Analysis of a Supercharged Gas Turbine Engine Concept and Preliminary Investigation of a Version Using Argon as the Working Fluid 2022-01-0595

The paper presents results from a study into the potential of a complex cycle gas turbine engine, originally investigated by the Ford Motor Company for truck applications in the 1960s, and updated to gauge the possible improvements by raising the efficiencies of its constituent components from the values used in period to more modern levels.

To perform this investigation, firstly a spreadsheet model was constructed and the data that Ford made available in the open literature were used to validate it. The methodology used in the model was to balance the power consumed by the compressors (and the auxiliaries where applicable) with that produced by their driving turbines, and to match the thermal power in the heat exchangers with the data provided. Using the quoted lower heating value of the diesel fuel originally used, this approach led to an accuracy in the match of brake specific fuel consumption (in terms of g/kWh) to three places of decimals. Using this validated model, any improvement in the performance of individual devices would then manifest in an increase in expansion ratio available at the power turbine and, for the same system heat input, concomitantly more power and an increase in thermal efficiency. The expected improvement in efficiency with an increase in turbine inlet temperature was also shown by increasing it from the original 1200 K up to 2000 K, with the efficiency relationship becoming asymptotic in line with theory.

The second stage of the study was a preliminary investigation of the effects of operating the concept using argon as the working fluid, this imagined to be achieved by closing the cycle and adding a heat exchanger at its bottom. This suggests the potential of the Joule cycle in this regard: the improvement in cycle efficiency at the overall system pressure ratio of 15.5 was predicted as 20.9% versus the 22.6% predicted from simple Joule cycle theory. While there are caveats arising from the fact that the engine studied has anything but a simple cycle, from this result it is considered that this concept is worthy of some further fundamental study.