Step-by-step evaluation of the fuel switch from kerosene to hydrogen on the thermodynamic cycle in gas turbine engines

Abstract

Hydrogen combustion engines are one of the few possible ways forward to drastically reduce climate impact of aviation. While there is many information about the engine performance of hydrogen combustion engines it is not clear to which extend each property of the fuel switch effects the engines thermodynamic cycle and component behavior. The basic architecture is identical for both fuels but it is not known to which extend already existing and fully designed components can be used for the new application. In this work the basic differences between both fuels are presented using a thermodynamic model of simplified turbojet. The archived knowledge is applied to a reference turbofan for an application similar to an Airbus A320 while burning hydrogen. Different effects occurring during the fuel switch, e.g. higher water loading after combustion and lower fuel mass flow, will be looked at separately. A retrofitted engine towards hydrogen combustion will use 1.5% less energy for the same thrust while operating at 60 K lower temperatures. The working line in the compressors will also switch towards higher mass flow rates despite the higher working fluid quality after combustion. Additionally, a new designed turbofan is presented on preliminary level for a constant fan diameter, to address the effects of different thrust requirements and has a 3.6% lower specific energy consumption.