than the ideal mixture model for the NF and RO processes by factors
of 1.2 and 1.1 respectively). The chemical exergy destruction is
significantly lower for the Debye-Huckel limiting law model (the
Davies model is greater than the Debye-Huckel model for t
mixture, and (b) the electrolytic solution using the Debye-Huckel
limiting law and the Davies model were calculated using (18) and (19)
respectively. 0 ln ln Ch Ch Ch w w NaCl NaCl RDS RDS w w NaCl NaCl E
N e N e RT N x N x (18) 0 ln ln ln Ch Ch Ch Ch w w
be very useful to know basic analytical relations. The aim of the
analytical solution is mainly to simplify and accelerate the calculation,
which will allow a short time calculations giving achievable
parameters. 6. Analytical formula for maximum steam cy
restricted (i.e. thermo-mechanical) dead state and the subscripts
relate to the species water, the ions sodium and chloride, and the
electrolyte NaCl. Note that the Debye-Huckel limiting law and the
Davies model activity coefficient calculation models cal
mining in northern Bohemia will be valid then deposits of brown coal
will be empty around the year 2043. Chart 1.Energy production ratio
To meet energetic sufficiency of Czech republic and state requirements
for sustainable development (in terms of primar
the NF and RO processes CONCLUSIONS This research used the Szargut
chemical exergy model approach to undertake the exergy analysis of a
seawater desalination plant. Following a detailed literature review,
this approach has not been applied to desalination
3 2( ) 2 M X M X MX I MX M X MX I z z A b I b I b v v I m I v I m v v C v
(17) In (17) is the activity coefficient of
the electrolyte and the other equation parameters are identical to
those defined previously in equation (12). DESALINATION PLANT
INFO
significantly higher levels than the Debye-Huckel limiting law for both
separation processes. The percentage difference values between each
of the other three models and the Pitzer model are quantified in Table
7. Based on these findings, it is evident th
found elsewhere. Current status and outlook of coal fired power plant
parameters is shown in table below. Chart 2 - Power plant status
listening Status Status Description netto [-] Temperature [C]
Pressure [MPa] Standard Yet built Older subcritical blocks
computer program, EEA, to get the energy and exergy analyses of the
steam power plants. It is written using an Object Oriented
Programming language (Microsoft Visual C#) with the aid of Microsoft
Excel and SAP Crystal Reports. Moreover, the visual basic c
responsible for energy destruction is the condenser and the boiler is
the main system responsible for the exergy destruction. Moreover,
Afifi [7] proved that using the fuel oil as the main fuel, achieving the
greatest exergy efficiency of the combustion p
(13) The Davies model [33] is suitable for an approximate ionic
strength of 0.5 I , see (14). The Davies equation typically results in
an error of 1.5% at an ionic strength less than 0.1 m and a 5 to 10%
error at ionic strength measurements between 0.1 an
concentration values in the final column of Table 2 can be converted
to ppm values by dividing by the solution density at the various
process stages. Estimated values of density for the relevant process
stages, which are based on the International Equatio
coming decades", Nature, Vol.452 (7185), pp. 301-310. [3] United
Nations website, Water for Life, [online],
http:/www.un.org/waterforlifedecade/scarcity.shtml. [4] Ahern, J.E.,
(1980), The Exergy Method of Energy Systems Analysis, (1st ed.), John
Wiley &
exergy rates and chemical exergy destruction rates for the two key
separation processes (reverse osmosis and nanofiltration). For
example, there were percentage differences of 61.8% and 44.7%
between the magnitude of chemical exergy destruction rates
calc
fully graphical environment. You are able to run first calculation
involving the only main cycle nodes. Gatecycle can also react to
changes of boundary conditions such as: change in fuel type or
composition, change in surroundings, change of desired power
viewed as off-setting the pressure exergy destruction associated with
membrane processes, i.e. the total exergy destruction rates, which
include the sum of the thermal, pressure and chemical exergy
destruction, are reduced by adding the negative value of
thermal cycles. Its not easy to compare different arrangements of
steam cycles. There are many factors influencing the results. The best
way to compare current solution is to make economic study based on
apropriate data from model. These data may be based
several ways. Following technical solutions were analyzed: 1. Optimal
feedwater temperature for boiler and steam cycle 2. Temperature
course of feedwater preheating 3. Power plant efficiency increasing by
usage of low-potential heat of flue gases in feedw
Figure below. Outgoing flue gas heat recovery system is done by
splitting flue gas into two separate streams. The first stream has a
temperature around 360C and is taken before rotating regenerative
air heater. It servers to heat feedwater via two separat
Table 4 Comparison of the activity and the mole fraction of water at
the relevant process stages RESULTS AND DISCUSSION The physical
and chemical exergy rates at each of the process stages are shown in
Table 5. As reported, the physical exergy rates are p
chemical exergy changes. The osmotic coefficient (12) was calculated
in order to determine the activity of water (11) at each of the process
stages. The activity was then compared to the corresponding mole
fraction of water, see Table 4. It is evident tha
arrangements are presented. Considerable potential to increase the
efficiency of power plant can be seen in the use of low-potential heat
from outgoing flue gases. Its well known that the power block
arrangement affects not just the cycle components and t
calculates the reversible, isentropic and the actual power of main
equipment of the plant. EEA calculates the thermal properties of all
supplied streams. It shows the thermal efficiency of the power plant
based on the lower and higher heating values. Furt
Spiegler, K.S.and El-Sayed, Y., (2001), "The energetics of desalination
processes", Desalination, Vol.134 (1-3), pp. 109- 128. [11] Cerci, Y.
(2002), "Exergy analysis of a reverse osmosis desalination plant in
California", Desalination, Vol.142 (3), pp. 2