Liquid hydrogen test tank

The test unit was installed in a blow-down arrangement (Fig. 4) using a 6000 gal liquid hydrogen storage tank as a pressurized reservoir. The hydrogen was vented to a flare after passing through the unit,... 

The purpose of this chapter is to present the experimental results for the full-scale LAD outflow tests in liquid hydrogen. Test conditions were taken over a wide range of liquid temperatures (20.3-24.2 K), tank pressures (100-350 kPa), and outflow rates (0.010-0.055 kg/s) thermally and operationally representative of an in-space propellant transfer from a depot storage tank or to a smaller scale in-space engine. Horizontal LAD tests were conducted to measure independently the frictional and dynamic losses down the channel. Flow-through-screen tests were performed to measure independently the dominate pressure loss in LEO, the FTS resistance. Meanwhile, 1-g inverted vertical LAD outflow tests were conducted to obtain performance data for two full-scale 325 x 2300 LAD channels. One of the channels had a perforated plate and a custom-built internal thermodynamic vent system to enhance performance. Model predictions from Chapter 3 are compared to each set of experimental data. 

To All a tank system in the test stand or in a car, liquid hydrogen is first transferred from the main tank to the conditioning container. There the pressure can be adjusted. From the conditioning container, the test tank is filled again by a pressure gradient. 

Before liquid hydrogen can be transported and filled, all parts have to be cooled to —253 °C. During the filling process, a certain amount of gaseous hydrogen has to be transferred back from the test tank system, the so called back-gas m g. This will be analyzed in more detail, compare [5]. 

This evaporation increases the pressure on the tank wall and the gaseous hydrogen must be vented to the atmosphere to keep the tank from rupturing. During tests at the Los Alamos National Laboratory a liquid hydrogen fueled vehicle tank of liquid hydrogen evaporated away in about 10 days. 

At Wright-Patterson Air Force Base, armor-piercing incendiary and fragment simulator bullets were fired into aluminum storage tanks containing both kerosene and liquid hydrogen. The test results indicated that the liquid hydrogen was safer than conventional aviation kerosene. 

Tests were conducted, die first with an LH2 tank of such a size, to investigate the thermodynamic behavior of the liquid hydrogen in the tank. One important goal was to examine the pressure rise in the closed tank. Three test series were conducted [52, 69] ... 

Answer by Author During the test a large leak occurred when an evacuation line was inadvertently opened. The liquid hydrogen boil-ofF rate increased considerably during the time air was condensed in the insulation. However, we successfully warmed the tank and removed all the air from the insulation with no difficulty or damage to the insulation. 

The stratification test program described here utilized a 70-ft vacuum-jacketed test vessel. The test vessel was a 4-ft-diameter x 6-ft-long stainless steel inner tank supported within a 6-ft-diameter outer tank by means of four legs, several tie rods, and a sway bar. The inner tank was designed for a working pressure of ISOpsig at liquid-hydrogen temperature. Its upper and lower domes w ere insulated with 1 in. of multilayer insulation to minimize inadvertent heat leak to the test fluid. Removal of the outer tank dome (Fig. 2) provides ready access to the inner tank. A 14-in. manhole in the upper dome of the inner tank provides access to the tank interior. 

To provide stratification test data in liquid hydrogen, an experimental program was conducted utilizing a 500-gal test tank. In the test program, the effects on stratification of the liquid height-to-diameter ratio were investigated. 

In all the tests, which included both self-pressurization and external pressurization procedures, the tank was initially filled with liquid hydrogen saturated at pressures close to 1 atm. The wall heat flux was then obtained from a boil-off calibration and the test begun immediately afterward. During testing, a continuous record of the various resistor and thermocouple readings was made. 

During a test period, the tank was filled with liquid hydrogen and the temperature history of the exterior of the insulation was cycled repeatedly as the hydrogen was allowed to boil off. Five thermocouples strategically distributed over the insulation surfaces indicated the temperatures of the outer surface, and the exact cycle time was controlled by the thermocouple that last reached the desired temperature. (The initial tests were observed... 

Fourteen commercially available organic foam insulations were examined to determine their suitability for insulating liquid hydrogen tanks of subsonic hydrogen fueled aircraft. Materials investigated were polyurethane, polymethacryllmide, polyisocyanurate, polymetric isocyanate, polybenzamidazole, toluenedi isocyanate, and isocyanate foam. The test specimens included foams with chopped fiberglass reinforcements, flame retardants, and vapor barriers. 

Foam thickness was scaled to simulate stress conditions encountered by insulation on a large diameter tank. Insulation specimens were bonded to a thin, flat aluminum tank, which had separate compartments for six specimens. The tests were conducted by filling the compartments with liquid hydrogen and exposing the outer surface of the insulations to a cyclic thermal environment representative of repeated subsonic aircraft flight. The boil-off rate in each compartment indicated insulation thermal performance. 

PERFORMANCE OF HIGH-EFFICIENCY INSULATION ON A 35-LITER CONTAINER. After completing tests on the small sample, attention was directed to the practical applications of this insulation on a liquid-nitrogen and liquid-hydrogen container, A tank 1 ft in diameter by 2 ft tall (approximately 35-liter capacity) was built. 

The neck heat losses and the heat losses through the structure supporting the inner tank were calculated to be approximately 10 of the total heat loss through 1 in. of insulation with a thermal conductivity of 0.0012 Btu-ia/hr- F-ft. Figure 4 shows the inside tank of this container and Fig. 5 shows the complete instrumentation for the test. Separate tests were run with liquid nitrogen and with liquid hydrogen in the tank. Insulation 1 in. thick and l/4 in. thick was used in these tests (see Table II). 

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