scholarly journals Effect of turbulence models on predicting convective heat transfer to hydrocarbon fuel at supercritical pressure

2016 ◽  
Vol 29 (5) ◽  
pp. 1247-1261 ◽  
Author(s):  
Zhi Tao ◽  
Zeyuan Cheng ◽  
Jianqin Zhu ◽  
Haiwang Li
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Turbulence Models ◽  
Hydrocarbon Fuel ◽  
Supercritical Pressure

Computational Study of Effect of Increasing Heat Flux on Convective Heat Transfer in Sub Channels of Carbon Dioxide Flow at Pressure above Critical Value

2015 ◽  
Vol 772 ◽  
pp. 8-13
Author(s):  
Deepak Sharma ◽  
Krishna Murari Pandey
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Flux ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Water Oxidation ◽  
Computational Study ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Supercritical Pressure

This paper is focused on flow simulation in the sub channel of fuel rod assembly using code ANSYS Fluent 14, which is commercial computational fluid dynamics (CFD) code. Computational simulations are reported on convective heat transfer to carbon dioxide at a pressure of 7.59MPa. Pressure which is used in this simulation are just above the thermodynamic critical pressure value of CO2. These have been carried out using a variable property, elliptic computational formulation incorporating low Reynolds number turbulence models ofk–ε. Firstly, the simulations were compared with the effect of increasing heat flux on heat transfer coefficient. It has been found that the effect of buoyancy on turbulence production and heat transfer in fluids at supercritical pressure can be very significant even under conditions of relatively low buoyancy parameter based on bulk properties. It is clear that new heat transfer correlations are needed to account for such effects on heat transfer to supercritical pressure fluids as they come to be used more and more in new energy systems applications such as, advanced water-cooled nuclear reactors, high pressure water oxidation plant for waste processing.

Computational analysis of convective heat transfer properties of turbulent slot jet impingement

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anuj Kumar Shukla ◽  
Anupam Dewan
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
High Efficiency ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Jet Impingement ◽  
Complex Flow ◽  
Content Type

Purpose Convective heat transfer features of a turbulent slot jet impingement are comprehensively studied using two different computational approaches, namely, URANS (unsteady Reynolds-averaged Navier–Stokes equations) and SAS (scale-adaptive simulation). Turbulent slot jet impingement heat transfer is used where a considerable heat transfer enhancement is required, and computationally, it is a quite challenging flow configuration. Design/methodology/approach Customized OpenFOAM 4.1, an open-access computational fluid dynamics (CFD) code, is used for SAS (SST-SAS k-ω) and URANS (standard k-ε and SST k-ω) computations. A low-Re version of the standard k-ε model is used, and other models are formulated for good wall-refined calculations. Three turbulence models are formulated in OpenFOAM 4.1 with second-order accurate discretization schemes. Findings It is observed that the profiles of the streamwise turbulence are under-predicted at all the streamwise locations by SST k-ω and SST SAS k-ω models, but follow similar trends as in the reported results. The standard k-ε model shows improvements in the predictions of the streamwise turbulence and mean streamwise velocity profiles in the zone of outer wall jet. Computed profiles of Nusselt number by SST k-ω and SST-SAS k-ω models are nearly identical and match well with the reported experimental results. However, the standard k-ε model does not provide a reasonable profile or quantification of the local Nusselt number. Originality/value Hybrid turbulence model is suitable for efficient CFD computations for the complex flow problems. This paper deals with a detailed comparison of the SAS model with URANS and LES for the first time in the literature. A thorough assessment of the computations is performed against the results reported using experimental and large eddy simulations techniques followed by a detailed discussion on flow physics. The present results are beneficial for scientists working with hybrid turbulence models and in industries working with high-efficiency cooling/heating system computations.

Experimental Investigation of Convective Heat Transfer of Supercritical Pressure Hydrocarbon Fuel in a Horizontal Section of a Rotating U-Duct

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Zelong Lu ◽  
Yinhai Zhu ◽  
Yuxuan Guo ◽  
Peixue Jiang
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Rotational Speed ◽  
Convective Heat Transfer Coefficient ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Secondary Flows ◽  
Horizontal Section ◽  
Static Conditions

Abstract The experimental and numerical investigations of the heat transfer of supercritical pressure n-decane flowing through a pipe at various rotational speeds, mass flow rates, heat fluxes, and pressures, are presented. This pipe is 2 mm in diameter, 200 mm in length, with a radius of 0.328 m, and is parallel to the rotating axis. The wall temperature was measured at four positions around the periphery of the pipe at each of the five selected cross section along the pipe's length. Maximum convective heat transfer was observed at the outer edge of the horizontal section, while its corresponding minimum was observed at the inner edge. The heat transfers at the two sides of the channel were observed to be similar. The density and pressure differences between the outer and inner edges increased at increasing rotating speeds. However, the temperature difference between the outer and inner edges decreased with increased rotational speed mainly because of the increase of secondary flows in the section. The section's average convective heat transfer coefficient increased with an increase in the rotational speed, and its value at 1000 rpm was approximately twice than that at static conditions. The phenomenon of oscillation was observed near the exit of the horizontal section, and was caused by the flow and considerable property changes near the pseudo critical temperature. A computational fluid dynamics (CFD) model was developed using the real gas thermal properties and was coupled with the heat transferred owing to fuel flow. The predicted fuel and wall temperatures were in good agreement with the experimental data. A new local Nusselt number correlation of the heat transfer of n-decane in a rotating horizontal section was proposed.

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