Thermo-fluid performance of a heat exchanger with a novel perforated flow deflector type conical baffles

Abstract

A study investigated how a new swirl airflow design could impact the heat transfer rate in a tubular heat exchanger with axial flow. A perforated conical baffle plate with rectangular air deflectors of different inclination angles was created to generate a swirl flow. The tubes in the heat exchanger were aligned longitudinally, and the heat flux across their surface was kept constant. Each plate had four deflectors with equal deflector angles and adjustable pitch ratios, which created a swirling airflow inside the circular duct containing the heated tubes. This increased turbulence and the rate of heat transfer across the tube surface. The Reynolds number stayed within the range of 93, 500 to 160, 500. The result indicates that the inclination angle and Pitch ratio profoundly impact the Nusselt number, while the pitch ratio has a greater effect on the friction factor. Furthermore, the conical baffle plate design resulted in an average improvement of 2.51 in thermal efficiency compared to a segmental baffle design with a deflector angle of 30° and a pitch ratio of 1, all under similar Reynolds number, pitch ratio, and blockage ratio conditions.