Transient Heat Transfer from a Horizontal Cylinder in the Perpendicularand Parallel flow of Helium Gas
Very High Temperature Gas-cooled Reactor system, using helium gas as primary coolant, has been developed to serve the dual role of providing high temperature thermal energy for chemical processing as well as electricity. It is important to clarify the forced convection transient heat transfer process as a database for the reactor system safety assessment. In this study, the transient heat transfer coefficients for helium gas flowing perpendicular (cross-flow) and parallel to a horizontal cylinder were measured. The platinum heater with a diameter of 1.0 mm or 0.7 mm and 2.0 mm was used as test heater and heated by electric current with an exponentially increasing heat input of Q0exp(t/τ). The test channel was a circular channel with an inside diameter of 20 mm, and the test heater was 100 mm in length for the parallel flow. In the case of cross-flow, the test channel was a rectangular channel with a width of 100 mm and a height of 50 mm, and the test heater was 60 mm in length. The periods ranged from 33 ms to 33 s, the helium gas temperatures ranged from 290 to 353 K, and the flow velocity ranged from 4 to 10 m/s for parallel flow and 0 to 0.6 m/s for cross-flow. It was clarified that the heat transfer coefficient approaches the quasi-steady-state one for the period τ over around 1 s, and it becomes higher for the period of τ shorter than about 1 s. The perpendicular flow shows large difference with the parallel flow on the heat transfer. Based on the experimental data, the ratio of transient heat transfer to the quasi-steady-state one was correlated as a function of the non-dimensional period of increasing heat input. For the non-dimensional period larger than about 300, the transient heat transfer approaches the steady-state heat transfer.
Transient Heat Transfer Convection VHTR Exponentially Increasing Period Helium Gas Cross-flow Parallel Flow
Qiusheng LIU Katsuya FUKUDA
Dept. Of Marine Engineering, Kobe University 1-1, 5-chome, Fukae-Minami-machi, Higashinadaku, Kobe 658-0022, Japan
国际会议
上海
英文
178-190
2010-10-10（万方平台首次上网日期，不代表论文的发表时间）