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 minichannels. 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 parts per thousand respectively. However, the computation time of the equivalent model is a factor of 77 below that of the actual model.