Component Integration and Loss Sources in 3 – 5 kW Gas Turbines

Abstract

The performance of a regenerated gas turbine generator in the 3–5 kW power range has been analyzed to understand why its measured efficiency was on the order of 6% rather than the 20% suggested by consideration of its components’ efficiencies as measured on rigs. This research suggests that this discrepancy can be primarily attributed to heat and fluid leaks not normally considered in the analysis of large gas turbine engines because they are not as important at large scale. In particular, fluid leaks among the components and heat leakage from the hot section into the compressor flow path contributed the largest debits to the engine performance. Such factors can become more important as the engine size is reduced. Other non-ideal effects reducing engine performance include temperature flow distortion at the entrance to both the compressor and turbine. A cycle calculation including all of the above effects matched measured engine data. It suggests that relatively simple changes such as thermal isolation and leak sealing can increase both power output and efficiency of this engine, over 225% in the latter case. The validity of this analysis was demonstrated on an engine in which partial thermal isolation and improved sealing resulted in a more than 40% increase in engine output power.

Small recuperated ceramic microturbine demonstrator concept

“…To a large extent the efficiency discrepancy between estimated performance and test data was rationalized, and simple changes such as thermal isolation and leak sealing were suggested as a means of restoring the target efficiency [27]. Lessons learned from this investigation would be taken advantage of in the design of the proposed 7.5 kW turbogenerator.…”

Advances in the Development of a Microturbine Engine

“…As a consequence, the thermal fluxes are no longer negligible and involve a severe decrease in the output power and the efficiency of the system as well [7,[16][17][18][19]. Hence, to assess the influence of the thermal losses on these performances, an aerothermodynamic simulation code called "Hot-Die" has been specifically developed.…”

Exploration of a simple, low cost, micro gas turbine recuperator solution for a domestic combined heat and power unit

“…This produced a system efficiency, s η , of 15%, using a heat exchanger effectiveness, HEX η , of 75% which from Figure 3 is shown to require a pressure drop ratio, P , of 90% or more. Other test based theoretical predictions of similar sized/duty MGT suggest system efficiencies between 16%-20% [22] and 6%-13.5% [23] are possible.…”