An experimental loop representing a compact plate heat exchanger was built up to study the two-phase distribution in the different header channels. The test section consists of a cylindrical horizontal header and eight rectangular channels in which the liquid and vapour flow rates are evaluated and the flow inside the header can be visualized. Several geometrical and functional parameters to study the two-phase distribution were tested using "HFE 7100" at a temperature close to 57 degrees C and a pressure close to 100 kPa. A flow pattern map in the header was built up using the different entry parameters on which a quantitative understanding of the two-phase distribution could be deduced. (c) 2008 Elsevier Ltd. All rights reserved.