Sizing of Supercritical Fluid Heat Transport Loop for Aircraft Propulsion

The Aviation sector today accounts for 2.5% of all global CO2 emissions per annum, and in the past two decades has outgrown every other major mode of transport. While significant gains in efficiency have been made year on year, the growth in air travel has outpaced these gains. In order to fulfill Net Zero carbon emissions targets by 2050, industry stakeholders would have to invest in novel technologies with the ability to cause disruptive change and be widely applicable across different aircraft types. The reduction in emissions from Aircraft Engines has been largely driven by reduced fuel burn and other CO2 emissions. This increase in fuel efficiency however has come at a cost of needing to have higher temperatures and pressures, leading to an increase in NOX emissions. Despite the best efforts of Aircraft Engine manufacturers, thermal efficiency of modern Aircraft Engines is still around 50%, and rate of improvements per annum is dropping, thus making further gains a challenge in current Turbofan Aircraft Engine architecture. Core exhaust losses are one of the two major losses in large Aircraft Engines where significant gains could be made via intercooling and recuperation of exhaust heat. Supercritical Fluids beyond critical point exhibit properties of both liquids and gases, which could be exploited to increase the energy density and heat capacity, while also improving flow and heat transfer of working fluids. Supercritical CO2 (sCO2) Brayton Cycles are known to be stable, compact, less complex, have lower cost and efficient thermodynamically. While using sCO2 as a working fluid for core exhaust heat recovery reaps benefits it also poses significant challenges : The complex behavior of sCO2 and its properties near the critical point, arising instabilities, associated pressure losses which are serious concerns for practical applications. There exists limited research into sCO2 loops for Aerospace applications, the methodical sizing of a closed supercritical loop and its components is also lacking. Through this work a methodology to size a sCO2 closed loop pertaining to Aircraft Propulsion waste heat recovery would be established through modeling. The model would act as a foundation to sizing of a sCO2 loop and its associated components, which would help establish a physical test bench to validate the model and further the understanding of sCO2 behavior and prospective application on Aircraft Engines.

Work In Progress