Experimental and Numerical Investigation of Heat Transfer in Annular Channels With Flow Twisting

2012 ◽  
Author(s):  
S. E. Tarasevich ◽  
V. L. Fedyaev ◽  
A. B. Yakovlev ◽  
I. V. Morenko
Keyword(s):  
Heat Transfer ◽  
Convex Surface ◽  
Annular Channel ◽  
Concave Surface ◽  
Channel Diameter ◽  
Convex Surfaces ◽  
Annular Channels ◽  
Annular Gap ◽  
Phase Water ◽  
Gap Height

In paper the experimental and numerical modeling results of a heat transfer in annular channels with continuous twisting at one-phase water flow are presented. For a flow twisting the wire was spirally coiled on the central body of an annular channel (diameter of a wire is equal to annular gap height). The generalizing associations for heat transfer calculation on the concave and convex surfaces in a single-phase phase are presented. The analysis of features of velocity profiles and temperatures on the concave and convex surfaces are carried out. The heat transfer on a convex surface of an annular channel with a twisting considerably above than the heat transfer on a concave surface. It’s caused by increase of displacement of a maximum of a velocity profile to a concave surface under the influence of mass forces with growth of a twisting extent.

Heat Transfer in Annular Channel With Continuous Flow Twisting

2010 ◽  
Author(s):  
S. E. Tarasevich ◽  
A. B. Yakovlev
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Boiling ◽  
Annular Channel ◽  
Equivalent Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Channel Diameter ◽  
Subcooled Flow Boiling ◽  
Annular Channels

In paper the experimental results on a heat transfer in annular channels with continuous twisting at length at one- and two-phase flows are observed. For a flow twisting the wire was spirally coiled on the central body of the annular channel (diameter of a wire is equal to annular gap altitude). Results of experimental data of a heat transfer of authors and various researchers at a single phase flow in annular channels with a continuous twisting are analyzed. Sampling of diagnostic variables (equivalent diameter and velocity) is spent and generalizing associations for heat transfer calculation on the concave and convex surfaces in a single-phase phase are offered. Also the technique of definition of temperature of the subcooled flow boiling beginning on surfaces of annular channels with a twisting is offered. Features of boiling, origination of heat transfer crisis and results of visualization of a two-phase flow structure in annular channels with twisting are described.

Turbulent Boundary Layer Heat Transfer on Curved Surfaces

1979 ◽  
Vol 101 (3) ◽  
pp. 521-525 ◽  
Author(s):  
R. E. Mayle ◽  
M. F. Blair ◽  
F. C. Kopper
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Convex Surface ◽  
Concave Surface ◽  
Turbulent Shear ◽  
Two Dimensional ◽  
Streamline Curvature ◽  
Turbulent Shear Stress ◽  
Two Dimensional Flow

Heat transfer measurements for a turbulent boundary layer on a convex and concave, constant-temperature surface are presented. The heat transferred on the convex surface was found to be less than that for a flat surface, while the heat transferred to the boundary layer on the concave surface was greater. It was also found that the heat transferred on the convex surface could be determined by using an existing two-dimensional finite difference boundary layer program modified to take into account the effect of streamline curvature on the turbulent shear stress and heat flux, but that the heat transferred on the concave surface could not be calculated. The latter result is attributed to the transition from a two-dimensional flow to one which contained streamwise, Taylor-Go¨rtler type vortices.

