International Journal of Exergy (60 papers in press)
Thermodynamics analysis of biomass fired brick drying process
by Aziz Dogru, Emre Camcioglu, Onder Ozgener, Leyla Ozgener
Abstract: For drying the bricks used in the construction sector in Turkey is estimated that the need to power of 460MW. Moreover, the estimated energy consumption and produced brick are 2,680,400MWh/ year and 5 million ton per year, respectively. Due to increasing global warming and climate change, the amount of energy consumed per year for drying decreases. As the outdoor temperature increases, the amount of energy supplied for drying the brick will be reduced. This study was carried out because of this high energy consumption during drying process in brick production sector. According to the case study, energy and exergy analyses of a brick factory with an annual production capacity of 150,000 tons in Manisa were conducted using real operating data. The drying system was analyzed according to ambient temperature (0-20
Keywords: thermodynamics; exergy.
An Exergy Analysis of a Concentric Tube Heat Exchanger using hBN-Water Nanofluids
by NESE BUDAK ZIYADANOGULLARI, Suleyman PERCIN
Abstract: This study investigated the effects of using nanofluids prepared with hexagonal boron nitride (hBN) nanoparticles on the thermal performance and pressure drop of a concentric tube heat exchanger. Experiments were carried out with water-hBN nanofluids for stable, dispersed, 0.01%, 0.1% and 1% volume concentrations, at different flow rates and Reynolds numbers under parallel- and counter-flow conditions. When the experimental results were examined, the exergy loss was higher in the parallel-flow heat exchanger compared to the counter-flow heat exchanger. The highest Exergy loss value was obtained for distilled water at the highest Reynolds number (Re = 7532) for parallel flow operation at 152 W. The exergy loss of water at the highest Reynolds number (Re = 7532) for parallel flow operation increased by 14.7%, 23.8% and 48.6% for hBN-water concentrations of 0.01%, 0.1% and 1% respectively. Exergy loss of water at the highest Reynold number (Re =7532) for counter flow operation increased by 9.23%, 15.3% and 27.1% for hBN-water concentrations of 0.01%, 0.1% and 1% respectively. When evaluating the exergy analysis of the system, exergy losses due to pressure drops were negligible for both flows (parallel and counter).
Keywords: hexagonal boron nitride–water nanofluid; concentric tube heat exchanger; exergy efficiency; exergy loss; pump power.
Energy, exergy, and exergo-economic analyses of a novel three-generation system to produce power, heat, and distilled water
by Malihe Pashapour, Samad Jafarmadar, Shahram Khalilarya
Abstract: In this study, energy, exergy, and exergo-economic analyses were conducted for a new system producing power, heat, and distilled water. First, the waste heat of a gas turbine was recovered by a heat recovery steam generator, and then by an organic Rankine cycle. Simultaneously, a geothermal energy resource was utilized for re-heating the organic fluid to increase the power and efficiency of the ORC. Moreover, this system encompasses a reverse osmosis desalination unit to produce freshwater. Feed-water is heated in the condenser before it enters into the desalination unit; hence, specific power consumption of the high-pressure pump reduces by 43.52%. Exergy efficiency of the system was estimated to be 53.86%, where was 5% higher than basic mode (i.e., with no desalination unit and re-heating). The exergo-economic factor was 12.14%, suggesting that exergy destruction accounts for a high proportion of costs.
Keywords: Energy; Exergy; Exergo-economic; Gas turbine; Organic Rankine cycle; Heat recovery; Re-heating; Geothermal energy; RO desalination.
ENERGY AND EXERGY ANALYSES OF EXPERIMENTAL COMPRESSED AIR VEHICLE PROTOTYPE WITH HEATING ELEMENT
by Reza Alizade Evrin, Ibrahim Dincer
Abstract: In this study, a new automobile powering system comprising of compressed air as a source of energy and as a non-polluting fuel is developed and tested. A working prototype for the pneumatic vehicle is developed at the Ontario Tech University, Oshawa and its performance is investigated. The compresssed air vehicle consists of a novel powering option integrated with a heating element prototype. The study introduces for the first time a compressed air vehicle prototype with 4 air mototrs powering the wheels. In addition, the compressed air exiting the motors is recovered for a second exapnsion to provide electrical power that heats the air before being recovered. The ACE dynamometer is used for investigating the performance of the developed prototype. The energy efficiency for the prototype is found to be 59.5%. Also, the exergy efficiency is 51.0%. The prototype driving range is calculated to be 128 km with 300 liters of air at a pressure of 350 bar. The maximum shaft work generated is measured as 20.84 kW.
Keywords: Compressed air vehicle; prototype; energy; exergy; efficiency;.
Exergetic Evaluation and Optimization of Primary Methane Steam Reformer (PMSR)
by Anthony Hamzah, Raden Cik Awang, Sri Haryati, Muhammad Djoni Bustan
Abstract: It is widely accepted that exergy diagnosis on reactor often overlooks the intrinsic reaction and physico-chemical factors in the reactor itself. In this work, these factors are included to analyze their influence on the exergetic performances of the primary steam reformer (PMSR). Thermal and steam to carbon (S/C) ratio sensitivity assessment was performed to obtain the optimal operating conditions of the reactor. Aside of the conventional exergetic analysis, physical-chemical exergy destruction ratio was also introduced to determine the most dominant irreversibility in the system. Results of numerical simulation showed that higher temperature increases hydrogen production and at the same S/C ratio, decreases chemically-driven exergy destruction. The exception applied on very low S/C (around 2) and very high temperature (880-900 oC), where significant physico-thermally-driven exergy destruction was observed. On the other hand, excessive steam lead to more exergy losses, while the exergy destruction was kept at minimal and more chemically-driven.
Keywords: exergy analysis; hydrogen production; steam reforming; physical-chemical exergy destruction ratio.
EXERGOECONOMIC AND EXERGOENVIRONMENTAL ASSESSMENT OF A PV/T ASSISTED WASTEWATER SOURCE HEAT PUMP SYSTEM FOR A SUSTAINABLE FUTURE
by Mustafa Araz, Arif Hepbasli, Huseyin Gunerhan
Abstract: In this paper, the exergetic, exergoeconomical and exergoenvironmental performances of a photovoltaic/thermal (PV/T) assisted wastewater source heat pump (WWSHP) system were investigated. In the first part of the study, the data gathered from the experiment conducted in the heating mode were used for the exergetic analysis while some performance indicators, such as exergy destruction, exergy efficiency, relative irreversibility and improvement potential of each component, were obtained. After that, economic and environmental life cycle analyses (LCA) were conducted to get the cost and environmental impact data related to every component of the system. Finally, the results of exergy analysis were combined with those of economic and environmental analyses by using exergoeconomic and exergoenvironmental methods. The highest relative irreversibility among all the components occurred in the PV/T unit, followed by the compressor. The functional exergy efficiencies of the WWSHP and whole system were found to be 0.10 and 0.15, respectively. The exergoeconomic factors of the condenser and wastewater heat exchanger (WWHE) were determined to be considerably high among all the components, which indicated that the main driver of the cost associated with them was related to investment costs. On the other hand, the highest exergy loss per unit price was due to the PV/T system. Exergoeconomic factors for each equipment and the entire system tended to decrease with increasing yearly working period and decreasing interest rate. The same trend was also observed in the specific cost of exergetic product. Exergy destruction related environmental impacts was found to be the major element in almost all of the components and therefore its reduction should be the main focus on exergoenvironmental performance improvements.
Keywords: waste heat; wastewater source heat pump; PV/T; exergoeconomic analysis; exergoenvironmental analysis.
