Exergy Efficiency Values Research Articles

Energy and Exergy Analysis of Transcritical Carbon Dioxide Refrigeration Cycle

The effects of conventional refrigerants on ozone layer and its effect on global warming are known. Refrigerants based on chlorofluorocarbons (CFC) and hydrochlorofluorocarbons (HCFCs) have been used in refrigeration systems for a long time and are still being used. Instead of these refrigerants, the use of natural refrigerants which are much less harmful to the environment, has been given importance. Carbon dioxide is the first that comes to mind among these fluids. In this study, energy and exergy analysis of transcritical carbon dioxide refrigeration cycle examined as theoretically. Energy and exergy analysis were made for different evaporator temperatures and outlet temperatures from gas cooler. Exergy losses of each component of the transcritical carbon dioxide refrigeration cycle were determined. In addition, the first and second law efficiencies of the refrigeration cycle were determined. When the evaporator temperature is -5 oC and the outlet temperature from the gas cooler is 20 oC, the highest exergy efficiency value was determined as 41.19 in this study.

Experimental and numerical analysis of energy and exergy performance of photovoltaic thermal water collectors

The aim of this paper is the investigation and comparison of PV (Photovoltaic) module and PV/T (Photovoltaic/Thermal) collectors regarding the energetic and exergetic point of view. A reference PV module and two different flow pattern PV/T collector was experimentally observed and evaluated results were compared concerning first and second law of thermodynamics. Experimentation results are also compared with the numerical results that were obtained by ANSYS Fluent software. Experimentation proceeded in Karabuk, Turkey. As a result, it was concluded that the PV module electrical efficiency is equal to its overall efficiency and is approximately 7.96%. Thermal, electrical, and overall energy efficiency values are 29.08%, 9.74%, and 38.82% for PV/T1, and PV/T2 are 49.68%, 10.19%, and 59.88%. The exergy efficiency of PV, PV/T1, and PV/T2 are determined at approximately 4.63%, 10.64%, and 11.53%. When the exergy efficiency values are compared, solar energy utilization in the renewable energy class for both PV/T collectors formed with the cooling units integrated with the PV panel has been almost doubled.

Effects of ternary mixtures of propane-butane-hydrogen and different liquid fuels on the performance specifications of a spark ignition engine

ABSTRACT This study reports the influences of ternary fuel mixtures consisting of liquefied propane-butane-hydrogen as additives and methanol, ethanol, iso-octane, hexane, benzene, toluene and gasoline as primary fuels on the performance specifications such as variation of power, thermal efficiency, exergy efficiency and NO of a spark ignition (SI) engine by using a combustion model. Mass ratio of one kind of gas fuels has been kept constant as 50%, mass ratios of other two kinds of gas fuels have been ranged from 10 to 50%. Hydrogen addition to mixtures has parabolically affected the variation of performance characteristics. However, they have been linearly affected by propane and butane additions. Increment and reduction trends of the performance characteristics have changed depending on liquid fuel kinds. Maximum power output is observed with 50% mixture of toluene, minimum power output is revealed with 50% mixture of methanol, maximum values of thermal and exergy efficiencies are acquired with 50% butane-30%-toluene-20% hydrogen, 50% propane-20% methanol-30% hydrogen mixture provides minimum thermal efficiency, 50% propane-30% methanol-20% hydrogen mixture provides minimum exergy efficiency. The maximum NO is observed with 50% mixture of benzene. Minimum NO is acquired with 50% mixture of propane. The maximum values of power, thermal efficiency, exergy efficiency and NO formation have been obtained as 14.16 kW, 34.37%, 33.49% and 5.78E-7 mol/cm^3 respectively. Their minimum values are 6.69 kW, 28.01%, 27.54% and 3.61E-9 mol/cm^3, respectively. The results revealed that ternary fuel mixtures considerably affect the performance specifications and NO releasement of the SI engine. An Artificial Neural Network (ANN) model of the engine is constructed for a wider view. The results of the presented study can be used to assess the effects of ternary fuel mixtures on the performance characteristics and NO formation of an SI engine.

