STUDY OF GERMANIUM DEVICES FOR USE IN A THERMOPHOTOVOLTAIC CONVERTER.
Rept. no. 2 (Final) 1 Jan-1 Aug 67,
GENERAL MOTORS CORP KOKOMO IN DELCO RADIO DIV
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Investigations of PN and non-absorptive devices, which are reported in detail in the first progress report, are summarized. Current work includes engineering investigations and optimization of the NP fabrication process. Power outputs in excess of 900 mw per device in a flux of 14.0 wattsq cm have been observed on optimized units. Measurements of effective minority carrier lifetime and equivalent nonchromatic conversion efficiency are described. An experimental model is presented which can be used to explain previous vacuum degradation data as well as to predict the behavior of a new coating. Detailed data on Sb2O3 coatings are given and this material is the best found to date for the TPV application. The design and fabrication of a thermophotovoltaic generator model is described. The model is powered by an electrically heated silicone carbide globar, and forced convection cooled by water. The active cell array consists of 132 series interconnected cells arranged on a 3.50 in dia. by 3 in high shell. The packing density of the cells is greater than 90. Power output obtained has been 57.65 watts at a radiant flux density of 8.67 wattssq cm, and with a water coolant flow rate of 4 gpm. Weight of the system, without globar, is 7.01 lbs. A detailed analytical analysis of the heat transfer and pressure drop characteristics of the model is presented, and are compared with actual test results. Also described in the report are repairability, problem area, and a design extrapolation to a 300 watt generator model.
- Electrical and Electronic Equipment
- Non-electrical Energy Conversion