Engineering topics

Almgren, D. W.

Publications and source records attributed to Almgren, D. W..

11 records

NASA NTRS1981

The use of a thermal utility with space-platform-mounted instruments

A thermal utility is a high-capacity heat transport system that serves as a common, temperature-controlled heat sink or source to more than one payload. The feasibility of using a thermal utility for space-platform-mounted instruments which have a range of temperature level and heat rejection requirements is examined and significant design parameters are identified. A baseline, pumped, two-phase heat transport system has been defined for NASA's proposed Space Platform, and its capability to satisfy the thermal requirements of a range of multidisciplinary instruments has been assessed.

Almgren, D. W.↗

NASA NTRS1981

Thermal protection systems for equipment pallets to be launched in Shuttle Orbiter

The thermal insulation for the OSS-1 Orbiter pallet is described and a design concept for future pallets is presented consisting of two independent thermal zones and new thermal insulation approaches. The application of these concepts is expected to reduce the effort required to integrate the payloads to their pallets and thereby reduce dollar costs and shorten time schedules. A stand-off insulation also is described for certain pallet areas to enclose the cabling and fluid lines in a controlled temperature environment. Methods for interfacing the payload and pallet insulations are presented and a number of areas are identified where the introduction of standards in the fabrication of thermal insulation can yield further savings.

Ruccia, F. E.↗

NASA NTRS1980

Gaalas/Gaas Solar Cell Process Study

Available information on liquid phase, vapor phase (including chemical vapor deposition) and molecular beam epitaxy growth procedures that could be used to fabricate single crystal, heteroface, (AlGa) As/GaAs solar cells, for space applications is summarized. A comparison of the basic cost elements of the epitaxy growth processes shows that the current infinite melt LPE process has the lower cost per cell for an annual production rate of 10,000 cells. The metal organic chemical vapor deposition (MO-CVD) process has the potential for low cost production of solar cells but there is currently a significant uncertainty in process yield, i.e., the fraction of active material in the input gas stream that ends up in the cell. Additional work is needed to optimize and document the process parameters for the MO-CVD process.

Almgren, D. W.↗

NASA NTRS1980

Evaluation of solar cell materials for a Solar Power Satellite

Alternative solar cell materials being considered for the solar power satellite are described and price, production, and availability projections through the year 2000 are presented. The chief materials considered are silicon and gallium arsenide.

Glaser, P. E.↗

NASA NTRS1980

Study of process technology for GaAlAs/GaAs heteroface solar cells

Two processes were considered: the infinite melt process and the finite melt process. The only technique that is developed to the point that 10,000 cells could be produced in one year is the infinite melt liquid phase epitaxy process. The lowest cost per cell was achieved with the advanced metal organic chemical vapor deposition process. Molecular beam epitaxy was limited by the slow growth rate. The lowest cost, an 18 percent efficient cell at air mass zero, was approximately $70 per watt.

Conway, E. J.↗

NASA NTRS1978

An assessment of thermal design procedures for Shuttle payloads

A review of the thermal design options for unmanned Shuttle payloads is presented. Because many future Shuttle payloads will have budgets and less time available for the definition of their thermal subsystems, simplified design procedures will be the most cost-effective. The thermal interface between an individual payload and the Orbiter is discussed. A simplified, modular thermal control system that will reduce the cost of providing thermal protection by minimizing both the initial procurement cost of any specialized hardware and the need for a detailed thermal interface analysis is described.

Almgren, D. W.↗

NASA NTRS1978

Thermal design analysis of shuttle cargo bay payloads

The thermal design analysis methodology, the thermal control philosophy, and preliminary thermal analysis results associated with specific shuttle payloads are presented. The payloads considered are the Get-Away Special canisters being developed by NASA Goddard, which may be flown on a variety of missions, and the six experiments which are mounted on the GSFC pallet to be flown on Operational Flight test No. 4 (OFT-4). The thermal control alternatives currently available to OFT-4 instruments are the use of pallet cold plates (if available) or operational constraints which allow passive thermal control without the use of excessive heater power. The characteristics of a completely passive thermal control design are evidenced by the results of the Get-Away Special canister analysis.

Bartoszek, J. T.↗

NASA NTRS1978

Evaluation of solar cells and arrays for potential solar power satellite applications

Proposed solar array designs and manufacturing methods are evaluated to identify options which show the greatest promise of leading up to the develpment of a cost-effective SPS solar cell array design. The key program elements which have to be accomplished as part of an SPS solar cell array development program are defined. The issues focussed on are: (1) definition of one or more designs of a candidate SPS solar array module, using results from current system studies; (2) development of the necessary manufacturing requirements for the candidate SPS solar cell arrays and an assessment of the market size, timing, and industry infrastructure needed to produce the arrays for the SPS program; (3) evaluation of current DOE, NASA and DOD photovoltaic programs to determine the impacts of recent advances in solar cell materials, array designs and manufacturing technology on the candidate SPS solar cell arrays; and (4) definition of key program elements for the development of the most promising solar cell arrays for the SPS program.

Almgren, D. W.↗

NASA NTRS1978

Candidate solar cell materials for photovoltaic conversion in a solar power satellite /SPS/

In recognition of the obstacles to solar-generated baseload power on earth, proposals have been made to locate solar power satellites in geosynchronous earth orbit (GEO), where solar energy would be available 24 hours a day during most of the time of the year. In an SPS, the electricity produced by solar energy conversion will be fed to microwave generators forming part of a planar phase-array transmitting antenna. The antenna is designed to precisely direct a microwave beam of very low intensity to one or more receiving antennas at desired locations on earth. At the receiving antenna, the microwave energy will be safely and efficiently reconverted to electricity and then be transmitted to consumers. An SPS system will include a number of satellites in GEO. Attention is given to the photovoltaic option for solar energy conversion in GEO, solar cell requirements, the availability of materials, the implication of large production volumes, requirements for high-volume manufacture of solar cell arrays, and the effects of concentration ratio on solar cell array area.

Glaser, P. E.↗

NASA NTRS1976

Investigation of the thermal control of instruments mounted in the Space Shuttle cargo bay

Results are presented for an investigation intended to examine the orbital averaged thermal response of a number of instruments, each being representative of a class of scientific instrumentation, when they are individually mounted on pallets and operated in the cargo bay of the Shuttle. The discussion covers mainly the Shuttle Orbiter thermal models, the solar viewing instrument, and the high-energy instrument. One approach to thermal insulation of smaller instruments is to provide a thermal canister insulated from the cargo bay and equipped with variable conductance heat pipes. Two approaches are proposed for larger instruments. One approach is to provide a thermal curtain across the top of the pallet which shields the pallet cavity from direct sunlight, while the second approach is to provide a fluid system to transfer heat from a specified location on an instrument to either a space viewing radiator on the pallet or instrument or the orbiter cooling system. These thermal control design concepts represent several ideas for standard reusable thermal control systems.

Bartoszek, J. T.↗

NASA NTRS1975

Thermal design support for the Explorer gamma ray experiment telescope

The results of a thermal design definition study for the GSFC Explorer Gamma Ray Experiment Telescope (EGRET) were documented. A thermal computer model of EGRET with 241 nodes was developed and used to analyze the thermal performance of the experiment for a range of orbits, payload orientations and internal power dissipations. The recommended thermal design utilizes a small radiator with an area of 1.78 square foot on the anti-sun side of the mission adaptor and circumferential heat pipes on the interior of the same adaptor to transfer heat from the electronics compartments to the single radiator. Fifty watts of thermostatically controlled heater power are used to control the temperature level to 10 C + or - 20 C inside the insulated dome structure.

Almgren, D. W.↗