Scopus İndeksli Yayınlar Koleksiyonu

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Citation - WoS: 38
Citation - Scopus: 40
A comparative study on conventional and advanced exergetic analyses of geothermal district heating systems based on actual operational data
(Elsevier Science SA, 2013) A. Hepbasli; Ali Keçebaş; Hepbasli, Arif; Kecebas, Ali
This paper comparatively evaluates exergy destructions of a geothermal district heating system (GDHS) using both conventional and advanced exergetic analysis methods to identify the potential for improvement and the interactions among the components. As a real case study the Afyon GDHS in Afyonkarahisar Turkey is considered based on actual operational data. For the first time advanced exergetic analysis is applied to the GDHSs in which the exergy destruction rate within each component is split into unavoidable/avoidable and endogenous/exogenous parts. The results indicate that the interconnections among all the components are not very strong. Thus one should focus on how to reduce the internal inefficiency (destruction) rates of the components. The highest priority for improvement in the advanced exergetic analysis is in the re-injection pump (PM-IX) while it is the heat exchanger (HEX-III) in the conventional analysis. In addition there is a substantial influence on the overall system as the total avoidable exergy destruction rate of the heat exchanger (HEX-V) has the highest value. On the overall system basis the value for the conventional exergetic efficiency is determined to be 29.29% while that for the modified exergetic efficiency is calculated to be 34.46% through improving the overall components. © 2013 Elsevier B.V. © 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 12
Citation - Scopus: 13
A comparative study on estimating the landfill gas potential: Modeling and analysis
(Taylor and Francis Inc. 325 Chestnut St Suite 800 Philadelphia PA 19106, 2016) Ali Kemal Çakir; Huseyin Gunerhan; A. Hepbasli; Hepbasli, A.; Gunerhan, H.; Cakir, A. K.
The main objective of this study is to investigate the use of the landfill gas as potential energy and electricity obtained from the municipal solid waste (domestic industrial medical waste and sewage sludge) stored regularly in the Harmandali solid waste landfill area within the boundaries of the contiguous area of Izmir. The most important factor in making a decision about energy potential in the landfill is the amount of methane in the landfill gas. There are several approaches that have been used to determine the amount of the landfill gas. In this study three different methods and one approach in the literature were used for this purpose. The methods used are the Multi-Phase the LandGEM and the IPCC 2006. The results of the landfill gas obtained using the three methods namely the Multi-Phase the LandGEM (k = 0.35 k = 0.1 and k = 0.05) and the IPCC 2006 were as follows respectively: 291897215 792073359 769734749 681685027 and 491752247 m3. It may be concluded that the Harmandali Landfill has high landfill gas potential based on the measurements and mathematical methods used in the Harmandali landfill. © 2017 Elsevier B.V. All rights reserved.
A comparative study on the exergoeconomic analysis of textile dryers using speco method
(2012) Ahmet Çay; Işik Tarakçioǧlu; A. Hepbasli
This study reveals the exergoeconomic analysis of stenters by using Specific Exergy Costing (SPECO) method. The cost balances and auxiliary thermoeconomic relations were developed for direct gas heated (DGHS) and hot oil heated (HOHS) stenters by the application of the control volume models. The exergy cost of the evaporation of water was selected to be the main parameter. It was shown that the falling-rate period of drying led to the highest exergy costs while exergy costs varied between 0.19 US$/GJ and 0.59 US$/GJ depending on the drying periods. Increasing the exhaust air humidity ratio and the residual moisture content of the fabric outlet decreased the exergy costs linearly. © 2012 Elsevier B.V. All rights reserved.
A comprehensive evaluation of PV electricity production methods and life cycle energy-cost assessment of a particular system
(Elsevier Ltd, 2019) Huseyin Gunhan Ozcan; Huseyin Gunerhan; Nurdan H. Yildirim; A. Hepbasli
This paper presents the study about electricity generation from solar photovoltaic technology based on four different methodologies with some performance indicators namely performance ratio system efficiency fill and capacity utilization factors respectively. In this regard not only theoretical approach and simulation programs (PVSOL and TRNSYS) were used to determine annual production but also experimental studies were carried out for the validation. While annual sum of electricity generation was evaluated between 3913.84 and 4323.94 kWh the PVSOL program was determined to be the method that best reflected the experimental studies with a rate of 94.33%. Moreover while fill and capacity utilization factors were annually obtained to be almost similar annual values for the performance ratio and system efficiency were evaluated to be partially close to each other based on the theoretical approach and PVSOL program. Besides evaluation of the power production and performance indicators a life cycle energy analysis was also made for a particular system with a capacity of 2.55 kWp and energy payback periods were obtained to be between 1.99 and 2.54 years considering four different methodologies. Moreover the life cycle cost analysis was performed with or without battery option and some improvement proposals were presented for the energy market to become investable. © 2019 Elsevier B.V. All rights reserved.
