The Influence of Distancing Bulges in a Small-Width Parallel-Plate Duct on its Thermal-Hydraulic Characteristics at the Laminar Flow

Abstract

The paper presents analytical study of the distancing bulges effect on the thermal-hydraulic characteristics of a band slotted heat-transfer matrix of the rotary heat exchanger. The work was carried out based on mathematical simulation of the thermal-hydraulic processes in the band parallel-plate duct of low height (0.4 mm) at the laminar flow regime characteristic for the rotary heat exchangers. Influence of the distancing elements number in the rows, distance between the rows, as well as the total number of elements in the channel on the average value of the Nusselt number and on the magnitude of the pressure drop was analyzed. Influence of alterations in speed and temperature regimes on the thermal-hydraulic characteristics was analyzed. It was found that installation of the distancing bulges in a band parallel-plate duct led to a decrease in the Nusselt number and the increase in hydraulic resistance of the parallel-plate duct compared to a flat slotted duct without bulges despite the laminar flow regime. It was noted that influence of the distancing elements mutual arrangement on the bands was insignificant for the flow thermal-hydraulic characteristics. It was established that an increase in the temperature of the parallel-plate duct walls also was not leading to significant alteration in the heat transfer nature inside the channels under study; and alteration in the laminar flow speed regime also practically did not affect the heat transfer intensity in the ducts under consideration