Exergy analysis and exergoeconomic assessment of trigeneration system: a case study
by Ana Livia Leite, Dos Santos , Alvaro Ochoa, Paula Michima
Abstract: An energetic and exergetic analysis based on the first and second thermodynamic Laws, and an exergoeconomic assessment by the SPECO method was applied to a trigeneration system. Two LiBr/H2O absorption chillers and a diesel combustion engine integrate the trigeneration system. The system was proposed to meet the energy demands of a resort in Piau
Keywords: Trigeneration; absorption chiller; diesel engine; energy and exergy efficiency; exergetic cost.
Exergetic design and optimization of LNG cold energy utilization system for dual-fuel main engine of a container ship
by Yao Shouguang, Zhang Zijing, Huang Haiqi, Feng Guozeng, Xu Jinjin
Abstract: In this paper, a 9200TEU container LNG fuel-powered ship is used as a prototype ship, and combined with the cooling load requirements of on-board cold storage, desalination and air conditioning, a LNG cold energy cascade comprehensive utilization system scheme is proposed. On the basis of system simulation analysis, the initial plan is optimized in terms of system process arrangement and power cycle working medium selection, and two optimized design system plans are determined. Based on the genetic algorithm, the global parameter optimization of the determined scheme is further carried out, and the annual net income and the initial investment cost of the two optimization design system schemes are analyzed. The results showed that the optimized exergy efficiency of the LNG cold energy full power utilization system proposed in this paper reaches 54.69%, which has the best cold energy utilization efficiency; and the optimized LNG cold energy cascade comprehensive utilization system scheme has the optimized exergy efficiency as 50.13%, but it has the best economic benefits.
Keywords: LNG vaporization cold energy; cascade utilization; container ship; exergy analysis.
Performance assessment of a solar tower assisted combined cycle power plant using supercritical carbon dioxide as a heat transfer fluid
by MUHAMMAD KHAN, MUHAMMAD ABID, M.I. YAN, TAHIR RATLAMWALA, ISHRAT MUBEEN
Abstract: The aim of the present research is to investigate the detailed exergo-environmental analysis of solar-assisted power and hydrogen production system in addition to the energetic and exergetic analysis. The proposed system consists of five sub-systems (heliostat field, solar tower, gas cycle, steam cycle and an electrolyzer). Mathematical model is developed using engineering equation solver (EES) to investigate the integrated system according to the thermodynamic point of view and parametric study is conducted to access the impact of key parameters on the overall performance of the integrated system. The results reveal that thermal efficiency of the receiver is noticed to be 72%, whereas, 42% is observed for the power cycle. The integrated first and second law efficiencies of power plant are 20.93% and 22.51%, accordingly. Exergo-environmental impact index decreases to 33.66% by increasing direct normal irradiation which is considered to be a favorable indicator for the environment, while exergo-environmental impact improvement and exergetic sustainability index increases by 55% and 33.6%, respectively. The net power output and rate of hydrogen production are found to be maximum at a pressure ratio of 10 and a gradual reduction is observed at elevated pressure ratios. Single objective optimization of the system reveals that the optimized overall efficiency of the system is 23.42%.
Keywords: s-CO2; Exergo-environmental; Sustainability; Heliostat; hydrogen;.
A constructal view of prefractal dendritic flow networks using an exergy analysis
by Antonio F. Miguel
Abstract: Evidence supports the interpretation that natural dendritic networks are described by fractal theory. It is recognized that the fractal description alone is not a complete description of nature of space filling. This study addresses the fundamental question of what the size of dendritic flow networks should be, in order to perform with the least irreversibilities, in addition to what fractal features-based pattern should have. Optimal shapes of symmetric and asymmetric networks for viscous flow and diffusion with junction loss effects are analyzed based on exergy minimization rate. Global size constraints included in the analysis are the volume and surface area. The optimal sizes of the flow networks are obtained, and prefractal dimensions that characterize these networks are computed. It is shown that the prefractal dimensions depend on both flow properties and space constraints. The physics link between prefractal regularity and optimal flow performance is clear presented.
Keywords: exergy analysis; prefractal dimension; constructal law; dendritic flow networks; scale factor; homothety ratio.
THERMODYNAMIC ANALYSIS OF A BINARY GEOTHERMAL POWER PLANT
by Zekeriya Ozcan, Ozgur Ekici
Abstract: In the frame of this study, performance of a geothermal power plant located in Germencik/Turkey is evaluated both from thermodynamic and economic perspectives. First and second law efficiencies of the plant are calculated to be 4.82% and 25.7% respectively. On plant level, it is found out that brine re-injection process is primarily responsible of exergy losses (21.9%). At organic Rankine cycles of examined plant, major sources of exergy losses are turbines and pumps (25.44%), heat exchangers (21.78%) and condensers (10.8%). In order to achieve more realistic conditions with modelling environment, thermal losses from heat exchangers are calculated and found to be around 444 kW. This amount corresponds to 0.27% of total heat transfer value during heat exchanging processes. After the thermodynamic analysis, case studies are conducted to evaluate the applicability of water-cooled condensers instead of the existing air-cooled condenser systems. Results indicate that it is possible to reduce the initial capital investment around 20% with such an application by using factorial cost estimation techniques. It is also demonstrated that it might be possible to further increase the exergetic efficiency of this hypothetical water-cooled condensers by increasing the rejection temperature and subsequently decrease the initial capital investment by 1.4%. An additional benefit of such an application would be a decline of the heat release to the environment, which is pointed out as a serious environmental issue in several studies for agricultural areas of Germencik.
Keywords: Binary Geothermal Power Plant; Plant Analysis; Exergy Flows; Heat Transfer; Factorial Cost Estimation Method.
Overall efficiency analysis of an innovative load-following nuclear power plant thermal energy storage coupled cycle
by Mohamed Ali, Ahmed K. Alkaabi, Saeed A. Alameri, Yacine Addad
Abstract: An innovative-coupled nuclear power plant (NPP) system is investigated in the present study. The system, proposed herein, is intended to have a better ability to follow the grid demand, hence, overcoming the current variable load limitations of existing NPPs systems. In the present design, the concept of integrating a thermal energy storage (TES) as an active component in the NPP system is evaluated. In this proposed design layout, the phase change material (PCM)-based TES is planned to have a dual role in acting as; a simple heat exchanger between the primary and secondary loops when the grid power demand exactly matches the one generated by the high temperature reactor, while it is mostly acting as storage or energy supplement source to account for the daily fluctuating energy demand. To assess the feasibility of the TES integration for different thermodynamic cycles, the efficiency of the overall coupled system is examined by computing the energy and exergy balances at the plant main components (turbines, compressors, pumps condensers, and heat exchangers) for two designs of the power generation process: Rankine and supercritical carbon dioxide (SCO2) Brayton cycles. The obtained results confirm that, as expected, around 50% of the exergy is lost during plant operation in the reactor core. Most importantly, it also reveals that the losses in the TES are actually in the same order as the ones in the remaining components (i.e. turbines, condensers, and pumps) which are much smaller (<10%) than the reactor core losses. SCO2 Brayton cycle with regenerator is found more efficient than Rankine cycle and overall efficiency can reach 50% using high effectiveness and high efficient components.
Keywords: Exergy; Energy; Thermal Energy Storage; Nuclear Power Plant.
Comprehensive investigation of using n-butanol/gasoline blends in a port-fuel injection spark-ignition engine
by Murat Kadir Yesilyurt, Hayri Yaman
Abstract: In this study, butanol was examined mixing with gasoline at different ratios (Bu0, Bu5, Bu10, Bu20, and Bu30) in a single-cylinder, four-stroke, PFI SI engine for monitoring engine characteristics at various loads to perform thermodynamic analyses. It can be reported that the maximum efficiencies were calculated at the highest load for tested fuels. Accordingly, the maximum thermal efficiencies were computed to be between 35.85-40.60% meanwhile corresponding exergetic efficiency results were found to be between 33.33-37.85% for tested fuel samples. In addition, the maximum SIN values were achieved between 1.500-1.609.
Keywords: Butanol; Economic; Emissions; Exergy; Higher alcohol; Performance; Sustainability.