Citation - WoS: 347
Citation - Scopus: 419
A key review of building integrated photovoltaic (BIPV) systems
(Elsevier B.V., 2017) Emrah Biyik; Mustafa Araz; A. Hepbasli; Mehdi Shahrestani; Runming Yao; Li Shao; Emmanuel A. Essah; Armando Coelho Oliveira; Teodosio del Caño; Elena Rico; Shahrestani, Mehdi; Hepbasli, Arif; Biyik, Emrah; Yao, Runming; Shao, Li; Araz, Mustafa; Atli, Yusuf Baver
Renewable and sustainable energy generation technologies have been in the forefront due to concerns related to environment energy independence and high fossil fuel costs. As part of the EU's 2020 targets it is aimed to reach a 20% share of renewable energy sources in final energy consumption by 2020 according to EU's renewable energy directive. Within this context national renewable energy targets were set for each EU country ranging between 10% (for Malta) and 49% (for Sweden). A large share of renewable energy research has been devoted to photovoltaic systems which harness the solar energy to generate electrical power. As an application of the PV technology building integrated photovoltaic (BIPV) systems have attracted an increasing interest in the past decade and have been shown as a feasible renewable power generation technology to help buildings partially meet their load. In addition to BIPV building integrated photovoltaic/thermal systems (BIPV/T) provide a very good potential for integration into the building to supply both electrical and thermal loads. In this study we comprehensively reviewed the BIPV and BIPVT applications in terms of energy generation amount nominal power efficiency type and performance assessment approaches. The two fundamental research areas in the BIPV and BIPVT systems are observed to be i) improvements on system efficiency by ventilation hence obtaining a higher yield with lowering the panel temperature ii) new thin film technologies that are well suited for building integration. Several approaches to achieve these objectives are reported in the literature as presented in this paper. It is expected that this comprehensive review will be beneficial to researchers and practitioners involved or interested in the design analysis simulation and performance evaluation financial development and incentives new methods and trends of BIPV systems. © 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 168
Citation - Scopus: 211
A key review of wastewater source heat pump (WWSHP) systems
(Elsevier Ltd, 2014) A. Hepbasli; Emrah Biyik; Orhan Ekren; Huseyin Gunerhan; Mustafa Araz; Ekren, Orhan; Araz, Mustafa; Hepbasli, Arif; Gunerhan, Huseyin; Biyik, Emrah
Heat pumps (HPs) are part of the environmentally friendly technologies using renewable energy and have been utilized in the developed countries for years. Wastewater is seen as a renewable heat source for HPs. At the beginning of the 1980s waste (sewage) water source heat pumps (WWSHPs) were widely applied in North European countries like Sweden and Norway and partially applied in China. In the past two decades the WWSHP has become increasingly popular due to its advantages of relatively higher energy utilization efficiency and environmental protection. The present study comprehensively reviews WWSHP systems in terms of applications and performance assessments including energetic exergetic environmental and economic aspects for the first time to the best of the authors' knowledge. In this context a historical development of WWSHPs was briefly given first. Next wastewater potential and its characteristics were presented while a WWSHP system was introduced. The previously conducted studies on WWSHPs were then reviewed and classified in a tabulated form. Finally some concluding remarks were listed. The COP values of the reviewed studies ranged from 1.77 to 10.63 for heating and 2.23 to 5.35 for cooling based on the experimental and simulated values. The performance assessments are mostly made using energy analysis methods while the number of exergetic evaluations is very low and has not been comprehensively performed. It is expected that the comprehensive review here will be very beneficial to those dealing with the design analysis simulation and performance assessment of WWSHP systems. © 2017 Elsevier B.V. All rights reserved.