Performance analysis of a textile based solar assisted air source heat pump with the energy and exergy methodology

Solar air collectors are integrated into the air source heat pump in order to increase the performance of the heat pump in cold climate regions. The evaporator air is heated by solar air collectors. In this study, two different types of solar air collectors which were textile based solar air collector and flat plate solar air collector were used. The thermal energy stored in the tank during the day was used to heat the room at day and night. The thermal storage tank was heated using three heating systems, textile based solar assisted air source heat pump (TSAHP), flat plate solar assisted air source heat pump (FSAHP) and air source heat pump (ASHP). In this study, energy, exergy and economic analysis of three different heating systems were performed. COP values increased by 32% in TSAHP and 21% in FSAHP compared to ASHP. Addition of solar air collectors to the ASHP heating system has been shown to improve thermal storage tank performance. Total exergy efficiency values were calculated as 14.4%, 13.4% and 11.3%, for TSAHP, FSAHP and ASHP heating systems, respectively. Levelized cost of heating of novel type system (TSAHP) ($/kWh) was 11.8% lower than conventional ASHP.

Performance comparison of the solar-driven supercritical organic Rankine cycle coupled with the vapour-compression refrigeration cycle

Abstract In this study, a parametric analysis was performed of a supercritical organic Rankine cycle driven by solar parabolic trough collectors (PTCs) coupled with a vapour-compression refrigeration cycle simultaneously for cooling and power production. Thermal efficiency, exergy efficiency, exergy destruction and the coefficient of performance of the cogeneration system were considered to be performance parameters. A computer program was developed in engineering equation-solver software for analysis. Influences of the PTC design parameters (solar irradiation, solar-beam incidence angle and velocity of the heat-transfer fluid in the absorber tube), turbine inlet pressure, condenser and evaporator temperature on system performance were discussed. Furthermore, the performance of the cogeneration system was also compared with and without PTCs. It was concluded that it was necessary to design the PTCs carefully in order to achieve better cogeneration performance. The highest values of exergy efficiency, thermal efficiency and exergy destruction of the cogeneration system were 92.9%, 51.13% and 1437 kW, respectively, at 0.95 kW/m2 of solar irradiation based on working fluid R227ea, but the highest coefficient of performance was found to be 2.278 on the basis of working fluid R134a. It was also obtained from the results that PTCs accounted for 76.32% of the total exergy destruction of the overall system and the cogeneration system performed well without considering solar performance.

Enhanced dynamic exergy analysis of a micro-jet (μ-jet) engine at various modes

In the current study, advanced exergo-dynamic analysis of a micro-turbo jet (μ-jet) along with conventional exergy analysis is presented in various running shaft speed modes. In this context, major advanced exergetic indicators of μ-jet components are evaluated at the various running testing. The operation modes were represented as operation shaft speeds between 48,850 and 77,000 RPM (revolution per minute), while μ-jet produced within the range of 45.01–121.27 N thrust force in these modes. Improvement potentials of turbomachinery components and exergy destruction rates are calculated throughout the real-time testing modes. According to the analysis, the combustor has the lowest exergy efficiency ranging from 41.06% to 50.18%. Also, the study shows that the exergy efficiency values of the experimental μ-jet are found to be as 6.56% at Mode-1, 10.12% at Mode-2, 15.46% at Mode-3 and 17.02% at Mode-4, respectively. Other important findings for μ-jet are that unavoidable exergy destruction rate varies between 94.89% and 95.79%, while endogenous exergy destruction value changes between 89.79% and 91.47% in these modes. Thanks to the present analysis, the methods decreasing avoidable exergy destruction that changes between 4.21% and 5.11% could be focused.

Thermodynamic and economic performance analysis of heat and power cogeneration system based on advanced adiabatic compressed air energy storage coupled with solar auxiliary heat

The advanced adiabatic compressed air energy storage system coupled with other systems not only has a high efficiency but also has the ability to produce heat and power simultaneously, which has great application potential. Reasonable allocation of heat generated by the system can improve the performance of the system. Therefore, a model of a cogeneration system based on advanced adiabatic compressed air energy storage coupled with solar auxiliary heat is proposed and five schemes of heat distribution are established. From the perspective of thermodynamics and economics, the performance of five heat distribution schemes (100%, 75%, 50%, 25%, 0%) is analysed and discussed. The effects of effectiveness of three types of heat exchangers, off-peak electricity and product prices on system performance are studied. In addition, the grey wolf algorithm is used for multi-objective optimization. The results show that the smaller the heat distribution ratio is, the greater the exergy efficiency and net present value. The large heat distribution ratio leads to a large energy storage density. The effect of the heat exchanger effectiveness on the system performance is different across different positions of the system. With the increase in on-peak electricity and hot water prices and the decline in low peak electricity price, the net present value increases. Under the optimal conditions, the ranges of the energy storage densities and the net present values of the five heat distribution schemes are 15.109∼17.466 MJ•m−3 and 13.992 × 107∼22.616 × 107$, respectively.

