Investigations on Thermo-Fluid Performance of a Milti-pass Shell-and-Tube Heat Exchanger with a Novel Trapezoidal Deflector-Type Baffle Plate

An axial flow tubular heat exchanger has been experimentally investigated to augment the heat transfer rate with a novel swirl flow of air past the heated tubes. The novel design has been made on the circular baffle plates provided with trapezoidal air deflectors of various inclination angles α, which is the angle made by the deflector surface with baffle plane. The arrangement of tubes, which were supported on baffle plates, was kept the same throughout the experiment analogy with the peripheral longitudinal air flow directed on it. All the tubes were maintained at constant heat flux condition over the entire surface. There were four deflectors developed on each of the baffle plate each deflector with equal inclination angle which generates air swirls inside the circular duct carrying the heated tubes that increase air side turbulence and hence the surface heat transfer rate. For every Re the baffle plates were placed equidistant from each other at different pitch ratios (PR = 0.6, 0.8, 1.0, and 1.2). The Reynolds number Re was kept in the range of 93 500–160 500. The effect of pitch ratios and the inclination angles on the thermo-fluid performance of the heat exchanger has been studied. The investigations reveal an average improvement of 25.1% in the thermo-fluid performance for a heat exchanger provided with the deflector baffle plates (DBP) having an inclination angle of 50° and a pitch ratio of 1.2 compared to that of a heat exchanger with a segmental baffle plate (SBP) tested under similar conditions of operation.