Bestimmung charakteristischer Geometrieparameter von Thermoblech‐Wärmeübertragern

Pillow‐plate heat exchangers are a promising alternative to conventional heat exchangers. Their design methods are based on characteristic geometric parameters, for which no established determination procedures are available in the literature. In this work, the complex pillow‐plate geometry is reproduced by accurate deformation simulations. In the following step, approximate equations describing the geometry are derived and validated. Based on this validation, suggestions for the preliminary evaluation of the characteristic geometrical parameters are made.     

Experimentelle Bestimmung von Wärmeübergang und Druckverlust in Multiportflachrohren

Heat transfer and pressure drop data of three smooth multiport minichannels featuring hydraulic diameters > 1 mm are presented. Experiments were conducted under single phase convection of heptane and under convection of condensing R134a. Two specifically designed testing facilities feature a novel measurement setup to register the amount of condensate generated and to measure the temperatures of the refrigerant and minichannel wall. The results for the smallest minichannel geometrie show that the assumption of an increasing heat transfer rate with decrasing hydraulic diameter is not generally valid.