EXPERIMENTAL INVESTIGATION OF TURBULENT HEAT TRANSFER TO SUPERCRITICAL WATER IN A TUBE WITH CIRCUMFERENTIALLY VARYING HEAT FLUXES

1970 ◽  
Author(s):  
B. Kamenetsky ◽  
M. E. Shitsman
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Supercritical Water ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat

scholarly journals Numerical Analysis on the Heat Transfer Characteristics of Supercritical Water in Vertically Upward Internally Ribbed Tubes

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 621
Author(s):  
Xianliang Lei ◽  
Ziman Guo ◽  
Ruifeng Peng ◽  
Huixiong Li
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Maximum Temperature ◽  
Clear Understanding ◽  
Turbulent Heat ◽  
Local Flow ◽  
Transfer Capability ◽  
Heat Transfer Capability

Internally ribbed tubes (IRTs) with better heat transfer capability have been widely applied in many fields. Several studies focused on the flow and heat transfer in IRTs with special structure configurations, but there is still lack of clear understanding regarding the influence of spiral ribs/grooves on the local flow structure and heat transfer capability of supercritical water. In the present paper, numerical simulation on turbulent heat transfer of supercritical water through a vertically upward IRTs is investigated. It is found at low heat fluxes, heat transfer enhancement occurs; the temperature of IRT is lower than that in the smooth tube by 6~7 °C, but at high heat fluxes; deteriorated heat transfer occurs in ST rather than in IRTs; the maximum temperature difference reaches 36 °C. The heat transfer ratio between IRT and ST is about 1.81 in the pseudocritical region, where the velocity deviation is about 20–50%. Once the deterioration heat transfer exists, a thin layer with high temperature but low density and low thermal conductivity so that (with a 20% reduction) fluids will be covered on the surfaces. Effects of rib height, width, lift angle and threads on turbulent heat transfer are analyzed, an optimum rib structure based on the performance evaluation criteria is obtained (α = 50°, e = 0.58 mm, S = 3.5 mm, m = 6), which can achieve the best performance.

DNS of Heat Transfer Reduction in Viscoelastic Turbulent Channel Flows

2015 ◽  
Author(s):  
Kyoungyoun Kim ◽  
Radhakrishna Sureshkumar
Keyword(s):  
Heat Transfer ◽  
Channel Flow ◽  
Reduction Rate ◽  
Turbulent Channel Flow ◽  
Passive Scalar ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Uniform Heat Flux ◽  
Turbulent Heat ◽  
Turbulent Heat Fluxes

A direct numerical simulation (DNS) of viscoelastic turbulent channel flow with the FENE-P model was carried out to investigate turbulent heat transfer mechanism of polymer drag-reduced flows. The configuration was a fully-developed turbulent channel flow with uniform heat flux imposed on both walls. The temperature was considered as a passive scalar. The Reynolds number based on the friction velocity (uτ) and channel half height (δ) is 125 and Prandtl number is 5. Consistently with the previous experimental observations, the present DNS results show that the heat-transfer coefficient was reduced at a rate faster than the accompanying drag reduction rate. Statistical quantities such as root-mean-square temperature fluctuations and turbulent heat fluxes were obtained and compared with those of a Newtonian fluid flow. Budget terms of the turbulent heat fluxes were also presented.

An Explicit Algebraic Model for Turbulent Heat Transfer in Wall-Bounded Flow With Streamline Curvature

2006 ◽  
Vol 129 (4) ◽  
pp. 425-433 ◽  
Author(s):  
B. A. Younis ◽  
B. Weigand ◽  
S. Spring
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
Algebraic Model ◽  
Heat Fluxes ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Streamline Curvature ◽  
Turbulent Heat Fluxes ◽  
The Mean

Fourier’s law, which forms the basis of most engineering prediction methods for the turbulent heat fluxes, is known to fail badly in capturing the effects of streamline curvature on the rate of heat transfer in turbulent shear flows. In this paper, an alternative model, which is both algebraic and explicit in the turbulent heat fluxes and which has been formulated from tensor-representation theory, is presented, and its applicability is extended by incorporating the effects of a wall on the turbulent heat transfer processes in its vicinity. The model’s equations for flows with curvature in the plane of the mean shear are derived and calculations are performed for a heated turbulent boundary layer, which develops over a flat plate before encountering a short region of high convex curvature. The results show that the new model accurately predicts the significant reduction in the wall heat transfer rates wrought by the stabilizing-curvature effects, in sharp contrast to the conventional model predictions, which are shown to seriously underestimate the same effects. Comparisons are also made with results from a complete heat-flux transport model, which involves the solution of differential transport equations for each component of the heat-flux tensor. Downstream of the bend, where the perturbed boundary layer recovers on a flat wall, the comparisons show that the algebraic model yields indistinguishable predictions from those obtained with the differential model in regions where the mean-strain field is in rapid evolution and the turbulence processes are far removed from local equilibrium.

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