Modal analysis of a full-scale microchannel heat exchanger: Numerical modelling, experimental validation and structural stiffening strategies

Microchannel heat exchangers are widely used in refrigeration and thermal management applications owing to their high heat transfer efficiency, compactness, and reduced refrigerant charge. However, pressure pulsations, compressor-induced vibrations, and flow-related loads may excite structural resonances, increasing vibration levels and the risk of fatigue damage. This study presents a combined numerical and experimental modal analysis of a full-scale aluminium microchannel heat exchanger representative of industrial refrigeration applications. A finite element model based on beam elements was developed to predict natural frequencies and mode shapes under representative mounting conditions. Predicted natural frequencies showed good agreement with measurements obtained through impact hammer testing on the complete assembly, supporting the simplified model's ability to capture its global modal characteristics. The model was subsequently used to investigate structural stiffening through intermediate transverse supports. These supports increased the predicted first natural frequency and modified the dominant bending patterns, demonstrating their potential for adjusting the structural response to avoid operating excitation frequencies. The proposed methodology provides a practical tool for vibration assessment and support design of microchannel heat exchangers.