Contents

HeatPipe_Wickless_Limits_CL

Call HeatPipe_Wickless_Limits_CL(T_e, L_e, L_a, L_c, theta, R_in, Fluid\$, th_ds, A, WFF, roughness, Flag: Q_dot_sonic, Q_dot_entr)

The function HeatPipe_Wickless_Limits_CL calculates the limits of performance of a wickless heat pipe using the program HTPIPE, translated from FORTRAN to Delphi.

Inputs:

T_e - temperature of vapor leaving the evaporator [K, C, F, or R]

L_e - length of evaporator [m or ft]

L_a - length of adiabatic section [m or ft]

L_c - length of condenser [m or ft]

theta - angle of heat pipe [rad or deg], note that positive corresponds to evaporator down

R_in - inner radius of heat pipe [m or ft]

Fluid\$ - fluid ('lithium', 'sodium', 'potassium', 'mercury', or 'water')

th_ds - the thickness of the distribution screen [m or ft]

A - velocity profile correction factor used by HTPIPE [-]

A is defined as u^2/V^2 where u = local velocity and V = average velocity at the evaporator exit

A = 1.234 for laminar flow and A = 2.22 for turbulent flow

WFF - wall friction factor [-], note, set to <0 to internally calculate

roughness - 1/2 peak-to-peak spacing of wall roughness [m or ft]

Flag - flag to set flow condition, set to 0 to ignore

1 = laminar vapor and laminar liquid

2 = turbulent vapor and laminar liquid

3 = laminar vapor and turbulent liquid

4 = turbulent vapor and turbulent liquid

Outputs:

Q_dot_sonic - sonic limit [W or Btu/hr]

Q_dot_entr - entrainment limit [W or Btu/hr]

The units for the inputs to the function are based on the unit setting in EES.

Example:

\$UnitSystem SI Mass J K Pa Radian

\$VarInfo Q_dot_sonic Units = 'W'

\$VarInfo Q_dot_entr Units = 'W'

T_e = 775 [K]

L_e = 1.35 [m]

L_a = 0.35 [m]

L_c = 1.5 [m]

theta = 0 [rad]

R_in = 0.0185 [m]

Fluid\$ = 'Sodium'

th_ds = 0.03048 [cm]*Convert(cm,m)

A = 1.4 [-]

WFF = -1 [-]

roughness = 0.0025 [cm]*Convert(cm,m)

Flag = 0 [-]

Call Heatpipe_Wickless_Limits_CL(T_e, L_e, L_a, L_c, theta, R_in, Fluid\$, th_ds, A, WFF, roughness, Flag: Q_dot_sonic, Q_dot_entr)

{Solution:

Q_dot_sonic = 3488 [W]

Q_dot_entr = 25451 [W]}