Heat Transfer and Fluid Flow Characteristics in Supercritical Pressure Water

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Jeremy Licht ◽  
Mark Anderson ◽  
Michael Corradini
Keyword(s):  
Heat Transfer ◽  
Bulk Water ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
High Mass ◽  
Wall Region ◽  
Law Of The Wall ◽  
Pressure Water ◽  
Integral Heat ◽  
Supercritical Pressure Water

A series of integral heat transfer measurements in a square annular flow passage was performed for bulk water temperatures of 175–400°C with upward mass velocities of 300 kg/m2 s and 1000 kg/m2 s and heat fluxes of 0, 200 kW/m2, and 440 kW/m2, all at a pressure of 25 MPa. Mean and turbulent velocities measured with a two-component laser Doppler velocimetry system along with simulations using the computational fluid dynamics (CFD) code FLUENT were used to explain the deterioration and enhancement of heat transfer in supercritical pressure water. At low mass velocities, the integral heat transfer measurements exhibited large localized wall temperature spikes that could not be accurately predicted with Nusselt correlations. Detailed mean and turbulent velocities along with FLUENT simulations show that buoyancy effects cause a significant reduction in turbulent quantities at a radial location similar to what is the law of the wall region for isothermal flow. At bulk temperatures near the pseudocritical temperature, high mass velocity integral heat transfer measurements exhibited an enhanced heat transfer with a magnitude dependent on the applied heat flux. Measured mean and turbulent velocities showed no noticeable changes under these conditions. FLUENT simulations show that the integrated effects of specific heat can be used to explain the observed effects. The experimentally measured heat transfer and local velocity data also serve as a database to compare existing CFD models, such as Reynolds-averaged Navier-Stokes (RANS) equations and possibly even large Eddy simulations (LES) and direct numerical simulations (DNS). Ultimately, these measurements will aid in the development of models that can accurately predict heat transfer to supercritical pressure water.

Pseudoboiling Heat Transfer to Supercritical Pressure Water in Smooth and Ribbed Tubes

1970 ◽  
Vol 92 (3) ◽  
pp. 490-497 ◽  
Author(s):  
J. W. Ackerman
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heated Surface ◽  
Supercritical Pressure ◽  
Heat Fluxes ◽  
Film Boiling ◽  
Fluid Temperature ◽  
Bulk Fluid ◽  
Pressure Water ◽  
Supercritical Pressure Water

Investigations of heat transfer to supercritical pressure fluids have been going on for some time, and correlations have been developed for both free and forced-convection conditions. In these investigations, unpredictable heat transfer performance has sometimes been observed when the pseudocritical temperature of the fluid is between the temperature of the bulk fluid and that of the heated surface. The unusual performance has been attributed to many causes, but one for which more evidence is being collected is that of a pseudofilm-boiling process similar to film boiling which occurs at subcritical pressures. This paper, which is an extension of work reported earlier on forced-convection heat transfer to supercritical pressure water, presents experimental evidence which suggests that a pseudofilm-boiling phenomenon can occur in smooth-bore tubes. During the period from 1963–1966, tubes with ID’s from 0.37 to 0.96 in. were tested at pressures from 3300–6000 psia and at heat fluxes and mass velocities in the range of interest in steam-generator design. The effects of heat flux, mass velocity, tube diameter, pressure, and bulk fluid temperature on both the occurrence and characteristics of pseudofilm boiling are discussed. Results of a second series of tests conducted in 1967, which show that ribbed tubes suppress pseudofilm boiling at supercritical pressure much like they do film boiling at subcritical pressures, are also discussed.

Numerical Analysis on Heat-Transfer Deterioration of Supercritical Fluid in the Vertical Upward Tubes

2016 ◽  
Vol 2 (3) ◽  
Author(s):  
Xianliang Lei ◽  
Huixiong Li ◽  
Weiqiang Zhang
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Heat Fluxes ◽  
Wall Region ◽  
Unstable Flow ◽  
Heat Transfer Deterioration ◽  
High Q ◽  
Flow Parameters ◽  
Pressure Water ◽  
Supercritical Pressure Water

Heat-transfer characteristics are especially significant among all issues for the supercritical water-cooled reactors (SCWRs). The two-peak wall-temperature phenomenon that could be verified by Shitsman and Jackson’s experiments occurred in the regions of tb<tpc<tw for vertical upward flow under the extreme heating conditions or accident cases (i.e., q/G>0.6  kJ/kg for water). However, so far the special two-peak result has not been paid much attention due to the difficulty of the experiments. Hence, in this study, numerical analysis was carried out to investigate the characteristics of heat-transfer deterioration (HTD) two-peak phenomenon of supercritical pressure water/carbon dioxide in the conditions of high q/G. The results showed that the higher the heat fluxes were, the more temperature peaks might appear and more unstable flow might be presented. Finally, the mechanism of two-peak HTD was studied through quantitatively analyzing the distribution of flow parameters and thermophysical properties in the near-wall region.

A New Correlation for Heat Transfer Coefficient Prediction of Supercritical Pressure Water Flowing in Vertical Upward Tubes

2016 ◽  
Author(s):  
Xiangfei Kong ◽  
Huixiong Li ◽  
Changjiang Liao ◽  
Xianliang Lei ◽  
Qian Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Supercritical Pressure ◽  
Good Prediction ◽  
Empirical Correlations ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Pressure Water ◽  
Supercritical Pressure Water

Supercritical pressure water has been widely used in many industrial fields, such as fossil-fired power plants and nuclear reactors because mainly of its high thermal efficiencies. Although many empirical correlations for heat transfer coefficients of supercritical pressure water have been proposed by different authors based on different experimental data base, there exist remarkable discrepancies between the predicted heat transfer coefficients of different correlations under even the same condition. Heat transfer correlations with good prediction performance are of considerable significance for developing supercritical (ultra-supercritical) pressure boilers and SCWRs. In this paper, the experimental data (about 7389 experimental data points) and 30 existing empirical correlations for heat transfer of supercritical pressure water (SCW) flowing in vertical upward tubes are collected from the open literatures. Evaluations of the prediction performance of the existing correlations are conducted based on the collected experimental data, and a detailed multi-collinearity analysis has been made on different correction factors involved in the existing correlations, and then based on the collected experimental data, a new heat transfer correlation is developed for the supercritical pressure water flowing in vertical upward tubes under normal and enhanced heat transfer mode. Compared with the existing correlations, the new correlation exhibits good prediction accuracy, with a mean absolute deviation (MAD) of 9.63%.

Sign in / Sign up

Export Citation Format

Share Document