Numerical Evaluation for Spacer Vane Effects on Flow and Heat Transfer of Water at Supercritical Pressure in Annular Channel

2021 ◽  
pp. 1-14
Author(s):  
Satish Kumar Dhurandhar ◽  
S. L. Sinha ◽  
Shashi Kant Verma
Keyword(s):  
Heat Transfer ◽  
Numerical Evaluation ◽  
Annular Channel ◽  
Supercritical Pressure ◽  
Flow And Heat Transfer

scholarly journals Heat transfer and flow region characteristics study in a non-annular channel between rotor and stator

2012 ◽  
Vol 16 (2) ◽  
pp. 593-603 ◽  
Author(s):  
M. Nili-Ahmadabadi ◽  
H. Karrabi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Characteristics ◽  
Annular Channel ◽  
Flow Region ◽  
Air Gap ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Slip Ring

This paper will present the results of the experimental investigation of heat transfer in a non-annular channel between rotor and stator similar to a real generator. Numerous experiments and numerical studies have examined flow and heat transfer characteristics of a fluid in an annulus with a rotating inner cylinder. In the current study, turbulent flow region and heat transfer characteristics have been studied in the air gap between the rotor and stator of a generator. The test rig has been built in a way which shows a very good agreement with the geometry of a real generator. The boundary condition supplies a non-homogenous heat flux through the passing air channel. The experimental devices and data acquisition method are carefully described in the paper. Surface-mounted thermocouples are located on the both stator and rotor surfaces and one slip ring transfers the collected temperature from rotor to the instrument display. The rotational speed of rotor is fixed at three under: 300rpm, 900 rpm and 1500 rpm. Based on these speeds and hydraulic diameter of the air gap, the Reynolds number has been considered in the range: 4000<Rez<30000. Heat transfer and pressure drop coefficients are deduced from the obtained data based on a theoretical investigation and are expressed as a formula containing effective Reynolds number. To confirm the results, a comparison is presented with Gazley?s (1985) data report. The presented method and established correlations can be applied to other electric machines having similar heat flow characteristics.

Investigation and Modeling of the In-Tube Heat Transfer of Fluids at Supercritical Pressure During Heating

2017 ◽  
Author(s):  
Chen-Ru Zhao ◽  
Zhen Zhang ◽  
Han-Liang Bo ◽  
Pei-Xue Jiang
Keyword(s):  
Heat Transfer ◽  
Numerical Modelling ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Vertical Tube ◽  
Supercritical Pressure ◽  
Flow And Heat Transfer ◽  
Pressure Water ◽  
Predicted Values ◽  
Semi Empirical

Investigations and numerical modelling are performed on the heat transfer to CO2 at supercritical pressure under buoyancy affected conditions during heating in a vertical tube with inner diameter of 2 mm. Numerical modelling are carried out using several low Reynolds number (LRN) k-ε models, including the model due to Launder and Sharma (LS), Abe, Kondoh and Nagano (AKN), Myong and Kasagi (MK) models. The numerical results are compared with the corresponding experimental data and the predicted values using the semi-empirical correlation for convection heat transfer of supercritical fluids without deterioration. The abilities of various LRN models to predict the heat transfer to fluids at supercritical pressures under normal and buoyancy affected heat transfer conditions are evaluated. Detailed information related to the flow and turbulence is presented to get better understanding of the mechanism of the heat transfer deterioration due to buoyancy, as well as the different behavior of various LRN turbulence models in responding to the buoyancy effect, which gives clues in future model improvement and development to predict the buoyancy affected heat transfer more precisely and in a broader range of conditions as they come to be used to simulate the flow and heat transfer in various applications such as in the supercritical pressure water-cooled reactor (SCWR) and the supercritical pressure steam generator in the high temperature gas cooled reactor (HTR).

Taylor-Couette-Poiseuille flow and heat transfer in an annular channel with a slotted rotor

2017 ◽  
Vol 112 ◽  
pp. 92-103 ◽  
Author(s):  
Nicolas Lancial ◽  
Federico Torriano ◽  
François Beaubert ◽  
Souad Harmand ◽  
Gilles Rolland
Keyword(s):  
Heat Transfer ◽  
Poiseuille Flow ◽  
Annular Channel ◽  
Flow And Heat Transfer ◽  
Taylor Couette

Numerical Study of Pyrolysis Effects on Supercritical-Pressure Flow and Conjugate Heat Transfer of N-Decane in the Square Channel

2017 ◽  
Author(s):  
Xizhuo Hu ◽  
Zhi Tao ◽  
Jianqin Zhu ◽  
Haiwang Li
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Conjugate Heat Transfer ◽  
Supercritical Pressure ◽  
Operating Conditions ◽  
Strong Impact ◽  
Heat Absorption ◽  
Regenerative Cooling ◽  
Flow And Heat Transfer ◽  
Bottom Interface

Regenerative cooling has become the most effective and practical method of thermal protection to the high temperature structures of scramjet engines. Pyrolytic reactions of endothermic hydrocarbon fuel have significant influence on the regenerative cooling process at high temperature due to a large amount of heat absorption and fluid components change. In this paper, a three-dimensional (3D) model is developed for numerically investigating the flow and heat transfer of pyrolytic reacted n-decane in the square engine cooling channel under supercritical pressure with asymmetrical heating imposed on the bottom channel surface. The one-step global pyrolytic reaction mechanism consisting of 18 species is adopted to simulate the pyrolysis process of n-decane. The governing equations for species continuum, momentum, energy and the k-ω turbulence equation are properly solved, with accurate computations of the thermophysical and transport properties of fluid mixture, which undergo drastic variations and exert strong impact on fluid flow and heat transfer process in the channel. The numerical method is validated based on the good agreement between the current predictions and the experimental data. Numerical studies of the pyrolysis effects on the characteristics of flow resistance and conjugate heat transfer under various operating conditions have been conducted. Results reveal that pyrolysis intensively takes place in high temperature regions. The pressure drop along the channel steeply rise due to the further fluid acceleration caused by pyrolysis. It is found that the variations of heat flux at the bottom, top and side fluid-solid-interface walls are totally different. Pyrolysis could lead to greater heat transfer enhancement at the bottom interface, consequently, more heat is transferred into the fluid region through the bottom interface. The dual effects of heat absorption and enhanced heat transfer caused by pyrolysis produce strong influence on the wall temperature. The mechanism of these physicochemical phenomena are also analyzed in detail, which is conducive to fundamentally understand the complicated physicochemical process of regenerative cooling. The present work has profound significance for the development of regenerative cooling technology.

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