Case Histories Of Specialized Turbomachinery Problems

PaperPg. 33-50.Vibration problems in turbomachinery occur due to many factors. Some of the problems could have been prevented if more detailed design analyses were performed. Other times the problems occur due to design extrapolations which are pushing the state of the art. The case histories of excessive vibrations and failures that will be discussed in this presentation are examples of those where additional design analyses would not necessarily have predicted or anticipated the problem that occurred because the analytical models are not sufficient to take into account all the variables

Chemical Compatibility Testing Final Report Including Test Plans and Procedures

This report provides an independent assessment of information on mixed waste streams, chemical compatibility information on polymers, and standard test methods for polymer properties. It includes a technology review of mixed low-level waste (LLW) streams and material compatibilities, validation for the plan to test the compatibility of simulated mixed wastes with potential seal and liner materials, and the test plan itself. Potential packaging materials were reviewed and evaluated for compatibility with expected hazardous wastes. The chemical and physical property measurements required for testing container materials were determined. Test methodologies for evaluating compatibility were collected and reviewed for applicability. A test plan to meet US Department of Energy and Environmental Protection Agency requirements was developed. The expected wastes were compared with the chemical resistances of polymers, the top-ranking polymers were selected for testing, and the most applicable test methods for candidate seal and liner materials were determined. Five recommended solutions to simulate mixed LLW streams are described. The test plan includes descriptions of test materials, test procedures, data collection protocols, safety and environmental considerations, and quality assurance procedures. The recommended order of testing to be conducted is specified

Energy Efficient, Environmentally Friendly Refrigerants

This paper describes a new family of safe, environmentally friendly, high performance substitute refrigerants for application in manufacturing and facilities operations. Due to the Montreal Protocol and subsequent environmental regulations, CFC refrigerants have become expensive or unavailable. A safe, environmentally friendly, high performance refrigerant mixture for replacement of R-12 and R-134a has been developed. The mixture, designated Ikon B, is nonflammable, has zero ozone depletion potential, low global warming potential, relatively low toxicity, is compatible with most common refrigeration system materials of construction, and is thermally stable. Ikon B was used as a drop-in replacement for R-12 in an instrumented 1.5 ton chiller. Operating pressures for Ikon B were essentially the same as for R-12. Analysis of test runs showed that Ikon B gave approximately 2% higher energy efficiency than R-12 with 16% greater capacity, and 17% higher energy efficiency than R-134a with 2% greater capacity

High efficiency, high capacity cooling and refrigeration. Semi-annual report for the period May-October 1999

Tasks 1 through 3 (identify candidate refrigerants, construct bench-top test device, test candidate refrigerants in the bench-top device) are complete. The project is on budget and on schedule. Significant positive results have been obtained

Applications Tests of Energy Efficient, Environmentally Friendly Refrigerants

This paper describes performance demonstrations of two members of the Ikon® family of safe, environmentally friendly, high performance substitute refrigerants for replacement of R-12 and R-134a in manufacturing and facilities operations. Preliminary development efforts for Ikon® C, an energy efficient R-22 replacement, will also be described. The Ikon® refrigerants are nonflammable, non-ozone-depleting, have low global warming, relatively low toxicity, are thermally stable, and are compatible with most common refrigeration system materials of construction. This paper presents (1) results of performance demonstration of Ikon® B in an instrumented spare of the Space Shuttle Cabin cooling system at NASA KSC; (2) results from performance demonstration of Ikon® A and Ikon® B in a domestic refrigerator; and (3) a brief update on the development status of lkon® C including predicted capacities and energy efficiencies of candidates. Results confirm the 10-20% increased energy efficiency of the refrigerants, due to greater volumetric capacity

Experimental comparison of a nearly azeotropic refrigerant blend and R-22 in a water-to-water laboratory test rig

A newly developed, non-ozone-depleting refrigerant blend containing a fluoroiodocarbon compound was compared with R-22 in a laboratory-scale, water-to-water refrigeration cycle test loop. The loop is equipped with a coaxial tube-in-tube condenser, a baffled shell-in-tube evaporator, and a variable-speed compressor. The blend and R-22 were tested at saturated evaporator temperature conditions of about {minus}10 F to {minus}20 F and saturated condenser temperature conditions from about 80--100 F. The compressor speed was varied such that evaporator (cooling) capacity was held constant at approximately the same value for both refrigerants for each test condition. To maintain equal capacity, results showed the compressor speed for the blend to be at least 53% greater than that for R-22. Measured system efficiency with the blend was at least 25% better than for R-22 for near equal operating temperature and capacity conditions. When allowing for maximum impact of the experimental uncertainties, the minimum COP improvement observed for the blend was about 10%. Ideal cycle calculations using the best available property estimates for the blend and the compressor efficiencies observed during the tests also suggested a 10% improvement for the blend over R-22 (almost all due to better isentropic efficiency of the compressor with the blend). Better thermodynamic property data are needed for the blend and further investigations are needed to fully assess its potential for refrigeration equipment applications

