Natural convection heat transfer from a vertical single cylinder with helical wire spacer in liquid sodium

Abstract

Natural convection heat transfer from a vertical single cylinder with helical wire spacer in liquid sodium was numerically analyzed on the following four effects, the influences of surface heat flux, gap between helical wire and heated cylinder surface, pitch of helical wire and helical wire diameter on heat transfer. The unsteady laminar three dimensional basic equations for natural convection heat transfer caused by a step heat flux were numerically solved until the numerical solution reaches a steady-state. The PHOENICS code was used for the calculation considering the temperature dependence of thermo-physical properties concerned. The heated cylinder for diameter (D=7.6 mm), heated length (L=200 mm) and L/d (=26.32), and the helical wire spacers for gaps (0 to 1 mm), pitches (100 to 200 mm), helical wire diameters (d=1 to 2 mm) and height (H=470 mm) were used in this work. The surface heat fluxes for each cylinder with helical wire spacer were equally given for a modified Rayleigh number, (Ra f,L ) w-s , ranging from 3.05910 4 to 3.14710 7 (q=110 4 to 710 6 W/m 2 ) in liquid temperature (T L =673.15 K). The values of gap were given from 0 to 1 mm at d=1.2 mm and a pitch of 165 mm, those of pitch were given from 100 to 200 mm at d=1.2 mm and a gap of 0.2 mm and those of wire diameter were given from 1 to 2 mm at a gap of 0.2 mm and a pitch of 165 mm on each cylinder with helical wire spacer. The spatial distributions of local and average Nusselt numbers, (Nu ,z ) w-s and (Nu av ) w-s , on each cylinder with helical wire spacer were clarified. The values of average Nusselt number, (Nu av ) w-s , for a vertical cylinder with helical wire spacer were calculated to examine the effects of (Ra f,L ) w-s , gap, pitch and helical wire diameter on heat transfer. The correlation for (Nu av ) w-s for a vertical cylinder with helical wire spacer above mentioned including the effects of (Ra f,L ) w-s , gap, pitch and helical wire diameter was developed.The correlation can describe the theoretical values of (Nu av ) w-s for a vertical cylinder with helical wire spacer within -2.74 to 1.63 % differences.

Natural convection heat transfer from vertical 9 × 9 rod bundles in liquid sodium

“…The general correlations for natural convection heat transfer from vertical 55 and 77 rod bundles with the ESA and ETA including the effects of array size, (Ra f,L ) NxNy,S/D and S/D were developed. The correlation of vertical 55 and 77 rod bundles can explain the theoretical value of (Nu av,B ) NxNy,S/D for each bundle geometry within a difference of -12.64 to 10.6% over a wide analysis range of S/D (=1.8 to 6) and modified Rayleigh number ((Ra f,L ) NxNy,S/D =3.0810 4 to 4.2810 7 ) [14][15][16][17][18].…”

“…The surface heat fluxes, q, for each cylinder were equally given in the range of 210 5 , 710 5 , 110 6 , 210 6 and 710 6 W/m 2 as an initial condition, and numerical calculations continued until a steady state was obtained. The surface temperature of the cylinder was analyzed by solving the heat conduction equation in liquid sodium, assuming that the calculated temperature, TEM, of the first control volume of the heated surface was located at the center of the control volume, as follows [14][15][16][17][18]:…”

“…The first control volume width for r-component, r (=x and y), on the heated section was determined as 0.4 mm as shown in Figs. 3 (a) and (b) [14][15][16][17][18]. The time step, t, was set to 3 ms.…”

Numerical Study of the Turbulent Flow from a Steam Dumping Pressurizer Relief Tank

“…There are a few studies [5][6][7] focused on numerical simulations of the PRT-related components and structures in a nuclear reactor. Seung Min Baek et al [8] established a nonequilibrium three-region model to accurately predict the pressure of the PRT under some special circumstances, and conducted a number of numerical tests for the actual accident and nuclear power plant.…”

Uncertainties Analysis on the Prediction of Flow and Heat Transfer of Liquid Sodium with CFD Technology

“…Wu et al [11] made an overview of the flow and heat transfer characteristics of liquid sodium in different channel geometries including circular tube, annular tube, and rod bundle. However, conducting experimental research is difficult and expensive in some specific flow regions, such as narrow channels, helical wire spacer [12,13], and sudden enlargement pipe. To predict the flow and heat transfer characteristics of liquid sodium more efficiently, numerical simulation method has been adopted.…”