A comprehensive investigation and optimization of superheat degree on performance of supersonic nozzle by considering non-equilibrium condensation and entropy generation analysis

Non-equilibrium condensation (NQC) induced heat transfer in the supersonic nozzle (SSN) results in entropy production and alters the flow structure. The analysis of entropy production offers valuable insights for enhancing the design of industrial equipment by pinpointing the origins of energy losses. The interplay between frictional entropy, thermal entropy, and NQC is a fascinating but relatively unexplored subject in the field. This study aims to examine the impact of the superheat degree on NQC, frictional entropy, and thermal entropy. The goal is to enhance our understanding of the interconnectedness among these three parameters and their relationship. The findings revealed that within the SSN, the generation of frictional entropy surpasses that of thermal entropy generation. Upon analyzing the variations in entropy production with an increase in the degree of superheat, a general trend of ascending-descending can be observed for thermal, frictional, and total entropy productions. Furthermore, as the degree of superheat increases, both the droplet diameter and liquid mass fraction within the nozzle decrease. Optimization techniques were employed to determine the optimal degree of superheat for the given scenario. After the optimization process, the range of 70-90 was identified as the optimal degree of superheat. At a superheat degree of 70, the parameters of production entropy, input flow rate, condensation loss, and energy kinetics undergo changes of 19.3%, 9.8%, 99.9%, and 14.3%, respectively.