Study on coupling performance of turbo-cooler in aircraft environmental control system

A reverse-bootstrap air cycle turbo-cooler with a coaxial expansion turbine, power turbine, and compressor has been developed for an aircraft environmental control system. The coupling relations of the coaxial three-impeller system are more complicated than those of the conventional turbo-expander with a brake blower or compressor. The coupling characteristics have a considerable impact on efficiency, and thus need to be studied. The performance curve for each impeller was obtained by CFX. The coupling model was established and experimentally validated on the basis of theoretical analysis and simulation results of the coaxial three-impeller system. The experimental results indicated that the turbo-cooler achieved good thermal performance under both design and off-design conditions, and the theoretical results from the coupling model agreed well with the experimental data. The results show that the total relative error between the theoretical calculations and experimental data was within ±15%, and for most experimental data it was within ±5%. Thereafter, the coupling performance was described through the coupling model, and the interactions among the coupling parameters were quantitatively explained. The coupling model could accurately describe the interaction between the coupling parameters and allow for performance prediction and design optimisation of the coaxial three-impeller turbo-cooler system.