transfer in compact plate-fin heat exchangers is augmented by the introduction of complex fin patterns in the channels. Kays and London presented a lot of experimental data for several types of fin configurations, and man), authors followed their example with other types of fins. For some fin types, the heat transfer correlation for the Nusselt number cannot be found in literature. Most of the data are given for large scale model fins in good controlled laboratory environments-little data is available for real heat exchangers. A test rig was constructed at Ghent University to verify the performance of several fin types. Measurements were done on a real heat exchanger and not on a large scale model in order to determine the performance under real operational conditions. The measurement setup consists of a hot water circuit and an air circuit with a fan. In the heat exchanger, 40 thermocouples are introduced on the air side and the wall. This way, the convection coefficient of the fins can be determined for a broad range of Reynolds numbers. In the paper the measurement set-up is discussed and the measurements are presented. An in depth error analysis is performed on the measurements. This way a heat transfer correlation is provided with a tight error margin for compact plate-fin air coolers.