Research Article The Impact of Climate Changes on the ...downloads.hindawi.com/journals/ijne/2014/793908.pdf · of a proposed pressurized water reactor nuclear power plant (PWR NPP)

Research ArticleThe Impact of Climate Changes on the Thermal Performance ofa Proposed Pressurized Water Reactor: Nuclear-Power Plant

Said M. A. Ibrahim,1 Mohamed M. A. Ibrahim,2 and Sami. I. Attia2

1 Department of Mechanical Power Engineering, Faculty of Engineering, AL-Azhar University, Nasr City, Cairo 11371, Egypt2 Nuclear Power Plants Authority, 4 El-Nasr Avenue, P.O. Box 8191, Nasr City, Cairo 11371, Egypt

Correspondence should be addressed to Sami. I. Attia; eng [email protected]

Received 17 February 2014; Accepted 14 March 2014; Published 10 April 2014

Academic Editor: Massimo Zucchetti

Copyright © 2014 Said M. A. Ibrahim et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

This paper presents a methodology for studying the impact of the cooling water temperature on the thermal performanceof a proposed pressurized water reactor nuclear power plant (PWR NPP) through the thermodynamic analysis based on thethermodynamic laws to gain some new aspects into the plant performance. The main findings of this study are that an increaseof one degree Celsius in temperature of the coolant extracted from environment is forecasted to decrease by 0.39293 and 0.16% inthe power output and the thermal efficiency of the nuclear-power plant considered, respectively.

1. Introduction

The main use of water in a thermoelectric power plant is forthe cooling system to condense steam and carries away thewaste heat as part of a Rankine steam cycle. The total waterrequirements of the plant depends on a number of factors,including the generation technology, generating capacity, thesurrounding environmental and climatic conditions, and theplant’s cooling system, which is the most important factorgoverning coolant flow rate.

Thermal power plants are built for prescribed specificdesign conditions based on the targeted power demand,metallurgical limits of structural elements, statistical valuesof environmental conditions, and so forth. At design stage,a cooling medium temperature is chosen for each siteconsidering long term average climate conditions. However,the working conditions deviate from the nominal operatingconditions in practice. For this reason, efficiency in electricityproduction is affected by the deviation of the instantaneousoperating temperature of seawater cooling water of a nuclearpower plant from the design temperature of the coolingmedium extracted from environment to transfer waste heatto the atmosphere via a condenser. Present nuclear plantshave about 34–40% thermal efficiency, depending on site(especially water temperature).

The cooling process in nuclear power plants requireslarge quantities of cooling water. The huge amounts of waterwithdrawal and consumption cause that the electricity hasto face the impacts of climate change, that is, in form ofincreasing sea temperatures or water scarcity. For instance, ifseas exhibit too highwater temperatures, the continued use ofwater for cooling purposes may be at risk because the coolingeffect decreases and also water quality regulations could beviolated.

An increase in the temperature of cooling water mayhave impact on the capacity utilization of thermal powerplants in two concerns: (1) reduced efficiency: increasedenvironmental temperature reduces thermal efficiency of athermal power plant, (2) reduced load: for high environ-mental temperatures, thermal power plant’s operation willbe limited by a maximum possible condenser pressure. Theoperation of plants with river or sea cooling will in additionbe limited by a regulatedmaximumallowable temperature forthe return water or by reduced access to water.

In the literature, there are few works published to identifythese climate change impacts, and few have tried to quantifythem. Ganan et al. [1] studied the performance of thepressurized-water reactor- (PWR-) type Almaraz nuclear-power plant and showed that it is strongly affected by theweather conditions having experienced a power limitation

Hindawi Publishing CorporationInternational Journal of Nuclear EnergyVolume 2014, Article ID 793908, 7 pageshttp://dx.doi.org/10.1155/2014/793908

2 International Journal of Nuclear Energy

due to vacuum losses in condenser during summer. Dur-mayaz and Sogut [2] presented a theoretical model to studythe influence of the cooling water temperature on the thermalefficiency of a conceptual pressurized-water reactor nuclear-power plant. Sanathara et al. [3] gave a parametric analysis ofsurface condenser for 120MWthermal power plant and focuson the influence of the cooling water temperature and flowrate on the condenser performance and thus on the specificheat rate of the plant and its thermal efficiency. Daycock et al.[4] measured the actual decrease in efficiencies of gas powerplants located in a desert. Linnerud et al. [5] concluded thata rise in temperature may influence the capacity utilizationof thermal power plants in two ways. Chuang and Sue [6]studied the performance effects of combined cycle powerplant with variable condenser pressure and loading. Costleand Finn [7] reviewed the evaporative cooling technique intemperature maritime climate.

