Performance improvement of centrifugal compressors by suppressing backward heat transfer

• Backward heat transfer of the solid housing leads to a decline in the performance. • Optimizing the structure to increase thermal resistance can improve performance. • Integrated cooling boosts efficiency by 2.05 % and pressure ratio by 4.3 %. • Suppressing backward heat transfer of the solid housing has significant engineering value. This study establishes a comprehensive heat transfer pathway between the air and the solid housing within the centrifugal compressor through three-dimensional fluid simulations combined with the Conjugate Heat Transfer (CHT) method. The results indicate significant heat transfer between the solid housing and the air, resulting in backward heat transfer within the solid housing. Compared to the ideal scenario without a solid housing, this backward heat transfer leads to a 1.42 % reduction in the efficiency and a 3.08 % reduction in the total pressure ratio. Optimizing the housing structure to increase thermal resistance effectively suppresses backward heat transfer, improving compressor performance. Furthermore, by adopting an integrated cooling scheme, backward heat transfer can be significantly reduced or even eliminated. With a water-cooling housing, the heat transferred to the solid housing from the downstream impeller passage and diffuser region is carried away by the cooling water, preventing reverse transfer to the upstream solid housing and heating the air. Compared to the prototype, the temperature of the solid housing with integrated cooling significantly decreases, resulting in a 2.05 % increase in efficiency and a 4.35 % increase in the pressure ratio. This study not only enhances the understanding of the heat transfer characteristics of centrifugal compressors but also proposes a design method to suppress backward heat transfer in the solid housing. This significantly improves compressor performance and has important engineering application value.