Applications Tests of Energy Efficient, Environmentally Friendly Refrigerants

This paper describes performance demonstrations of two members of the Ikon® family of safe, environmentally friendly, high performance substitute refrigerants for replacement of R-12 and R-134a in manufacturing and facilities operations. Preliminary development efforts for Ikon® C, an energy efficient R-22 replacement, will also be described. The Ikon® refrigerants are nonflammable, non-ozone-depleting, have low global warming, relatively low toxicity, are thermally stable, and are compatible with most common refrigeration system materials of construction. This paper presents (1) results of performance demonstration of Ikon® B in an instrumented spare of the Space Shuttle Cabin cooling system at NASA KSC; (2) results from performance demonstration of Ikon® A and Ikon® B in a domestic refrigerator; and (3) a brief update on the development status of lkon® C including predicted capacities and energy efficiencies of candidates. Results confirm the 10-20% increased energy efficiency of the refrigerants, due to greater volumetric capacity

Nonflammable, Nonaqueous, Low Atmospheric Impact, High Performance Cleaning Solvents

For many years, chlorofluorocarbon (CFC) and chlorocarbon solvents have played an important part in aerospace operations. These solvents found extensive use as cleaning and analysis (EPA) solvents in precision and critical cleaning. However, CFCs and chlorocarbon solvents have deleterious effects on the ozone layer, are relatively strong greenhouse gases, and some are suspect or known carcinogens. Because of their ozone-depletion potential (ODP), the Montreal Protocol and its amendments, as well as other environmental regulations, have resulted in the phaseout of CFC-113 and 1,1,1-trichloroethane (TCA). Although alternatives have been recommended, they do not perform as well as the original solvents. In addition, some analyses, such as the infrared analysis of extracted hydrocarbons, cannot be performed with the substitute solvents that contain C-H bonds. CFC-113 solvent has been used for many critical aerospace applications. CFC-113, also known as Freon (registered) TF, has been used extensively in NASA's cleaning facilities for precision and critical cleaning, in particular the final rinsing in Class 100 areas, with gas chromatography analysis of rinse residue. While some cleaning can be accomplished by other processes, there are certain critical applications where CFC-113 or a similar solvent is highly cost-effective and ensures safety. Oxygen system components are one example where a solvent compatible with oxygen and capable of removing fluorocarbon grease is needed. Electronic components and precision mechanical components can also be damaged by aggressive cleaning solvents

Highly Effective, Low Toxicity, Low Environmental Impact Total Flooding Fire Suppressants

Halon 1301 (CF3Br) has been used for decades as the primary fire suppression agent for areas where powder agents cannot be used because of concerns for sensitive equipment. Halon 1301 is an excellent extinguishing agent, effective at about 3% in air and quite non-toxic. It has an effective exposure limit much greater than its extinguishing concentration, so it can be used in normally occupied areas. The ability of a chemical to destroy stratospheric ozone is its ozone-depletion potential (ODP). ODP is the amount of ozone destroyed per pound of a chemical, relative to the standard CFC-11 with an ODP = 1.0. Because halons have been implicated in stratospheric ozone depletion, their production was stopped at the end of 1995 under the provisions of the Montreal Protocol plus later amendments. In the US, the Clean Air Act Amendments of 1990, Presidential directives, and DoD Directive 6050.9 implemented this phaseout. These regulations and penalties have provided strong incentives for US businesses to decrease CFC use. The Omnibus Budget Reconciliation Act of 1989 mandates high Federal taxes on CFCs and halons, designed to price them out of the market. The taxes also capture for the government the windfall profits that would otherwise go to producers as scarcity drives up prices. Several replacements have been developed for Halon 1301. One is carbon dioxide, which has been used as a firefighting agent for many years. However, a high concentration of carbon dioxide is necessary to inert fuels. The effective concentration for inerting with carbon dioxide is approximately 29%, which is above the concentration lethal to humans. HFC-227ea is being used extensively to replace Halon 1301 systems in nominally occupied areas and some normally unoccupied areas. However, since the effective concentration of HFC-227ea is about three to four times that of Halon 1301 the extinguishing systems have to be larger and new extinguishing systems have to be installed. HFC-125 is also being sold as an extinguishing agent (Nimitz). It has problems similar to HFC-227ea, with a greater concentration needed for effectiveness and the need to use a larger system. This is a particularly onerous penalty in aircraft and spacecraft, where weight and space are extremely important, and substitution is often impossible in existing aircraft due to space limitations