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Natsume, Kyohei; Murakami, Haruyuki; Kizu, Kaname; Yoshida, Kiyoshi; Koide, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101(1), p.012113_1 - 012113_8, 2015/12
Times Cited Count：2 Percentile：64.53(Thermodynamics)Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kawakami, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101, p.012108_1 - 012108_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)Supercritical hydrogen with a temperature of less than 20 K and a pressure of 1.5 MPa is used as moderator material at J-PARC. Total nuclear heating of 3.75 kW is generated by three moderators for a 1-MW proton beam operation. We have developed an orifice-type high-power heater for thermal compensation to mitigate hydrogen pressure fluctuation caused by the abrupt huge heat load and to reduce the fluctuation in the temperature of the supply hydrogen to less than 0.25 K. Through a performance test, we confirmed that the developed orifice-type heater could be heated uniformly and showed fast response, as expected. Furthermore, a simulation model that can describe heater behaviors has been established on the basis of the experimental data. The heater control approach was studied using the aforementioned heater simulation model and a dynamic simulation code developed by the authors.
Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Naruo, Yoshihiro*; Kobayashi, Hiroaki*; Nonaka, Satoshi*; Inatani, Yoshifumi*
IOP Conference Series; Materials Science and Engineering, 101, p.012177_1 - 012177_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)Transient heat transfers from PtCo wire heaters inserted into vertically-mounted pipes, through which forced flow subcooled liquid hydrogen was passed, were measured by increasing the exponential heat input with various time periods at a pressure of 0.7 MPa and inlet temperature of 21 K. The flow velocities ranged from 0.3 to 7 m/s. The PtCo wire heaters had a diameter of 1.2 mm and lengths of 60 mm, 120 mm and 200 mm and were inserted into the pipes with diameters of 5.7mm, 8.0 mm, and 5.0 mm, respectively. With increase in the heat flux to the onset of nucleate boiling, surface temperature increased along the curve predicted by the Dittus-Boelter correlation for longer period, where it can be almost regarded as steady-state. For shorter period, the heat transfer became higher than the Dittus-Boelter correlation. In nucleate boiling regime, the heat flux steeply increased to the transient critical heat flux (CHF), which became higher for shorter period. Effect of flow velocity, period, and heated geometry on the transient CHF was clarified.
Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kawakami, Yoshihiko; Aoyagi, Katsuhiro; Muto, Hideki
IOP Conference Series; Materials Science and Engineering, 101, p.012107_1 - 012107_8, 2015/12
Times Cited Count：0 Percentile：0.00(Thermodynamics)The Japan Proton Accelerator Research Complex (J-PARC) cryogenic hydrogen system was completed in April 2008. The proton beam power was gradually increased to 500 kW. A trial 600-kW proton beam operation was successfully completed in April 2015. We achieved long-lasting operation for more than three months. However, thus far, we encountered several problems such as unstable operation of the helium refrigerator because of some impurities, failure of a welded bellows of an accumulator, and hydrogen pump issues. Furthermore, the Great East Japan Earthquake was experienced during the cryogenic hydrogen system operation in March 2011. In this study, we describe the operation characteristics and our experiences with the J-PARC cryogenic hydrogen system.
Tatsumoto, Hideki; Otsu, Kiichi; Aso, Tomokazu; Kawakami, Yoshihiko
IOP Conference Series; Materials Science and Engineering, 101, p.012109_1 - 012109_8, 2015/12
Times Cited Count：1 Percentile：49.66(Thermodynamics)The J-PARC cryogenic hydrogen system provides supercritical cryogenic hydrogen to the moderators at a pressure of 1.5 MPa and temperature of 18 K and removes 3.8 kW of nuclear heat from the 1 MW proton beam operation. We prepared a heater for thermal compensation and an accumulator, with a bellows structure for volume control, to mitigate the pressure fluctuation caused by switching the proton beam on and off. In this study, a 1-D simulation code named DiSC-SH2 was developed to understand the propagation of pressure and temperature propagations through the hydrogen loop due to on and off switching of the proton beam. We confirmed that the simulated dynamic behaviors in the hydrogen loop for 300-kW and 500-kW proton beam operations agree well with the experimental data under the same conditions.
