Enhanced Heat Transfer Characteristics of Single-Phase Flows in a Plate Heat Exchanger with Mixed Chevron Plates

The enhanced thermal-hydraulic performance of single-phase flows in a plate heat exchanger with mixed chevron plates is investigated experimentally. The mixed arrangement consists of plates with chevron angle β = 30° and 60°, alternatingly stacked in a single-pass, U-type, counterflow configuration. Vegetable oil (130 < Pr < 220) and water (2.4 < Pr < 4.5) are used as test fluids, with flow rates in the laminar, transition, and turbulent flow regimes (2 < Re < 6000). Results for isothermal friction factor and heat transfer under cooling conditions, along with respective correlations for laminar (2 < Re < 400) and fully developed turbulent (Re ≥ 1000) flows are presented; transition is observed to set in when Re ∼ 500. The heat transfer data are obtained from controlled experiments, employing an extension of the Wilson Plot technique. A comparison of the data with previously reported results and predictive equations for Nu and / highlights the latter’s lack of general applicability, and the need for a larger database. The relative impact of using mixed chevron plate arrangement is discussed, and their enhanced performance, in comparison with parallel-plate channels, is evaluated.