Improve the thermal performance of precooler by enhancing the utilization of chemical heat sink: Refined design method and characteristic analysis

The chemical heat sink of the coolant plays a crucial role in enhancing the performance of the precooler, which affects the overall performance of the air-breathing precooled engines. The conventional thermal design method for precoolers cannot accurately evaluate the chemical heat sink of coolants. To address this crucial issue, this paper proposes a refined model that considers the chemical reaction processes of n-Decane, based on a two-dimensional discretization unit model and the plug flow reactor model incorporating molecular-level chemical reaction mechanisms. The validation of this model is conducted by comparing it with publicly accessible data and computational fluid dynamics simulations, thereby demonstrating its excellent accuracy. Subsequently, an analysis is conducted on the factors influencing the chemical heat sink release of the coolant within the precooler, and enhanced design criteria for optimizing chemical heat sink utilization are proposed. Building upon these considerations, the performance of a precooler with a design point of Mach number 5 under off-design conditions was analyzed. The findings indicate that employing rational design methods can enhance the chemical heat sink efficiency of endothermic fuels by 8.0%, along with a concurrent 10.3% increase in the total heat sink. This underscores the significance of considering the impact of the chemical heat sink of endothermic fuels in the design of precoolers. In the case presented in this paper, the contribution of the chemical heat sink to the total heat sink within the n-Decane precooler could reach 35.3%.