Exergoeconomic analysis of a combined water and power plant 2

A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Acknowledgements ACKNOWLEDGEMENTS The author would like to express his profound gratitude and appreciation to his supervisor and mentor Associate Professor M.N.A. Hawlader for his invaluable guidance, supervision and inspiration. He also would like to thank his co-supervisor Professor A. S. Mujumdar for his supervision and inspiration. The author would like to extend his gratitude to the FYP students working on this project, Mr. Chang He, Mr. Ang Boon Wee, Mr. Kuan Sien. He is also thankful for the technical help received from Mr. Yeo Khee Ho and Mr. Chew Yew Lin, Thermal Process Lab1 and Mr. Tan Tiong Thiam, Energy Conversion Lab. Finally, the author would like to express his heartfelt gratitude to his family members whose inspirations have helped him to carry on studies at this level. i Table of Contents Table of Contents ACKNOWLEDGEMENTS i TABLE OF CONTENTS ii SUMMARY viii NOMENCLATURE x LIST OF FIGURES xv LIST TO TABLES xxiv Chapter Chapter INTRODUCTION 1.1 Background 1.2 Research objectives 1.3 The Scope LITERATURE REVIEW 2.1 Combined Water and Power Plant 2.2 Desalination Processes 2.3 Thermal desalting processes 2.3.1 Multistage flash distillation (MSF) 10 2.3.2 Multi-effect distillation (MED) 11 2.3.3 Comparisons of MED and MSF 13 2.4 Reverse Osmosis (RO) 14 2.5 Simulation of Thermal Desalting Process 17 2.6 Experimental investigations 19 2.7 Waste heat utilization in MED 20 2.8 Heat transfer augmentation 23 2.9 Exergy Analysis of Desalination Plants 27 2.10 Exergoeconomic Analysis 29 ii Table of Contents Chapter 2.11 Summary 30 MODELING AND SIMULATION 32 3.1 Gas Turbine Plant 35 3.2 Steam Cycle 38 3.3 Part Load Calculations 41 3.3.1 Gas Turbine Plant 41 3.3.2 Steam Turbine Plant 42 3.4 Combined Water and Power Plant 43 3.5 MED Mathematical Model 44 3.5.1 Overall Plant Calculations 44 3.5.2 Individual Effect Calculations 46 3.6 Exergy Analysis of thermal desalination processes 49 3.7 Vertical Single tube heat exchanger 57 3.7.1 Water Temperature variation 59 3.7.2 Two-phase flow: vapor generation 67 3.7.3 Model for Pressure drop in two phase region 71 3.7.4 Heat Transfer Coefficient for Tubes with Inserts 76 3.7.5 Experimental & Theoretical Overall Heat Transfer 78 Coefficients 3.8 Performance Ratio 79 3.9 Water Production Rate 79 3.10 Specific Heat Transfer Area 80 3.11 Mathematical Model of Reverse Osmosis (RO) system 80 3.11.1 Average volumetric flux 82 3.11.2 Average salt flux 82 iii Table of Contents Chapter Chapter 3.11.3 Correlations 83 3.11.4 Permeate Concentration 86 3.11.5 Product flow rate 86 3.11.6 Concentration of reject flow 87 3.11.7 Determining the number of RO modules 87 3.11.8 Simulation Procedure 88 3.11.9 Exergy Analysis for a RO module 89 3.11.10 Exergoeconomic Model of RO plant 91 EXPERIMENT 97 4.1 The Desalination Unit 97 4.1.1 Operation of the desalination unit 98 4.1.2 Specifications of the components 100 4.2 Design of the components 101 4.3 Test procedure 109 4.4 Vertical Single tube heat exchanger 110 4.5 Uncertainty analysis 124 4.6 Experiments on Reverse Osmosis system 126 4.6.1 Operations of the RO system 126 4.6.2 128 Calibration of measuring instruments 4.6.3 Experimental program 129 4.6.4 Experimental procedure 129 4.6.5 Water analysis 130 RESULTS AND DISCUSSION 131 5.1 Combined cycle power plant: simulation results 131 5.1.1 Power plant simulation results 133 iv Table of Contents 5.2 5.1.2 Power plant simulation: validation with Thermoflow® 133 Combined water and power plant: simulation results 134 5.2.1 Effect of Combined cycle load on Thermal Efficiency 135 5.2.2 Combined Water and Power Plant (CWPP): comparison of performance with Rensonnet et al. (2007) 136 5.3 5.4 5.2.3 Effect of Combined cycle load on Water Production 137 5.2.4 Electricity cost variation with Oil Price 138 Experimental results of MED 139 5.3.1 Effect of Heating Medium Flow Rate 140 5.3.2 Effect of Heating Medium Temperature 143 5.3.3 Effect of Feed Flow Rate 146 5.3.4 Effect of feed temperature and flashing 149 5.3.5 Effect of top-brine temperature 152 5.3.6 Effect of variable concentration 154 Thermal hydraulic performance comparisons for different 157 tube profiles 5.4.1 Feed temperature distribution inside the tube 157 5.4.2 Variation of vapour quality