The paper presents the experimental results on heat transfer characteristics of air forced convection over two ribbed not-thin plates and a flat plate for comparison, obtained by infrared thermography. This technique is attractive because it allows a full-field, non-contact, high spatial resolution, measurement of the surface temperature and heat transfer coefficient distribution if heat flux distribution is given. In the present case, heat flux is known but at a some depth from the surface convectively cooled while heat diffusion through the plate being not negligible. In this paper, we first present the procedure for processing thermographic images and then thermal performances of two roughened surfaces with square cross-section ribs perpendicularly arranged to airflow, with two values of the corrugation pitch to rib side ratio, i.e., 33.3 and 13.3. Convection data are for air flows at room temperature with a speed between 2.3 and 11.6 m/s, corresponding to ReL ranging from 31000 to 155000, and for heat fluxes between 650 and 820 W/m2.
HEAT TRANSFER MEASUREMENTS BY IR-THERMOGRAPHY OVER ENHANCED SURFACES WITH TRANSVERSE RIBS
COLOMBO, LUIGI PIETRO MARIA;NIRO, ALFONSO
2008-01-01
Abstract
The paper presents the experimental results on heat transfer characteristics of air forced convection over two ribbed not-thin plates and a flat plate for comparison, obtained by infrared thermography. This technique is attractive because it allows a full-field, non-contact, high spatial resolution, measurement of the surface temperature and heat transfer coefficient distribution if heat flux distribution is given. In the present case, heat flux is known but at a some depth from the surface convectively cooled while heat diffusion through the plate being not negligible. In this paper, we first present the procedure for processing thermographic images and then thermal performances of two roughened surfaces with square cross-section ribs perpendicularly arranged to airflow, with two values of the corrugation pitch to rib side ratio, i.e., 33.3 and 13.3. Convection data are for air flows at room temperature with a speed between 2.3 and 11.6 m/s, corresponding to ReL ranging from 31000 to 155000, and for heat fluxes between 650 and 820 W/m2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
