Session: 01-07 Thermal Management Systems and Heat Exchangers

Paper Number: 152723

Conceptual Design Exploration of Hydrogen Enhanced Intercooling for Future Aeroengines 

While technological advancements in the aviation industry have led to a substantial reduction in emissions per passenger kilometer, the overall increase in air travel has resulted in a net rise in emissions. Hence, to meet the climate neutrality goal by 2050 set forth by ACARE radical engine solutions are required, as shown in the EU-project ULTIMATE. One promising approach is the integration of carbon free energy carriers, such as hydrogen. Hydrogen, particularly in its cryogenic form, has been extensively used as rocket fuel, primarily due to its exceptional gravimetric energy density. Moreover, for the same rocket applications, due to the cryogenic temperatures and high heat capacity, hydrogen is frequently employed in regenerative cycles. In such cycles, hydrogen is used to cool the rocket nozzle and at the same time increase the energy content in the fuel prior to combustion, hence improving the efficiency of the propulsion system. The same principle can be applied in future hydrogen powered aeroengines. Hence, transitioning to hydrogen fuel, including cryogenic storage, would present several challenges and opportunities, including novel and effective thermal management synergies.

This study aims to explore a novel thermal management component where a combination of hydrogen and bypass air flow is utilized for the purpose of intercooling in a composite cycle engine for short to medium-range aircraft. This engine resembles a conventional high-bypass turbofan, but features a constant volume piston engine combustion system instead of a conventional constant pressure combustion chamber. Such an engine requires a more advanced thermal management system, where intercooling takes a primary function, ensuring that the mass of the piston engine is kept within reasonable values. Intercooling will also allow to control the combustor inlet temperature and therefore limit NOx emissions. The work presents the conceptual design of an advanced intercooler concept that features two serial coupled heat exchangers: one air-to-air and the other air-to-hydrogen. This configuration is chosen to enhance thermal management, improve the overall efficiency of hydrogen-fueled aeroengines and reduced emissions. Suitable materials, aerothermal enhancement methods and risk mitigation strategies for a wide temperature range of hydrogen heat exchangers are discussed. The initial approach is to compare various layouts of idealised intercoolers and to investigate performance penalties from various operational constraints. After, the in-house developed Generalized Heat Exchanger (GenHEX) method, as introduced by Miltén et al. (2024), is applied on the selected intercooler configurations. The GenHEX method provides a novel approach for the conceptual design of heat exchangers, allowing estimation of key performance parameters, such as pressure loss, build volume and heat transfer surface weight, for a continuous design space bridging heat exchanger families. After, a sizing study is presented, where a number of configurations of the hydrogen-enhanced intercooler are evaluated using aeroengine specific trade factors. The aim is to investigate trade-offs between aerothermal performance, weight, volume and integration aspects for equal thermal load. The results indicate that the novel hydrogen-enhanced intercooler design offers significant improvements in system efficiency over an equivalent intercooler using only air extracted from the bypass stream.

Presenting Author: Petter Miltén Chalmers university of technology

Presenting Author Biography: Petter Miltén is a PhD student in the research group for turbomachinery and aeroacoustics, Division of Fluid Dynamics at the Department of Mechanics and Maritime Sciences. He is working on “aerothermal design of light-weight heat-exchangers for aircraft” which includes conceptual design and simulations as well as performing experiments in Chalmers turbine rig.

Authors:

Petter Miltén Chalmers university of technology
Isak Jonsson Chalmers university of technology
Anders Lundbladh GKN Aerospace Sweden
Carlos Xisto Chalmers university of technology