STUDY OF MINIATURE ENGINE-GENERATOR SETS

Abstract : The state of development of miniature engine-generator sets is being studied, and procedures and techniques of design, analysis, and performance testing are being developed. Tests showed that the specific power out-puts of 15 commercial miniature 2-cycle engines were very high and that their economy was very poor. The maximum specific power output obtained was 2 1/4 bhp/cu in. displacement with a specific fuel consumption of 2 3/4 to 5 lb/bhp-hr. The speed range of the engines was from 7000 to 18,500 rpm. The engines were structurally inadequate for engine-generator applications. A 2-cycle test engine is being built which has a piston displacement of 0.6 cu in. and an expected maximum sea-level power potential close to 1.5 hp at speeds of about 16,000 rpm. Analysis showed that engine-generator sets have a large weight advantage over batteries for constant load and continuous or over-all service beyond 10 hr. Between 3 and 10 hr the weight of these sets could range from 10 to 80% of the weight of batteries. Operation between 1 and 3 hr with dc would probably favor batteries, but for ac operation the sets would still seem preferable.