DEVELOPMENT OF EMPIRICAL MODELS FOR ESTIMATION DIFFUSE SOLAR RADIATION EXERGY IN TURKEY
by Nurullah Arslanoglu
Abstract: In this study, exergy of diffuse solar radiation is estimated using empirical models. Long-term meteorological data (1983-2005) consisting of monthly mean diffuse solar radiation for 7 selected stations were available from from NASA Langley Research Center. Empirical models were developed by correlating diffuse solar radiation exergy in terms of relative sunshine period. Three different regression models (Linear, quadratic, cubic) are presented to predict diffuse solar radiation exergy. The empirical models performance is determined with the most frequently utilized statistical methods. The performance ranking of the models is carried out by using the global performance indicator method (GPI). The maximum diffuse solar radiation exergy value (53 MJ/m2year) belongs to Adana for selected provinces . Quadratic type is the best predictive method for Bursa, Ankara, Adana, Gaziantep provinces located in Turkey, and Igdir and Trabzon regions are excellently predicted by Cubic type. Linear type is then used for the best prediction of the Izmir city of Turkey. Consequently, The empirical models obtained in this study can successfully predict diffuse solar radiation exergy. Therefore, it is easy to apply for other places with similar climatic conditions all over the world. In this way, it will be possible to design solar systems correctly by scientists and industrialists.
Keywords: Diffuse solar radiation; exergy; empirical models; clearness index; sunshine period.
Exergy Analysis of a HDH-VCR Cycle for Water and Air Conditioning
by Tangellapalli Srinivas
Abstract: The fresh water and space conditioning are the human needs for the comfort living. Humidification dehumidification vapour compression refrigeration (HDH-VCR) cycle for combined portable water and air conditioning (A/C) has been studied with exergy approach. HDH-VCR cycle has been studied with thermodynamic exergy approach for efficient operation of the cycle. The focused options in this work are dehumidification with normal water (HDH), dehumidification with chilled water (HDH-VCR 1) and dehumidification with VCR (HDH-VCR 2). The exergy losses of the components are compared for these three units. As per the exergy analysis, HDH-VCR 2 has been highlighted with higher exergy efficiency compared to the others.
Keywords: air conditioning; HDH-VCR; exergy; psychrometry; second law of thermodynamics.
Maximization of Energy and Exergy Efficiencies for a Sustainable Thermoelectric Cooling System by applying Genetic Algorithm
by JITENDRA MOHAN GIRI, Pawan Kumar Singh Nain
Abstract: The efficient thermal management of thermoelectric cooler (TEC) as a sustainable cooling technology is important. The energy loss, electrical power requirement, and irreversibility of the TEC system need to be minimized. Hence, the loss of energy and energy quality (exergy) are two significant points of concern. Thus, energy and exergy efficiency can be used as the key indicators to optimize TECs performance. Through this work, authors separately optimized TEC energy efficiency (?I) and exergy efficiency (?II) considering thermoelectric elements geometry and electric current by using the genetic algorithm (GA). The effects of electrical contact resistance and thermal resistance are considered in the mathematical model of this work. Unlike previously reported works, the authors have used junction temperatures different from surface temperatures at the respective cold and hot sides of TEC. This study reveals that maximum energy and exergy efficiencies are obtainable at the same values of electric current, length, and cross-sectional area of thermoelectric elements. It is significant as these identical optimum design variables assert maximum ?I and ?II. At cold surface temperature (Tc) of 20?, the maximum energy efficiency of 4.11 and the maximum exergy efficiency of 0.0715 are obtained. Exergy efficiency can be used as the basis to choose TEC since it assures better energy quality and connects with sustainable development. The genetic algorithm optimization result is validated through ANSYS
Keywords: thermoelectric cooler; energy efficiency; exergy efficiency; genetic algorithm; optimization; finite-element simulation.
EXERGETIC PERFORMANCE ANALYSIS OF HIGH PRESSURE AIR SYSTEMS ON SHIPS
by Asim Sinan KARAKURT, Ibrahim OZSARI, Veysi BASHAN
Abstract: Energy consumption, energy/exergy efficiency, and being more ecologically issues are among the most scientifically researched topics today. These three important aspects also attract attention to ships that have many high energy consumption systems. One of the highly energy consumed system in ships is high pressure start air systems with relatively have high capacity consuming compressors. In this study, energy and exergy analyses are made to optimize the use of a ship high pressure air system according to performance outputs such as power consumption, exergy destruction, and ecological coefficient of performance (ECOP). Exergy destructions caused by the power consumed by the main compressors and the improper use of the air stored at high pressures are calculated. And also, the ECOP criterion was used to compare 3 different models according to the first and second laws of Thermodynamics. The general results obtained from the analysis are as follows. The power consumption of models are 1530, 1283, and 1276 kW (38%, 31%, and 31%); the exergy destruction values are nearly 250, 471, and 450 kW (21%, 40%, and 39%); ECOP values are 6.15, 2.72, and 2.84 (53%, 23%, and 24%), respectively. Moreover, the effects of different sea water temperature, ambient temperature, and isentropic efficiencies of compressors on the power consumption, exergy destruction, and ECOP values are presented.
Keywords: Air storage; ECOP; Exergy analysis; Ship compressed air system.
Why brain functions may deteriorate with aging: A thermodynamic evaluation
by Cennet Yildiz, Mustafa Özilgen
Abstract: Loss of the brain functions with ageing is related to decrease of its oxygen utilization in the literature. Although we have much more limited data obtained with the brain, when compared with the muscles, at the present level of our knowledge, we may say that the loss of ageing damage to the brain functions may be caused by the brain work performance caused by deterioration of the energy generation capacity of the mitochondria and work performance ability of the warned out ion pumps upon ageing. Thermodynamic assessment points the muscle work performance as the place to look at. Nature has equipped the muscle cells with healing capability, in terms of fixing the damage to the mitochondria or multiplying their numbers. If the same natural healing technologies may be implemented to the brain cells, ageing damage to the brain cells may be at least partly recovered.
Keywords: Ageing in the brain; mitochondrial energy; entropy generation; Gibbs free energy utilization; ion pumps; work performance efficiency.
Thermodynamic analysis of a new multi-generation plant based on the waste heat from the cement industry for improved energy management
by Mehmet Altinkaynak, Murat Ozturk, Ali Kemal Yakut
Abstract: In this paper, the hydrogen production and liquefaction option by utilizing the waste heat from the raw material preheating sub-unit of cement facility are investigated thermodynamically. The gas turbine plant and Rankine cycle are chosen to generate power and, also in order to generate hydrogen, a part of the produced power is used for PEM electrolysis. In these conditions, the hydrogen generation from analyzed integrated plant is computed as 0.028 kg/s. The energetic and exergetic effectiveness of Brayton and Rankine cycles integrated with the waste heat recovery process in the cement facility are computed as 58.24% and 42.17%, respectively, for the chosen working condition. It is also asserted that increasing the input temperature of gas turbine depended on the cyclone gas temperature increases the exergy efficiency of investigated system.
Keywords: Waste heat; cement facility; energy; exergy; efficiency; hydrogen production and liquefaction.
Development of exergy maps as a tool for assessing solar energy potential in Iraq
by Abdul Hadi Khalifa, Fadhil Kareem
Abstract: This work aims to develop three sets of maps for solar intensity and the exergy efficiency of the solar and PV systems for Iraqi cities. The first is for the global solar radiation that falls on a horizontal surface; the second is solar exergy efficiency. In contrast, the third set is for the exergy efficiency of a 20 kW hybrid-connected PV system installed at the Middle Technical University's presidency, Iraq- Baghdad. The development of the solar exergy and the exergy efficiency map sets are based Petela model; the model equations were programmed depending on the Iraqi weather data and solved using the Engineering Equation Solver (EES) software. Meteonorm package was used to collect the weather data for 48 sites inside and outside Iraq to cover this country's entire area. From the weather data and the theoretical model, it is found that: The average daily global solar intensity in January is varied from 275 to 375 W/m2, while it is varied from 530 to 710 W/m2 in July. The western regions of Iraq, which are often desert lands, suffer from the low intensity of solar radiation due to the dusty weather that characterizes this region. The solar exergy is 70 to 138 W/ m2 in January, and this range in July is 260 to 330 W/ m2. The higher average exergy efficiency ranges from 15 to 19.3 % in the winter, while the lower is 7.5 to 13.8% in the summer. Finally, the site at lower latitudes has more global solar radiation. On the other hand, higher latitudes have more exergy efficiency than those for the sites at lower latitudes.
