An experimental analysis of the flow pattern in heat exchangers with an egg carton configuration (parallel, convergent and divergent cases)

An experimental analysis about the flow patterns that appear in the channel formed between two corrugated plates with an egg carton configuration is reported. The types of flow instabilities caused by the corrugated plates are identified and described by means of flow visualization experiments, and photographic sequences illustrate the flow features present for each case. The influence on flow instabilities of Reynolds number, phase angle, convergence/divergence angle and spacing between corrugated plates is investigated. The corrugated plates are set divergent and convergent in order to investigate if recirculations are broken by chaotic advection. The improvement of heat transfer in the laminar regime has become an essential task in many applications and therefore the experiments are conducted in this regime.The corrugated plates geometry provides two main advantages over the conventional plane plates: the recirculation zones observed in the longitudinal direction and the three-dimensionality of the flow, i.e. the recirculations reduce the thermal resistances while the three-dimensionality of flow generates a better mixing and a more uniform temperature distribution.This experimental study contributes to the general knowledge on the subject being the first that addresses the analysis of convergent and divergent egg carton plates. It is expected that the results presented here will shed some light as to advantageously use these geometries in the near-future heat exchangers. (Because of the improve chaotic mixing in divergent corrugated plates, this configuration may be a good option to improve heat exchangers performance, because a better mixing is always related to the presence of core fluid near exchange surfaces, and consequently an increase in temperature gradients and heat transfer.)