用于清洁发电的新型混合海洋热能转换系统的能源火用和经济分析外文文献

Contents lists available at ScienceDirect Energy Conversion and Management journal homepage Energy exergy and economic analyses of a novel hybrid ocean thermal energy conversion system for clean power production Fatih Yilmaz Vocational School of Technical Sciences Aksaray University 68100 Aksaray Turkey A R T I C L E I N F O Keywords Energy Exergy Economic assessment OTEC Wind A B S T R A C T In this study comprehensive thermodynamic performance and economic evaluation of the ocean thermal energy conversion OTEC and wind turbine combined hybrid plant is investigated The proposed system consists of the two main sub cycles which are isobutene working fl uid ocean thermal energy conversion system and wind turbine The proposed study is projected to meet the daily total electrical power demands for a petrol station on the edge of the Mediterranean Sea in Turkey Antalya Energetic exergetic performances and total irreversi bility as well as economic assessment of the whole plant and its components are investigated according to various factors for example dead state temperature turbine isentropic effi ciency and inlet pressure of turbine The results obtained by calculating the eff ects of these parameters on the ocean thermal energy conversion wind plant performance energy and exergy effi ciency are presented in graphs According to the results the total energy and exergy effi ciencies of the ocean thermal energy conversion plant are 4 49 and 14 84 re spectively Also the overall energy and exergy effi ciency of the hybrid system are 12 27 and 23 34 re spectively In addition the total exergy destruction rate of the modelled plant is 2168 405 kW and the heat exchanger has maximum exergy destruction ratio with 44 77 Finally the total cost of the proposed hybrid study is found as 3 03 hr 1 Introduction Recently electrical energy demand in the world is increasing day by day because of the increase in such globalization economic progress and the human population According to World Bank Data electrical power consumption in the world increased by approximately 160 from the 1960 year to 2014 1 At this stage fossil based fuels are still expected to remain a dominant energy source for the next few decades 2 In parallel with this increase the use of fossil fuels increases lin early to meet the demands electrical power Therefore the release of harmful gases will continue in the atmosphere resulting from the burning of fossil based fuels Correspondingly the above mentioned harmful gases give rise to environmental problems for example global warming acid rain climate change It is clear that global warming has a negative impact on our entire world Simply speaking in order to overcome these negative environmental problems the renewable en ergy supported electrical power generation systems are a very im portant technology for a clean and sustainable environment 3 Undoubtedly solar wind geothermal and biomass energy are more prominent among the renewable energy sources However in recent years ocean thermal energy has become important in the sustainable energy production systems Ocean thermal energy conversion system OTEC produce clean power energy using the thermal energy between the hot water on the surface and the deep cold water of the ocean 4 5 These systems off er a signifi cant advantage especially for settlements close to the seaside The effi ciency of these systems is lower than the general Rankine cycles because the sea water is about 15 25K diff er ence between the bottom and surface water temperatures 6 The basis of the OTEC cycle is based on the Organic Rankine cycle ORC using for the power production in low temperature applications In the lit erature there are some studies about to OTEC system in recent years for clean and sustainable power production Idrus et al 7 have reported the geothermal energy based OTEC power system Their suggested plant consists of an OTEC sub system and geothermal waste energy sub system They calculated that a max imum power production rate of the plant is 32 593 MW and the capital cost of the plant is 4 489 kW Uehara et al 8 have investigated the optimization of a closed OTEC cycle They have used Powell Method in their optimization calculations In their study they proposed a 100MW OTEC cycle with heat exchangers using ammonia and also compared with the calculation outcomes for turbine effi ciency Ahmadi et al 9 have examined an OTEC plant for hydrogen generation using multiobjective