In this study, an energy analysis is performed to evaluatethe impact of the change in cooling medium temperatureon the thermal efficiency of a PWR NPP. The objective is toestablish a theoretical methodology to assess the plant per-formance in different climatic conditions and to emphasizethe importance of plant site selection from the environmentaltemperature point of view. A model for condenser heatbalance is developed to determine the functional relationshipbetween the cooling water temperature and the condenserpressure considering that saturation condition exists in thecondenser and there is a finite amount of temperaturedifferences between this saturation temperature and the cool-ing water exit temperature. Employing this condenser heatbalancemodel, a cycle analysis is carried out to determine theheat balance conditions and corresponding power output andthermal efficiency for the prescribed range of cooling watertemperatures.

2. Methodology

The development of a mathematical model depends uponstudying, analysis, and evaluation of the thermal perfor-mance and thermodynamics of the secondary cycle of nuclearpower plant. This model describes how the impacts of cli-matic variables and conditions of environment affect the tem-perature marginal limits of condenser cooling water and theextent of its impacts on the efficiency and performance of thenuclear plant. The thermal and thermodynamic properties,parameters, variables, and mathematical relationships will beformulated to determine the thermal efficiency through theapplication of the energy and mass conservation laws thatgovern the mass and heat balance.

Figure 1 illustrates a diagram of a proposed PWR nuclearpower plant, to address the thermodynamic and heat balanceanalysis of a PWR NPP. Typical PWR consists of a pri-mary cycle which includes nuclear reactor, steam generator,pressurizer, and reactor coolant pump and the secondarycycle which consists of high-pressure steam turbine (HPST),three low-pressure steam turbines (LPST), moisture sep-arator and reheater (MS/R), deaerator feed water heater,two high-pressure feed water heaters (HPFWH), and three

low-pressure feed water heaters (LPFWH), condenser, andnecessary pumps (feed water pump and condensate pump).

A computer program based on the mathematical modelrepresenting the secondary circuit of the plant and its com-ponentswas performedusing the engineering equation solvercomputer program (EES) [8].

The algorithm procedures are performed as follows.

(i) Thermodynamic properties (pressure (P), tempera-ture (T), entropy (S), enthalpy (h), and moisturecontent (X)) at all the inlet and exit of all parts andcomponents of the plant.

(ii) Heat balance for each feed water heater and the steamgenerator.

(iii) Output useful work of the turbines and pumps.

(iv) Calculation of the amount of heat added to generatesteam, as well as the amount of heat rejected fromcondenser, and calculation of the efficiency of thestation.

(v) Hence temperature entropy (T-S) diagramof the plantand its components, as well as numerical tabulation ofresults, being reported.

(vi) Determination of the cooling water inlet temperature(𝑇in) and exit temperature (𝑇out) and the temperaturedifference.

(vii) Assigning the range of change of cooling water tem-perature 𝑇cwi during the entire year for the Mediter-ranean sea as (15–30∘C).

(viii) Computing the impact of the changes of coolingwatertemperature 𝑇cwi on the thermal efficiency 𝜂th andoutput work𝑊net of the plant.

(ix) Drawing the relation of 𝑇cwi versus 𝜂th and𝑊net of theplant.

The energy balance equations for the various processesinvolving steady-flow equipment such as nuclear reactor, tur-bines, pumps, steam generators, heaters, coolers, reheaters,and condensers in a PWR NPP are as follows.

2.1. Heat Balance Equations

(i) The total turbine work,𝑊T, kJ/kg, is as follows:

𝑊T = 𝑊HPT +𝑊LPT

𝑊HPT = ��st (ℎin − ℎout)

𝑊LPT = ��st (ℎin − ℎout) ,

(1)

where ��st is steam mass flow rate inlet to each turbine, kg/s,ℎin is enthalpy of steam inlet to each turbine, kJ/kg, ℎout isenthalpy of steam outlet from each turbine, kJ/kg, 𝑊HPT ishigh pressure turbine work, kJ/kg, and𝑊LPT is low pressureturbine work, kJ/kg.

International Journal of Nuclear Energy 3

HPT LPT

Condenser

1HPFWH 2HPFWH 5LPFWH4LPFWH3LPFWHD

eaer

ator

cpfwp

Reheater

S.G

RCPCold leg

MS

1 2

3

6

7

8

9

10

1112 13

14

1523

2019

4 5

1618 1722 21

Reactorcore

Hot

leg

Figure 1: Diagram of PWR nuclear power plant.