Advanced Exergy Analysis of Waste-Based District Heating Options through Case Studies

The heating of the buildings, together with domestic hot water generation, is responsible for half of the total generated heating energy, which consumes half of the final energy demand. Meanwhile, district heating systems are a powerful option to meet this demand, with their significant potential and the experience accumulated over many years. The work described here deals with the conventional and advanced exergy performance assessments of the district heating system, using four different waste heat sources by the exhaust gas potentials of the selected plants (municipal solid waste cogeneration, thermal power, wastewater treatment, and cement production), with the real-time data group based on numerical investigations. The simulated results based on conventional exergy analysis revealed that the priority should be given to heat exchanger (HE)-I, with exergy efficiency values from 0.39 to 0.58, followed by HE-II and the pump with those from 0.48 to 0.78 and from 0.81 to 0.82, respectively. On the other hand, the simulated results based on advanced exergy analysis indicated that the exergy destruction was mostly avoidable for the pump (78.32–78.56%) and mostly unavoidable for the heat exchangers (66.61–97.13%). Meanwhile, the exergy destruction was determined to be mainly originated from the component itself (endogenous), for the pump (97.50–99.45%) and heat exchangers (69.80–91.97%). When the real-time implementation was considered, the functional exergy efficiency of the entire system was obtained to be linearly and inversely proportional to the pipeline length and the average ambient temperature, respectively.

An experimental study optimization of a solar assisted D.C refiergerter under Iraqi climate.

Solar photovoltaic to derive a small dc domestic refrigerator is becoming beneficial for remote areas where electricity is not available. This article presents an experimental energetic and exergetic analysis for a small dc refrigerator driven by a solar photovoltaic (PV) panel. The performance parameters, such as exergy losses compressor, exergy losses condenser, exergy losses expansion valve, exergy losses evaporator, efficiency exergy refrigerator, average optimum exergy efficiency (refrigerator), efficiency system (PV panel plus dc refrigerator) were investigated. The mentioned parameters were measured along the time of the day under the climate of Baghdad city. The experimental test has been carried out with load refrigerator (5 liters of water), to the evaluate the average optimum value of the refrigerator exergy efficiency under different thermostat. this work aims to identify an optimal average exergy loss for D.C refrigerator during the day, which can work at the optimum condition in evaporator temperature. The average exergy losses optimum value in evaporated temperature (-6) is 24.63

Exergy and exergoeconomic comparison between multiple novel combined systems based on proton exchange membrane fuel cells integrated with organic Rankine cycles, and hydrogen boil-off gas subsystem

A comparative study is applied to evaluate four combined power producing systems based on low-temperature and high-temperature proton exchange membrane fuel cells (LT-PEMFC and HT-PEMFC) with equal power generation of 1056 kW. Single-stage organic Rankine cycle (SORC) and cascade two-stage ORC (CTORC) are employed to recover the waste heat from the fuel cells as well as exploiting the hydrogen boil-off gas for generating excess power, and feeding to the fuel cells. The performance of the proposed systems is compared to energy, exergy, and exergoeconomic viewpoints. Also, a parametric analysis is carried out to assess the effects on the thermodynamic and economic performance of the investigated systems by considering main parameters such as current density, fuel cell operating pressure and temperature, turbine inlet pressure, and expander lead. The results obtained from the parametric analysis reveal that with increasing the fuel cell operating temperature the overall exergy efficiencies for the proposed combined systems based on LT-PEMFC and HT-PEMFC decreases and increases, respectively. Also, the net output power and the total product unit cost of the considered systems are optimized at a specific value of BOG expander inlet pressure. The results indicate that albeit the highest values of energy and exergy efficiencies among the considered systems (61.42% and 63.20%) are related to LT-PEMFC/CTORC but the lowest total product unit cost of 33.75 $/GJ is related to HT-PEMFC/SORC.