along the length of the 159 tube 5.5 5.4.3 Shell side heat transfer coefficient 160 5.4.4 Tube side heat transfer coefficient 161 MED parametric evaluation 163 5.5.1 Distillate production with varying number of effect 163 5.5.2 Effect of Top Brine Temperature on Distillate 164 production 5.5.3 Effect of Top Brine Temperature on exergy efficiency 165 v Table of Contents 5.5.4 Exergy efficiency for varying number of effects 166 5.5.5 Cost per unit exergy for varying number of effects 166 5.5.6 Overall heat transfer coefficient for varying number 167 of effects 5.6 Experimental Results for single tube vertical heat exchanger 168 5.6.1 Effect of Heating Medium Temperature 169 5.6.2 Effect of insertions on water production 170 5.6.3 Effect of heating medium flow rate on Overall heat 172 transfer coefficient 5.7 5.8 Chapter 5.6.4 Effect of Feed Temperature 176 5.6.5 Effect of Feed Flow Rate 180 5.6.6 Effect of Insertions and Corrugated Tube Profile 184 5.6.7 Effect of Corrugation Pitch and Depth 186 RO parametric evaluation 187 5.7.1 Validation of the RO simulation program 187 5.7.2 Effect of Feed Flow rate 189 5.7.3 Effect of Feed pressure 189 5.7.4 Effect of Feed pressure and flow rate on water cost 191 5.7.5 Effect of Volumetric flow rate on exergy efficiency 191 Optimization of the CWPP plant 192 5.8.1 Optimization study of the MED plant 192 5.8.2 Fuel Cost sensitivity on the water cost 194 CONCLUSIONS 196 RECOMMENDATIONS 198 vi Table of Contents 199 REFERENCES APPENDIX A MED simulation program 208 APPENDIX B Calibration graph 214 APPENDIX C Uncertainty analysis 219 APPENDIX D Spiral Wound Membrane Specification 224 APPENDIX E MED Experimental Results 226 APPENDIX F Property functions of Seawater 237 APPENDIX G Heat transfer characteristics of tubes 241 vii Summary SUMMARY The efficiency of a combined cycle (CC) power plant depends to a great extent on the production of electricity. Under part-load operation of the power plant, the efficiency is affected significantly. Developments in desalination methods such as the Reverse Osmosis (RO) require electricity to produce water. Moreover, thermal desalination system like MED (multi-effect distillation) requires low grade heat source eg. waste heat from power plant. So, an integrated system (Combined water and power plant,CWPP) offers synergistic improvement. A simulation model was developed to predict the performance of the system, which includes both power and water. Computations indicated that the performance can be improved with the integration of MED and RO. When MED and RO plants are coupled to the combined power plant, the thermal efficiency of the plant increases by about 15%. This leads to a lower cost of water production, which is about 0.63 US$/m3. The study of the CWPP has shown that, the CC+MED+RO produce the distillate and the electricity with the lowest cost under the set conditions. Also, CC+MED+RO exhibits maximum overall exergetic efficiency. Experimental investigation of the MED system reveals the significant effect of flashing on the overall performance of the system. For a 100C superheat of the feed water, the system produces 41.45 kg/hr of fresh water from an effective heat transfer area of 5.32 m2 with a performance ratio of 1.45 in the corrugated profile. The performance ratio was found to increase significantly during the preheating of the feed temperature. Experiments were performed with various salt concentrations of 15,000-35,000 ppm to find the sensitivity of the system to feed water concentrations. Hot water was used as the heating fluid in the shell and tube two-phase heat exchanger and the viii Summary temperatures were varied between 47 and 850C. The flow rates of the hot water were varied from 1.5 to 3.5 m3/hr for the single effect experiment. Four different types of tube-profiles were considered, such as, single-fluted aluminum, smooth Copper-Nickel (90-10), Corrugated Copper-Nickel and PolyTeflon (PTFE) coated aluminum. Moreover, inserts were used to further enhance the heat transfer coefficient. The purpose was to find a better combination of tube material and geometry for the design of a desalination unit utilizing waste heat from the power plant. A lab scale experimental set up for RO was designed to work with variable feed concentration of 25,000ppm – 33,000ppm. The feed temperature and pressure were