Keywords: Solar radiation; Solar exergy; PV exergy efficiency; Exergy maps.
EXERGY ANALYSIS OF A NATURAL GAS COMBINED CYCLE POWER PLANT: A CASE STUDY
by Gabriel Marques Pinto, Christian Jeremi Rodriguez Coronado, Tulio Augusto Zucareli De Souza, Eudes Muller D’Oliveira Santos
Abstract: This work performs energetic and exergetic analysis of a CCPP, by using a full-scope simulator, which faithfully reproduces the operation of a real Brazilian CCPP. The analyses are performed for design and off-design conditions. The results present, for the design condition, a power generated of 820.6 MW, a first law efficiency of 51.54% and a second law efficiency of 49.32%. The equipment responsible for the main irreversibilities were: the combustion chamber (70.24%), gas turbine (10.75%) and heat recovery steam generator (7.37%). In the off-design scenario, the first and second law efficiencies were decreased by 2.65% and 2.54%, respectively.
Keywords: Combined cycle; Exergy; Efficiency; Exergy destruction rate.
Exergoeconomic analysis of a solar CCHP with partially porous material filled collector
by Navid Tonekaboni, Hesamoddin Salarian, Majid Eshagh Nimvari, Jahanfar Khaleginia
Abstract: In this research, a parabolic solar collector is analyzed in solar combined cooling, heating and power cycle by adding porous materials in five stages are investigated. This research focus on use of flat plate collectors in solar CCHP. Following this study, the exergoeconomic analysis of the system was performed for financial analysis and calculation of the payback period. The average enhancement of collectors efficiency and solar CCHP cycle using porous media is 16% and 11% respectively. By using flat solar collector fully filled porous media, the cost of the cogeneration cycle reduces up to 38% in comparison with other CCHP.
Keywords: Solar collector; exergoeconomic; porous materials; partially porous; payback period.
Investigation of effects of several design parameters on exergo-sustainability metrics for two-spool turbojet engine at different flight conditions
by Hakan AYGUN
Abstract: In this study, performance and exergy analyses of twin-spool turbojet engine (TS-TJE) were carried out at different flight conditions (sea level-zero Mach (phase-I) and altitude of 11000 m-0.8 Mach (phase-II)). According to performance analysis of TS-TJE, the rising of turbine inlet temperature (TIT) leads to increase thrust and specific fuel consumption while the increase in low pressure compressor pressure ratio (LPC PR) results in decreasing of these parameters. Moreover, overall efficiency of turbojet becomes higher due to rising LPC PR. However, the higher is the TIT, the overall efficiency the lower. On the other hand, amongst the components, exergy efficiency of the combustor has the lowest value. Considering variation of LPC PR from 2.4 to 3.4 as well as constant TIT at 1240 K, exergy efficiency of the combustor varies from 70.87 % to 73.07 % at phase-I and from 75.3 % to 76.7 % at phase-II. On the other hand, exergetic sustainability index of TSTJE experiences an increase from 0.265 to 0.299 at phase-I and from 0.28 to 0.302 at phase-II. It is thought that the current analysis may seem to yield new insight so as to enhance energetic and exergetic performance of turbojet engine by considering optimum design parameters.
Keywords: Two-spool turbojet; exergy; turbojet performance; exergo-environmental; exergo-sustainability.
Energy and exergy analyses of a cryogenic reverse Brayton cycle with waste heat recovery
by Shanju Yang, Qi Wang, Jie Hao, Bao Fu, Lina Wang, Yu Hou
Abstract: In a typical reverse Brayton cycle (RBC), a great amount of compression heat is just wasted, for which there exit two different temperature levels. The basic organic Rankine cycle (ORC) and the regenerative ORC with improvement were then applied to recover waste heat. Considering that the waste gas after ORC was reused, the total exergy efficiency was defined to evaluate different cycles. A simulation method was conducted to predict cycle performances and the coupling between RBC and ORC was clarified. The feasibility of replacing the after cooler with the evaporator was analyzed. Compared with the typical RBC, a relative improvement of 18.2% was achieved for COP in the combined system, and the cooling exergy efficiency was increased by 16.8%. The correspondence of the total exergy efficiency and the COP of whole system exited in different cycle layouts. Proper organization of the RBC with ORC could promote the energy efficiency.
Keywords: cooling; expander; energy utilization; exergy efficiency; organic Rankine cycle; reverse Brayton cycle;.
Multi-Objective Optimal Design of Solar-Gas Turbine Driven Polygeneration System based on 4E Analysis
by Khodadoost Rostami Zadeh, Seyed Ali Agha Mirjalily, Seyed Amir Abbas Oloomi, Gholamreza Salehi, Mohammad Hasan Khoshgoftar Manesh
Abstract: In this paper, a novel polygeneration system for an office building based on an integrated flat plate solar collector and gas turbine to produce simultaneous power, freshwater, cooling, and heating has been introduced. The proposed system includes a heat recovery steam generator, a Multi-Effect Desalination (MED), Reverse Osmose (RO), a steam turbine, a solar plate collector, and an absorption chiller. The transient simulation and analysis for the solar system have been done in TRNSYS software. Also, a computer code was built to compute Energy, Exergy, Exergoeconomic, and Exergoenvironmental (4E) analysis dynamically. Furthermore, multi-objective optimization process using Genetic Algorithm (MOGA) and Water Cycle approach (MOWCA) to maximize the exergy efficiency, minimize the total cost of exergy, and minimize the total environmental impacts of exergy has been conducted simultaneously. Genetic Programing has been employed to generate correlations for objective function estimation with high accuracy for reducing computation time. Results show the overall exergetic efficiency, which is improved by 12.65 % and 12.67% using MOGA and MOWCA. Also, the overall exergoeconomic cost of power and water is reduced by 27.66%, 32.97%, 27.83%, and 32.96% using MOGA and MOWCA, respectively.
Keywords: Polygeneration; Exergetic; Exergoeconomic; Exergoenvironmental; Water Cycle Algorithm.
Thermodynamic and exergo-environmental assessment of the organic Rankine cycle and S-CO2 Brayton cycle for heat recovery in a gas turbine
by Mehmet Altinkaynak
Abstract: The general purpose of this study is to make feasible the recovery of waste heat in gas turbines. An integrated power generation system consisting of a gas turbine-powered by supercritical carbon dioxide closed Brayton cycle and organic Rankine cycle working with n-pentane is designed. The actual operating conditions of combined system are examined thermodynamically to establish the limiting states. Thermodynamic examination is performed for all elements of integrated system. The total net power generation of overall system is found to be 2789 kW. The energetic and exergetic efficiencies of combined plant are found to be 44.71% and 42.05%, respectively. As a result of thermodynamic analyses, the irreversibility amount of system is also calculated and found to be 13810 kW. System equipment with the highest exergy destruction is found in the heat exchangers with 56%. The temperature and pressure of turbine inlet conditions have considerable impact on the whole system performance.
Keywords: S-CO2 power plant; energy; exergy; efficiency; waste heat.
