Citation: S.A. Klein


LiBr External Routines

The thermodynamic properties of mixtures of lithium bromide and water are implemented as an externally compiled EES routine.  The routines operate in either English or SI units.  The unit specification is a string constant or variable which is set to  either 'Eng' or 'SI' and provided as the first parameter in the functions.  (An older form in which the units is indicated with a 1 or 2 in an extra parameter is still accepted.)  Click on property for which you would like more information.

H_LIBR	(enthalpy)

T_LIBR	(temperature)

P_LIBR	(pressure)

V_LIBR	(volume)

X_LIBR	(concentration)

Q_LIBR	(quality)

VISC_LIBR	(viscosity)

COND_LIBR	(thermal conductivity)

The LIBR.DLL external routine provides five EES external functions and one EES external procedure in a single DLL file.  The LIBR.DLL routine was written and compiled in DELPHI 5.


H_LIBR

h_LiBr returns the enthalpy [Btu/lb or kJ/kg] of lithium bromide water solutions as a function of temperature and concentration depending on unit specification, either 'Eng' or 'SI'.

The correlation used here is taken from the 1989 ASHRAE Handbook of Fundamentals.  The correlation is applicable for 40<=X<=70% and 60 F<T<330 F.

Example:  h=H_LiBr('SI' or 'Eng', T, X)


T_LIBR

T_LiBr returns the saturation temperature [F or C] over a solution of lithium bromide and water as a function of pressure [psia] and concentration [%].  The function will accept and return values in English Units if the unit specification (first parameter) is 'Eng' and it SI if the unit specification is 'SI'.

The correlation used here is taken from the 1989 ASHRAE Handbook of Fundamentals.  The correlation is applicable for 45<=X<=75.

Example:  T=T_LiBr('SI' or 'Eng', P, X)


P_LIBR

P_LiBr returns the vapor pressure [psia or kPa] over a solution of lithium bromide and water as a function of temperature and mass percent lithium bromide. The function will accept and return values in English Units if the unit specification (first parameter) is 'Eng' and it SI if the unit specification is 'SI'.

The correlation used here is taken from the 1989 ASHRAE Handbook of Fundamentals.

The correlation is applicable for 45<=X<=75 and 40 F<T<350 C.

Example:  P=P_LiBr('SI' or 'Eng', T, X)


V_LIBR

This function returns the specific volume of a lithium bromide - water solutionat temperature T [C or F] and lithium bromide mass percent X.  Units (first parameter) is either 'Eng' or 'SI'.

In English units, T is in F and specific volume is returned in ft3/lb. In SI units, T is in C and specific volume is returned in cm3/g.

This correlation was developed by Keith E. Herold at University of Maryland based on data from: Uemura, T., Hasaba, S., Tech. Repr. Kansai Univ., 6, 31-55, 1964.

Example: v=V_LiBr('SI' or 'Eng', T, X)


X_LIBR

X_LiBr returns the saturation composition (%) corresponding to specified temperature [F or C] and pressure [psia or kPa].  The function uses correlations from the 1989 ASHRAE Handbook of Fundamentals.  The function accepts and returns values in English units if Units=1 and in SI if Units=2.

Example:  x=X_Libr('SI' or 'Eng', T, P)


Q_LIBR

Q_LiBr is a Procedure which returns the quality (%), temperature (F or C), liquid composition (%), and liquid and vapor enthalpies (Btu/lb or kJ/kg) of a lithium bromide-water two-phase mixture given the enthalpy [Btu/lb or kJ/kg], pressure [psia or kPa], and the solution composition (Z) [%].

Call Q_LiBr('SI' or 'Eng', H, P, Z: Q, T, xL, hL, hV)


VISC_LIBR

VISC_LIBR returns the viscosity of lithium-bromide water solutions in units of Pa-s or lbm/ft-hgr using the correlation published by:

  Lee, R.J., DiGuilio, R.M., Jeter, S.M., and Teja, A.S., " Properties of Lithium Bromide-Water Solutions at High Temperatures and Concentrations  - II Density and Viscosity", ASHRAE Transactions, Paper 3381, RP-527, pp. 709-714, 1990

The VISC_LIBR function requires three parameters.  The first parameter is a string, either 'SI' or 'ENG'  indicating the unit system.  The second parameter is temperature in °C for 'SI' or °F (for 'ENG').  The third parameter is the weight percent of LiBr in the solution.

The valid range for this correlations is :  25°C < T < 200°C  and 45% < X < 65%

Example:

V=VISC_LIBR('SI', 90,55)  "[Pa-s]  viscosity of a 55% weight percent solution of lithium-bromide water at 90°C"


COND_VISC

COND_LIBR returns the viscosity of lithium-bromide water solutions in units of W/m-K or Btu/hr-ft-F using the correlation published by:

DiGuilio, R.M., Lee, R.J., Jeter, S.M., and Teja, A.S., " Properties of Lithium Bromide-Water Solutions at High Temperatures and Concentrations  - I Thermal Conductivity", ASHRAE Transactions, Paper 3380, RP-527, pp. 702-708, 1990

The COND_LIBR function requires three parameters.  The first parameter is a string, either 'SI' or 'ENG'  indicating the unit system.  The second parameter is temperature in °C for 'SI' or °F (for 'ENG').  The third parameter is the weight percent of LiBr in the solution.

The valid range for this correlations is :  20°C < T < 190°C  and 30% < X < 65%

Example:

K=COND_LIBR('SI', 90,55)  "[W/m-K]  thermal conductivity of a 55% weight percent solution of lithium-bromide water at 90°C"