To meet the demand of thermal protection in aero engines, this paper presents a novel compact cross-flow air-air heat exchanger based on the Cooled Cooling Air (CCA) technology. This novel air-air heat exchanger consisting of 4 × 10 serpentine tubes (4.4 mm I.D., 5.0 mm O.D., stainless steel type 321) was designed using the classic Logarithmic Mean Temperature Difference (LMTD) method. Experimental verification has been done to research the hydraulic and heat transfer performance of the heat exchanger. The results show that the 1.48 kg serpentine tube air-air heat exchanger can cool the high pressure compressor bleeding air by 200 K at the mass flow rate of 0.05 kg/s using bypass duct cold air. Comparisons between calculated and experimental data have been done and good agreement between them was obtained in both flow resistance and heat transfer characteristics. Thus, the LMTD method could be well adopted in designing compact air-air heat exchanger for aero-engines. A new empirical heat transfer coefficient correlation for the tube outside is obtained using Wilson plot method, and it can be helpful designing heat exchanger with similar structures. This research is a great proof of CCA’s feasibility in terms of theory and practice.

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