Thermodynamic vent systems

Thermodynamic Vent System Heat Exchanger Analysis. 238... 

Thermodynamic Vent System Cooled 325 x 2300 Channel Performance. ..252... 

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. 

HGURE 9.18 325 x 2300 Thermodynamic Vent System Cooled Channel. 

Thermodynamic Vent System 325 x 2300 Channel at (a) First Helium Bubble Ingestion and (b) Total Breakdown. 

Thermodynamic Vent System Cooled 325 x 2300 Channel Performance Figure 9.26 plots the exposed screen length for the TVS cooled 325 x 2300 chtinnel as a function of tank liquid temperature and LAD outflow rate, and Table 9.10 summarizes TVS performance. For all points shown in Figure 9.26, the TVS was engaged, and the flow rate through the TVS coil was approximately the same, 1.14 g/s. However the amoimt of... 

FIGURE 9.27 Exposed Screen Height as a Function of Mass Fiow Rate through the Thermodynamic Vent System Cooled 325 X 2300 Channel with the Thermodynamic Vent System Engaged and Disengaged. 

FIGURE 9.28 Thermodynamic Vent System Heat Exchanger Efficiency in Terms of the Temperature Difference between Bulk Liquid in the Tank and the Liquid inside the Channel. Data points are for 24.2 K liquid temperature tests. 

Winters, BA., 1996. Analysis of the solar thermal upper stage technology demonstrator liquid acquisition device with integrated thermodynamic vent system. In AIAA-96-2745 32nd Joint Propulsion Conference, Lake Buena Vista, FL, July 13. 

FIGURE 9.24 Pre and Post Isopropyl Alcohol Bubble Point Testing of the (a) 325x2300 Standard Channei and (b) Thermodynam ic Vent System Channei. The biack iine is the prediction curve based on the temperature of the iPA and 325 X 2300 pore diameter from Chapter 4. 

Fig. 22.6. Redox potentials (mV) of various half-cell reactions during mixing of fluid from a subsea hydrothermal vent with seawater, as a function of the temperature of the mixture. Since the model is calculated assuming 02(aq) and H2(aq) remain in equilibrium, the potential for electron acceptance by dioxygen is the same as that for donation by dihydrogen. Dotted line shows currently recognized upper temperature limit (121 °C) for microbial life in hydrothermal systems. A redox reaction is favored thermodynamically when the redox potential for the electron-donating half-cell reaction falls below that of the accepting half-reaction.

Physical and thermodynamic property data, such as thermal expansion coeffici t, are important in process engineering. The following brief discussion illustrates such importance. Liquids contained in process equipment will expand with an increase in temperature. To accommodate such expansion, it is necessary to design a relief system which will relieve (or vent) the thermally expanding liquid and prevent pressure build-up from the expansion. If provisions are not made for a relief system, the pressure will increase from die diermally expanding liquid. If the pressure increase is excessive, damage to the process equipment vtdll occur. 

Besides these thermodynamic criteria, the most common approach used in the literature is based on the operation at pressures above the binary (liquid - SC-CO2) mixture critical point, completely neglecting the influence of solute on VLEs of the system. But, the solubility behavior of a binary supercritical COj-containing system is frequently changed by the addition of a low volatile third component as the solute to be precipitated. In particular, the so-called cosolvency effect can occur when a mixture of two components solvent+solute is better soluble in a supercritical solvent than each of the pure components alone. In contrast to this behavior, a ternary system can show poorer solubility compared with the binary systems antisolvent+solvent and antisol-vent+solute a system with these characteristics is called a non-cosolvency (antisolvent) system. hi particular, in the case of the SAS process, they hypothesize that the solute does not induce cosolvency effects, because the scope of this process lies in the use of COj as an antisolvent for the solute, inducing its precipitation. 

The initial procedure for membrane formation from such ternary systems is always to prepare a homogeneous (thermodynamically stable) polymer solution. This will often correspond to a point on the polymer/sol vent axis. However, it is also po.ssible to add nonsolvent to such an extent that all the components are still miscible. Demixing will occur by the addition of such an amount of nonsoivent that the solution becomes thermodynamically unstable. 

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