Accession Number : AD0642480

Title :   'MAN-PACK' 250 WATT THERMOELECTRIC GENERATOR (REBUILD).

Descriptive Note : Final rept.,

Corporate Author : MINNESOTA MINING AND MFG CO ST PAUL THERMOELECTRIC PRODUCTS

Personal Author(s) : Miller,D. F. ; Mayala,A. H.

Report Date : 24 MAR 1964

Pagination or Media Count : 37

Abstract : The mode of failure of the 3M-5B1 generator after only 500 hours operation was due to overheating the cold-end solder-type hermetic seal, leading to oxidation of the PbTe thermoelectric material. The overheating was caused by inadequate cooling due to: (a) too small of a safety factor on the original cooling system design; (b) direct coupling of the cooling system to the main power output, which permitted the cooling fans to be 'starved' when the generator was loaded down too heavily. The hermetic sealing system was redesigned in the rebuilt unit and a repetition of the failure is considered to be remote. The 'P' type PbTe thermoelectric legs used in the 3M-5B1 were replaced by (Pb,Sn)Te 'P' type legs. The new type thermoelectric material is chemically more stable and shock resistant than PbTe formally used. A new cooling system was developed. The only modification in the burner system was in the orifice design. Gross electrical power of the thermopile while under electrical testing (water cooled) was 554 watts as compared with 381 watts for the 3M-5B1. The completed generator as delivered produces 280 watts at 27 volts and weighs 44 pounds.

Descriptors :   *GENERATORS, *THERMOELECTRICITY, PORTABLE EQUIPMENT, THERMOCOUPLES, FAILURE(MECHANICS), HERMETIC SEALS, COOLING, HEATERS, PERFORMANCE(ENGINEERING), LEAD(METAL), TIN, TELLURIUM.

Subject Categories : Electric Power Production and Distribution

Distribution Statement : APPROVED FOR PUBLIC RELEASE