optimization methods Their proposed study involving an OTEC cycle with a solar collector and also a PEM https doi org 10 1016 j enconman 2019 06 028 Received 6 April 2019 Received in revised form 21 May 2019 Accepted 14 June 2019 E mail address fatihyilmaz aksaray edu tr Energy Conversion and Management 196 2019 557 566 Available online 20 June 2019 0196 8904 2019 Elsevier Ltd All rights reserved T electrolyzer for hydrogen production The study results illustration that the system performance particularly aff ected by warm seawater inlet mass fl ow rate Yamada et al 10 have investigated performance evaluation of solar energy based OTEC SOTEC plant The study of Ref 10 ex amines SOTEC plant and their results show the net thermal effi ciency of the SOTEC system with the supports with 20 K solar boost in the day time conditions under the Kumejima Island is 2 7 times that of the OTEC plant Straatman et al 11 have studied cost optimization of the integrated OTEC system with off shore solar pont They dimensioned a 50 MW production OTEC cycle and the energy effi ciency of a typical OTEC system determined to be 3 Wand et al 12 have reported the multiobjective optimization and performance assessment of an innovative ORC based OTEC plant They have used working fl uids as R717 R152a R134a R227ea R600 and R601 in the plant The best exergy effi ciency among the proposed fl uids has R601 with 28 47 The work of Yoon et al 13 discusses the performance evaluation of a high effi ciency ammonia OTEC plant Their plant consists of the OTEC system an expansion valve and a cooler sub unit It illustrated that the effi ciency of their proposed study found to be 2 401 Sun et al 14 have reported thermo economic performance ana lyses of geothermal assisted ORC system They have stated that the evaporator pinch temperature diff erence PPTD is a key parameter eff ect on thermodynamics and economic performance Also they stated that ORCs produce about 1 7 and 2 6 more than power with very decrease in 1 oC of the evaporator PPTD Liu et al 15 have surveyed a performance evaluation of hybrid geothermal fossil based power gen eration plant Their proposed plant that includes a super critical 1000 MW power unit and a geothermal feed water preheating system Also R601a isopentane refrigerant is used in ORC system Bernardoni et al 16 have debated technoeconomic evaluation of the OTEC plant for power production The effi ciency of their proposed system is calculated to be 2 2 in hot sea water temperature 28 C and in the cold sea water temperature 4 C At the same time 2 35MW of power is produced with the R717 fl uid under the above conditions Khosravi et al 6 have reported a thermodynamic and cost evaluations of a OTEC cycle with PV system for hydrogen generation The study results confi rmation that maximum specifi c power generation found as 0 3622 kW m2 for R717 fl uid Also the total energy effi ciency of the hybrid OTEC plant are computed as 3 318 Nihous 17 has investigated an Atlantic OTEC plant resources In its work it concluded that under current circumstances and in stan dardized OTEC operations the net energy generation density would reach an extreme of 80kW km2with a cold sea water draft of ap proximately 14m year per unit area Soto and Vergara 18 have sur veyed the increased thermal power plant effi ciency with OTEC system In their work the simulation has fi nally aimed at optimizing the power generation of the plant to increase 25 37 MW according to the season Also they emphasized that they can be implemented to diff erent fl ow and temperature situations with the developed model Jung and Hwang 19 have presented the feasibility study of in tegrated OTEC plant in South Kore In their proposed study they dis cussed thermodynamic analysis and fl uid selection for integrated OTEC They concluded that for the 1 5 MW integrated OTEC plant around 3m3 s cold sea water is necessary Semmari et al 20 have off ered a novel OTEC cycle with Carnot assisted They proposed a system which is Carnot based OTEC are calculated global net effi ciency is about 1 2 and the net total electrical power production rate 6 6kW per cycle The global net effi ciency of the Carnot based OTEC is nearby 1 2 and the net total electric power rate is 6 6kW per cycle Yuan et al 21 have explored the experimental examination NH3 H2O based OTEC plant In their experimental study when the hot source is between 30 and 40 C and the cold source is between 5 and 15 C the thermal effi ciency of the system