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The progress of work on the evacuated receiver, lens design, lens die fabrication, and improvements on components, production techniques, and performance testing is discussed.
A test bed for experimental evaluation of a fixed solar collector which combines an evacuated glass tube solar receiver with a flat plate/black chrome plated copper absorber and an asymmetric vee-trough concentrator was designed and constructed. Earlier predictions of thermal performance were compared with test data acquired for a bare vacuum tube receiver; and receiver tubes with Alzak aluminum, aluminized FEP Teflon film laminated sheet metal and second surface ordinary mirror reflectors. Test results and system economics as well as objectives of an ongoing program to obtain long-term performance data are discussed.
Analysis of Viking Orbiter data suggests that Arsia Mons, Pavonis Mons, and Ascreus Mons, three large shield volcanoes of the Tharsis volcanoes of Mars, have had similar evolutionary trends. Arsia Mons appears to have developed in the following sequence: (1) construction of a main shield volcano, (2) outbreak of parasitic eruption centers on the northeast and southwest flanks, (3) volcano-tectonic subsidence of the summit and formation of concentric fractures and grabens, possibly by evacuation of an underlying magma chamber during eruption of copious lavas from parasitic eruption centers on the northeast and southwest flanks, and (4) continued volcanism along a fissure or rift bisecting the main shield, resulting in flooding of the floor of the volcano-tectonic depression and inundation of the northeast and southwest flanks by voluminous lavas locally forming parasitic shields. In terms of this sequence Pavonis Mons has developed to stage (3) and Ascreus Mons has evolved to stage (2). This interpretation is supported by crater frequency-diameter distributions in the 0.1- to 3.0-km diameter range.
Lonar Crater (India) basalt and lunar basalt 75035 were shock loaded under controlled laboratory conditions up to 1000 kbar, generally in a CO/CO2 (1:1) environment evacuated to 10 to the minus seventh power torr. The Kieffer et al. (1976) classification scheme of progressive shock metamorphism is found to apply to lunar basalts. The major shock features of the five classes that span the range 0 to 1000 kbar are described. Only three out of 152 basalt specimens show shock effects in their natural state as severe as Class 2 features. The scarcity of shocked basalt hand samples in contrast to the abundance of shock-produced agglutinates and homogeneous glass spheres in the lunar regolith indicates the dominant role of micrometeorite impact in the evolution of the lunar regolith. The overall glass content in asteroidal and Mercurian regoliths is considered.
Easily-displayed low-cost radar targets signal distress to orbiting satellites. Effective medical and evacuation efforts can be carried out successfully around globe due to this early warning. Another application is to measure rainfall, surface runoff, evaporation, and soil moisture.
Evacuated all-glass concentric tube collector using air or liquid transfer mediums is very efficient at high temperatures. Collector can directly drive existing heating systems that are presently driven by fossil fuel with relative ease of conversion and less expense than installation of complete solar heating systems.
Calcium superoxide is prepared in high yields by spreading a quantity of calcium peroxide diperoxyhydrate on the surface of a container, positioning said container in a vacuum chamber on a support structure through which a coolant fluid can be circulated, partially evacuating said vacuum chamber, allowing the temperature of the diperoxyhydrate to reach the range of about 0 to about 40 C; maintaining the temperature selected for a period of time sufficient to complete the disproproriation of the diperoxyhydrate to calcium superoxide, calcium hydroxide, oxygen, and water; constantly and systematically removing the water as it is formed by sweeping the reacting material with a current of dry inert gas and/or by condensation of said water on a cold surface; backfilling the chamber with a dry inert gas; and finally, recovering the calcium superoxide produced.
The system identified operates from the primary arc furnace evacuation system as a heat source. Energy from the fume stream is stored as sensible energy in a solid medium (packed bed). A steam-driven turbine is arranged to generate power for peak shaving. A parametric design approach is presented since the overall system design, at optimum payback is strongly dependent upon the nature of the electric pricing structure. The scope of the project was limited to consideration of available technology so that industry-wide application could be achieved by 1985. A search of the literature, coupled with interviews with representatives of major steel producers, served as the means whereby the techniques and technologies indicated for the specific site are extrapolated to the industry as a whole and to the 1985 time frame. The conclusion of the study is that by 1985, a national yearly savings of 1.9 million barrels of oil could be realized through recovery of waste heat from primary arc furnace fume gases on an industry-wide basis. Economic studies indicate that the proposed system has a plant payback time of approximately 5 years.
The Vee-Trough/Evacuated Tube Collector (VTETC) was analyzed rigorously and various mathematical models were developed to calculate the optical performance of the vee-trough concentrators, and the quasi-steady state thermal performance of the evacuated tube receivers. Tests were run to verify the mathematical analyses. Back-silvered glass mirror, Alzak, Aluminized Teflon, and Kinglux (electropolished aluminum reflectors) were tested. Additional tests were run at temperatures ranging from 80 to 190 C (176-374 F). For the glass mirror reflectors, peak efficiencies, based on aperture area and operating temperatures of 125 C (257 F), were over 40%. Efficiencies of about 40% were observed at temperatures of 150 C (302 F) and 30% at 175 C (347 F). Test data for several days, predicted daily useful heats, and efficiency values are presented for a full year. These theoretical values were then compared with actual data points for the same temperature range.