Investigation of Maximum Performance Characteristics of Seven-Process Cycle Engine
by GÜVEN GONCA, Bahri Sahin
Abstract: Emissions released from internal combustion engines (ICEs) should be minimized due to environmental harmful effects and engine performance should be maximized owing to economical concerns. In the recent years, it has been indicated that the Miller cycle applications into the ICEs could provide a remarkable abatement in emissions. Combustion temperatures during heat addition to engine cylinder can be held constant by applying Takemura cycle. This study investigates the maximum performance characteristics such as power, power density and thermal efficiency for the combinationof the Miller cycle and the Takemura cycle in seven processes depending on engine speed and ratios of compression, equivalence, exhaust temperature, Takemura cycle, cut-off, cycle pressure, cycle temperature. An Artificial Neural Network (ANN) modeling approach is also investigated as an alternative and simpler method. The results acquired could be utilized by engine modelers in order to determine the performance characteristics.
Keywords: Maximum power; Maximum power density; Takemura cycle; Dual Miller cycle; Optimization; Performance analysis.
Irreversibility analysis of various components in a supercritical thermal power plant
by Naveen Kumar Gavirineni, Edison Gundabattini
Abstract: Supercritical coal-based 660 MW plant is analyzed to estimate the irreversibility at different atmospheric conditions. The overall outcomes indicated that the boiler has the highest exergy destruction in the system followed by the condenser. The exergy destruction increases with the increase in the atmospheric temperature and decreases with the decrease in the atmospheric temperature. The exergy destruction of the boiler is 1198 MW followed by the exergy destruction of turbine 50.7MW at 35oC, in Indian climate condition. At 20oC atmospheric temperature exergy destruction of boiler decreases at the rate of 2% while at 40oC it increases at the rate of 0.67%. Similarly, at 20oC atmospheric temperature exergy destruction of turbine decreases at the rate of 12.6% while at 40oC the value increases at the rate of 7.9%.
Keywords: Plant load factor; Auxiliary power; Energy; Exergy; Specific coal consumption.
Entropy Generation and Hybrid Fluid-Solid-Fluid Heat Transfer in 3D Multi Floors Enclosure
by Mohammad Mohsen Peiravi, Javad Alinejad
Abstract: The innovation of this paper is fins shape and arrangement effects on entropy generation and hybrid fluid-solid-fluid heat transfer in 3D multi floors enclosure with heat flux boundary condition by lattice Boltzmann method (LBM). The results signified that maximum and minimum of mean nondimensional temperature on the wall (z=0)were in enclosure with 22 rectangular fins in hot and cold zones that was equal to 0.503 (%15.1) and 5 horizontal ellipse fins in hot zone that was equal to0.445 (%1.8), respectively.
Keywords: Different fins arrangement; Entropy generation; Fluid-solid-fluid interface; Heat flux; Hybrid thermal field; Lattice Boltzmann model.
Thermodynamic analysis of novel absorption type pressure reducing station
by Rahul Patil, Sunil Bhagwat
Abstract: Steam is an important utility in the process industry such as oil refinery, paper mill etc. In industries, boiler generates utility steam at high pressure and distribute it through different pressure headers as per the pressure requirements of the process. The distribution of steam from high pressure header to low pressure header is done by pressure reducing station. It was found that in the depressurization process a significant amount of exergy destruction happens up to 42 %. The present work proposes the novel absorption type pressure reducing station which addresses the exergy destruction issue. In this work, the mathematical model and simulation of absorption type pressure reducing station (APRS) and absorption-ejector type pressure reducing (AEPRS) station has been done in Scilab (open source software) using highly accurate thermodynamic correlations available in the literature. Sensitivity analysis has been done for various operating parameters. The performance of both APRS and AEPRS is compared with conventional PRS and steam ejector system and it was found that APRS and AEPRS have low exergy destruction up to 9.5 %.
Keywords: Absorption; Pressure reducing station; LiBr-water; Exergy destruction.
ENERGY AND EXERGY ANALYSES OF HYDROGEN ADDITION IN A DIESEL ENGINE
by Kubilay BAYRAMOGLU, Semih Yilmaz, Mustafa Nuran
Abstract: In the study, the effect of hydrogen addition with air taken from the intake manifold at different rates on performance and emissions in a single-cylinder, four-stroke diesel engine has been numerically investigated. The first and second law analyses of thermodynamics are performed for each hydrogen addition condition. Numerical analysis has been performed with Ansys-Forte, energy and exergy calculations have been carried out according to the analysis results. The results of the analysis show that with the addition of hydrogen, CO emissions decrease while the engine performance and NOx emissions increase.
Keywords: Diesel engine; Chemical exergy; Combustion; Hydrogen addition.
Effect of Pilot injection and Injection pressure on Combustion, Performance, Exergy and Exhaust Emission of Bioethanol-Diesel Fueled Common-rail Direct Injection Engine
by Abhishek Paul, Subata Bhowmik, Nirupam Pal, Rajsekhar Panua
Abstract: This investigation highlights the preeminence of Bioethanol-Diesel blended fuels on the combustion, performance, exhaust emission and exergy paradigms of a common-rail direct injection engine under varying pilot fuel mass share, fuel injection pressure and load conditions. The investigation begins with a Fourier-transform infrared spectroscopy followed by a stability estimation of Bioethanol on Bharat stage-IV Diesel. The engine is operated with 0%, 10% and 20% pilot fuel mass for 5% and 10% (by volume) Bioethanol blended Diesel fuel at 300 bar and 500 bar fuel injection pressure and 50%, 75% and 100% of full load conditions. The pilot fuel with higher fuel injection pressure and Bioethanol addition advances the position of combustion parameters of the engine. The pilot fuel and Bioethanol addition also improves the brake thermal efficiency, brake specific energy consumption, oxides of nitrogen, unburned hydrocarbon, carbon monoxide and smoke opacity of the engine. This investigation consequently made a substantial approach to deal with the economic and environment contribution by concomitantly addressing to the effective energy utilization, energy extraction and reasonable exhaust emissions under Diesel-Bioethanol strategies.
Keywords: FT-IR spectroscopy; Bioethanol; Pilot fuel strategy; Exergy; Combustion.
An Analysis Approach for Entropy Generation in Bounded Solids Subject to Sudden Heat Flux
by M. Sunar
Abstract: This work addresses the problem of entropy generation rate due to conduction for a one-dimensional bounded solid onto which a sudden heat flux is applied from one of its surfaces and the other surface is insulated. A theoretical procedure is presented using the infinite series to solve for temperature distribution with different forms of the applied heat flux. The considered cases include, but not limited to, constant, ramp and sinusoidal types of heat fluxes. The theoretical temperature results are found to be closely matching with those available in literature for one case and with those obtained by the finite element approach for all the cases. Entropy generation rate due to thermal field is presented in all the 3 cases with the conclusion that an energy balance is attained at some depth below the surface.
Keywords: Bounded Solid; Conduction; Heat Flux; Entropy Generation Rate; Theoretical; Finite Element Method.
Energy Efficient Distillation Column Configuration: An Exergy Analysis
by Laxmi Patil, Vinay Amte
Abstract: The column targeting tools and exergy analysis are used to set energy targets and improve energy efficiency in distillation column. The combination of process options like feed stage location, reflux ratio, feed conditioning, side-reboiler and side-condenser greatly improves thermodynamic efficiency and reduces exergy loss throughout the column. The converged base-case simulation for propane-propylene binary mixture obtained from Aspen Plus was evaluated with both column targeting tools and exergy loss analysis. The study reveals significant decrease in reboiler (~29%) and condenser (~15%) duties, and increase in thermodynamic efficiency by ~33% as compared to base-case design by reduction in total exergy losses.
Keywords: Column targeting; Exergy analysis; Distillation column; Reflux ratio; Side-reboiler; Side-condenser; Thermodynamic efficiency.
