Computer analysis and large-scale model experiments to determine the air side performance of louvered fin evaporator cores are discussed. Heat transfer and pressure drop are determined for several configurations and compared with calculated values. The experimental setup and digital computer program used for both experiments are described. Effects of condensation, fins per inch, fin thickness, and other core characteristics are determined.The computer model for heat transfer rate appears valid over a Reynolds number of at least 10. Two empirical parameters of the program, one on the liquid side and one on the air side, should be adjusted after comparison with highly accurate empirical data. Additional work is needed to improve the accuracy of data from the large-scale models, although determination of relative performance of different cores appears to be a present capability.The present theoretical model does not have the capability for calculating the liquid side heat transfer coefficient, the effect of louver angle or louver fin center distribution, or the effect of water droplet formation on the airflow and pressure drop.