varied from 26oC – 32oC, 48.16 bar to 56.16 bar, respectively. The performance of the system was evaluated in terms of heating medium and feed water temperature and flow rate, top brine temperature (TBT) and feed concentration. Comparison between experimental and simulation results showed good agreement. The RO experimental results showed that, feed pressure had strong positive impact on the product flow rate and exergy destruction. Also, the exergetic efficiency increases rapidly with increase of the feed flow rate. Results showed that the use of a power plant coupled with MED and RO can save about 20% energy savings. Moreover, it can reduce the water production cost by about 23%. The simulation results for the optimization study reveals that, MED performs better with total number of effects of 11.The product salt concentration was in the range of 20-30 ppm. This experimental and simulation study indicated that, the CWPP system could effectively be used as a probable solution for arid and semi arid areas economically. ix Mathematical Model of Combined Water and Power Plant 6. Constant fluid properties. 7. Negligible components of brine and permeate velocities along the y (tangential) and x (axial) axis respectively. 8. Negligible diffusive mass transport along the x and y direction in both channels. This means that the flux through the membrane due to diffusion is much smaller to the flux due to convection. The driving force for the water transport is the effective pressure across the membrane. 9. The brine concentration varies linearly with the distance L, in the axial direction. cb = c f + fx In the above equation, f is a concentration gradient coefficient and given by the following expression: f = cb ( L) − c f L 10. Validity of the thin film theory, with the approximation which is given by, J cbw = cb (1 + ) k 11. A constant mass transfer coefficient, given by ( khb µ 0.17 u f ρhb 0.40 c f −0.77 Pf −0.55 ) = km ( ) ( ) ( ) ( ) D ρD µ ρ Po 12. Osmotic pressure proportional to the concentration. π = ωc ________________________________________________________________________ 81 Mathematical Model of Combined Water and Power Plant 3.11.1 Average volumetric flux The average volumetric water flux is given by: J = A1 ( A2 A3 − A4 + A5 − A6 ) q where, A1 = ( w q wfωl (3.114) ) A2 = (k + k1ωc f ) k + k1ωcb ( L) k A3 = ln( ) ∆Peff (0, w  + )  k k + k1ωc f  A4 = kω (cb ( L ) − c f ) A5 = c f u f k fb µ f (k1ω (c b ( L) − c f ) − k ln( kω (c b ( L) − c f ) cb ( L) ) ln cf k A6 = k1 ω 2 (cb ( L ) − c f ) 4k 3.11.2 Average salt flux The average salt flux is given as: J = B1 ( B2 + B3 ( B4 B5 ) B6 + B7 B8 ) where B1 = (3.115) k2 wL B2 = c f wL + fL2 w w q B3 = k1 fω k q ________________________________________________________________________ 82 Mathematical Model of Combined Water and Power Plant B4 = k1ω (cb ( L ) − c f ) B5 = ( ∆Peff (0, w)( k1ωc f )) + B6 = ln k ωk (cb ( L) − c f ) − k1 k + k1ωcb k (∆P + ) k + k1ωc f k1 B7 = ku f k fb µcb ( L ) B8 = k ln k + k1ωcb ( L ) k1 ω 2 + k1ωcb ( L ) + (cb ( L ) − c f ) k 4k There are quantities, namely ∆Pef (0, w) , and q which are properties that are lumped together. These lumped quantities are explicitly stated as follows: ∆Pef (0, w) = q= ∆P − ω c f k + k1ωc f hp 2k1k fp µ (3.116) (3.117) Also, there are some properties and quantities that are to be calculated using certain correlations given, namely kfb, k1, k2, kfp, ω , uf, f and k These correlations are stated and explained in the section below. 3.11.3 Correlations For the quantities kfb, kfp, k1 and k2, their correlations are obtained from experimental data in the work of Avlonitis et al. (2007). Taking into account that, all the membrane makers used similar feed and permeate spacers the brine friction parameter, kfb, was assumed to ________________________________________________________________________ 83 Mathematical Model of Combined Water and Power Plant be given by (3.118) and the permeate friction parameter was assumed constant at kfp = 1.1 *109 m-2 k fb = 309 Re f 0.83 (3.118) The membrane permeability coefficient for each different type of membrane, k1, can be expressed by (3.119) and the salt permeability coefficient by (3.120) 8.6464( T − T20 k1 =k 1m e T20 ) − 0.028P f (3. 