3D CFD modelling and exergy loss minimization within a high-pressure vortex tube
by Abbas Aghagoli, Mikhail Sorin
Abstract: In the present study, 3D CFD simulation of vortex tubes at high operating pressure is investigated. The impact of inlet pressure and the cold mass fraction is investigated in terms of the exergy losses within the vortex tube. The results show that the minimum exergy losses occur at cold mass fraction equals 0.5, meanwhile, the exergy efficiency achieves its maximum at cold mass fraction equals 0.9. It is illustrated that friction has a major impact on the entropy generation rate near the wall and at the center of the vortex tube.
Keywords: Entropy generation rate; Vortex tube; Exergy loss; CFD.
Energy and exergy analysis of co-gasification of crude glycerol and animal fat mixtures
by Ana Almeida, Rosa Pilão, Elisa Err@isep.ipp.pt, Carlos Pinho
Abstract: This work presents an energy and exergy analysis of co-gasification tests of crude glycerol and animal fat mixtures, in order to obtain first and second law efficiencies, the last ones representing a novelty in the field of gasification technology. Mixtures with 5 % (w/w) of dry animal fat, 57 % (w/w) of dry treated crude glycerol and 38 % (w/w) of water were studied in a fixed bed down flow gasification reactor at 800
Keywords: animal fat; co-gasification; crude glycerol; energy; exergy.
6E Analysis of a Direct Steam Generation PTC-based Solar Power Plant
by Mohammad Hasan Khoshgoftar Manesh, Mohsen Yazdi, Saeed Kabiri
Abstract: The present study focuses on the energy, exergy, exergoeconomic, exergoenvironmental, Emergoeconomic, and Emergoenvironmental (6E) analyses, besides advanced exergy-based analysis, for a solar thermal power plant with Direct Steam Generation (DSG). The solar filed is is considered and verified based on the DISS test facility. In this regard, computer code has been developed for 6E analysis with high accuracy. The thermodynamic simulation has been verified with Thermoflex software and also the primary reference data with high accuracy. Results show that the overall Emergoeconomic factor of the DSG solar power plant is 85.34%, and its total Emergoenvironmental factor is 85.56%. After the solar field, low-pressure and high-pressure turbines are the preferred priority. Advanced exergy analysis reveals that the avoidable percentage of the Emergoenvironmental rate allocated to exergy destruction of the solar field, low-pressure turbine, and high-pressure turbine is 10%, 42%, and 34%, respectively. These values are equal to 11%, 45%, and 38%, respectively, for the Emergoeconomic rate allocated to exergy degradation. Therefore, it is essential to improve the low and high-pressure turbines economically and environmentally.
Keywords: PTC Solar Power Plant; Exergoeconomic; Exergoenvironmental; Advanced exergy analysis; Emergy.
Effects of various long-chain alcohols as alternative fuel additives on exergy and cost in a spark-ignition engine
by Battal Dogan, Murat Kadir Yesilyurt, Dervis Erol, Hayri Yaman
Abstract: This paper deals with exergy and exergoeconomic analyses of gasoline-hexanol and gasoline-heptanol blends as alternative additives were performed in a spark-ignition engine at a constant speed (1600 rpm). Fuel cost rate, cost per unit of exergy for power, cost rate of total exergy loss, exergonomic factor, and relative cost difference were calculated. The lowest cost of the power acquired from the engine for G100, HEX20, and HP20 at 5 kW was 0.122, 0.656, and 1.042 $/MJ, respectively, and the corresponding fuel cost rates were 1.07, 5.2, and 8.26 $/h, respectively.
Keywords: Spark-ignition engine; Hexanol; Heptanol; Exergy; Exergoeconomic.
Exergy analysis of a diesel hydrotreater and mild hydrocracking unit in a petroleum refinery
by Cagatay Yaylaci, Mahmut R. Bayramoglu
Abstract: The aim of this research work is to analyse the exergy efficiency of the Diesel Hydrotreater and Mild Hydrocracking unit of Turkish Petroleum Refineries Corporation Izmit Refinery (TUPRAS). For this purpose, the process was simulated by using Aspen HYSYS
Keywords: exergy efficiency; exergy destruction; diesel hydrotreater; mild hydrocracking; Aspen HYSYS; feed heater.
AN APPLICATION OF EXERGY ANALYSIS OF THE ENERGY USE IN CAMEROON
by TALLA KONCHOU Franck Armel, ALOYEM KAZÉ Claude Vidal, NGOUATEU WOUAGFACK Paiguy Armand, TCHINDA René
Abstract: In this work, the concept of energy and exergy used applied to Cameroon is analysed. The analysis of the exergetic flux is applied to various sectors (residential, industrial, transport, agricultural and others) in order to bring the various points of exergetic losses and to propose some means to remedy these losses. It is observed that other sectors (hotels and restaurants, administrative buildings, hospitals ...) are less efficient. An analysis of the situation in the whole Cameroon for the year 2010 gives 37.9% and 10.81% for the energetic and exergetic efficiency respectively. The results are compared with those of other countries.
Keywords: Cameroon; Energy analysis; Exergy flow; Exergy efficiency; Fossil Energy.
Exergy analysis of an electric grain drying system with internal circulation of the drying medium of corn
by Guiying Wang, Wenfu Wu, Wen Xu, Yan Xu, Yaqiu Zhang, Daping Fu
Abstract: In recent decades, exergy analysis has become an important tool to assess drying systems and optimize drying processes. This research work uses a corn drying experiment to analyse the exergy performance of a newly developed drying system, where, all exhaust air recirculated is dehumidified by condensation to achieve energy savings and environmental protection. The results show that under the experimental conditions, the exergy efficiency of the drying process was 34.03-64.90%, and the drying rate of corn was stable at 0.3-0.4% when the condensation intensity was 1.1-4.9 g/m3. The improvement potential rate of the drying process was 109-115 kJ/s and 37-52 kJ/s when the drying temperature was 90-100
Keywords: exergy analysis; electric grain drying system; internal circulation of the drying medium; drying characteristics; condensation characteristics.
Multi-objective Optimization of Supercritical CO2 Combined Cycles Based on Energy-Exergy-Economy balanced Analysis
by Chunlei Li, Qitai Eri
Abstract: In this paper, the supercritical CO2 (sCO
Keywords: supercritical CO2; combined cycle; SPECO; Multi-objective-Optimization.
Exergy analysis and optimisation of a two-stage thermoelectric generator with tapered legs
by Mkpamdi Eke, Chika Maduabuchi
Abstract: Numerous previous studies indicate that the performances of thermoelectric generators are enhanced by incorporating legs with variable area geometries. However, there is a dearth of comprehensive optimisation studies on these new thermoelectric generator designs. More so, the few optimisation studies that exist have rather employed unrealistic isothermal boundary conditions in their numerical models. Furthermore, these new leg geometries have not been applied to multi-stage systems. Accordingly, to address these gaps, a numerical optimisation, using ANSYS 2020 R2 software, is performed on a two-stage thermoelectric generator with variable area leg geometries; with optimisation parameters that include: leg geometry (height and area), intensified insolation with external load resistance, i.e., geometrical, thermal and electrical operation of the device. An exergy/irreversibility analysis is also carried out and techniques of minimising thermodynamic losses while allowing for the useful exergy output after solar energy conversion are proposed. Results indicate that, for an optimum leg height, area, concentrated solar radiation intensity and load resistance of 10 mm, 0.7 mm2, 20 suns and 1.3 , respectively. Maximum energy and exergy efficiencies of 7.03% and 7.55% respectively, were obtained for the proposed system. This improves the energy and exergy efficiencies of the standard device by 23.44%.
Keywords: Irreversibility analysis; solar power generation; variable leg geometry; two-stage thermoelectric generators; exergy optimisation; thermodynamic analysis.
