1. Shanghai Jiao Tong University Effect of pressure control range on the thermodynamic venting of liquid hydrogen in a tank at zero gravity Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University, P.R. China *Corr.: Dr. Yonghua Huang, huangyh@sjtu.edu.cn; TEL: +86-21-34206295 B. Wang, Y.H. Huang*, Z.C. Chen, J. Y. Wu, P. Li, P. J. Sun

2. Shanghai Jiao Tong University 2 Content Introduction Modeling Results and discussion Conclusions

3. Shanghai Jiao Tong University 3 Introduction  Technologies of cryogenic fluids storage tank and lorry tanker on ground [thermal and structure design…]  Thermal insulation performance calculation and test

4. Shanghai Jiao Tong University 4 Introduction Multilayer insulation (VD-MLI) Zero boiling off (ZBO) NASA has conducted plentiful studies in this area since 1960 What about cryogenic fluids storage in space (zero gravity)? How to control the pressure in tank? How to vent vapor/gas only instead of vapor-liquid mixture? Thermodynamic Vent System (TVS) Vapor Cooling Shield (VCS) … …

5. Shanghai Jiao Tong University 5 Introduction 1.Marshall Space Flight Center (1996) : experimental study TVS in LH 2 tank. 2.Marshall Space Flight Center (1999) : experimental study TVS in LN 2 tank. 3.Lewis Research Center (2004) : theoretical research TVS in LH 2 tank. 4.Glenn Research Center (2008) : experimental study TVS in LO 2 tank. 5.… 1.Marshall Space Flight Center (1996) : experimental study TVS in LH 2 tank. 2.Marshall Space Flight Center (1999) : experimental study TVS in LN 2 tank. 3.Lewis Research Center (2004) : theoretical research TVS in LH 2 tank. 4.Glenn Research Center (2008) : experimental study TVS in LO 2 tank. 5.… 1.difference between mixing mode and venting mode 2.effect of pressure control range on TVS 1.difference between mixing mode and venting mode 2.effect of pressure control range on TVS What about ? 

6. Shanghai Jiao Tong University 6 Modeling Spray bar TVS schematic

7. Shanghai Jiao Tong University 7 Calculation process Visual studio IDE + Intel Fortran For example the vapor

8. Shanghai Jiao Tong University 8 Results and discussion 23.1K 21.53K 140.3kPa 172.4kPa Ullage temperature rise rate: 3.63 K/s, liquid temperature rise rate: 0.67 K/s. Ullage pressurization rate: 1.03Pa/s, liquid pressurization rate: 0.07Pa/s. Gravity: 0-g, Tank volume: 18.09 m 3 Fluid: hydrogen, filling rate: 75% Initial temperature 21.5 K and pressure 137.9 kPa. Self- pressurization

9. Shanghai Jiao Tong University 9 Results and discussion ΔT1ΔT1 ΔT2ΔT2 ΔT3 ΔT4 ΔT 1 =0.01h, ΔT 2 =0.026h, ΔT 1 /ΔT 2 =0.40 ΔT 3 =1.05h, ΔT 4 =2.150h, ΔT 4 /ΔT 3 =2.05 Mixing and venting process

10. Shanghai Jiao Tong University 10 Results and discussion ullage pressure variation compared with that in Ref.8 Pressure control range of present study [Modeling]: 165.5-172.4 kPa Pressure control range of ref. 8 [Exp]: 131-137.9kPa T1T1 T2T2 For the same gap 6.9 kPa T 1 = 32,000 s T 2 = 61,000 s Ref. 8: Hastings L J, Flaehbart R H, Martin J J, et al. Spray bar zero-gravity vent system for on-orbit liquid hydrogen storage[R], NASA/TM (2003).

11. Shanghai Jiao Tong University 11 Results and discussion Pressure variation profile for three different pressure-control-range cases parameter Tank volume ( m 3 ) Heat leak ( W/m 2 ) Fill level ( % ) Flow rate of pump ( L/min ) Initial temperature ( K ) Initial pressure ( kPa ) Pressure control range ( kPa ) value18.090.7675107021.5137.9 165.5-172.4 165.5-179.3 165.5-182.2 Tank size and working condition parameters ΔP 1 = 6.9 kPa ΔP 2 = 13.8 kPa ΔP 3 = 20.4 kPa ΔP2ΔP2 ΔP3ΔP3 ΔP1ΔP1

12. Shanghai Jiao Tong University 12 Results and discussion TVS cycle numbers and cycle interval time under different pressure control range The cycle number decreased by ~ 66% The cycle interval time increased by ~ 2.1 times 1.9 3.8 5.8 62 31 21

13. Shanghai Jiao Tong University 13 Results and discussion TVS running time [turn-on] and fluid mass loss under different pressure control range The cycle duration hour reduced by ~18%. The fluid mass loss decreased by ~19%. 1.09 0.94 0.89 473 403 385

14. Shanghai Jiao Tong University 14 Conclusions An analytical model is established to predict the behavior of pressure variation inside a liquid hydrogen tank with TVS installed. The TVS control system is effective in maintaining the tank pressure within specified pressure-control-ranges. The pressure-ranges have great influence on the TVS performance and the fluid mass loss. When the pressure range increases from 6.9 kPa to 20.4 kPa, the cycle number decreases from 62 to 21, and the cycle duration hour reduces from 1.09 to 0.89. The rate of LH 2 evaporation loss in 24 hours decreases from 0.17% to 0.14%. If higher weight load and pressure proof of the tank are allowed, larger control-range is preferred.

15. Shanghai Jiao Tong University 15