Study on a numerical homogenization method for printed circuit heat exchanger with hybrid mini-channels

Compact heat exchangers, such as printed circuit heat exchangers (PCHEs), are key components in the supercritical CO₂ system for Generation IV nuclear reactors. The PCHEs must work under ultra-high-temperature and high-pressure environment to achieve the high efficiency required by advanced nuclear power systems. Operating under such extreme conditions presents a substantial challenge to the safety and reliability. Therefore, it is necessary to conduct thermal–mechanical numerical analysis of the whole-scale PCHE with numerous mini-channels. This paper presents a general framework to derive and evaluate the equivalent mechanical properties for PCHE with hybrid mini-channels. Simplified mathematical equations are proposed to define the upper and lower limits of the equivalent elastic coefficients for the hybrid mini-channels. These equations are formulated based on homogenization method of strain energy and incorporate characteristic displacements into the framework. The numerical implementation of homogenization for a hybrid PCHE, with semicircular and rectangular holes arranged in hot and cold plates respectively, is subsequently conducted. The equivalent Young's modulus, Poisson's ratio, and shear modulus of the hybrid mini-channels are fitted as functions of temperature. Subsequently, the thermal–mechanical performance of the equivalent hybrid PCHE core model is compared with the actual model. The results show that the maximum deviations in mechanical and thermal–mechanical deformations between the equivalent and actual hybrid PCHE core models are less than 3.654% and 0.077‰ respectively. However, the computation time of the equivalent model is a factor of 77 below that of the actual model.