Special Issue on: IEEES-12 Exergetic Solutions for Better Environment
AN EXPERIMENTAL STUDY ON GAS-TO-LIQUIDS (GTL) AND BIOGAS DUAL FUEL OPERATION OF A DIESEL ENGINE
by Saket Verma, L.M. Das, S.C. Kaushik
Abstract: In the present configuration, GTL replaces diesel, and biogas is used as gaseous fuel in the Dual Fuel (DF) operations. The effects of this substitution have been evaluated from the perspectives of second-law of thermodynamics. The results are compared with the diesel single-fuel, GTL single-fuel and GTL-biogas DF operations. Also, engine out emissions have been compared to understand the environmental impact of these fuel combinations. The results show that DF operation offers up to 80% pilot liquid fuel replacement by biogas, however, some reductions in energy and exergy efficiencies are observed.
Keywords: Biogas; Diesel; Dual fuel; Exergy; GTL; Irreversibility; Renewable fuels.
Numerical Analysis of a Hybrid Thermal Energy Storage System Using Thermochemical and Phase Change Material for Constant, Low Temperature Applications
by Swaraj Kumar B, James Varghese, Stiben Paul
Abstract: A novel hybrid energy storage method is proposed in this paper to overcome high temperature levels at the start of the reaction in thermochemical energy storage, which causes this technology to be unsuitable for constant temperature applications. This numerical study shows that the hybrid storage system with thermochemical material and phase change material is a promising method in the field of low temperature thermal energy storage. The melting temperature of the PCM and the flow rate of the heat transfer fluid must be chosen carefully to enhance the performance of the system.
Keywords: Hybrid thermal energy storage; Thermochemical Energy storage; Packed bed reactor.
EVALUATION OF THE EFFICIENCY OF THE DRYERS IN THERMOPLASTIC VULCANIZATE EXTRUSION PRODUCTION LINES WITH THE ENERGY AND EXERGY ANALYSIS METHOD
by Aziz Kagan Dogru, Onder Ozgener, Leyla Ozgener
Abstract: In this study, energy and exergy analysis of the drying process in producing a sealing profile with extrusion in Manisa, using real operational data was conducted. The drying system was analysed in regards to changes in ambient temperature (0-30?C) and drying air temperature (75-105?C). The energy efficiency of the system was in the range of 80.79-88.24% and the exergy efficiency was in the range of 15.88-41.94%. As a result of the analysis, it can be concluded that the drying conditions with the highest efficiency values were at 0?C outdoor temperature and 75?C drying air.
Keywords: Energy Efficiency in Industry; Drying; Exergy; Energy; Extrusion.
4-E analysis of an ammonia-water mixture based automobiles air conditioning system assisted by exhaust gas and solar energy
by Santi Sarkar, GOUTAM KHANKARI, Sujit Karmakar
Abstract: The proposed system is modeled in Cycle-Tempo software where R22 and NH3-H2O mixture are used as working fluid of the existing and proposed automobiles AC system, respectively. The proposed system can produce about 2.12 kW of electric power which improves the COP from 2.453 to 2.823 and reduces CO2 emissions by about 4.42 kg/day. Ammonia mass fraction of about 0.9094 is an optimum value that yields maximum energy and exergy efficiencies of about 4.38 % and 15.27 %, respectively. The capital cost of the proposed system is about 11870.70 USD.
Keywords: Air conditioning system; COP; Energy; Exergy; Environment; Economic; Engine exhaust; Solar energy.
Techno-Economic Analysis of a 500MWe Supercritical Coal-based Thermal Power Plant with Solar Assisted MEA-based CO2 Capture
by RAJESH KUMAR, Sujit Karmakar
Abstract: Thermal power plants running with coal are the major carbon dioxide(CO2) emitters in the atmosphere. The higher concentration of CO2 in the atmosphere leads to global warming. The integration of the post-combustion CO2capture system (CCS) with coal-fired thermal power plant has the techno-economical potential to mitigate CO2 but huge energy penalty resulting in a significant decrease of plant energy and exergy efficiencies. The present study deals with the techno-economic analysis of a 500 MWeSupercritical (SupC) thermal power plant integrated with Solar assisted MEA absorption-based CCS. The analysis includes energy, exergy, environment, and economic (4-E) study. The thermodynamic analysis of different plant configurations is carried out using a computer simulation program, \'Cycle-Tempo.\' The analysis revealed that maximum loss of energy takes place in cooling water(condenser) followed by flue gas cooling and stack. The maximum exergy destruction has been observed in the combustor. The addition of solar energy for Monoethanolamine (MEA) regeneration helps in increasing the plant energy and the exergy efficiencies by about 2.2%- and 5%-points, respectively, and about 26% of the total energy demand is being utilized for the CO2 capture unit. The Levelized Cost of Electricity (LCoE) generation is 4.96 INR/kWh. The Payback period of the proposed plant is 4.18 years. The sensitivity analysis of the plant shows that fuel cost and escalation rate have a greater effect on the cost of electricity production. Moreover, CO2 avoided by this novel plant configuration is increased by 12.5%. The study also shows that the total area required for installing the solar trough is about 326 acres at 60 percent trough efficiency and 500W/m2 solar irradiation.
Keywords: Energy; Exergy; CO2 capture; MEA; Solar energy.
Evaluation and comparison of exergy-based resource consumption for fly ash utilization in cement clinker production system and landfill disposal
by Yanjing Wang, Suping Cui, Yu Liu, Boxue Sun
Abstract: It is unclear whether utilization of fly ash as valuable resource is preferable to landfill disposal from the resource perspective. The objective of this study was to evaluate and compare the resource consumption of fly ash utilization in cement clinker system compared to landfill disposal. The results indicated that when fly ash as substitute for clay, resource-saving potential of clinker system reached 147.47 MJ/t-clinker. The comparative analysis displayed that exergy-based resource consumption is reduced by 2020.48MJ when 1t fly ash used in clinker system instead of landfill.
Keywords: Fly ash; Cement clinker; Landfill; Cumulative Exergy Demand; Land use.
Thermo-hydraulic and Exergy Analysis of Parabolic Trough Collector with Wire Matrix Turbulator: An Experimental Investigation
by Varun K, Arunachala Chandavar
Abstract: The present energy crisis due to the exhaustion of fossil fuels, global warming, the surging gap between energy supply and demand, high electricity price, etc. has paved a path to harness renewable energy resources effectively. Among various sources, due to enormous potential and implicit superiority, solar thermal energy has been proved to be the best solution for the energy crisis. As an outcome, the oldest and prevailing solar concentrating technology i.e. parabolic trough collector (PTC) is being used extensively. However, the majority of studies are numerical as its receiver is subjected to highly non-uniform concentrated heat flux (circumferentially). Further, the outdoor testing is a laborious task due to the transient operating condition. Hence a novel method having a combination of differential heating, analytical model, and SOLTRACE
Keywords: Parabolic trough collector; Non-uniform heat flux; SOLTRACE®; Wire matrix; Performance evaluation criterion; Exergy enhancement ratio.
Design and comparative analysis of a geothermal energy supported plant for tri-generation purposes
by Nejat Tukenmez, Fatih Yilmaz, Murat Ozturk
Abstract: In this study, two geothermal-based energy systems that provide beneficial outputs of hydrogen, electricity and hot-water are proposed. In this study, two thermoelectric generators are included in the second system, unlike the first system, proposed to analyze the impact of thermoelectric generators on plant performance. For comprehensive thermodynamic and performance analysis of the proposed systems, the proposed systems are modeled according to thermodynamic equilibrium equations. The parametric works are performed to address the impact of different system indicators affecting the useful outputs and performance of the modeled systems. In addition, the performance evaluation of the modeled systems is conducted in comparison with several working fluids. The energetic and exergetic efficiencies of the designed first cycle are 40.4% and 31.57%, while the energetic and exergetic efficiencies of the suggested second cycle are found as 49.36% and 41.79%. The hydrogen generation realized by both proposed systems per unit time is 0.001196 kg/s.
Keywords: Energy; Exergy; Geothermal Energy; Thermodynamic Analysis; Thermoelectric Generator.
