A Numerical Analysis of Heat Transfer to Fluids Near the Thermodynamic Critical Point Including the Thermal Entrance Region

Abstract

A two-dimensional numerical method has been developed to predict heat transfer to near critical fluids in turbulent flow through circular tubes. The analysis is applicable to the thermal entry region as well as fully developed flows. Agreement with experimental data for water at 31.0 MN/m2 is quite good. A correlation in the form of the heat flux parameter of Goldmann was found to be satisfactory for water at that pressure. Results are presented in graphical form which apply to a wide range of heat fluxes, mass velocities, and tube diameters. Preliminary results in the entrance region show that film coefficients remain well above the corresponding fully developed values for a larger distance downstream than would be the case with a constant property fluid. This effect becomes more pronounced as the heat flux is increased.

Effect of heat transfer correlations on the fuel temperature prediction of SCWRs

“…The only difference between the Dittus-Boelter and McAdams correlations is that the latter has a larger coefficient. According to Schnurr et al [10], it agrees with experimental data. However, it was noted that the correlation might produce unrealistic temperature results near the critical and pseudocritical points, due to it being very sensitive to variations in the thermophysical properties.…”

Heat Transfer

“…The temperature difference is directly proportional to heat flow, while it decreases with increasing mass flow. DHT also occurs in horizontal tubes, although being smoother compared to that in vertical tubes with a higher temperature increase on the upper part of the tube than on the lower part [17] The equation was used also at supercritical pressure with good agreement to experimental data [31]. Near the critical point, Equation (4.16) may give wrong results since the dependence on the fast varying properties cannot be represented (see Figure 4.6).…”

Forced convection heat transfer to supercritical helium

“…A += 26 is an empirical constant. For fluids with variable properties the same equations are used, with the fluid properties evaluated locally [21,24,26,27]. According to these references the local shear stress should be used rather than the wall shear stress.…”

“…All experimental and analytical investigations are on pipe flow with a constant heat flux applied to the wall. Schnurr, Sastry and Shapiro [26] solved the equations numerically using the Patankar/Spalding method [28,21]. The coordinates are transformed by the Von Mises transformation, relating the cross stream grid distribution at a specific position to the local Stream line distribution.…”