Flow_Boiling

Flow_Boiling_Shah

Procedure Flow_Boiling_Shah(Fluid$, T_sat, G, d, x, q``, OR$ : h, T_w ) implements the Shah (1982) correlation to determine the heat transfer coefficient for a boiling fluid in a tube considering both convective and nucleate boiling contributions as discussed in section 7.3.2 of Heat Transfer by Nellis and Klein. and in section 11.3.2 of Introduction to Heat Transfer by Nellis and Klein

Inputs

Fluid$ - string variable representing a real fluid in the EES data base.

T_sat - the saturation temperature of the incoming vapor in [C], [K], [F] or [R] (units depend on unit system selected in EES).

G - mass velocity, i.e., the ratio of the mass flow rate to the cross-sectional area of the tube [kg/s-m^2] or [lbm/hr-ft^2]

d - diameter of the tube [m] or [ft].

x - quality (must be between 0 and 1)

q`` - surface heat flux [W/m^2] or [Btu/hr-ft^2]

OR$ - a string constant or variable that must be either 'HORIZONTAL' or 'VERTICAL'

Outputs

h - heat transfer coefficient [W/m^2-K] or [Btu/hr-ft^2-F] including convective and nucleate boiling contributions.

T_w - estimated temperature of the inside surface of the tube in [C], [K], [F], or [R].

Notes:

1. This procedure is responsible for determining the property data of the specified fluid . Fluid$ must be a provided with a string variable or string constant that is one of the (non-ideal gas) fluids in EES. It uses the correlation developed by Shah (1982).

2. At x=1, the procedure returns that heat transfer coefficient expected for a single phase vapor at the given mass velocity and diameter

3. At high values of quality that would result in a Reynold's number less than 2300, linear interpolation is used between the heat transfer coefficient at a quality that results in Re=2300 and the x=1 value.

4. This function was originally named Flow_Boiling but has been renamed to Flow_Boiling_Shah to distinguish it form the Flow_Boiling_Chen correlation. Calling Flow_Boiling will still work for backward compatibility.

5. See also the Flow_Boiling_Chen and Flow_Boiling_Hamilton correlations.

Example:

$UnitSystem SI K Pa J

$TabStops 3.5 in

$VarInfo q`` units=W/m^2

$VarInfo h units=W/m^2-K

$VarInfo T_w units=K

$VarInfo U units=W/m^2-K

F$='R22'

T_sat=250 [K] "boiling saturation temperature"

G=200 [kg/m^2-s] "mass velocity"

d=0.0172 [m] "tube inner diameter"

x=0.05 "quality"

Call flow_boiling_shah(F$,T_sat, G, d, x, q``, 'horizontal': h, T_w)

q``=U*(T_h-T_sat) "heat flux"

T_h=261 [K] "temperature of fluid on outside of pipe"

h_h=5400 [W/m^2-K] "heat transfer coefficient on outside surface of pipe"

U=(1/h+1/h_h)^(-1) "overall heat transfer coefficient between fluids on either side of the pipe wall"

{Solution

h=1890 [W/m^2-K]

q``=15401 [W/m^2]

T_w=258.1 [K]

U=1400 [W/m^2-K]}