Cryogenic Hydrogen in Aero Engine Performance Calculations

Journal of Engineering for Gas Turbines and Power, vol. 148

Abstract

Abstract In this paper, the impact of cryogenic hydrogen preconditioning on aero engines is investigated using thermodynamic models of three fuel system architectures. Furthermore, highly simplified approaches that are useful for preliminary studies and conceptual design work are developed and evaluated. Fuel systems for cryogenic hydrogen require fuel preheating in addition to the fuel–oil heat exchanger. Three options are investigated: electric, bleed, and combustion preheating. All are modeled in the gasturb performance software using property functions and thermodynamic change-of-state equations. The reduction in thrust-specific energy consumption of the hydrogen engine compared to the kerosene reference engine depends on the required injection temperature. Without preheating, a reduction of 4 % would be achievable in cruise. With preheating to an injection temperature of 273.15 K, a reduction of 1.7 % is achieved with electric preheating, and up to 3 % with bleed or combustion preheating. The results are compared to highly simplified approaches in which the fuel preconditioning is approximated by adjusting mechanical efficiencies, secondary air system inputs, and the fuel heating value. The errors introduced by these simplifications are well below 0.5 % in fuel flow at operating points such as takeoff and cruise, thus, such simplified approaches are often justified. In summary, heat release varies strongly with fuel temperature, especially for cryogenic hydrogen, and the associated power and bleed offtakes for fuel-preheating must be included in performance calculations. This paper presents both simplified approaches and rigorous models to achieve this.

Authors 2

1. Christian Klumpp corresponding Aachen Institute of Jet Propulsion and Turbomachinery

   RWTH Aachen University

   Affiliation as printed

   Institute of Jet Propulsion and Turbomachinery, RWTH Aachen University , Aachen 52062, Germany

2. Peter Jeschke corresponding Aachen Institute of Jet Propulsion and Turbomachinery

   RWTH Aachen University

   Affiliation as printed

   Institute of Jet Propulsion and Turbomachinery, RWTH Aachen University , Aachen 52062, Germany