Session: 01-03 Advanced Concepts III

Paper Number: 83409

83409 - Parametric Analysis for On-Board Thermal Regulation in a Hybrid-Electric Aircraft 

The driving force behind the presented research is the need for more ecological applications in the aviation sector. According to the European Aeronautics Environmental Report [EAER] 2019, the aviation sector accounts for 3% of global carbon emissions. The number of flights in Europe is projected to increase by 42% in 2040 compared to 2017, increasing CO2 emissions by 21%. Hybrid-electric propulsion systems are considered a promising alternative technology capable to provide fuel savings, reduced emissions and lower noise levels. Despite the added benefits, there are several pitfalls such as the commonly known issues of batteries’ low energy density - compared to that of jet-fuels-, as well as the need to efficiently regulate the various heat loads generated from the electrical propulsion system. The design of the Thermal Management System (TMS), for a hybrid-electric aircraft, alone constitutes of a ubiquitous task, due to its impact on the aircraft’s total weight, cooling drag and overall performance. Some research work has already been conducted towards finding set-up solutions and architectures that tackle the emerging problems while on the conceptual design phase of such systems.

This study aims to focus on investigating the operating and geometric parameters, of a selected TMS, and their impact during the conceptual design phase of the system. The first of those parameters is the selected working medium of the system, where atmospheric air and several liquid coolants are evaluated. On one hand, the air’s capability to transfer heat with increasing altitude is investigated. On the other hand, various liquid coolants are evaluated over their performance to remove heat loads but also, to not exceed their evaporation, boiling and autoignition points, while doing so. The working fluids consist of deionized water, three water-based solutions with other substances to improve their thermophysical properties, mechanical oil and jet propulsion fuel. Furthermore, a sensitivity analysis is carried out for the main heat exchanger dimensioning, material selection and overall performance.

The simulations are conducted with the use of Modelon Impact, implementing the Modelica Liquid Cooling Library. Utilizing the 1D modeling software, the incorporation of all relevant sub-systems needed for optimizing a unified large-scale model is achieved. The analysis is based on transient, real-time, simulations to account for the dynamic effects of temperature change and thermal inertia of the various system elements.

The results of this research study provide insights regarding the performance of the thermal management system when operating parameters are altered. The expected working medium that performs better is a Propylene-Glycol Water Mixture, due to its high temperature limits and good thermophysical properties. In regard to the heat exchanger, its dimensioning is anticipated to be proportional to its performance, but the specific effect of the examined design parameters is presented.

Presenting Author: Orestis S. Valsamis Mylonas Aristotle University of Thessaloniki

Presenting Author Biography: Orestis Valsamis Mylonas holds a Master’s degree in Mechanical Engineering with specialty over Fluid Mechanics and Turbomachinery. He is currently a Research Associate at the Laboratory of Fluid Mechanics and Turbomachinery in the Department of Mechanical Engineering of Aristotle University of Thessaloniki. His research interests and scientific expertise focus on Propulsion and Powertrain Systems, Hybrid Power and Thermal Management Systems. Also involved in industry R&D sector, during his work as a mechanical engineer at SIELMAN S.A., a high technology defense manufacturing and maintenance company, in Greece.

Authors:

Orestis S. Valsamis Mylonas Aristotle University of Thessaloniki
Vasilis G. Gkoutzamanis Aristotle University of Thessaloniki
Anestis I. Kalfas Aristotle University of Thessaloniki