Steam generation and exhaust water recovery for the Water Enhanced Turbofan (WET)

Abstract

In order to combat the climate change, all industries must reduce their environmen tal impact. The aviation industry is no exception and new solutions must be found in order to make aircraft more environmentally friendly. One such solution could be the Water Enhanced Turbofan (WET), which is an engine concept presented by engineers at MTU Aero Engines in Germany [1] [2]. According to the authors, the engine concept promises a reduction of CO2 emissions, NOx emissions and forma tion of contrails [1]. This master’s thesis investigates the potential of the WET concept during max cruise conditions from a thermodynamical perspective. The WET concept was applied to a conventional, simple cycle, turbofan, with GEnx-1B engine data generated by GESTPAN at Chalmers University of Technology. The WET concept utilizes steam injection and exhaust water recovery by the addition of two heat exchangers. The first heat exchanger, called the HRSG, heats the supplied water to steam which is injected into the combustion chamber. The second heat exchanger, called the condenser, is a plate heat exchanger where steam in the flue gas is condensed and separated. The HRSG could be designed with a weight of approximately 630 kg. The condenser was designed for several different configurations, but all different de signs resulted in a weight of at least 3700 kg. Results from this work show that the WET concept could reduce the SFC by up to 20 %, compared to a conventional turbofan, which is in somewhat alignment with the results published in the presenting articles [1] [2]. The addition of the heat ex changers resulted in a weight increase of the propulsion system by more than 70 % in relation to the original weight. A weight increase of 70 % of the propulsion system did not match the results in the article by MTU [1]. According to the authors of the MTU article, the total weight of the propulsion system was expected to increase by 40 %. As a conclusion, it can be stated that theoretical results show that the WET con cept has a potential to reduce emissions. However, for the WET concept to be implemented practically, thorough studies would have to be conducted on the con densation process in both the condenser and the mixe