Continuous Rib Research Articles

Experimental investigation on heat-transfer enhancement due to a gap in an inclined continuous rib arrangement in a rectangular duct of solar air heater

Artificial roughness in the form of repeated ribs has been proposed as a convenient method for enhancement of thermal performance of solar air heaters. This paper presents the experimental investigation of heat transfer and friction factor characteristics of a rectangular duct roughened with repeated square cross-section split-rib with a gap, on one broad wall arranged at an inclination with respect to the flow direction. The duct has a width to height ratio ( W/ H) of 5.84, relative roughness pitch ( P/ e) of 10, relative roughness height ( e/ D h) of 0.0377, and angle of attack ( α) of 60°. The gap width ( g/ e) and gap position ( d/ W) were varied in the range of 0.5–2 and 0.1667–0.667, respectively. The heat transfer and friction characteristics of this roughened duct have been compared with those of the smooth duct under similar flow condition. The effect of gap position and gap width has been investigated for the range of flow Reynolds numbers from 3000 to 18,000. The maximum enhancement in Nusselt number and friction factor is observed to be 2.59 and 2.87 times of that of the smooth duct, respectively. The thermo-hydraulic performance parameter is found to be the maximum for the relative gap width of 1.0 and the relative gap position of 0.25.

정사각 덕트 내에서 열/물질전달 촉진을 위한 경사진 단락 요철의 좁은 틈새 효과

Local heat/mass transfer and friction loss in a square duct roughened with various types of continuous and discrete rib turbulators are investigated. The combined effects of the gap flows of the discrete ribs and the secondary flows are examined for the purpose of the reduction of thermally weak regions and the promotion of the uniformity of heat/mass transfer distributions as well as the ;augmentation of average heat/mass transfer. The rib-to-rib pitch to the rib height ratio (p/e) of 8 and the rib angles of 90° and 60° are selected with e/Dh/

Effects of Discrete Rib-Turbulators on Heat/Mass Transfer Augmentation in a Rectangular Duct

The influence of arrangement and length of discrete ribs on heat/mass transfer and friction loss is investigated. Mass transfer experiments are conducted to obtain the detailed local heat/mass transfer information on the ribbed wall. The aspect ratio (width/height) of the duct is 2.04 and the rib height is one tenth of the duct height, such that the ratio of the rib height to hydraulic diameter is 0.0743. The ratio of rib-to-rib distance to rib height is 10. The discrete ribs were made by dividing each continuous rib into 2, 3 or 5 pieces and attached periodically to the top and the bottom walls of the duct with a parallel orientation The combined effects of rib angle and length of the discrete ribs on heat/mass transfer ae considered for the rib angles . As the number of the discrete ribs increases, the uniformity of the heat/mass transfer distributions increases. For , the heat/mass transfer enhancement with the discrete ribs is remarkable, while the heat/mass transfer performances are slightly higher than that of the transverse continuous ribs due to the accompanied high friction loss penalty. For , the average heat/mass transfer coefficients and the heat/mass transfer performances decrease slightly with the discrete ribs compared to the case of the angled continuous ribs

Local Heat/Mass Transfer Measurements in a Rectangular Duct With Discrete Ribs

The influence of arrangement and length of discrete ribs on heat/mass transfer and friction loss is investigated. Mass transfer experiments are conducted to obtain the detailed local heat/mass transfer information on the ribbed wall. The aspect ratio (width/height) of the duct is 2.04 and the rib height is one tenth of the duct height, such that the ratio of the rib height to hydraulic diameter is 0.0743. The ratio of rib-to-rib distance to rib height is 10. The discrete ribs were made by dividing each continuous rib into two, three, or five pieces, which were attached periodically to the top and bottom walls of the duct with a parallel orientation. The combined effects of rib angle and length of the discrete ribs on heat/mass transfer are considered for the rib angles (α) of 90 and 45 deg. As the number of the discrete ribs increases, the uniformity of the heat/mass transfer distributions increases. For α=90 deg, the heat/mass transfer enhancement with the discrete ribs is remarkable, while the heat/mass transfer performances are slightly higher than that of the transverse continuous ribs due to the accompanied high friction loss penalty. For α=45 deg, the average heat/mass transfer coefficients and the heat/mass transfer performances decrease slightly with the discrete ribs compared to the case of the angled continuous ribs.[S0889-504X(00)00103-3]

High performance heat transfer ducts with parallel broken and V-shaped broken ribs

The effect of the broken rib orientation on the local heat transfer distributions and pressure drop in a square channel with two opposite in-line ribbed walls is investigated for Reynolds numbers from 15 000 to 90 000. The square channel is composed of ten isolated copper sections and has a length-to-hydraulic diameter ratio of 20. The rib height-to-hydraulic diameter ratio is 0.0625, and the rib pitch-to-height ratio equals 10. The results show that the 60° parallel broken rib or 60° V-shaped broken rib provides a higher heat transfer augmentation than the 45° parallel broken rib or 45° V-shaped broken rib and, subsequently, higher than the 90° broken rib. The parallel ‘broken rib’ or V-shaped ‘broken rib’ has 2.5–4 times heat transfer augmentation compared with the previous parallel ‘continuous rib’ or V-shaped ‘continuous rib’ with 2–3 times heat transfer augmentation for the same amount of 7–8 times pressure drop penalty.

Some structural considerations in the design of nuclear containment liners

The evaluation of forces and deformations of liner plate anchors in containment structures is studied. These forces and deformations are due to buckling, and hence reduction in load carrying capacity, of a panel of the liner plate. Specifically, the behavior of headed stud and of continuous rib type anchors is investigated. The stiffness characteristics of the anchors are based on experimental evidence, and are nonlinear. Parameters which are varied include the plate thickness, yield stress, and anchor spacing. The results of several representative configurations are presented from which behavior trends can be observed. It is found that an increase in yield stress, of an amount often encountered in practice causes a large increase in anchor force and deformation. On the other hand, a plate thickness increase of 15% results in a much smaller increase of anchor force and displacement.