Abstract
In this study, the effect of intersecting ribs with inclined ribs on the heat transfer and flow characteristics of a high aspect ratio duct has been numerically investigated. The Relative roughness pitch (P/e) is 10 and the Reynolds number range from 35,700 to 72,800. ANSYS (Fluent-Workbench 18.0) software has been utilized to solve the Reynolds averaged Navier-Stokes (RANS) equations with the Standard k-ε turbulence model. Three ribbed models have been used in this study. Model 1 which is a just inclined ribs, Model 2 which has a single longitudinal rib at the center with inclined ribs and Model 3 which has two longitudinal ribs at the sides. The results showed that the heat transfer rate has been enhanced when the intersecting ribs are used. Model 3 has achieved the highest overall thermal performance. The increasing in Nusselt number ratio (Nu /Nus ) for Model 3 and 2, relative to Model 1, are 13.19% and 7.03%, respectively. Consequently, the hybridizing by intersecting ribs with inclined ribs is considered as an advantageous technique to enhance the heat transfer.
Highlights
Many of thermal systems require an enhancement in the heat transfer rates for saving power exhaustion
The artificial surface roughness in the form of ribs has been suggested to use. This type may be used in several engineering applications, such as solar air heater and gas turbines. (Lee et al, 2009) investigated the flow characteristics and local heat/mass transfer on the effect of aspect ratio (AR) for ribbed duct for two different V-shaped rib configurations. They were observed that the heat/mass transfer at the center zone of channel was significantly affected by the (AR), since heat/mass transfer rate decreased as the (AR) increased
The results showed that the heat transfer coefficients increase with increasing the flow rate and decreasing with reduced the spacings
Summary
Many of thermal systems require an enhancement in the heat transfer rates for saving power exhaustion. (Lee et al, 2009) investigated the flow characteristics and local heat/mass transfer on the effect of aspect ratio (AR) for ribbed duct for two different V-shaped rib configurations. (Lu and Jiang, 2006) experimentally and numerically investigated the effect of mass flow rate on the heat transfer and flow characteristics for inclined ribs in a rectangular duct. (Chung et al, 2015) experimentally and numerically investigated the intersecting rib effect with inclined ribs at 60o attack angle on heat/mass transfer efficiency They used a rectangular duct with different aspect ratio (W/H) was varied from 1 to 4. The present work objective is to numerically investigate the effect of used intersecting ribs with inclined ribs in a rectangular duct of a high aspect ratio, on heat transfer and characteristics of flow. To determine the optimum model that achieves the highest heat transfer enhancement with the lower pressure dropز
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