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Ary Bachtiar Krishna Putra(아리바시아 크리시나 부트라),Ho Keun Kang(강호근),Dae Hee Lee(이대희),Soo Whan Ahn(안수환) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Numerical predictions and experiment of a hydrodynamic and thermally developed turbulent flow through square channels with one or two ribbed walls were performed to determine the pressure drop and heat transfer. The CFX software package was used for the computations. The rough wall had 45°-inclined square ribs. All four walls in the channel were heated, and a uniform heat flux was maintained on the entire inner heat transfer channel area. Experimental data were also obtained for four Reynolds numbers ranging from 7,600 to 24,900, a pitch-to-rib-height ratio of 8.0, and a rib-height-to-channel hydraulic diameter ratio of 0.0667. The numerical results were in agreement with the experimental data and showed that the values of the local heat transfer coefficient and friction factor in a square channel with two ribbed walls were greater than those with one ribbed wall.
Heat Transfer and Friction Behaviour in a Channel with Inclined Perforated Baffle
Ary Bachtiar Krishna Putra(아리바시아 크리시나 부트라),Soo Whan Ahn(안수환) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
This experimental study investigates the local heat transfer enhancement characteristics and the associated frictional head loss in a rectangular channel with a single inclined baffle. Four different types of the baffle are used. The inclined baffles have the width of 19.8 em, the square diamond of 2.55 ㎝ × 2.55 ㎝, and the inclination angle of 5˚. Reynolds number is varied between 23,000 and 57,000. Results show that the heat transfer and friction factor depend significantly on the number of baffle holes and Reynolds number. The friction factor decreases with increasing Reynolds number and the number of holes on the baffle. It is found that the heat transfer performance of baffle type Ⅱ (3 hole baffle) has the best values.
Fluid Flow Resistance in a Channel with Wire-mesh Baffles
Ary Bachtiar Krishna Putra(아리바시아 크리시나 부트라),Soo Whan Ahn(안수환) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
An experimental investigation was conducted to examine the fluid flow resistance in rectangular channel with two inclined wire mesh baffles. Two different types of wire meshes, namely dutch weave and plain weave, were used as baffle materials in this experiment. Three kinds of baffles with different mesh specifications were made up of dutch weave type and four different kinds of baffles were made up of plain weave type. The stainless steel wire mesh baffles were mounted on bottom wall with varied angle of baffle inclination. Reynolds numbers were varied from 23,000 to 57,000. Results show that the number of mesh of the baffle plate plays an important role on friction factor behavior. It is found that baffle plate with the most number of mesh (type SA) has the highest fluid flow resistance.
Heat Transfer and Friction Behaviour in a Channel with an Inclined Perforated Baffle
Krishna Putra, Ary Bachtiar,Ahn, Soo-Whan The Society of Air-Conditioning and Refrigerating 2008 International Journal Of Air-Conditioning and Refr Vol.16 No.2
The effects of the inclined perforated baffles on the distributions of the local heat transfer coefficients and friction factors for air flows in a rectangular channel were determined for Reynolds numbers from 23,000 to 57,000. Four different types of the baffle are used. The inclined baffles have the width of 19.8cm, the square diamond type hole having one side length of 2.55cm, and the inclination angle of $5^{\circ}$, whereas the corresponding channel width-to-height ratio was 4.95. Results show that the heat transfer and friction factor depend significantly on the number of baffle holes and Reynolds number. The friction factor decreases with increasing Reynolds number and the number of holes on the baffle, and the heat transfer performance of baffle type II (3 hole baffle) has the best value.
Heat Transfer Enhancement in a Channel with Wire-mesh Baffles
Ary Bachtiar Krishna Putra(아리바시아 크리시나 부트라),Soo Whan Ahn(안수환) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
The heat transfer characteristics of flow through two inclined wire-mesh baffles in a rectangular channel were investigated experimentally with varying the mesh number of wire screens and inclination angle of the baffles. Two different types of wire meshes, namely dutch weave and plain weave, were used in this experiment. Three kinds of baffle plates with different mesh specifications in the dutch weave and four different kinds in the plain weave were manufactured. Baffles were mounted on bottom wall with varied angle of inclination. Reynolds number was varied from 23,000 to 57,000. It is found that the placement of inclined wire-mesh baffles in the channel affects the heat transfer characteristics by combining both jet impingement and flow disturbance. The wire screen modified the flow structure leading to a change in the heat transfer characteristics. The results show that the baffle plate with the most number of mesh (type SA) has the highest heat transfer rate.
2개의 경사진 배플에 의한 열전달과 마찰계수에 관한 수치해석
아리바시아 크리사나 부트라(Ary Bachtiar Krishna Putra),안수환(Soo Whan Ahn),강호근(Ho Keun Kang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.11
Baffles enhance heat transfer by disturbing boundary layer and bulk flow, creating impingement, and increasing heat transfer surface area. This study was performed to determine how the two inclined baffles (α =5˚; perforated models) placed at a rectangular channel affect heat transfer and associated friction characteristics. The parametric effects of perforated baffles (3, 6 and 12 holes) and flow Reynolds number ranging from 28,900 to 61,800 on the heated target surface are explored. Comparisons of the experimental data with the numerical results by commercial code CFX 10.0 are presented. As for the investigation of heat transfer behaviors on local Nusselt number with two baffles placed at x/D<SUB>h</SUB> =0.8 and x/D<SUB>h</SUB> =8.0 of the edge of baffles, it is evident that the inclined perforated baffles augment overall heat transfer significantly by both jet impingement and boundary layer separation. There exists an optimum perforation density to maximize heat transfer coefficients; i.e., the average Nusselt number increases with increasing number of holes, but the friction factor decreases with an increase in the hole number placed at baffles.
Characteristics of Heat Transfer in the Ribbed Rectangular Channel with Variable Heating Condition
Kim Won-Cheol,Putra Ary Bachtiar Krishna,Kang Ho-Keun,Ahn Soo-Whan The Society of Air-Conditioning and Refrigerating 2007 International Journal Of Air-Conditioning and Refr Vol.15 No.1
Surface heat transfer of a fully developed turbulent air flow in a $45^{\circ}$ inclined ribbed square duct with two and four heating walls was experimentally investigated, at which the experimental works were performed for Reynolds numbers ranging from 7,600 to 24,900. The pitch-to-rib height ratio, p/e was kept at 8 and rib-height-to-channel hydraulic diameter ratio, $e/D_h$ was kept at 0.0667. The channel length-to-hydraulic diameter ratio, $L/D_h$ was 60. The heat transfer coefficient values were decreased with the increase in the number of heating walls. Results of this investigation could be used in various applications of internal channel turbulent flow involving roughened walls.