Thermal Augmentation in a Force Convective Cabinet Dryer Using Zigzag Ribs Fitted on Air Heater Section
S. Chokphoemphun, Pitak Promthaisong, Namphon Pipatpaiboon, Nirut Onsalung
Abstract
This paper presents the influence of zigzag ribs placed on an air heater section of a force convective cabinet dryer on thermal, and fluid flow behaviors in the air heater section and temperature distribution in a cabinet dryer section. The experimental study was carried out in simulated conditions: a uniform absorbed thermal energy and an inlet air velocity under forced convection in the Reynolds number range of 5300–26,000. In this work, the zigzag ribs were mounted on the inner surface of the test section of an air heater channel in two different locations, upper and lower plate with four different pitch length of 15, 30, 45, and 60 mm. The zigzag ribs arrangement was set in two directions, vertical and horizontal arrays. The results showed that the heat transfer and friction loss increased with a decrease in pitch length. The vertical direction provided the heat transfer, friction loss, and thermal performance higher than the horizontal direction. At the same conditions, the zigzag ribs on upper plate provided an average heat transfer and thermal performance higher than the zigzag ribs on the lower plate. The maximum heat transfer enhancement was about 2.95 times over the smooth channel and the best thermal performance was 1.55.