Partload Fuel Economy Characteristics of 300 kW Class Gas Turbines

Abstract

The partload fuel consumption characteristics of single and, two shaft recuperated, and two spool intercooled recuperative small 300 kw class gas turbines were studied in order to compare with an advanced diesel engine. With variable speed and either constant turbine inlet temperature or constant turbine exhaust temperature these three engines were judged to potentially possess a normalized fuel consumption versus load characteristic comparing favorably with that of a Diesel engine. This is moreover without the complications of many past patented Brayton cycle novel concepts conceived to achieve nearly constant thermal efficiency. Fundamentally part load optimization for a specific gas turbine engine focuses upon the slope of its fuel consumption versus power from the design point to the idle condition. The idle condition is typically set by a specified accessory load above that of the no load, or self sustaining speed, and or lean blow out limit of the combustor. It is shown that although this fuel flow slope can be slightly changed with component efficiency fall off characteristics, or with dual engine packs, for a single engine it is dominated by the two end points, the design and no load fuel flows. The premise that such 300 kw class gas turbines could however challenge the manufacturing, and direct operating costs of an advanced technology Diesel engine, besides meeting future emissions regulations remains to be aggressively pursued.