119) T −To 14.648 T0 k = k me (3.120) where, k1m and k2m are constants depending on the membrane type. As for kfp, it is observed to be almost constant, and the value is: k fp = 1.1×109 m −2 (3.121) For ω , it should be observed as the proportional constant in the relationship of osmotic pressure with concentration. The equation for osmotic pressure is given as: π= RTc M (3.122) Also as in assumption (12), π = ωc (3.123) By comparing equations (3.122) and (3.123), ω= RT M (3.124) ________________________________________________________________________ 84 Mathematical Model of Combined Water and Power Plant There is also a feed velocity uf that appears in the Reynold’s number, Re in the equations for kfb, average volumetric flux J, and average salt flux. In order to calculate it, it is necessary to apply the definition of a flux entering a control surface. Q f = ∫ u f dS where S is the control surface under consideration. With uf considered to be an averaged quantity, it is possible to reduce (3.125) to Q f = u f As (3.125) From the study of Figure 3.17, it is deduced that the flow Qf is as shown in the diagram below. hb hm uf hb w Figure 3.17 Unwound spiral wound module (1 leave) There would be a number of leave N for a particular spiral wound module. With Figure 3.17, the surface associated with the flow rate Qf, would be given by As = N ( hb + hm + h p ) w (3.126) Combining (3.125) and (3.126), feed velocity uf becomes, ________________________________________________________________________ 85 Mathematical Model of Combined Water and Power Plant uf = Q N ( h p + h b + hm )( w) f is the concentration gradient coefficient, a term which is the outcome of assumption (9) and k is the mass transfer coefficient. Rewriting the correlation, k can be expressed as: (k m ( k= µ 0.17 u f ρhb 0.40 c f ) ( ) ( ) ρD µ ρ hb − 0.77 ( Pf Po ) −0.55 ) D (3.127) 3.11.4 Permeate Concentration The average salt flux is related to the volumetric average water flux, J, by Eq. 3.128. The permeate flow rate can be found as the product of the total active membrane area (excluding the glued area of the membrane) and the volumetric average water flux. After knowing the average salt flux and volumetric flux, it is possible to calculate the salinity of the permeate. It is given as J = Jc p ⇒ cp = J2 J (3.128) 3.11.5 Product flow rate By definition, the product flow rate is related to the average volumetric flux as follows: Q p = JA (3.129) ________________________________________________________________________ 86 Mathematical Model of Combined Water and Power Plant 3.11.6 Concentration of reject flow The concentration of the reject flow would be the brine concentration at the end of the RO module, which is essentially cb(L). In order to calculate this, apply the mass balance equations to the salt. m f c f = mrej cb ( L ) + m p c p ⇒ cb ( L) = m f c f − mpcp mrej (3.130) 3.11.7 Determining the number of RO modules The simulation is only capable of determining the permeate flow rate and the permeate concentration for a single module. Therefore, the number of modules must be determined so that the total amount of distillate can be determined for the amount of load that the RO plant would be drawing from the combined water and power plant. When the RO draws a portion of electrical load from the power plant, the following equation can be written for the pump work: Q f ,total ∆P = W ⇒ Q f ,total = W ∆P (3.131) The amount of feed flow rate entering into module is pre-determined. With this feed flow rate entering into module, the number of permeators can be calculated out by N peremeators = Q f ,total Q f ,1 (3.132) ________________________________________________________________________ 87 Mathematical Model of Combined Water and Power Plant To determine the amount of distillate produced in total: Q p ,total = N permeators Q p ,1 (3.133) 3.11.8 Simulation Procedure For the simulation, the following variables are to be pre-determined. The flow chart of the simulation model is given in Figure 3.18. • Number of leaves(N) • permeate channel height (hp) • brine channel height (hb) • membrane channel height (hm) • feed salinity (cf) • Feed temperature(Tf) • Area of membrane (Am) • Applied pressure (Pf) • Membrane length (L) • active width of membrane (w2) • constant in water permeability coefficient (k1m) • constant in salt permeability coefficient, (k2m) • constant in mass transfer coefficient, (km) The steps in the simulation procedure are as follows: 1. With the feed temperature, and salinity, compute properties like density. 