MULTIPLE EFFECT DISTILLATION OF SEAWATER WATER USING SOLAR ENERGY - THE CASE OF ABU DHABI SOLAR DESALINATION PLANT - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 45

where C 1 , C 2 and C 3 are given by the following equations:

C = γ . A

1 c

' '

C = γ . A ( T − 2 T ) + β . A . I − 2 m . C . I

(48)

2 c c 1 a c t c p t

2 ' ' 2 '

C = γ . A .( T − 2 T ) + 2 β A . I ( T − 2 T ) + 4 α . A . I + 4 m . C . I . T

3 c c 1 a c t c 1 a c t c p t c 1

with this equation the collector outlet water temperature can be obtained at each hour of the
day given the inlet water temperature, the solar radiation, water flow rate, and the collector
parameters αi,β and γ.

7.

Evaporator performance

A simple model is used for predicting the performance of the MED evaporator at part
load given the evaporator's capacity, maximum brine temperature, number of effects, heating
water flow rate, heating water temperature and seawater temperature. The aim is to calculate
the hourly distillate production, the hourly heating water outlet temperature and the hourly
pumping power requirement.

The performance ratio and specific heat consumption of the evaporator depends on the
number of effect and was estimated from the following equations provided by the
manufacturer (Sasakura):
Number of effects N ≤ 13:

− 2 2

PR = − 1 875 × 10 × N + 1 15 × N − 1 625

(49)

Number of effects N > 13:

PR = − 2 500 × 10

− 3

× N

2

+ 0 625 × N + 2 56 (50)

Specific heat consumption, SPC (kcal/kg):

526

SHC = (51)

PR

The effective temperature difference per single effect δ T at the design condition was
estimated from the equation:
`

( T − T − BPE × N )

2 d 1 d av

δ T =

(52)

N