Energy, exergy, exergoeconomic and exergoenvironmental analysis and optimization of quadruple combined solar, biogas, SRC and ORC cycles with methane system

The present work deals with a novel configuration of four cycles such as steam gas cycles and an organic Rankine cycle and a biogas Brayton cycle and a solar Brayton cycle are introduced for recovering energy from hot exhaust gas and its simulation and optimization are discussed. Also, a carbon-amine adsorption system has been utilized for separating and storing carbon dioxide from hot exhaust gases and convert it to methane. For this new system, exergy, economical exergy, energy, economic and environmental exergy evaluations have been performed. To analyze the different parts, their thermodynamic and economic models, EES and MATLAB software have been used to optimize the exergy-economic cycle in order to reduce costs and increase exergy. In this research, genetic algorithm has been used for optimization. At the optimal point, the values of exergy efficiency are equal to 61.7% and the cost of electricity generation is 6.36 cent per kilowatt hour. The results show that adding Rankine cycles to the gas cycles increments the exergy and energy efficiency to 73.7 and 71.8, respectively. Nevertheless, integrating the carbon capture unit with this system reduced the exergy and energy efficiency to 51.9% and 50.5%, respectively. Based on the economic results for the presented system, it is indicated that the simple return on investment and return on investment are both 1.5 years. In addition, internal rate and net present value of return were 0.68 and 3.13*09 $ respectively. This system can generate 327,160 kW of electricity in addition, the carbon capture system unit can prevent and convert 627,000 tons of carbon dioxide into methane fuel annually.

Energy, exergy and techno-economic analysis of novel solar stills for sea coastal area

This paper presents the energy, exergy, and economic analysis of conventional solar still (CSS) and Modified solar still integrated with sand bed earth (MSSIE). The energy analysis has been done with the help of Dunkle and Kumar & Tiwari after using modified relations of Tsilingiris. Throughout the experimentation, the internal efficiency of MSSIE is higher than CSS (viz. 14.67%). The MSSIE shows a 41.9% higher value of exergy efficiency after 14:00 h than CSS. The distillate yield recorded from MSSIE is 12.64% higher than CSS. The AWC has been evaluated as 1.2, 1.33, 1.47 and 1.29, 1.44, 1.59 INR/l at an interest rate of 8, 10 and 12% for CSS and MSSIE with GI tray, respectively. Whereas, AWC for MSSIE get reduced by 9.2, 8.3 and 8.8% compared to CSS for the same rate of interest without GI tray.Abbreviations: AC: Total annual cost (INR); AMC: Annual maintenance cost (INR); ASV: Annual Salvage value (INR); AWC: Annual water cost (INR/l); CRF: Capital recovery factor; FAC: First Annual Cost (INR); GI: Galvanised Iron; INR: Indian National Rupee; LLDPE: Linear low density polythene; SFF: Sinking fund factor

Energy-exergy-economic-environmental-energo-exergo-enviroecono (7E) analysis of solar photovoltaic power plant: A case study of 7 airport sites in India

Solar PV development gained airport operators' attention in the wake of its negligible carbon emission and onsite electricity generation. The solar PV projects in airports cater to its energy, economic and environmental needs. A comprehensive study on multi-dimensional performance aspects of the airport-based solar PV system is not presented anywhere. This study investigates the energy, exergy, economic, environmental, energoeconomic, exergoeconomic, and enviroeconomic (7E) performance of solar PV power plant proposed in the premises of 7 Indian airports. For the ease of performance comparison, an identical 5 MW solar PV system is designed for each airport location. At first, the energy generation, economic, and environmental performance are assessed with the help of RETScreen software. Then, an Excel-based mathematical model was developed to estimate exergy, energoeconomic, exergoeconomic, and enviroeconomic parameters. Satisfactory performance ratio (more than 79%) and system efficiency (more than 14%) are predicted in all the selected airport locations. The minimum and maximum values of exergy efficiency are estimated as 9.89% (Goa airport) and 12.00% (Lucknow airport), respectively. Except for Ahmedabad airport and Dehradun airport, the IRR value is less than the discount rate (10%) for the five airports, with Goa airport on the borderline (9.5%). Dehradun airport has the most favorable 7E parameters among the selected seven airports with 82.21% PR, 20.56% CUF, 15.13% exergy efficiency, 3.7 years payback, 13.30% IRR, 7.5 cents LCOE, 8060 tCO2 avoided/ annum. In addition, it has the lowest value of exergoeconomic & energoeconomic parameter and the highest value of enviroeconomic performance among the selected locations. The application of the 7E framework is expected to provide valuable insights into the feasibility study of the solar photovoltaic system in airports.