2. Calculate kfb, k1, k2, kfp, ω, uf, k and f with the correlations given above. ________________________________________________________________________ 88 Mathematical Model of Combined Water and Power Plant 3. Compute A1 to A6 to calculate the volumetric flux with the equation of (3.53) 4. Compute B1 to B8 and calculate the volumetric solute flux with the equation of (3.54). 5. Calculate the permeate concentration. 6. Calculate the volume flow rate. 7. Calculate the reject salinity. 8. If reject salinity differs from the reject salinity of the previous iteration or the first guess by a predetermined limit, use the calculated salinity in step to repeat steps to 8. Otherwise, proceed to step 9. 9. Print results. 3.11.9 Exergy Analysis for a RO module From the schematic of the RO plant in Figure 3.19, the streams that are entering and leaving the module are shown. There are streams entering, namely the feed seawater stream and the electrical work. There are streams exiting, they are namely the reject and the distillate. X des = ∑ X in − ∑ X out = X elec + X sw − X dist − X rej (3.134) ________________________________________________________________________ 89 Mathematical Model of Combined Water and Power Plant Get input variables: N, hp, hm, cf, Tf, Am, Pf, L, w2, k1m, k2m, km. Guess reject concentration. Calculate properties like density with salinity and temperature. Calculate kfb, k1, k2, kfp, ω, uf, k and f Calculate f. Calculate with average volumetric flux. Calculate permeate concentration. No Calculate reject salinity. check convergence Reject Salinity Yes Exergy Analysis Print Results Figure 3.18 Flowchart of RO Mathematical Model ________________________________________________________________________ 90 Mathematical Model of Combined Water and Power Plant Feed seawater Membrane module Distillate Electrical Work Feed pump Reject Figure 3.19 A schematic summarizing the exergy flows in and out of the RO module The product is defined as the exergy of the distillate and the fuel is defined as the seawater intake and the electrical work. Adopting this definition for this report, the exergy efficiency is computed as η II = X dist X sw + X elec (3.135) 3.11.10 Exergoeconomic Model of RO plant Thermoeconomy is based on the thermodynamic potential exergy, which takes into account the energy as well as its potential use (quality). Thermoeconomic analysis provides valuable information about the influence of the efficiency and cost of equipment on the efficiency of the global plant and the cost of the product. Therefore, this thermoeconomic analysis can identify where the major chances of improvements are in the production process. This thermoeconomic model of RO plant follows that of the Vicente et al. (2005) model. ________________________________________________________________________ 91 Mathematical Model of Combined Water and Power Plant The effects of irreversibility and fixed costs on the exergoeconomic cost of the products were evaluated. Details about fixed costs, thermoeconomic fundamentals and economic settings are given for the Reverse Osmosis desalination facility. Fixed costs represent the sum of all those costs not included as exergy terms in the flow chart, Figure 3.22. Thus, fixed costs consist of two main groups of costs: investment and O&M. For the Santa Cruz de Tenerife desalination facility, O&M costs include proper operational and maintenance, spare parts, membrane replacement and auxiliary consumption expenditures. Auxiliary consumption represents all external consumption not included in the flow chart: chemical dosing, membrane cleaning, regulation and control, blow down pumping, lighting and other minor consumables. The thermoeconomic analysis is based on the following criteria: • For any flow, economic cost per unit of exergy (unit exergoeconomic cost) is assigned. Exergoeconomic cost is equal to the unit exergoeconomic cost multiplied by the exergy rate. • For any flow from the environment, external valuation of the unit exergoeconomic cost is performed. For our system, this involves the use of seawater (free) and external consumption of steam from power plant. • For any flow without later usefulness (losses), zero unit exergoeconomic cost is assigned. This involves