Backstreaming from oil diffusion pumps Final report, Dec. 1, 1963 - May 30, 1966

Backstreaming from oil diffusion and turbomolecular pump

NASTRAN analysis of heat-transfer fluid fill pipe failure

An example that shows the difficulties of failure analyses and the advantage of the finite element method (NASTRAN) in assisting in determining the true cause of a failure is presented. In this example, cracks were developing along a pipe weld. After discarding several possible causes for the failures, it was finally determined that the problem was due to stress corrosion cracking associated with a rather unusual and novel environmental condition

Diffusion pump modification promotes self-cleansing and high efficiency

Modifications eliminate contaminant substances from pump fluid during operation, which are principal causes of torpidity on evaporative surface. Diffusion pump is also acting as still. Resulting 100 percent vigorous working surface provides much greater molecular throughput and greatly improved efficiency

Processing ceramics

A method of hot hydrostatic pressing of ceramics is described. A detailed description of the invention is given. The invention is explained through an example, and a figure illustrates the temperature and pressure during the hot hydrostatic pressing treatment

Evaluation of advanced combustion concepts for dry NO sub x suppression with coal-derived, gaseous fuels

The emissions performance of a rich lean combustor (developed for liquid fuels) was determined for combustion of simulated coal gases ranging in heating value from 167 to 244 Btu/scf (7.0 to 10.3 MJ/NCM). The 244 Btu/scf gas is typical of the product gas from an oxygen blown gasifier, while the 167 Btu/scf gas is similar to that from an air blown gasifier. NOx performance of the rich lean combustor did not meet program goals with the 244 Btu/scf gas because of high thermal NOx, similar to levels expected from conventional lean burning combustors. The NOx emissions are attributed to inadequate fuel air mixing in the rich stage resulting from the design of the large central fuel nozzle delivering 71% of the total gas flow. NOx yield from ammonia injected into the fuel gas decreased rapidly with increasing ammonia level, and is projected to be less than 10% at NH3 levels of 0.5% or higher. NOx generation from NH3 is significant at ammonia concentrations significantly less than 0.5%. These levels may occur depending on fuel gas cleanup system design. CO emissions, combustion efficiency, smoke and other operational performance parameters were satisfactory. A test was completed with a catalytic combustor concept with petroleum distillate fuel. Reactor stage NOx emissions were low (1.4g NOx/kg fuel). CO emissions and combustion efficiency were satisfactory. Airflow split instabilities occurred which eventually led to test termination

Design of Mach-4 and Mach-6 Nozzles for the NASA LaRC 8-Ft High Temperature Tunnel

The aerodynamic contours for two new nozzles have been designed for the NASA Langley Research Center 8-Foot High Temperature Tunnel. The new Mach-4 and Mach-6 contours have 54.5-inch exit-diameters allowing for testing at high dynamic pressures. The Mach-4 nozzle will extend the test capability of the facility and allow turbine-based combined-cycle propulsion systems to be tested at conditions appropriate for the transition from the turbine to the scramjet flowpath. The Mach-6 nozzle will serve a dual purpose; to provide a Mach-6 test capability at high dynamic pressure and to be used in conjunction with an existing mixer section for testing at lower enthalpy conditions. This second use will extend the life of the existing Mach-7 nozzle which has been used for this purpose. The two new nozzles, in conjunction with existing nozzles, will allow for testing at Mach numbers of 3, 4, 5 and 6 at high dynamic pressures, and Mach 4, 5 and 7 at lower dynamic pressures but larger scales

A mathematical model for breath gas analysis of volatile organic compounds with special emphasis on acetone

Recommended standardized procedures for determining exhaled lower respiratory nitric oxide and nasal nitric oxide have been developed by task forces of the European Respiratory Society and the American Thoracic Society. These recommendations have paved the way for the measurement of nitric oxide to become a diagnostic tool for specific clinical applications. It would be desirable to develop similar guidelines for the sampling of other trace gases in exhaled breath, especially volatile organic compounds (VOCs) which reflect ongoing metabolism. The concentrations of water-soluble, blood-borne substances in exhaled breath are influenced by: (i) breathing patterns affecting gas exchange in the conducting airways; (ii) the concentrations in the tracheo-bronchial lining fluid; (iii) the alveolar and systemic concentrations of the compound. The classical Farhi equation takes only the alveolar concentrations into account. Real-time measurements of acetone in end-tidal breath under an ergometer challenge show characteristics which cannot be explained within the Farhi setting. Here we develop a compartment model that reliably captures these profiles and is capable of relating breath to the systemic concentrations of acetone. By comparison with experimental data it is inferred that the major part of variability in breath acetone concentrations (e.g., in response to moderate exercise or altered breathing patterns) can be attributed to airway gas exchange, with minimal changes of the underlying blood and tissue concentrations. Moreover, it is deduced that measured end-tidal breath concentrations of acetone determined during resting conditions and free breathing will be rather poor indicators for endogenous levels. Particularly, the current formulation includes the classical Farhi and the Scheid series inhomogeneity model as special limiting cases.Comment: 38 page

Potential shale oil recovery methods in the Green River Formation and associated environmental problems

The United States faces a serious energy crisis and needs to develop new long term domestic sources of energy. One important and untapped source is oil shale. Tapping this resource is an alternative way to lessen U.S. dependence on foreign oil and become more self sufficient. The oil shale, an oil bearing rock that fills the uplands of Colorado, Utah, and Wyoming, contains an estimated 1.8 trillion barrels of oil, or three times the known reserves of the Middle East. At the current rate of consumption, that amount of shale would supply U.S. needs for more than a century. Although oil shale companies know where to find their fuel, they differ on the best way to get it out. The original idea of the oil shale developers relied on so-called surface retorting technology. The shale was strip mined, crushed, and then heated to very high temperatures in huge chambers. The temperature was kept at about 900°F, and this process was called "retorting." This high temperature breaks down the rock's solid hydrocarbon component, kerogen, into oil. The raw shale oil is then cleaned for use as refinery feedstock. To obtain increased yields, cut mining and processing equipment costs, reduce spent shale surface disposal, and limit pollutants emitted in the air, the competitive technology developed the "modified in situ" method below ground. This method extracts shale oil from rock by heating it in underground chambers called retorts. Explosives are detonated in the retorts to reduce the shale to rubble. The shale heap is then lit, and the fire is drawn down through the chamber. The intense heat of the blaze frees the oil from the rocks; then it settles to the bottom and is collected for refining into the desired hydrocarbon products. The greatest unknown about shale-oil production is its impact on the environment. Conservationists claim that one to five barrels of water are required for each barrel of oil extracted from shale. Critics also complain about the release of salts and arsenic into the region's groundwater from surface runoff of the piles of leftover shale rubble. The air could become filled with dust from all the rock that is being unearthed and processed. The final, but poignant protest, concerns the scenic destruction of the Rocky Mountain Valleys. Piles of spent shale residue could clog the valleys if mass stabilization is not accomplished by contouring and planting the dump with local grass and wildflowers. This is a big problem considering the fact that a 400,000 bbl-a-day industry requires 500,000 tons of shale to be mined and retorted. This paper will attempt to address and clarify these problems.No embarg