(ii) The pumping work,𝑊p, kJ/kg, is as follows:

𝑊p = 𝑊cp +𝑊fwp

𝑊fwp = ��fw (ℎin − ℎout)

𝑊cp = ��fw (ℎin − ℎout) ,

(2)

where ��fwh is steammass flow rate inlet to each turbine, kg/s,ℎin is enthalpy of steam inlet to each Turbine, kJ/kg, ℎout isenthalpy of steam outlet from each turbine, kJ/kg, 𝑊fwp ishigh pressure turbine work, kJ/kg, and 𝑊cp is low pressureturbine work, kJ/kg.

(iii) Heat added to steam generator, 𝑄add, kJ/kg, is asfollows:

𝑄add = ��st (ℎout − ℎin) , (3)

where ��st is steam mass flow rate exit from steam generator,kg/s, ℎin is enthalpy of feed water inlet to steam generator,kJ/kg, and ℎout is enthalpy of steam outlet from steamgenerator, kJ/kg.

(iv) Heat rejected from condenser, 𝑄Rej, kJ/kg, is asfollows:

𝑄Rej = (��mix ∗ ℎin − ��mix ∗ ℎout) , (4)

where ��mix is mixture mass flow rate through condenser,kg/s, ℎin is enthalpy of mixture inlet to condenser, kJ/kg, andℎout is enthalpy of feed water outlet from condenser, kJ/kg.

(v) Network done,𝑊net , kJ/kg, is as follows:

𝑊net = 𝑊𝑇 −𝑊p. (5)

(vi) The cycle efficiency, 𝜂th, %, is as follows:

𝜂th =𝑊net𝑄add. (6)

2.2. Heat Balance of Feed Water Heaters

(i) Closed feed water heaters are as follows:

��st ∗ (ℎ1 − ℎ2) = ��fw ∗ (ℎout − ℎin) , (7)

where ��st is steam mass flow rate extracted from turbine tofeed water heater, kg/s, ��fwh is steam mass flow rate inlet tofeed water heater, kg/s, ℎ

1is enthalpy of steam inlet to feed

water heater, kJ/kg, ℎ2is enthalpy of steam outlet from feed

water heater, kJ/kg, ℎin is enthalpy of mixture inlet to feedwater heater, kJ/kg, and ℎout is enthalpy of feed water outletfrom feed water heater, kJ/kg.

(ii) Deaerator is as follows:

(��st + ��fw) ∗ ℎout = (��st ∗ ℎ1) + (��fw ∗ ℎin) , (8)

where ��st is steam mass flow rate extracted from turbine tofeed water heater, kg/s ��fwh is steam mass flow rate inlet tofeed water heater, kg/s, ℎin is enthalpy of mixture inlet to feedwater heater, kJ/kg, and ℎout is enthalpy of feed water outletfrom feed water heater, kJ/kg.

2.3. Heat Balance of Steam Generator. Consider

��RCW ∗ 𝐶RCW ∗ (𝑇HL − 𝑇CL)

= (��st ∗ ℎout) − (��fw ∗ ℎin) ,(9)


where ��RCW is reactor coolant water mass flow rate ofprimary circuit, kg/s, ��fw is feed water mass flow rate inletto steam generator, kg/s, ��st is steam mass flow rate outletfrom steam generator, kg/s, ℎin is enthalpy of feed water inletto steamgenerator, kJ/kg, ℎout is enthalpy of steamoutlet fromsteam generator, kJ/kg, 𝑇HL is temperature of reactor coolantg water at hot leg, ∘C, 𝑇CL is temperature of reactor coolantg water at cold leg, ∘C, and 𝐶RCW is specific heat of reactorcoolant water of primary circuit, kJ/kg⋅K.

2.4. Heat Balance of Moisture Separator and Reheater. Con-sider

��st ∗ ℎin = (��st ∗ ℎ𝑠) + (��fw + ��st) ∗ ℎout, (10)

where ��st is steam mass flow rate inlet to moisture separatorand reheater, kg/s, ��

𝑠is water mass flow rate exit from

moisture separator and reheater to feed heater, kg/s ℎinis enthalpy of feed water inlet to moisture separator andreheater, kJ/kg, ℎout is enthalpy of steam outlet frommoistureseparator and reheater, kJ/kg, and ℎ

𝑠is enthalpy of steam

outlet from moisture separator and reheater, kJ/kg.

