Numerical simulations have been performed to investigate the flow and heat transfer characteristics of near-critical and supercritical CO_2) in the thermally driven high pressure CO_2, circular system proposed by the authors by using of a CFD code, FLUENT. Since the flow can be easily turbulence due to its low kinematic viscosity, the renormalization group (RNG) k-c model was adopted to account for the turbulent flow appropriately. The physical property temperature dependence of CO_2 was considered with piecewise-linear profile (properties vs temperature) under constant pressure. It was found that M-shape radial velocity profile of heating zone was developed by sharply high flow near the wall and relatively slow main flow and that the average circulation flow rate was comparable to that measured by tracer method.

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超臨界水酸化技術の設計支援ツールとしての熱流動解析システムの構築を目指しており、その一環として表面反応と物質移動の粒子間相互の影響を調べるために炭素粒子2個の超臨界水酸化の解析を行った.炭素粒子は流れ方向に2個並べ、粒子間距離を0、2、4mmと変えて解析を行った。炭素粒子は活性炭とし、反応は表面反応として扱う。下流側の粒子は粒子間距離が大きくなると反応量が上流側の粒子に比べてmmで25%、2mmで21%、4mmで18%小さくなる。また、多粒子系での反応工学モデルを構築する場合、粒子表面温度の考慮が必要であることが分かった。

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In this paper, fine particles forming process within the new beadless disperser is simulated by finite based lattice Boltzmann method. With the calculating results, the new disperser's ability to make fine discussed. The simulation results have a good agreement with the test ones. It shows that the lattice method is convenient and effective for the simulation of two phase shear flow.

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This paper describes a numerical study of a information preservation (IP) method for low-Mach number, microscale gas flows. Reliability of the method is examined for the flows about a micro circular cylinder at the Mach number range from 0.01 to 0.1-and the Knudsen number range from 0.01 to 1.0.. The IP method gives reasonable results at a moderate number of sample size with which the, conventional direct simulation Monte Carlo (DSMC) method gives no meaningful results.

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This paper describes a preliminary study of a hybrid simulation method for multi-scale gas flows using the Boltzmann equation and the Navier-Stokes equations. Reliability and flexibility of the method are demonstrated for the flow simulation about a micro circular cylinder at the Mach number range from 0.01 to 0.1 and the Knudsen number range from 0.01 to 1.0. Reliable results-without any oscillation and fluctuation at the interface of hybrid scheme are obtained even for the low Mach number flows. It may be promised that the hybrid method will become a good simulation tool for analyzing multi-scale gas flows.

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