blow down. ________________________________________________________________________ 92 Mathematical Model of Combined Water and Power Plant • For any equipment, fuel-product balance of exergoeconomic cost is performed from Bejan et al. (1996). In this balance, the sum of the exergoeconomic costs of the products (outlet useful flows) is equal to the sum of the exergoeconomic costs of the fuel components (exergy flows which contribute to generate the products) and the fixed costs: Product cost (Cp)= Fuel cost(Cf) + Annualized Fixed costs (Z) (3.136) Discounting affects all the terms of the fuel product balance. As a result, the unit exergoeconomic cost of the product (cp) is given below. It is determined by the unit costs (cF) and exergy rates (ExF) of the fuel components or the incoming streams, the rate of discounted fixed costs (Y) and the exergy rate of the product (Exp). The rate of discounted fixed costs takes into account discounted fixed costs during the lifetime of the desalination facility (Zn), availability (A) and discount factor tr. Unit exergoeconomic cost of product, c p = ∑ cF F Ex F Ex F Zn Y + = ∑ cF + Ex P Ex p F Ex P At r Ex P (3.137) In an RO plant, seawater undergoes three stages to be processed as pure water distillate. Exergetic change is more significant in the treatment stage compared to the pretreatment and post-treatment stage. As a result in this project, our main focus will be on the treatment stage which comprises the RO skid, the energy recovery turbine and the high pressure pump. ________________________________________________________________________ 93 Mathematical Model of Combined Water and Power Plant W8 Pretreatment 32 Regulation Valve 54 43 Postreatment 87 75 98 RO Skid 21 W10 High Seawater Pressure Pump W3 10 Distribution 09 Municipal 65 Storage Turbine 06 Seawater Figure 3.20 Schematic Diagram of RO plant For example in Figure 3.20, the product is stream (21) which is the outcome of incoming streams of sea water (10) and pump work (10). So, from Equation 3.137, average unit cost of outgoing stream will be, c 21 = c10 Ex10 W Z + cW 10 10 + Ex 21 Ex 21 Ex 21 Pretreatment Pumped seawater : c 21 = c10 E10 W Z + cW 10 10 + E 21 E 21 E 21 Feed: c32 = c 21 E 21 Z + E32 E32 High pressure feed: c 43 = c32 E32 W W Z + cW 30 30 + wW 36 36 + E 43 E 43 E 43 E 43 ________________________________________________________________________ 94 Mathematical Model of Combined Water and Power Plant Treatment High pressure feed to skid c54 = c 43 High pressure blowdown c65 = c54 Product c75 = c54 E 43 , Z4 ≅ E54 E54 E Z E − c65 65 + − c w 06 E75 E75 E75 E 75 Energy recovery cW 36 = c65 Blowdown c06 = E65 Z + W36 W36 Post treatment Post treated product c87 = c75 Pumped product c98 = c87 E 75 Z + E87 W46 E87 W Z + cW 80 80 + E98 E98 E98 ________________________________________________________________________ 95 Mathematical Model of Combined Water and Power Plant 3.12 Simulation flow chart of the combined water and power plant Power Plant RO MED Initialize variables for power plant Conpute mass of air and fuel input Compute mass of steam in steam cycle and power produced Initialize variables Compute specific exergy, ψ Get input variables: N, hp, hm, cf, Tf, Am, Pf, L, w2, k1m, k2m, km. Guess reject concentration. Calculate density with salinity and temperature. Compute exergy,X Calculate kfb, Calculate f. k1, k2, kfp, ω, Compute cost of electricity based on installation cost and cost of fuel Compute cost of steam Compute exergy destruction using exergy balance Compute exergy efficiency Calculate with average volumetric flux. Calculate permeate concentration. No Calculate reject salinity. Reject Salinity Compute cost of stream in MED from MED installation cost Yes Exergy Analysis Compute avg. cost of water from MED and RO plant Compute average cost of steam from both MED and RO Figure 3.21 Flowchart for simulation of combined water and power plant ________________________________________________________________________ 96 [...]... List of figures Figure B5 Calibration graph of Channel -2 216 Figure B6 Calibration graph of Channel-3 21 6 Figure B7 Calibration graph of Channel-4 21 7 Figure B8 Calibration graph of Channel-5 21 7 Figure B9 Calibration graph of Channel-6 21 8 Figure G1 Variation of overall HTC with HM temperature for corrugated 24 1 tubes with variable corrugation pitch and depth Figure G2 Variation of overall heat transfer... 