has changed between 0 and 0 75 Yilmaz et al 22 have performed thermodynamic analyses of OTEC assisted hydrogen gen eration plant Their study consists of an OTEC system hydrogen gen eration and liquefaction sub system with a PEM electrolyzer and a solar collector The whole energy and exergy effi ciency of plant are de termined as 43 49 and 36 49 respectively Moreover energy exergy and economic analysis is an important method to understand and improve energy systems and there are a lot of works about to these topics Xu et al 23 have performed an ex ergetic and economic evaluation of modelled solar heat powered re frigeration cycle comparing convectional cycle They conclude that a new modelled cycle has cost rate about 24 4 lower than conventional cycle Gargari et al 24 have examined an energetic exergetic eco nomic and environmental analyses of biomass based multigeneration plant The energy and exergy effi ciency of the overall plant are 72 75 and 50 21 receptively Xu et al 25 have investigated a comparative energy exergy economic and environment analyses of two low tem perature absorption and refrigeration cycle They compared with ab sorption and refrigeration cycle in terms of 4E viewpoint Based on the review of previous studies there are many papers related to OTEC systems as shown above section However usually in these studies supported by solar energy The main problem of such solar powered systems is that they require storage in the nighttime absence of the sun In addition it is seen that when the literature studies ex amined the OTEC systems run with ammonia working fl uid in general This work presents the modeling of a wind energy assisted hybrid OTEC system in terms of thermodynamic and economic viewpoints In addi tion to the system a wind turbine has been added to the integrated system as the hot sea water pump used to compress the ocean water into the proposed system consumes much energy The main purpose of this paper is to investigate thermodynamic performance and economic evaluation of hybrid OTEC plant for clean Nomenclature E energy kW Ex exergy kW Q heat transfer rate kW W work rate kW ex specifi c exergy kJ kg h specifi c enthalpy kJ kg s specifi c entropy kJ kgK Ttemperature C K Zpurchase cost rate Greek letters energy effi ciency exergy effi ciency Subscripts concondenser gengenerator HEXheat exchanger ininlet OTECocean thermal energy conversion outoutlet Ppump phphysical Tturbine wtwind turbine F YilmazEnergy Conversion and Management 196 2019 557 566 558 power production This system is also modeled in order to supply the total daily electricity demands of a petrol station in Alanya where it is approximately 200m from the coastal of the Mediterranean Sea In addition in the OTEC system R600a fl uid as the working fl uid has been preferred due to its environmental and thermophysical properties In addition the particular points of this study can be given as follows To perform a comprehensive thermodynamic analyses of the wind supported hybrid OTEC system To conducted an economic assessment of the wind supported hybrid OTEC plant To investigate power production rate of the hybrid OTEC system for isobutane and butane fl uids To conduct energy and exergy analyses and in addition total exergy destruction rate of the ORC and hybrid integrated OTEC systems To explore clean and sustainable electrical power generation from the ocean and wind turbine 2 Case study In this case study the system design has been made according to the daily total electrical power consumption of a petrol station located on Alanya Antalya from Turkey which is the shore of the Mediterranean Sea latitude 36 5990 and longitude 31 8084 Fig 1 shows the geo graphic location of the located place of this petrol station 26 In ad dition Figs 2 and 3 illustrates the average wind speed at 50m and the environment temperature at 2m which is the location of the petrol station 26 These parameters directly aff ect the power production rate of the OTEC system In this study it is aimed to meet the electricity demand with hybrid wind OTEC system since this petrol station is at a distance of about 200m to the Mediterranean seaside On the other hand the maximum and average seawater temperature are specifi ed in Fig 4 As can be shown above fi gure the maximum average sea water temperature in the summer months is about 30 C for this place Therefore OTEC systems in coastal areas such as this place can be said to be quite important for clean and sustainable electrical