the same load condition of the pipe with the same dimensionless factors, the limit load of the internal defected pipe was compared with that of the external defected pipe. The results of this study can provide a reference for safety assessment and structural integrity analysis of high temperature creep pressure pipe with pit defects.

Pressure Transient Behavior In Reservoirs With An Internal Circular Discontinuity

SPE Journal ◽  
1996 ◽  
Vol 1 (01) ◽  
pp. 83-92 ◽  
Author(s):  
Adalberto J. Rosa ◽  
Av. Antonio Carlos Magalhaes ◽  
Roland N. Horne
Keyword(s):  
Transient Behavior ◽  
Pressure Transient

A Brief Overview on High Temperature Friction and Wear

2010 ◽  
Author(s):  
Mustafa Bulut Coskun ◽  
Mahmut Faruk Aksit
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Friction And Wear ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Wear Performance ◽  
Large Pressure ◽  
Higher Power ◽  
Vibratory Motion ◽  
Increasing Temperature

With the race for higher power and efficiency new gas turbines operate at ever increasing pressures and temperatures. Increased compression ratios and firing temperatures require many engine parts to survive extended service hours under large pressure loads and thermal distortions while sustaining relative vibratory motion. On the other hand, wear at elevated temperatures limits part life. Combined with rapid oxidation for most materials wear resistance reduces rapidly with increasing temperature. In order to achieve improved wear performance at elevated temperatures better understanding of combined wear and oxidation behavior of high temperature super alloys and coatings needed. In an attempt to aid designers for high temperature applications, this work provides a quick reference for the high temperature friction and wear research available in open literature. High temperature friction and wear data have been collected, grouped and summarized in tables.

Creep-Fatigue Interaction Effects On Pressure-Reducing Valve Under Cyclic Thermo-Mechanical Loadings Using Direct Cyclic Method

2021 ◽  
Author(s):  
Nak-Kyun Cho ◽  
Youngjae Choi ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Fatigue Failure ◽  
Material Properties ◽  
Structural Integrity ◽  
Direct Method ◽  
Element Model ◽  
Critical Loading ◽  
Creep Fatigue ◽  
Pressure Reducing Valve

Abstract Supercritical boiler system has been widely used to increase efficiency of electricity generation in power plant industries. However, the supercritical operating condition can seriously affect structural integrity of power plant components due to high temperature that causes degradation of material properties. Pressure reducing valve is an important component being employed within a main steam line of the supercritical boiler, which occasionally thermal-fatigue failure being reported. This research has investigated creep-cyclic plastic behaviour of the pressure reducing valve under combined thermo-mechanical loading using a numerical direct method known as extended Direct Steady Cyclic Analysis of the Linear Matching Method Framework (LMM eDSCA). Finite element model of the pressure-reducing valve is created based on a practical valve dimension and temperature-dependent material properties are applied for the numerical analysis. The simulation results demonstrate a critical loading component that attributes creep-fatigue failure of the valve. Parametric studies confirm the effects of magnitude of the critical loading component on creep deformation and total deformation per loading cycle. With these comprehensive numerical results, this research provides engineer with an insight into the failure mechanism of the pressure-reducing valve at high temperature.

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