3.1 Schematic of a combined water and power plant 33 Figure 3 .2 Schematic Diagram of Combined Cycle Power Plant 34 Figure 3.3 T-s diagram of a Brayton Cycle 36 Figure 3.4 T-s diagram of a Rankine Cycle 39 Figure 3.5 T-s diagram of a Rankine Cycle (for bled steam) 42 Figure 3.6 A schematic summarizing the exergy flows into a MED plant 50 Figure 3.7 Schematic Diagram of Forward Feeding MED Plant 51 Figure... major sources of inefficiencies, and introduce measures to overcome it 1 .2 Research Objectives The main idea of this project was to propose a combined system that can fulfill both water and power demand at a reasonable cost and efficiency Most of the power plants run at part load condition and only occasionally it runs at peak load (usually 8-10 hours maximum per day) As a result, there is a lot of. .. systems to enhance their efficiencies Producing both power and desalted water by a combined water and power plant has better efficient use of fuel as compared to separate power and desalting plants Therefore, cogeneration of electricity and water from a single fuel has been gaining an increasing interest to produce water more energy-efficiently and economically In recent years, as a result of the continuing... Technical Specification of PTFE Coating 105 Table 4.4 Operating variables and their ranges during the 110 experiment Table 4.5 Common Materials used as MED evaporator tubes in 113 Desalination industry Table 4.6 Specifications of the twelve evaporator tubes 114 Table 4.7 Experimental variables 122 Table 4.8 Uncertainty of measurement 124 Table 4.9 Range of experimental parameters 129 Table 4.10 Water analysis. .. xiv List of figures LIST OF FIGURES Figure 2. 1 Various Types of Desalting Processes 8 Figure 2. 2 Installed Desalination Capacity by Process 9 Figure 2. 3 Overall Scheme of seawater distillation 10 Figure 2. 4 Schematic presentation of a Multi-Stage Flash desalination plant 11 Figure 2. 5 Schematic presentation of a Multi-effect distillation (MED) plant 12 Figure 2. 6 Schematic of a RO plant layout 15 Figure... possibility of systematically generating insight towards improvement; and the relative ease of its application to automated optimal searches Fiorini et al (20 05) described a combined power and water plant with Multi Stage Flash (MSF) 3 Introduction only with varying number of stages and opined that capital and steam costs are equally important in determining the optimal operative conditions Mehdizadeh (20 06)... Diagram of RO plant Figure 3 .21 Flowchart for simulation of combined water and power plant 96 Figure 4.1 Schematic diagram of the desalination system 98 Figure 4 .2 A Photograph of the desalination Rig 101 Figure 4.3 A Photograph of the Evaporator 1 02 Figure 4.4 The layout of tubes inside the evaporator 1 02 Figure 4.5 Corrugated Cu-Ni (90-10) Tube-bundle 104 Figure 4.6 Schematic diagram of the feed water. .. Detailed Specification of Spiral Wound Membrane 22 4 Table D2 Membrane Manufacturer data 22 5 Table E1 Experimental results for the variation of heating medium 22 6 flow rate (Single-fluted Aluminum Tube bundle) Table E2 Experimental results for the variation of heating 22 6 medium flow rate (Smooth Cu-Ni (90-10) Tube-bundle) xxiv List of table Table E3 Experimental results for the variation of heating 22 7... for 25 1 corrugated tubes with variable corrugation pitch and depth Figure G 22 Variation of overall heat transfer coefficient with feed flow rate 25 2 for smooth tubes xxii List of figures Figure G23 Variation of performance ratio with feed flow rate for corrugated 25 2 tubes with variable corrugation pitch and depth Figure G24 Variation of specific heat transfer area with feed flow rate for 25 3 corrugated . Schematic presentation of a Multi-effect distillation (MED) plant Schematic of a RO plant layout Schematic of a combined water and power plant Schematic Diagram of Combined Cycle Power Plant. Schematic Diagram of RO plant Flowchart for simulation of combined water and power plant Schematic diagram of the desalination system A Photograph of the desalination Rig A Photograph of. SIMULATION Gas Turbine Plant Steam Cycle Part Load Calculations 3.3.1 Gas Turbine Plant 3.3 .2 Steam Turbine Plant Combined Water and Power Plant MED Mathematical Model 3.5.1 Overall Plant