15.07.2015   EuroSun2008-7

The basic absorption model

Fig. 2 represents the thermodynamic states of the ideal simple effect absorption cycle, assuming mechanical, thermal and chemical equilibrium and assuming energy degradation exclusively concentrated on expansion valves. Steady state mass and energy balance in components yield the following equations:

Evaporator (no superheating):

Qm= m ref, K — h1); h1 = К

(2)

m ref, i X strong X weak

Considering =

(3)

weak strong

strong x weak

 

(4)

 

strong

 

2v

 

GENERATOR

 

CONDENSER

 

image641image642

image371

(a) (b)

Fig. 2. (a) LiBr/water absorption cycle. (b) Diagram P(T)-T LiBr/water

Generator (no superheating):

Mass balance:

Energy balance:

Qoi = ™strong • h2s — mweak * К + ™^ ,г * h2v ; T2s = T2v

Подпись: (5)

image643 Подпись: (6) (7) (8)

™ weak = ™ strong + ™ ref, г

Solution heat exchanger:

Подпись: (9)T — T T — T

n = Js _4s = 2s 3s

hex, i

T1’s — T4s T2s — T 3’s

image355

image646

(10)

(11)

 

h5s — h4s = wpi

 

(12)

(13)

(14)

 
image647

h6s = К, К (h4s + Wpi)

 
image648

V

 
image649
image650

(15)

 

The above expressions will be used next as a reference to evaluate the performance of the absorption facility.