Flow Field Structure, Characteristics of Thermo-Hydraulic and Heat Transfer Performance Analysis in a Three Dimensions Circular Tube with Different Ball Turbulators Configurations

2021 ◽  
Author(s):  
Ahmed Ramadhan Al-Obaidi ◽  
Issa Chaer
Keyword(s):  
Heat Transfer ◽  
Performance Analysis ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Circular Tube ◽  
Field Structure ◽  
Three Dimensions ◽  
Transfer Performance ◽  
Structure Characteristics

scholarly journals The Effect of Periodic Ribs on the Local Aerodynamic and Heat Transfer Performance of a Straight Cooling Channel

1996 ◽  
Author(s):  
G. Rau ◽  
M. Çakan ◽  
D. Moeller ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Transfer Performance ◽  
Local Pressure ◽  
Reynolds Analogy ◽  
Law Of The Wall

The local aerodynamic and heat transfer performance were measured in a rib-roughened square duct as a function of the rib pitch to beight ratio. The blockage ratio of these square obstacles was 10% or 20% depending on whether they were placed on one single (1s) or on two opposite walls (2s). The Reynolds number, based on the channel mean velocity and hydraulic diameter, was fixed at 30000. The aerodynamic description of the flow field was based on local pressure distributions along the ribbed and adjacent smooth walls as well as on 2D LDV explorations in the channel symmetry plane and in two planes parallel to the ribbed wall(s). Local heat transfer distributions were obtained on the floor, between the ribs, and on the adjacent smooth side wall. Averaged parameters, such as friction factor and averaged heat transfer enhancement factor, were calculated from the local results and compared to correlations given in literature. This contribution showed that simple correlations derived from the law of the wall similarity and from the Reynolds analogy could not be applied for the present rib height-to-channel hydraulic diameter ratio (e/Dh=0.1). The strong secondary flows resulted in a three-dimensional flow field with high gradients in the local heat transfer distributions on the smooth side walls.

Heat Transfer Enhancement With Delta Winglets Vortex Generator for Different Arrangement in a Circular Tube

2018 ◽  
Author(s):  
Md. Islam ◽  
A. Nurizki ◽  
A. Kareem ◽  
A. Baba
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Circular Tube ◽  
Flow Behavior ◽  
Vortex Generator ◽  
Attack Angle ◽  
Transfer Performance ◽  
Pitch Ratio

Various technologies have been developed to enhance the heat transfer. Vortex generator (VG) is one of the passive techniques which can change the flow behavior and ultimately enhances the heat transfer performance. Delta winglet (DW) vortex generator can create longitudinal and horseshoe vortices which do not decay until further downstream and consequently increase heat transfer coefficient with comparatively lower pressure drop. With this vortex generator, it is expected to have higher Nusselt number with some increase of friction factor. Therefore, this study is to study the effect of pitch ratio (PR) and attack angle (B) of DW vortex generator to increase the thermal performance of heat exchanger. Four delta winglets are attached into a ring. Those rings attached with VGs will be used to investigate the influence of different parameters to heat transfer performance. In this study VGs were placed inside a circular copper tube and the heating coil was wrapped up around the outer surface of the copper tube to generate a constant heat flux condition. The experimental setup consists of a blower, orifice meter, flow straightener, calm/flow developing section and test section. The results show the friction factor, Nusselt number, and Thermal Performance Enhancement. It increases the thermal performance due to the formation of longitudinal vortex inside the circular tube. Pitch ratio and attack angle seem to have significant impact on the flow and heat transfer. The Pitch ratio of 1.6 have the highest impact on both (f/f0) and (Nu/Nuo) followed by attack angle. Smoke flow visualization technique was used to study flow behavior and flow structures.

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