Investigation Into Thermal Stress Characteristics of Pipe-in-Pipe Under High Temperature Condition

In this paper, the thermal stress characteristics of the pipe-in-pipe (PIP) system under high temperature condition are analyzed. The PIP is a type of pipe applied in sodium-cooled faster reactor (SFR) and has a different geometry from a single pipe. In particular, under the high temperature condition of the SFR, the high thermal stress is generated due to the temperature gradient occurring between the inner pipe and outer pipe. To investigate the thermal stress characteristics, three cases are considered according to geometry of the support. The fully constrained support and intermediate support are considered for case 1 and 2, respectively. For case 3, both supports are applied to the actual curved pipe. The finite element (FE) analyses are performed in two steps for each case. Firstly, the heat transfer analysis is carried out considering the thermal conduction, convection and radiation conditions. From the heat transfer analysis, the temperature distribution results in the piping system are obtained. Secondly, the structural analysis is performed considering the temperature distribution results and boundary conditions. Finally, the effects of the geometric characteristics on the thermal stress in the PIP system are analyzed.

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Analysis to Reduce Thermal Stress in Oxide Single Crystal During Czochralski Growth

Heat Transfer, Volume 2 ◽

10.1115/imece2004-59134 ◽

2004 ◽

Author(s):

Shigeki Hirasawa ◽

Hiroyuki Ishibashi ◽

Kazuhisa Kurashige ◽

Akihiro Gunji

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

Temperature Distribution ◽

Thermal Radiation ◽

Single Crystal ◽

Radiation Heat Transfer ◽

Heat Transfer Analysis ◽

Czochralski Growth ◽

Radiation Heat ◽

Radial Temperature

Temperature distributions and thermal stress distributions in a semi-transparent GSO crystal during Czochralski (CZ) single crystal growth were numerically investigated by thermal radiation heat transfer analysis and anisotropy stress analysis. As GSO has special optical properties, such as semi-transparency at a wavelength shorter than 4.5 μm, thermal radiation heat transfer was calculated by the Monte Carlo method. These calculations showed that thermal stress is caused by the radial temperature distribution on the outside of the upper part of the crystal. To reduce this temperature distribution, the following three manufacturing conditions were found to be effective: use a sharp taper angle of the crystal, install a lid to the top of the insulator, and install a ring around the tapered part of the crystal.

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Modeling of Thermal and Mechanical Behavior of ZrB2-SiC Ceramics after High Temperature Oxidation

Journal of Ceramics ◽

10.1155/2014/169748 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Jun Wei ◽

Lokeswarappa R. Dharani ◽

K. Chandrashekhara ◽

Gregory E. Hilmas ◽

William G. Fahrenholtz

Keyword(s):

Heat Transfer ◽

Finite Element ◽

Thermal Stress ◽

High Temperature ◽

Mechanical Behavior ◽

Stress Analysis ◽

Heat Transfer Analysis ◽

Temperature Oxidation ◽

Thermal Stress Analysis ◽

Sic Ceramics

The effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramics at high temperature are modeled using a micromechanics based finite element model. The model recognizes that when exposed to high temperature in air ZrB2-SiC oxidizes into ZrO2, SiO2, and SiC-depleted ZrB2 layer. A steady-state heat transfer analysis was conducted at first and that is followed by a thermal stress analysis. A “global-local modeling” technique is used combining finite element with infinite element for thermal stress analysis. A theoretical formulation is developed for calculating the thermal conductivity of liquid phase SiO2. All other temperature dependent thermal and mechanical properties were obtained from published literature. Thermal stress concentrations occur near the pore due to the geometric discontinuity and material properties mismatch between the ceramic matrix and the new products. The predicted results indicate the development of thermal stresses in the SiO2 and ZrO2 layers and high residual stresses in the SiC-depleted ZrB2 layer.

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