Inverted bubble point

Room temperature reseal pressure data was collected simultaneously with bubble point data. The same inverted bubble point test configuration used to measure the bubble point was used to measure reseal pressures. A bubble point test ceases once pressurant gas breaks through the wetted pore. To commence a reseal point test, the pressurant gas flow rate beneath the screen is slowly reduced in fixed quasi-static increments to slowly encroach upon the differential pressure across the screen at which the screen reseals. Eventually the screen rewets/reseals itself as evident in visualization of no more bubbles... 

Testing was conducted in the CCL-7 facility at GRC. Two LAD screen samples were tested, a 200 X 1400 and 325 x 2300 Dutch Twill screen. The thickness of the 200 x 1400 and 325 X 2300 screen samples were 152 and 89 jim, respectively. Screen samples were each mounted onto a 2.38 cm tall, 5.08 cm (2 in.) OD cup as shown in Figure 6.1. Note that the LAD cup used in the high-pressure tests was smaller than the screen and cup assembly used in the low-pressure LH2 bubble point tests. As in previous tests, an inverted bubble point test configuration was implemented for the high-pressure LOX tests. The cup was... 

FIGURE E.5 Heated Non-inverted Bubble Point Data in Liquid Nitrogen from Castle (1972). 

Fig. 32). Using a fine pipette insert about i cm. length of the liquid into the bottom of the tube. Now place in the tube A a fine inverted melting-point tube B of about i mm. diameter, sealed at the upper end. Fasten the capillary tube to the ther- Fio. 32. mometer by means of a rubber band and place in a melting-point apparatus. Heat slowly until a stream of bubbles rises from the bottom... 

Note also the inverted configuration in Figure 3.3 for laboratory bubble point testing it is easier to deduce the bubble point when precisely controlling the liquid head pressure on top of the screen and pressurizing the pore from beneath. 

The same IBP test configuration used to measure the bubble point is the ideal test configuration for measuring the reseal pressure for a given screen. Each controlled bubble breakthrough test allows for a controlled reseal pressure test. Details of the inverted reseal pressure test are reserved for Chapter 4 along with the IBP test configuration. 

Bubble point testing was performed in an inverted configuration with the liquid on top and gas on the bottom. The flange was mated with a bottom blind flanged section to create a tight seal at the edges and to allow a small gap beneath the screen for pressurant gas to build up. The bottom section was fitted with pressurization and sensing port lines to... 

The flange was mated with a cylindrical cup shown in Figure 5.2. The purpose of the cup was to create the L/V interface at the screen by pressurizing from imdemeath. Bubble point tests were conducted in an inverted fashion with liquid on top and vapor or gas on the bottom. The cup was equipped with a custom-built cross to allow uniform injection of pressurant gas and slow pressure rise inside the cup. The cup was equipped with a custom fabricated central rod to support three doughnut style heaters which were mounted on the... 

Substituting the hydrostatic, FTS, and frictional and dynamic models from Chapter 3 into Equation (3.3), the total ID pressure drop for the LAD channel in 1-g steady flow is determined, and the model can be used to predict the breakdown point as a function of the liquid temperature and mass flow rate through the LAD. To demonstrate general model trends and predictions, setting Equation (3.3) equal to the bubble point pressure in Equation (3.16), one can then simulate LAD outflow in an inverted 1 -g configuration in LHa for the LAD channels and test conditions that would be typical of an in-space propellant transfer. For a fixed 325 X 2300 screen mesh and LAD channel geometry, examination of the hydrostatic, FTS, frictional, and dynamic pressure drop equations show that the steady state pressure drop is a function of LAD dimensions, liquid temperature, pressure, and mass flow rate. 

With the exception of warm pressurant gas bubble point tests conducted in Chapter 8, the majority of data in the literature was taken with the temperature of the pressurant gas approximately equal to the liquid temperature. This is due to the standard inverted testing configuration used for measuring cryogenic bubble point pressures which forces uniform,... 

A stable operating region beyond flooding (above points D and D ) was discovered (48,49). In this region, the packed column is eessn-tially inverted to a "bubble column. This region is of little significance in industrial practice. 

Place 0.5 gram of cuprous chloride in the bottom of a dry test tube. Fill it completely with 6 N NH4OH and immediately stopper it tightly, allowing no air bubble to remain at the top. Invert the tube a number of times until the salt is dissolved. At this point, the solution should be nearly colorless, and it would be quite so if the salt had been pure and air had been completely excluded. Pour the solution into an open beaker and note the change in color. Equations ... 

Place the microscale assembly in a standard melting-point apparatus (or a Thiele tube if an electrical apparatus is not available) to determine the boiling point. Heating is continued until a rapid and continuous stream of bubbles emerges from the inverted capillary. At this point, stop heating. Soon, the stream of bubbles slows down and stops. When the bubbles stop, the liquid enters the capillary tube. The moment at which the liquid enters the capillary tube corresponds to the boiling point of fhe liquid, and fhe femperafure is recorded. 

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