CHF_tube

CHF_tube

The procedure CHF_Tube(D, L, m_dot, P, X_in: CHF, T_in) returns the critical heat flux for flow boiling of water flowing through a vertical tube as well as the inlet temperature. The function uses the technique presented by Groeneveld et al. (2007) to determine the maximum uniform heat flux that can be applied to a vertical tube with water flowing through it before the critical heat flux phenomenon is experienced at the outlet.

Inputs

D - diameter (m or ft)

L - length (m or ft)

m_dot - mass flow rate (kg/s or lbm/hr)

P - pressure (Pa, kPa, bar, MPa, psia, or atm)

X_in - thermodynamic quality at the inlet (note that a negative value indicated subcooled):

where hin is the inlet enthalpy and hf and hg are the enthalpies of saturated liquid and vapor, respectively.

Outputs

CHF - critical heat flux (W/m2 or Btu/ft^2)

T_in - inlet temperature (C, K, R, or F)

Example:

$UnitSystem SI Mass J C kPa

$VarInfo CHF units=W/m^2

$VarInfo T_in units=C

P=1500 [kPa]

X_in= 0.32 [-]

D=0.009 [m]

L=1 [m]

m_dot=0.1 [kg/s]

Call chf_tube(D, L, m_dot, P, X_in: CHF, T_in)

{Solution:

CHF=1.079E+06 [W/m^2]

T_in = 198.3 [C]}

Reference:

Groeneveld, D.C., J.Q. Shan, A.Z. Vasic, L.K.H. Leung, A. Durmayaz, J. Yang, S.C. Cheng, and A. Tanase, "The 2006 CHF look-up table," Nuclear Engineering and Design, Vol. 237, pp. 1909-1922, (2007).