Working state map of hydrocarbon fuels for regenerative cooling

Chen Zhang ^a,b, Hui Gao ^a,b,*, Jiajun Zhao ^a,b, Guice Yao ^a, Dongsheng Wen ^c,**

a. School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China
         b. Aircraft and Propulsion Laboratory, Ningbo Institute of Technology, Beihang University, Ningbo 315100, China
         c. Institute of Thermodynamics, Technical University of Munich, 85747, Germany

Abstract: Regenerative cooling by endothermic hydrocarbon fuel (EHF) is one of the most promising techniques for thermal management of supersonic or hypersonic aircraft. How to maintain the fuel working in proper states is an important issue to maximize the cooling potential of EHT. This work proposes a novel working state map, including risking zone (RZ), thermal cracking zone (TCZ), supercritical zone (SupZ) and subcritical zone (SubZ), to differentiate possible working states of an EHF during regenerative cooling. Using n-decane flowing in a circular tube as an example, the boundaries of four zones are determined by numerical simulation covering different heat fluxes (0.2-4.0 MW·m^-2) and mass flow rates (0.5-10.5 g·s^-1) under two operating pressures (3.45 and 5.00 MPa). Empirical correlations for three boundary lines are obtained and the maximum cooling capacity is identified, as well as the identification of the pressure effect. The revelation of such new perspective of regenerative cooling is of great implication to the design and optimization of cooling system for future thermal management.

Keywords: Regenerative cooling; Hydrocarbon fuel; State map; Chemical heat sink; Thermal management

https://doi.org/10.1016/j.jppr.2023.05.002