2.5. Heat Balance of Cooling Water System (Condenser). Thecondenser is a large shell and tube type heat exchanger. Thesteam in the condenser goes under a phase change fromvaporto liquid water. External cooling water is pumped throughthousands of tubes in the condenser to transport the heatof the condensation of the steam away from the plant. Uponleaving the condenser, the condensate is at a low temperatureand pressure. The phase change in turn depends on thetransfer of heat to the external cooling water. The rejectionof heat to the surrounding by the cooling water is essentialto maintain the low pressure in the condenser. The heat isabsorbed by the cooling water passing through the condensertubes. The rise in cooling water temperature and mass flowrate is related to the rejected heat as

𝑄Rej = (��mix ∗ ℎin) − (��fw ∗ ℎout)

𝑄Rej = ��CW ∗ 𝐶 ∗ Δ𝑇

Δ𝑇 = (𝑇cwo − 𝑇cwi) ,

(11)

where ��CW is coolingwatermass flow rate of condenser, kg/s,��fw is feed water mass flow rate of outlet from condenser,kg/s, ��mix is mixture mass flow rate of inlet to condenser,kg/s, ℎ

𝑖is enthalpy of mixture inlet to condenser, kJ/kg,

ℎout is enthalpy of feed water outlet from condenser, kJ/kg,𝑇𝑐is condenser saturation temperature, ∘C, 𝑇cwo is temper-

ature of cooling water outlet from condenser, ∘C, 𝑇cwi istemperature of cooling water inlet to condenser, ∘C, ΔT istemperature difference between the cooling water exit andinlet temperature, ∘C, and Δ𝑇hot is temperature differencebetween the saturation temperature and the cooling waterexit temperature, ∘C.

Modeling assumptions for the secondary cycle are asfollows.

(i) The thermodynamic conditions of steam at exit of theSG are fixed.

(ii) Thermal power of the PWR changes slowly to provideconstant thermodynamic properties of steamat exit ofthe SG since the variation in cooling water tempera-ture occurs seasonally and very slowly.

(iii) The condenser vacuum varies with the temperatureof cooling water extracted from environment at fixedmass flow rate into the condenser.

(iv) There are constant mass flow rates of condensate andcooling water.

(v) There is no pressure drop across the condenser.

(vi) The potential and kinetic energies of the flow and heatlosses from all equipment and pipes are negligible.

3. Results and Discussions

Thermodynamic analysis of the proposed PWR NPP is con-ducted to investigate the key parameters such as heat added tosteam generator, heat rejection, net turbine work, and overallthermal efficiency. Figure 2 illustrates the calculation of thethermodynamic and heat balance analysis of the proposedPWR NPP.

Figure 3 showed the thermodynamic and heat balanceanalysis of the proposed PWR NPP, on the T-S diagram ofsteam Rankine cycle as obtained from the heat balance of theplant.

Table 1 summarizes the calculation of the thermodynamicproperties at design conditions satisfying the heat balance forthe proposed PWR NPP. Figure 2 and Table 1 are the basis ofthe parametric study and analysis of the present work.

A parametric study is performed to determine the satu-ration temperature T

𝐶, corresponding condensate pressure

P𝐶, and also the cooling water exit temperature 𝑇cwe for the

cooling water inlet temperature 𝑇cwi and condenser terminaltemperature difference (T

𝐶− 𝑇cwe) by using the condenser

heat balance model. The results are given in Figures 4 and5. Figure 4 shows that the relation between 𝑇cwi and 𝑇cweexhibits a proportional linear variation with no effect of thecondenser terminal temperature difference (T

𝐶− 𝑇cwe). The

variation of T𝐶with 𝑇cwi also shows a linear dependency

having approximately 1∘C difference in T𝐶for subsequent

condenser terminal temperature difference (T𝐶−𝑇cwe) values

at any constant value of 𝑇cwi.Figure 4 depicts the variation between cooling water

exit temperature 𝑇cwe and saturation temperature T𝐶

incondenser with cooling water inlet temperature 𝑇cwi. 𝑇cwiincreases, the saturation temperature T

𝐶increases, and this

affect the output work and consequently the efficiency.Figure 5 illustrates variation of the saturation pressureP

𝐶,

corresponding to the saturation temperatureT𝐶, with cooling

water inlet temperature 𝑇cwi. It is seen that an increase in 𝑇cwiof 1∘C, 5∘C, 10∘C, and 15–30∘C results is an increase in P

𝐶of

0.00238, 0.01215, 0.02989, and 0.051 bar, respectively.Figure 6 presents the variation of thermal efficiency𝜂th with cooling water inlet temperature 𝑇cwi. When 𝑇cwiincreases by 1∘C, 5∘C, 10∘C, and (15–30∘C), the thermal effi-ciency 𝜂th decreases by 0.16, 0.76, 1.52, and 2.27%, respectively.


