Comparison of heat and mass transfer in different heat exchanger geometries with corrugated walls

In systematic comparative analyses heat exchangers with corrugated walls are analysed. The wall corrugation is generated by sinusoidally shaped walls as well as by crosswise corrugated cylinders of different cross-section on plane walls like those being used as spacers in membrane technology. Corrugated structures in crosswise orientation are composed of passages formed by layers of corrugated structures with opposite orientation of the corrugation lines. The main geometrical parameters of such structures are the inclination angle ϕ, the wavelength λ, the amplitude a and the shape of the corrugation. The effect of different geometrical parameters of these corrugated structures on the local and integral heat and mass transfer are discussed. It is shown, that the flow phenomena caused by the different geometries are of significant influence on the homogeneity and on the quantity of the local heat and mass transfer as well as on the pressure drop. Independent of the sinusoidal or cylindrical surface structure the heat and mass transfer as well as the pressure losses are fixed by basic flow characteristics. Here three different flow types can be separated, depending on the geometry and flow parameters. For applications of heat transfer in fluids with particulates the use of corrugated walls in the free-flow arrangement becomes more interesting. Therefore results for this heat exchanger geometry are presented, where the transition from laminar to turbulent flow range is dominated by the Görtler–Dean instability. Besides a detailed flow analysis, comparison of the local heat and mass transfer and the pressure losses for these geometries are presented. The measurements were made at the same flow velocity, channel height and channel width as the crosswise corrugated structures. A direct and accurate comparison of the different structures is thus possible.