<p>This work investigates the impact of liquid–vapor mechanical interactions and liquid distribution on heat and mass transfer in falling film compact grooved plate heat exchangers devoted to NH₃/H₂O absorption chillers. A key contribution is the extension of an existing numerical model—originally developed for conventional geometries—to confined configurations, where the characteristic length becomes comparable to the capillary length. In such systems, interfacial interactions and film distribution effects become significant and must be accounted for. The average liquid and vapor cross-sections are estimated using force balance equations that incorporate interfacial interactions and are then integrated into the heat and mass transfer model. The refined model is applied to simulate two critical components of the chiller: the generator (counter-current configuration) and the absorber (co-current configuration). Critical performance factors are examined, including the influence of interfacial waves on film thickness, film distribution, and heat and mass transfer coefficients. The model provides a comprehensive simulation framework that improves the understanding of flow dynamics, film behavior, and transfer processes in compact geometries. The results highlight the significant impact of film distribution and liquid-side transfers on the heat exchanger performance, offering valuable insights for the design and optimization of compact chillers.</p>