277710089.932 179.6

1286171.173.8 289.5

761.51769.932 179.6

2583100.721.55 216.22678153

41.68 252.8

247813559.932 179.6

2763171.173.8 289.5

2763143773.8 289.5

27630.997573.8 289.5

1080160873.8 248.8

1286171.173.8 289.5

909.6160873.8 212.2

109915321.55 216.2

926.1253.721.55 216.2

771.1160873.8 181

761.511849.932 179.6

926.1133.79.932 179.6

602.169.453.93 143

602.169.451.267 106.4

446133.71.267 106.4

27610089.932 65.75

429.710089.932 102.4

585.310089.932 139

109915341.68 252.8

Temperature (∘C)

Pres

suriz

er

Dea

erat

or

2

3Moisture

HP turbine

7 911

512

13

Control rod23

36

1st HP.F.W.H

19

17

16

35

2025 26

21

27 28 29 3015 33

31 32

R.C. pump

F.W. pump C. pump

Reactor vesselPressure (bar)

Flow rate (kg/s) Enthalpy (kJ/kg)

292186.10.05079 33.16

84.12411973 20

125.8411972 30

2.314821.60.05079 33.16

140.210089.932 33.27

251052.420.3088 69.78

268964.211.267 106.4

285969.453.93 199.5

302810089.932 289.5

138.910080.05079 33.16

292186.10.3088 69.75

446133.70.3088 69.75

4

separator 8

1

22 2nd HP.F.W.H

24

3rd LP.F.W.H 18

1112

Condenser

5th LP.F.W.H4th LP.F.W.H

Reheater

14

13

Core

6

S.G

LP turbine LP turbine LP turbine

34

Primary circuit Secondary circuit

10

Figure 2: Illustration of the EES model equivalent to the proposed PWR NPP thermodynamic and heat balance analysis.

400

35030

300 3231 73.8 bar 1 6

250 20 41.68 bar 219

20022 21

18 21.55 bar 3

15017 2316

2415

9.932 bar 4 5

3.93 bar 7

100 2614 25 1.267 bar 8

28 271350 12 2911

0

0.3088 bar 9

0.05079 bar 100.2 0.4 0.6 0.8

0 1 2 3 4 5 6 7 8 9S (kJ/kg·K)

T(∘

C)

Figure 3: T-S diagram of the proposed PWR nuclear power plantthermodynamic and heat balance analysis.

20

25

30

35

40

45

50

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Tcwi (∘C)

Tcw

e,Tc

(∘C)

TcweTTD = 3∘C

TTD = 4∘CTTD = 5∘C

Figure 4: Variations of cooling water exit temperature 𝑇cwe andsaturation temperatureT

𝐶

with coolingwater inlet temperature𝑇cwi.

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Tcwi (∘C)

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

Pc

(bar

)

TTD = 3∘CTTD = 4∘CTTD = 5∘C

Figure 5: Variation of saturation pressure P𝐶

, corresponding to thesaturation temperature T

𝐶

, with cooling water inlet temperature𝑇cwi.

Figure 7 gives the variation of net power output ��net withcooling water inlet temperature 𝑇cwi. An increase in 𝑇cwi of1∘C, 5∘C, 10∘C, and 10–35∘C corresponds to decrease in ��netby 0.39293, 2.166, 4.3683, and 6.547%, respectively.

The change of condenser conditions, that is, 𝑇C and P𝐶,

with 𝑇cwi results in a decrease of 6.547% in output powerof the plant ��net for the 𝑇cwi range of 15–30

∘C as shown inFigure 7. It is observed from Figure 6 that an increase from15 to 30∘C in the temperature of the coolant extracted fromenvironment results in a decrease from 37.57 to 35.3% in thethermal efficiency of the NPP.

4. Conclusions

A condenser heat balance model is developed to determinethe functional relationship between the cooling water tem-perature and the condenser pressure. Thus, a cycle analysis


Table 1: Thermodynamic data for the proposed pressurized water reactor nuclear power plant.