Potential energy optimisation in a domestic air to water heat pump
by Stephen Tangwe, Kanzumba Kusakana
Abstract: The study focused on the determination of the coefficient of performance (COP) and exergy losses of a 1.2 kW, 150 L add-on air to water heat pump (AWHP). It further justifies opportunity to optimise both the exergy losses and COPs of the system. Adequate sensors were installed at precise locations within the AWHP. Specific controlled hot water of 150, 50 and 100 L were drawn off from the AWHP during the morning, afternoon and evening for a full year. The results depicted that the average week-day COP, electrical and thermal energy consumed was 3.420, 3.478 kWh and 11.896 kWh, respectively. The associated exergy loss rate at the evaporator, compressor, condenser and expansion valve was 11.63, 41.89, 18.90 and 27.58%, respectively. The results of the experiments and in conjunction with the energy and exergy analyses, demonstrate potential opportunities of improving the efficiency of the AWHP.
Keywords: Air to water heat pump (AWHP) ; Coefficient of performance (COP); Exergy analysis method; Energy analysis method; Enthalpy.
A sustainable PV-powered energy retrofit modeling to achieve net ZEB in churches: A simulation study for San Marcello Al Corso
by Mohammad Mohammadzadeh, Navid Hadifar, Bahareh Mohammadzadeh
Abstract: This interdisciplinary study proposes practical modifications for achieving net-zero energy building (net ZEB) in historical churches while all the values of the church have been recognized and preserved. The church studied from structural, mechanical, and electrical perspectives. A 40.7% rise in energy efficiency and a 12% rise in exergy efficiency are observed after applying modifications. The concept of net ZEB has been accomplished in the church. A 98% balance in annual energy exchange is reached between the on-site and the utility grid power generation by applying the net metering method.
Keywords: energy retrofit; PV system; net-zero energy building (net ZEB); net metering; sustainability; horizontal air curtain; exergy analysis.
Exergy analyses of a tunnel furnace and a tunnel dryer
by Gurhan Tahtali, Hayati Olgun, Mustafa Gunes, Arif Hepbasli
Abstract: The main objective of this study is to comprehensively perform exergy analysis of the tunnel furnace and the tunnel dryer, which was selected as the control volume and involved in a brick production line. The analysis was based on the real data measured over one year period at a working brick factory with a daily production capacity of 392 tons fired bricks. Energy and exergy efficiencies of the control volume were obtained to be 76.46% and 12.90% for dead state values of 25 ?C and 1.013 atm, respectively.
Keywords: brick factory; tunnel furnace; tunnel dryer; energy and exergy analysis.
Influence of boundary conditions on the exergetic performance of the combination of a Thermal Energy Storage System and an Organic Rankine Cycle
by Andreas König-Haagen, Dieter Brüggemann
Abstract: The combination of a high-temperature packed bed Thermal Energy Storage (TES) with an Organic Rankine Cycle (ORC) named ORCTES is analyzed and optimized numerically for different boundary conditions from an exergetic point of view. The temperature dependency of all relevant material properties is taken into account. Characteristic curves from literature are used to model the ORC. Pressure and heat losses as well as convection, diffusion and radiation in the packed bed are included in the TES model. To identify the optimization potential and interactions in the system, a detailed exergetic evaluation method is applied. For one set of boundary conditions, an optimization is performed and compared with a previous publication. These two cases refer to the highest and lowest overall exergetic efficiency in the non-optimized case. Interestingly, the effect of physical aspects on the exergetic efficiency can be higher or lower for the TES itself compared to the effect on the overall system and these effects strongly depend on the boundary conditions. The optimization raised the exergetic overall efficiency from 36.1 % to 43.4 % and from 7.6 % to 28.0 %.
Keywords: Exergy; Detailed Analysis; Optimization; Thermal Energy Storage; Organic Rankine Cycle;.
Thermo-environmental analysis and performance comparison of solar assisted single to multi-generation systems
by Muhammad Khan, MUHAMMAD ABID, Mi Yan, Tahir Ratlamwala
Abstract: In the present study, a novel multi-generation system producing electricity, heating, cooling, thermal energy storage and hydrogen is investigated according to the thermodynamic and environmental point of views. The purpose of the present work is to thermodynamically examine and evaluate the performance of solar-aided multi-generation system. Different operating parameters are varied to assess the performance of the integrated multigenerational system. The results of the study illustrate that overall energy and exergy efficiency of the proposed integrated system is 51.62% and 53.45%, respectively while, hydrogen production rate is observed to be 0.00742 kg/s.
Keywords: Heliostat; multi-generation; overall energy; exergy; exergo-environmental; hydrogen.
Exergy analysis of a biogas-diesel fuelled dual fuel engine
by Feroskhan M, Sreekanth Manavalla, Saleel Ismail
Abstract: This work presents the exergy analysis of a biogas-diesel dual fuel engine for various operating loads and flow rates using simulated biogas. The engine is operated with pure methane and raw biogas with variable CH4:CO2 ratios to assess the effects of carbon dioxide extraction, termed as methane enrichment. Addition of biogas reduces exergy destruction and improved exergy efficiency vis-
Keywords: Biogas; Dual fuel; Exergy; Exergy efficiency; Exergy destruction.
Exergy and CO2 emission analysis of rotary hearth furnace-electric arc furnace routes of steelmaking
by Binay Kumar, Gour Gopal Roy, Prodip Kumar Sen
Abstract: Model-based analysis of exergy and CO2 emission of an emerging steelmaking process through rotary hearth furnace-electric arc furnace (RHF-EAF) system has been studied. Exergy indices of two RHF based processes yielding either iron nugget (ITmk3 process) or DRI (FASTMET process), operating with EAF are found to be either superior or comparable to conventional steelmaking (BF-BOF) process. Net CO2 emissions through RHF-EAF processes are found to be comparable to emissions from BF-BOF process. Considerable improvement in main-product exergy efficiency and CO2 emission are observed on utilisation of RHF off-gases to in-house power generation.
Keywords: Exergy analysis; CO2 emission; Emerging routes of steelmaking; RHF-EAF process; BF-BOF process.
Influence of Orifice in Entropy Generation and Exergy Analysis under transient condition for Large Diameter Natural Circulation Loops
by Elton Dylan Nazareth, Arunachala U. Chandavar, Rajat A. Chandavar
Abstract: Stable power generation is of concern due to instability in NCL. The entropy generation analysis in a 38.89 mm diameter loop identified the flow reversals by a drop in its value after a peak. Orifice plates and operating procedures lead to a change in threshold value. During unsteady state, the least entropy generation was observed with ? = 0.77. At higher power, constant power generation is possible with low orifice as it exhibits better exergy efficiency. The entropy generated due to friction was negligible compared to that by heat transfer
Keywords: Natural circulation systems; single phase; instantaneous entropy generation; instability; orifice; large-diameter loop; exergy analysis.
Comparative Exergetic, Economic and Exergoeconomic analysis of a hybrid cascade refrigeration system using ammonia-propane, propane-propylene and isobutane-propane refrigerant pairs
by Kaushalendra Kumar Singh, Rajesh Kumar, Anjana Gupta
Abstract: In the present study a comparative exergetic, economic and exergoeconomic analysis is done on a hybrid cascade refrigeration system using ammonia-propane, propane-propylene and isobutane-propane refrigerant pairs. Overall system cost rate, component-wise exergy destruction rates, exergetic efficiencies and exergoeconomic factors are investigated for the three refrigerant pairs at thermodynamic optimal operating conditions. The study concludes that ammonia-propane is the best refrigerant pair with maximum exergetic efficiency of 24.83% and minimum total cost rate of 564469 $/yr, whereas isobutane-propane is thermodynamically superior, but economically inferior than propane-propylene refrigerant pair.
Keywords: Cascade refrigeration system; Optimization; Exergy and Economic; Comparative analysis; Exergoeconomic factor; Natural refrigerants.