A study of multiwall TPS as an alternative to LRSI for the space shuttle indicated that vented multiwall, with foil thicknesses limited to those used in multiwall fabricated to date, is some what heavier than LRSI. With reduced foil thicknesses, multiwall TPS may equal the weight of LRSI. Metallic conduction through multiwall TPS transfered less heat than gas conduction or radiation. Radiation heat transfer was greatest at high temperatures; however, the number of layers selected can significantly reduce radiation. At low-to-intermediate temperatures, gas conduction transfered the most heat through multiwall TPS. Gas conduction may be eliminated by evacuation of panels. Oxidation rates required a trade of foil thickness against life.
The solar heating and hot water system installed in existing buildings at the Cherry Hill Inn in Cherry Hill, New Jersey is described in detail. The system is expected to furnish 31.5% of the overall heating load and 29.8% of the hot water load. The collectors are liquid evacuated tube type. The storage system is an above ground insulated steel water tank with a capacity of 7,500 gallons.
The primary objectives of the fire tests are: (1) conduct full scale test with 737 fuselages by the end of 1980; (2) demonstrate evacuation time increase to five minutes minimum; (3) show that exterior fire will not penetrate an intact cabin for five minutes; (4) show that closed cabin will not have excess smoke or temperatures above 400 F; and (5) demonstrate that fire in cabin opening will not propagate throughout cabin. The test program has three phases. A test schedule and status of required materials are presented.
The test program has the objectives to: (1) increase passenger evacuation time to a minimum of five minutes from commercial aircraft in case of a fire; (2) prevent an external fire from entering closed cabins for five minutes by using fire barrier materials in the exterior wall; (3) demonstrate that a closed cabin will not reach 400 F; and (4) prove that a fire near a cabin opening will not propagate through the cabin for a minimum of five minutes. The materials status is outlined for seat cushions, upholstery and associated seat materials, wall and ceiling panels, floor panels, carpet and carpet underlay, windows, cargo bay liners, insulation bagging, and thermal acoustical insulation.
A new long-wavelength infrared test facility is being developed to conduct proof-of-performance tests of focal plane arrays for the Infrared Astronomical Satellite (IRAS) telescope. This facility is believed to be unique in that it will calibrate full-sized arrays designed for the 5-120-micron region of the IR spectrum under simulated spaceflight conditions and at background levels as low as 8 million photons/sq cm-sec. Most of the tests will be performed in a main test chamber which contains a liquid helium shroud, blackbody sources, an arrangement to simulate zodiacal background, and spot scanning optics. A noncontaminating high-vacuum pumping system will be used to evacuate the chamber prior to cool-down to prevent molecular deposition. All housekeeping and focal plane signal outputs are multiplexed, digitized, and transmitted on high-speed data lines to a PDP-11/70 computer. The computer provides real-time displays on a color CRT terminal and stores data for subsequent reduction and hard copy output. An overview of the conceptual design and performance specifications of the test facility are given.
Absorption spectroscopy has been performed in the reflected-shock region of a shock tube. Acetylene was shock-heated to produce a mixture, at around 4000 K, rich in C3 and C2H to simulate the ablation layer over the Jovian entry probe, and the spectral range from 140 to 700 nm was surveyed with an evacuable spectrograph. The observed spectra were dominated by those of C2 and C3 and an unknown band at wavelengths below 300 nm. The cross sections of the C3 Swings band in the 300 to 450 nm range agreed with previous measurements within a factor of 1.5. No absorption was observed in the wavelength range from 550 to 700 nm. The unknown broadband absorption with a peak cross section of 4 times 10 to the minus 17/sq cm at around 170 nm was attributed tentatively to the C2H radical. A preliminary calculation showed that the newly found absorption band would reduce the radiative heat flux to the stagnation point wall by about 12.5% in a typical flight condition.
Drop tube makes possible preparation of exotic materials. The 100 foot tube is oriented precisely vertical to prevent free-falling drop from hitting tube walls. Inert-gas supply, evacuation pumps, viewing ports, and flexibility in choice of melt technique allow precise control and monitoring of solidification.
Switching unit changes power and cooling-water connections between two vacuum-brazing machines. It allows both units to be powered by single radio-frequency (RF) generator. One machine can be used for brazing while bell jar of other is being evacuated (20 minute process) in preparation for brazing or is being cooled after brazing (10 minute process).
Thin cooling jacket of recirculating liquid nitrogen is contained by relatively thin walls. Nitrogen is maintained at slight positive pressure, unlike full atmospheric pressure of conventional Dewar design, eliminating need for evacuated insulating spaces and heavy-walled shells. Besides cryogenic applications, design keeps liquids hot when recirculating liquid hotter than nitrogen is used.