Numerical Simulations of Natural Convective Heat Transfer in Vertical Concentric and Eccentric Annular Channels

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
A. A. Busedra ◽  
S. Tavoularis
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Mass Flow Rate ◽  
Convective Heat ◽  
Mass Flow ◽  
Flow Rate ◽  
Annular Channel ◽  
Diameter Ratio ◽  
Fluid Temperature ◽  
Annular Channels

Natural convective heat transfer in a concentric and a highly eccentric, vertical, open ended, annular channel has been investigated numerically. The inner to outer diameter ratio was 0.61, and the height to hydraulic diameter ratio was 18:1. Three heating modes were considered, all having uniform heat flux applied to one or both of the two walls, while the unheated wall was kept adiabatic. The wall temperature distribution, mass flow rate, and midchannel Nusselt number for the case with both walls heated were found to be in excellent agreement with available experimental results. For the same heating conditions, the heat transfer rate in the concentric annular channel was found to be greater than that in the highly eccentric channel, while the mass flow rate was higher in the eccentric channel. A novel finding for the eccentric channel was that the location of maximum velocity was intermediate between the narrow and wide gaps. Another novel observation, which was attributed to radiation effects, was that the fluid temperature in the wide gap region was lower than that of an adiabatic wall. The paper contains additional observations that would be of interest to designers of systems containing annular channels.

Prediction of Post-Dryout Heat Transfer in Vertical Annular Channels Using Artificial Neural Network Method

2008 ◽  
Author(s):  
D. W. Zhao ◽  
G. H. Su ◽  
S. Z. Qiu ◽  
W. X. Tian
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Artificial Neural Network ◽  
Nusselt Number ◽  
Annular Channel ◽  
Experimental Investigations ◽  
Gap Size ◽  
Annular Channels ◽  
Artificial Neural ◽  
Artificial Neural Network Ann

Experimental investigations on post-dryout heat transfer in 10×8.1, 10×7 and 10×6mm annular test sections have been carried out under low-pressure and low mass flow rate conditions. An Artificial Neural Network (ANN) was trained successfully based on the experimental data for predicting the average post-dryout Nusselt number. Based on the ANN, the effects of gap size, pressure, steam Reynolds number, Reg, inlet quality, xi, Prandtl number, (Prg)W, and the ratio of heat flux of inner-tube to that of outer-tube, qi/qo, on post-dryout heat transfer were analyzed, respectively. In present study, Nusselt number in annular channels with big gap size is larger than that in annular channels with small gap size. Nusselt number increases significantly in 1.5mm and 2.0mm annular channels while it is almost constant in 0.95mm annular channel with increasing pressure or qi/qo. Nusselt number increases with Reg in case of 0.95mm and 1.5mm gap sizes. However, Nusselt number in 2.0mm annular channel firstly increases and then decreases with increasing Reg. Nusselt number decreases with increasing inlet quality under all three annular channels condition. Nusselt number decreases significantly with increasing (Prg)W when (Prg)W is less than 1.5. The changes of Nusselt number in 1.5mm or 2.0mm annular channels are larger than that in 0.95mm annular channel.

An Experimental Study of Mixed Convection in Vertical, Open-Ended, Concentric and Eccentric Annular Channels

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
L. Maudou ◽  
G. H. Choueiri ◽  
S. Tavoularis
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Turbulent Flows ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Annular Channel ◽  
High Eccentricity ◽  
Convection Regime ◽  
Annular Channels

The effect of eccentricity on heat transfer in upward flow in a vertical, open-ended, annular channel with a diameter ratio of 0.61, an aspect ratio of 18:1, and both internal surfaces heated uniformly has been investigated experimentally. Results have been reported for eccentricities ranging from the concentric case to the near-contact case and three inlet bulk Reynolds numbers, equal approximately to 1500, 2800, and 5700. This work complements our recently reported experimental results on natural convection in the same facility. The present results are deemed to be largely in the mixed convection regime with some overlap with the forced convection regime and likely to include cases with laminar, transitional, and turbulent flows in at least a part of the test section. Small eccentricity had an essentially negligible effect on the overall heat transfer rate, but high eccentricity reduced the average heat transfer rate by up to 60%. High eccentricity also resulted in wall temperatures in the narrow gap region that were much higher than those in the open channel. The concentric-case Nusselt number was higher than the Dittus–Boelter prediction, whereas the highly eccentric-case Nusselt number was significantly lower than that.

