Active Thermal Cooling Technologies - Low Energy Cooling for Sustainable Buildings - page 185

enthalpy h ev :

h A = Q c,A + h ev (5.12)

c P,a T A,out T A,in c PD T A,out x A,out T A,in x A,in

− + − +

x A h V

h c,A A
m A

T W −

T A

c P,W x A T W,in +

x A h V = +

Mass balance: the increase in water content of the ambient air x A corresponds to
the evaporated liquid water in the film m W referenced to the ambient air mass flow
rate m A :

m W
m A

x A = (5.13)

Liquid/Wall/Liquid Node 2 Energy balance: the differential enthalpy of the liquid
water h W and the salt solution h S corresponds to the sum of the heat given off to
the air and the heat supplied convectively by the return air Q c,R plus the absorption
enthalpy h ab :

h W + h S =− Q c,A − h ev + Q c,R + h ab (5.14)

c P,S 1

T S,out −

T S,in c P,W 1

T W,out −

T W,in

m S
m S

m W
m W

+ + +

h c,A A
m A

T W − T A c P,W x A T W,in + x A h V

=− −

h c,R A
m R

T R −

T S

c P,W x R T R,in +

h d )

+ + x R ( h V +

Mass balance:

m W + m S = m A x A + m R x R (5.15)

Return Air Node 3 Energy balance: the differential enthalpy of the return air h R
corresponds to the convective heat transfer to the liquid Q c,R plus the absorption
enthalpy h ab :

h R = Q c,R + h ab

(5.16)