Heat Transfer Characteristics of a Horizontal Wire in Pools of Liquid and Supercritical Hydrogen

Abstract

Abstract.Heat transfer from a horizontal wire immersed in liquid and supercritical hydrogen was measured with a quasi-steady increase of a heat generation rate for wide range of bath temperatures and pressures. The nucleate boiling heat transfer coefficient is higher for higher pressure. The CHF is highest in the vicinity of 0.4 MPa and is expressed by Kutateladze's equation. The CHFs become higher for higher subcooling. The heat transfer under supercritical pressure is the same as natural convection heat transfer in liquid hydrogen, but it detoriorates for the heated surface temperautre higher than pseudo-critical temperature. The heat transfer correlation was derived based on the experimental data.

Survey on the nucleate pool boiling of hydrogen and its limits

“…Shiotsu et al [30] have experimentally revealed the impact of the exponential period on the CHF by modifying the pressure. Tatsumoto et al [31] found the experimental results of the action of pressure on CHF, the latter increases, reaches a peak then decreases. Ohk and Chung [32] visualized experimentally the inclination effect of the wall on the CHF by a non-heating method, and compared the results with existing correlations.…”

“…Sets of experimental assemblies have been developed to study nucleate boiling, to identify the beginning of boiling and the limit of critical flux. An overall review and collection of experimental data relating to nucleate boiling [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], ONB [21,26,28,30], and CHF [20,24,26,[28][29][30][31][32][33], was made for the pool boiling of hydrogen under saturation conditions.…”

“…The curve starts from a low value increases passing through an extremum then tends towards zero at the approach of the pressure critical. Some points are scattered and do not follow the shape of the curve, other points indicate several values of CHF for the same value of the ratio, the peak is reached for a reduced pressure lying between 0.3 and 0, 4; 130 points were collected from experiences [20,24,26,[28][29][30][31][32][33].…”

“…An exhaustive review of the experimental data was made, presented in table 1, totaling 1200 points and concerning the nucleate pool boiling of hydrogen under saturation conditions. In this study, the pressure varies from 6.9×10 3 to 11×10 5 Pa, the heat flux extends over a range of 70 to 220×10 3 W/m², the temperature difference ΔT is limited between 0.03 and 27.93 K. The analysis of the experiments showed that different geometries were chosen for the body of the heating element, we note a tube [17], a ribbon [19], a cylinder [25], a sphere [22], wires [15,20,22], plates [16,18,[29][30][31] and the most used are disks [21][22][23][24][26][27][28]. These heating elements were made of various materials such as Lead, Platinum, Aluminum alloy, Chromel A, Teflon, Glass, Bronze, Steel, Stainless Steel, Manganin and the one that comes back the most is Copper.…”

“…In the analyzed experiments, several variables were treated to determine their effects on the nucleate boiling, one distinguishes the material of the heater [21,22,26], its geometry [22,26], its state of surface [ 21], and its orientation [16,21,27,28]. The effect of pressure has also studied extensively [16,19,24,25,26,28,29,31], as well as the direction of the heat flux, ascendant or descendant [21,22,[26][27][28]30], fast or slow [30]. Figure 4 exhibit us the heat flux as a function of the temperature difference for all the experimental data that has been collected, a dispersion of the points over a wide band is noted with homogeneous concentrations, and particularly important in the middle.…”