power gen eration 2 1 System description The schematic illustration of the integrated hybrid wind OTEC plant is presented in the Fig 5 This system is mainly composed of an ORC which are a pump a heat exchanger a turbine and a condenser In the low boiling point working fl uid enters heat exchanger and evaporates by using the heat of the hot sea water stage 2 to 3 and then electricity is produced at the turbine stage 3 to 4 Then in the condenser be tween points 4 and 1 the working fl uid condenses with the using the cold sea water from point 5 The working fl uid enters in the pump 1 as the saturated liquid at point 1 Some technical information used in the proposed hybrid OTEC system design are presented in Table 1 6 27 29 On the other hand as shown in Fig 5 this system is supported by a wind turbine because the hot sea water pump Pump 2 consumed more energy As shown in above Fig 2 this place has a high potential in terms of wind source 3 Thermodynamic and economic modelling In this part of work the thermodynamic and cost modeling of the new hybrid wind OTEC system for the power generation is conducted depends on the energy exergy and economic viewpoints In addition the exergy destruction rate is carried out to defi ne the irreversibility values for the proposed plant and its components For these calcula tions the EES mathematical program has been used 30 Thermo dynamic calculations are generally based on the mass energy entropy and exergy equilibrium equations according to the inlet and outlet of each control volume 31 Also some assumption of the thermo dynamic modelling are given as below 32 33 The heat loses from the cycle are negligible The kinetical and potential energies are disregard for the thermo dynamic calculation The plant runs steady state and fl ow circumstances The pressure drops in pipes and system components neglected The working fl uid accepted as the saturated liquid in the inlet of the ORC pump The general mass energy entropy and exergy equilibrium equa tions descripted as below respectively 31 32 mm in in out out 1 Fig 1 Geographic location of the located place of the proposed petrol station 26 F YilmazEnergy Conversion and Management 196 2019 557 566 559 QWmh V gZ QWmh V gZ 2 2 inin in inin in i outout out outout out out 2 2 2 m sS Q T ms Q T in in ingen in k k out out out out k k 3 m exExExmexExExEx in inin QW out outout QW dest 4 were in and out denotes inlet and outlet stream of the component In addition Q W S gen h s andEx destcharacterizes the rate of heat transfer and work entropy generation specifi c enthalpy and entropy and then exergy destruction rate respectively exexexexex phchptkn 5 whereexph exch exptandexkndenote the physical chemical potential and kinetic exergy In this work expt exknandexchare putative as dis regarded The physical or fl ow exergy is exhhT ss phooo 6 the exergy rates of heat transfer and work can be written as follows Ex T T Q 1 Q o 7 ExW W 8 3 1 OTEC system In this proposed study in Fig 5 the OTEC system is designed ac cording to the seawater temperature in Alanya conditions The general thermodynamic correlations of OTEC system and its components are presented below Pump1 mm 12 9 m hWm h P11122 10 m sSm s gen P1 1 12 2 11 m exWm sEx Pdes P1112 2 1 12 HEX Fig 2 The average wind speed from rom January 1 2017 to January 1 2019 years 26 Fig 3 The average environment temperature from January 1 2017 to January 1 2019 years 26 Fig 4 The average and maximum seawater temperature from 1966 to 2017 years F YilmazEnergy Conversion and Management 196 2019 557 566 560 mmmm 2389 13 m hm hm hm h 22883399 14 m sm sSm sm s gen HEX2 28 8 3 39 9 15 m exm exm exm exEx D HEX22883399 16 Turbine mm 34 17 m hm hW T33441 18 m sSm s gen T3 3 14 4 19 m exm sExW des TT334 4 11 20 Condenser mmmm 4156 21 m hm hm hm h 44551166 22 m sm sSm sm s gen Con4 45 5 1 16 6 23 m exm exm exm exEx D Con44551166 24 Pump2 mm 78 25 m hWm h P77288 26 m sSm s gen P7 7 28 8 27 m exWm sEx Pdes P7718 8 2 28 Fig 5 Schematic illustration of the proposed hybrid OTEC system Table 1 Design parameters used in the proposed system according to studies in the energy fi eld Design parametersValue OTEC Turbine isentropic effi ciency88 Warm sea water pump isentropic effi ciency85 6 Cold sea water pump isentropic effi ciency85 6 Turbine inlet pressure300 400kPa Cold deep sea water inlet temperature5 10 C Warm sea water inlet temperature30 35 C ORC pump effi ciency85 29 Working fl uidsR600a Wind turbine Average wind speed5 3m s Wind turbin