Heat exchangers with corrugated walls are well known as macro heat exchangers. In previous systematic analyses heat exchangers with crosswise corrugated walls at large Reynolds-numbers were analyzed. The wall corrugation was generated by sinusoidally shaped walls (Fig. 1) as well as by crosswise corrugated cylinders of different cross-section on plane walls (Fig. 2) such as those being used as spacers in the membrane technology. The low Reynolds-numbers range of these structures is also interesting for the application as micro heat exchangers. Therefore first results will be presented, where such structures are experimentally analyzed in the low Reynolds-number range up to Re ≥ 10, especially interesting for applications as micro heat exchangers.
For the use of corrugated walls in the free-flow arrangement (Fig. 3) first new results at low Reynolds-numbers for this heat exchanger geometry are presented, where the transition from turbulent to laminar flow range is dominated by the Gortler-Dean instability.