scholarly journals Periodic Unsteady Flow Aerodynamics and Heat Transfer: Studies on a Curved Surface, Combined Part I and II

2000 ◽  
Vol 6 (6) ◽  
pp. 393-416 ◽  
Author(s):  
M. T. Schobeiri ◽  
L. Wright ◽  
P. Chakka
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Convex Surface ◽  
Separation Bubble ◽  
Local Heat Transfer ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Concave Surface ◽  
Layer Transition ◽  
Wake Passing

Aerodynamic and heat transfer investigations were done on a constant curvature curved plate in a subsonic wind tunnel facility for various wake passing frequencies and zero pressure gradient conditions. Steady and unsteady boundary layer transition measurements were taken on the concave surface of the curved plate at different wake passing frequencies where a rotating squirrel-cage generated the unsteady wake flow. The data were analyzed using timeaveraged and ensemble-averaged techniques to provide insight into the growth of the boundary layer and transition. Ensemble-averaged turbulence intensity contours in the temporal spatial domain showed that transition was induced for increasing wake passing frequency and structure. The local heat transfer coefficient distribution for the concave and convex surface was determined at those wake passing frequencies using a liquid crystal heat transfer measurement technique. Detailed aerodynamic and heat transfer investigations showed that higher wake passing frequency caused transition to occur earlier on the concave surface. Local Stanton numbers were also calculated on the concave surface and compared with Stanton numbers predicted using a differential boundary layer and heat transfer calculation method. On the convex side, no effect of wake passing frequency on heat transfer was observed due to a separation bubble that induced transition.

scholarly journals Investigation of the influence of Taylor-Gortler vortexes on heat transfer of annular channel

2021 ◽  
Vol 2039 (1) ◽  
pp. 012026
Author(s):  
E V Pankratov
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Radial Velocity ◽  
Heat Flux Density ◽  
Annular Channel ◽  
Swirling Flows ◽  
Velocity Fluctuations ◽  
Annular Channels ◽  
Channel Surface ◽  
Flux Density Distribution

Abstract This article is about the influence of Taylor-Gortler vortices on heat transfer in concentric annular channels with turbulent decaying swirling flows. The study shows that the occurrence and transformation of secondary vortex structures has a significant effect on the distribution of heat flux over the annular channel surface. An explicit is relationship between the radial velocity fluctuations and the heat flux density distribution. The highest intensity of heat transfer on the outer surface is observed in the areas of positive radial velocity values, while on the inner surface it is observed in the areas of negative radial velocity values.

scholarly journals Intensification of heat transfer in the inlet of the convective stage of the recuperative-burner unit

2021 ◽  
Vol 2088 (1) ◽  
pp. 012024
Author(s):  
Yu L Leukhin ◽  
P D Alekseev
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Three Dimensional ◽  
Annular Channel ◽  
Initial Section ◽  
Stagnant Zone ◽  
Original Design ◽  
Ansys Fluent ◽  
Annular Gap ◽  
Burner Unit

Abstract The study of aerodynamics and heat transfer in the recuperator convective stage of the recuperative-burner unit with the jet leakage of the flue gas flow onto the outer cylindrical surface is carried out. Numerical modeling of the problem was carried out in a three-dimensional formulation using the ANSYS Fluent software package. It was found that in the original design of the recuperative-burner unit, there is a significant unevenness of heat transfer along the length and perimeter of the working surface of the convective stage. In the initial section of the annular gap, a stagnant zone with the lowest heat transfer rate is observed. To eliminate the stagnant zone and to intensify heat transfer on the surface in this area, it is proposed to make the entrance to the perforated pipe in the form of an inner quarter of a torus; to install smooth protrusions on its surface; to locate an annular flow divider on the inner surface of the heat transfer wall, which separates the front part of the annular channel with formation of a set of vortex chambers. The research results are presented.

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