Pressurization and expulsion of cryogenic liquids: Generic requirements for a low gravity experiment

Requirements are presented for an experiment designed to obtain data for the pressurization and expulsion of a cryogenic supply tank in a low gravity environment. These requirements are of a generic nature and applicable to any cryogenic fluid of interest, condensible or non-condensible pressurants, and various low gravity test platforms such as the Space Shuttle or a free-flyer. Background information, the thermophysical process, preliminary analytical modeling, and experimental requirements are discussed. Key parameters, measurements, hardware requirements, procedures, a test matrix, and data analysis are outlined

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure

A review of candidate multilayer insulation systems for potential use on wet-launched LH2 tankage for the space exploration initiative lunar missions

The storage of cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) for the future Space Exploration Initiative (SEI) will require lightweight, high performance thermal protection systems (TPS's). For the near-term lunar missions, the major weight element for most of the TPS's will be multilayer insulation (MLI) and/or the special structures/systems required to accommodate the MLI. Methods of applying MLI to LH2 tankage to avoid condensation or freezing of condensible gases such as nitrogen or oxygen while in the atmosphere are discussed. Because relatively thick layers of MLI will be required for storage times of a month or more, the transient performance from ground-hold to space-hold of the systems will become important in optimizing the TPS's for many of the missions. The ground-hold performance of several candidate systems are given as well as a qualitative assessment of the transient performance effects

Autogenous pressurization of cryogenic vessels using submerged vapor injection

Experimental results are reported for submerged injection pressurization and expulsion tests of a 4.89 cu m liquid hydrogen tank. The pressurant injector was positioned near the bottom of the test vessel to simulate liquid engulfment of the pressurant gas inlet; a condition that may occur in low-gravity conditions. Results indicate a substantial reduction in pressurization efficiency, with pressurant gas requirements approximately five times greater than ideal amounts. Consequently, submerged vapor injection should be avoided as a low-gravity autogenous pressurization method whenever possible. The work presented herein validates that pressurent requirements are accurately predicted by a homogeneous thermodynamic model when the submerged injection technique is employed

Gaseous-Hydrogen Pressurant Requirements for the Discharge of Liquid Hydrogen from a 3.96 Meter /13 ft/ Diameter Spherical Tank

Hydrogen gas pressure requirements during pressurization and transfer of liquid hydrogen from spherical tank

The Techniques for Overcoming Depression Questionnaire: Mokken Scale Analysis, Reliability, and Concurrent Validity in Depressed Cardiac Patients

The Techniques for Overcoming Depression (TOD) questionnaire assesses the frequency with which patients being treated for depression use cognitive-behavioral techniques in daily life. This study examined its latent structure, reliability and concurrent validity in depressed cardiac patients. The TOD was administered at the initial and final treatment sessions in three trials of cognitive behavior therapy (CBT) (n = 260) for depression in cardiac patients. Mokken scaling was used to determine its dimensionality. The TOD is unidimensional in depressed cardiac patients, both at the initial evaluation (H = .46) and the end of treatment (H = .47). It is sensitive to change and the total score correlates with therapist ratings of the patient’s socialization to CBT (r = .40, p < .05), homework adherence (r = .36, p < .05), and use of cognitive-behavioral techniques (r = .51, p < .01). TOD scores were associated with post-treatment depression scores in two of the trials (p < .01 in both analyses). The TOD is a unidimensional, reliable, valid, and clinically informative measure of self-reported use of cognitive-behavioral techniques for overcoming depression in cardiac patients. Studies of the TOD in other depressed patient populations are needed. © 2016, Springer Science+Business Media New York