Electrolyzer-fuel cell combination for grid peak load management in a geothermal power plant: Power to hydrogen and hydrogen to power conversion

This study provides comprehensive energy, exergy, and economic evaluations and optimizations of a novel integrated fuel cell/geothermal-based energy system simultaneously generating cooling and electricity. The system is empowered by geothermal energy and the electricity is mainly produced by a dual organic cycle. A proton exchange membrane electrolyzer is employed to generate the oxygen and hydrogen consumed by a proton exchange membrane fuel cell utilized to support the network during consumption peak periods. This fuel cell can be also used for supplying the electricity demanded by the network to satisfy the loads at different times. All the simulations are conducted using Engineering Equation Solver software. To optimize the system, a multi-objective optimization method based on genetic algorithm is applied in MATLAB software. The objective functions are minimized cost rate and maximized exergy efficiency. The optimum values of exergy efficiency and cost rate are found to be 62.19% and 18.55$/h, respectively. Additionally, the results reveal that combining a fuel cell and an electrolyzer can be an effective solution when it comes to electricity consumption management during peak load and low load periods.

Sawdust drying process in a large-scale pellets facility: An energy and exergy analysis

Abstract Biomass is an important renewable resource that can be directly used as a raw material in energy converting processes, in wood-based industries, or it can be transformed into other types of biofuels. Its thermochemical properties, such as moisture content and chemical composition, directly influence the lower heating value and, consequently, systems' efficiency. To overcome these problems, drying processes are being optimized. This study aims to perform an energy and exergy analysis of a facility's sawdust drying process performance with an installed capacity to produce 1.8 tons per hour of high-quality pellets over two different seasons of the year. In this regard, energy and exergy analyses were carried out for the nominal operating conditions, and temperature measurements of the flue gases flow rate and moisture content were considered. Sawdust samples were collected before the drying process to determine the moisture content, corresponding to 53.49% and 50.23% for the winter and summer seasons, respectively. The analysis was conducted considering that the drying process should guarantee a reduction of the sawdust moisture content to a value of 10%, so the pellets produced at the facility could be certified following EN14961:2010 European certification standard. Consequently, energy and exergy efficiency values of the rotary dryer were found to be 1.5% and 2.2% higher in the summer season since the woodchips and sawdust moisture content are lower on that season and, therefore, less heat is necessary to dry the sawdust to 10% of moisture content. These results demonstrated that wood chips with higher moisture content require more effective fuel mass flow rates to the system to guarantee constant production. The ambient temperature does not seem to affect the efficiency of the dryer significantly. As a recommendation, using the waste enthalpy of flue gases for biomass pre-heating purposes is proposed.

Energy, exergy, exergoeconomic, and exergoenvironmental analyses and multi-objective optimization of a CPC driven solar combined cooling and power cycle with different working fluids

This paper aims to provide comprehensive 4E (energy, exergy, exergoeconomic, and exergoenvironmental) and advanced exergy analyses of the Refrigeration Cycle (RC) and Heat Recovery Refrigeration Cycle (HRRC) and comparison of the performance with R744 (CO2) and R744A (N2O) working fluids. Moreover, multi-objective optimization of the systems has been considered to define the optimal conditions and the best cycle from various perspectives. In HRRC, heat recovery is used as a heat source for an organic Rankine cycle. The energy and exergy analysis results show that utilizing HRRC with both refrigerants increases the coefficient of performance (COP) and exergy efficiency. COP and exergy efficiency for HRRC-R744 have been obtained 2.82 and 30.7%, respectively. Due to the better thermodynamic performance of HRRC, other analyses have been performed on this cycle. Exergoeconomic analysis results show that using R744A leads to an increase in the total product cost. Total product cost with R744 and R744A have been calculated by 1.56 $/h and 1.96$/h, respectively. Additionally, to obtain the processes' environmental impact, Life Cycle Assessment (LCA) is used. Exergoenvironmental analysis showed that using R744A increases the product environmental impact by 32%. Owning to the high amount of endogenous exergy destruction rate in the compressor and ejector compared to other equipment, they have more priority for improvement. Multi-objective optimization has been performed with exergy efficiency and total product cost objective functions as well as COP and product environmental impact for both refrigerants, which indicates that HRRC-R744 has better performance economically and environmentally. In optimal condition, the value of exergy efficiency, total product cost, COP, and the product environmental impact have been accounted for by 28.51%, 1.44 $/h, 2.76, and 149.01 mpts/h, respectively.