Station number Temperature,𝑇 (∘C)

Pressure,𝑃 (bar)

Enthalpy,ℎ (kg/kj)

Entropy,𝑆 (kj/kg⋅k)

Quality,𝑥

Mass flow rate,�� (kg/s)

1 289.5 73.8 2763 5.779 0.9975 16082 289.5 73.8 2763 5.779 0.9975 171.13 289.5 73.8 2763 5.779 0.9975 14374 252.8 41.68 2678 5.82 0.9283 1535 216.2 21.55 2583 5.868 0.8841 100.76 179.6 9.932 2478 5.926 0.8513 13557 179.6 9.932 761.5 2.136 0 1768 179.6 9.932 2777 6.588 1 10089 289.5 73.8 1286 3.154 0 171.110 289.5 9.932 3028 7.085 Superheated 100811 199.5 3.93 2859 7.177 Superheated 69.4512 106.4 1.267 2689 7.288 Superheated 64.2113 69.78 0.3088 2510 7.419 0.9503 52.4214 33.16 0.05079 2314 7.579 0.8978 821.615 33.16 0.05079 138.9 0.4799 0 100816 33.27 9.932 140.2 0.481 Sub. liquid 100817 65.75 9.932 276 0.9022 Sub. liquid 100818 102.4 9.932 429.7 1.333 Sub. liquid 100819 139 9.932 585.3 1.728 Sub. liquid 100820 179.6 9.932 761.5 2.136 0 118421 181 73.8 771.1 2.141 Sub. liquid 160822 212.2 73.8 909.6 2.436 Sub. liquid 160823 248.8 73.8 1080 2.774 Sub. liquid 160824 252.8 41.68 1099 2.819 0 15325 216.2 21.55 1099 2.836 0.09234 15326 216.2 21.55 926.1 2.483 0 253.727 179.6 9.932 926.1 2.499 0.08166 133.728 143 3.93 602.1 1.77 0 69.4529 106.4 1.267 602.1 1.79 0.0697 69.4530 106.4 1.267 446 1.378 0 133.731 69.75 0.3088 446 1.401 0.06599 133.732 69.75 0.3088 292 0.9519 0 186.133 33.16 0.05079 292 0.9796 0.06319 186.134 252.8 41.68 1286 3.174 0.11 171.135 20 3 84.12 0.2961 Sub. liquid 4119736 30 2 125.8 0.4365 Sub. liquid 41197

for the proposed NPP is carried out to determine the heatbalance conditions originating from temperature changeof cooling medium. It can be concluded that the outputpower and the thermal efficiency of the plant decrease byapproximately 0.3929 and 0.16%, respectively, for 1∘C increasein temperature of the condenser coolingwater extracted fromthe environment.

The impact of climate changes in condenser coolingwateris an important design consideration when constructing

PWR NPP. A reduction in production capacity due to anincrease in environment temperature would represent a dropof production that might need to be replaced somewhere.The effect of climatic changes shows to be important in thedesign of more effective cooling technique and to devicemethods to compensate for the loss in plant output andsystem capacity. Climate considerations will also becomeeven more important when deciding where to build newthermal power plants.


34.5

35

35.5

36

36.5

37

37.5

38

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Tcwi (∘C)

𝜂th

(%)


Figure 6: Variation of thermal efficiency 𝜂th with cooling water inlettemperature 𝑇cwi.

9.25E + 05

9.50E + 05

9.75E + 05

1.00E + 06

1.03E + 06

1.05E + 06

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Tcwi (∘C)


Wne

t(w

att)

Figure 7:Variation of net power output ��net with coolingwater inlettemperature 𝑇cwi.

Nomenclature

C: Specific heat (kJ/kg⋅K)h: Enthalpy (kJ/kg)��: Mass flow rate (kg/s)p: Pressure (bar)��: Net rate of heat transferred (kW)T: Temperature (K)TTD: Terminal temperature difference��net: Net rate of work (kW)𝜂: Efficiency (%)add: Addedc: Condenser

cp: Condensate pumpCW: Cooling watercwi: Cooling water inletCL: Cold legcwo: Cooling water outletfw: Feed waterfwp: Feed water pumpHL: Hot legHPT: High pressure turbineLPT: Low pressure turbinein: Inletmix: Mixtureout: Outletp: PumpRCW: Reactor cooling waterRej: RejectionT: Turbine.: Per unit timeHP: High pressureLP: Low pressureNPP: Nuclear power plantPWR: Pressurized water reactorRC: Reactor coolantSG: Steam generator.

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper.

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