Investigation of the Exergy Analysis and Efficiency in the Turning of DIN 1.2367 Material

Increases of product in manufacturing processes have made its impact felt in Turning, one of the important branches of the industry. Increases in manufacturing also increase energy consumption. We can achieve this with efficiency studies in energy consumption. Energy efficiency studies to be carried out will reduce carbon emissions that will be revealed in turning processes and harm the environment. There are many studies on optimization of cutting parameters in turning processes. However, there are few studies on the effect of optimization of cutting parameters on energy efficiency and carbon emission values. This study has been trying to resolve this tartness. In the study, the efficiency calculation was made by extracting the exergy values of the processes of turning DIN 1.2367 steel material. In addition, processes in turning other metals can be determined and exergy calculations and efficiency values of these processes can be derived.

Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef

In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.

Thermal balancing and exergetic performance evaluation of a compression ignition engine fuelled with waste plastic pyrolytic oil and different fuel additives

This study aims at evaluating the heat energy and exergy values of waste plastic oil (WPO) blended diesel mixed with different fractions of fuel additives (ethanol as oxygenated fuel additive and nano graphene as nano additive) with a view to establish the thermal balancing of a diesel engine analytically taking experimental data and comparing with neat diesel oil. The research engine used was a four stroke, constant speed, stationary, direct injected, single cylinder, water-cooled compression ignition engine tested at different loading conditions. The thermal balance was prepared in respect of work output, heat loss in cooling, heat loss in exhaust gas, heat loss in lubrication and additional unaccounted heat losses in order to measure the efficiency of the engine in agreement with thermodynamics energy principles. Three test fuels with same plastic oil and different fuel additives concentration (comprising of 80% Diesel+20%WPO, 60% Diesel + 20%WPO+20% Ethanol and 80%Diesel +20% WPO+100 ppm nano graphene) are prepared for the engine test. The addition of ethanol in WPO blended diesel fuel mixture contributes marginal increase in brake thermal efficiency, decrease in brake specific fuel consumption, higher exhaust gas temperature and lower exergetic efficiency as compared to that of diesel. Nano graphene added to WPO blended diesel enhanced its energy along with exergy efficiency values as compared to other fuel mixtures under higher operating load condition. Fuel exergy for this fuel was increased by 18.57% in comparison to diesel at highest load. However, Exergy destruction and exhaust exergy were decreased by 34.97% and 14.03% respectively in comparison to diesel at highest load. Moreover, exergetic efficiency was enhanced by 18.9% than diesel at maximum load condition.

Municipal solid waste fired combined cycle plant: Techno-economic performance optimization using response surface methodology

This paper aims to design, analyze, and find the optimized performance of a novel municipal solid waste fired combined cycle power plant, to cater the utility electrical needs of an urban municipality. Performance of the plant is evaluated through energy, exergy, economy and environmental analyses. Response surface methodology is used as optimization tool for finding the optimal performance of the plant. Air compressor outlet pressure, air turbine inlet temperature, hot end temperature difference of the dual combustor and heat recovery unit, organic vapor turbine inlet temperature, and organic vapor turbine inlet pressure are considered as input parameters for finding out the optimal values of the response parameters such as exergy efficiency and levelized unit cost of electricity. This particular regression model offers extremely accurate results for the response parameters. The optimal values of exergy efficiency and cost of electricity are found to be about 39% and 0.085 $/kWh (5.3 INR/kWh), respectively at the air compressor outlet pressure of 4 bar, air turbine inlet temperature of 1100 °C, hot end temperature difference of 70 °C, and organic vapor turbine inlet temperature and pressure of 201.8 °C and 5 bar, respectively. At this optimal operating point, the plant can deliver 1810 kW electricity with an environmental damage cost savings of 270 $/year compared to the environmental damage cost associated with the conventional land-filling of municipal solid waste. Composite desirability for this model is found to be 1, indicating the fact that the model predicts the best suitable results for the proposed plant’s performance optimization.