Citation - Scopus: 2
A Long-term Period Performance Assessment of a Building Integrated Photovoltaic System
(EDP Sciences, 2019) Mustafa Araz; Emrah Biyikt; A. Hepbasli; Hepbasli, Arif; Araz, Mustafa; Biyikt, Emrah; N. Caetano
Building Integrated Photovoltaic (BIPV) systems can be defined as PV modules which can be integrated in building's envelope by replacing conventional building materials such as windows tiles etc. and have an impact on the functionality of the buildings. Considering the huge share (40%) of buildings in total energy consumption and nearly zero-energy building target of the European Union (EU) BIPV systems present a sustainable solution and have gained increased interest in last years. In this study the performance of a BIPV system which was installed on Feb. 8 2016 on the façade of a campus building at Yasar University Izmir Turkey within the framework a EU/FP7 project and has a capacity of 7.44 kWp is evaluated for a three-year period using first and second laws of thermodynamics. Within this context real (experimental) monthly and yearly electricity productions are determined and compared with the results obtained from the simulations. Energy and exergy efficiencies and performance ratios of the system are also calculated based on the cell and total areas. © 2019 Elsevier B.V. All rights reserved.
Citation - WoS: 58
Citation - Scopus: 63
A method of strategic evaluation of energy performance of Building Integrated Photovoltaic in the urban context
(ELSEVIER SCI LTD, 2018) V. Costanzo; R. Yao; E. Essah; L. Shao; M. Shahrestani; A. C. Oliveira; M. Araz; A. Hepbasli; E. Biyik; Essah, E.; Shahrestani, M.; Yao, R.; Biyik, E.; Shao, L.; Costanzo, V.; Oliveira, A. C.
This paper presents an integrated bottom-up approach aimed at helping those dealing with strategical analysis of installation of Building Integrated Photo Voltaic (BIPV) to estimate the electricity production potential along with the energy needs of urban buildings at the district scale. On the demand side hourly energy profiles are generated using dynamic building simulation taking into account actual urban morphologies. On the supply side electricity generated from the system is predicted considering both the direct and indirect components of solar radiation as well as local climate variables. Python-based Algorithm editor Grasshopper is used to interlink four types of modelling and simulation tools as 1) generation of 3-D model 2) solar radiation analysis 3) formatting weather files (TMY data set) and 4) dynamic energy demand. The method has been demonstrated for a cluster of 20 buildings located in the Yasar University in Izmir (Turkey) for which it is found the BIPV system could achieve an annual renewable share of 23% in line with the Renewable Energy Directive target of 20%. Quantitatively compared demand and supply information at hourly time step shows that only some energy needs can be met by BIPV so there is a need for an appropriate matching strategy to better exploit the renewable energy potential. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.
Citation - WoS: 27
Citation - Scopus: 27
A new approach to determine the outdoor temperature distributions for building energy calculations
(Pergamon-Elsevier Science Ltd, 2014) Can Coskun; Mustafa Ali E. Ertürk; Zuhal Oktay; A. Hepbasli; Oktay, Zuhal; Ertürk, Mustafa; Coskun, Can; Hepbasli, Arif
This study formulated annual monthly and hourly ambient temperature distributions for simplifying the calculation of cooling and heating degree-hours. In this regard Turkey was selected as an application country of which 79 cities were considered for modeling purposes. The temperature data over a period of 42 years were also utilized in the analysis. Similar outdoor distributions were categorized in the same group. The analysis results showed eight main annual distribution trends for the cities in Turkey. Such a detailed analysis and categorization for the outdoor temperature has been done for the first time in the literature. The outdoor temperature distributions are very useful tools for determination of heating and cooling loads while they enable the calculation of the annual- monthly- and hourly-based degree-hours values. In this regard a population-based outdoor temperature distribution concept was also introduced to the literature and tested for Turkey. One temperature distribution was achieved for Turkey with reference to population. © 2013 Elsevier Ltd. All rights reserved. © 2013 Elsevier B.V. All rights reserved.
Citation - WoS: 86
Citation - Scopus: 90
A new correlation for predicting the thermal conductivity of nanofluids, using dimensional analysis
(Elsevier Ltd, 2015) S. Hassani; Rahman Saidur; Saad Mekhilef; A. Hepbasli; Mekhilef, Saad; Hassani, Samir; Saidur, R.; Hepbasli, Arif
Abstract Thermal conductivity of nanofluids is a key thermophysical property which depends on concentration and size of nanoparticles temperature and thermophysical properties of the base fluid. Over last decades several works have been done on the thermal conductivity of nanofluids while a number of numerical and theoretical models have been proposed. However most of these models were not able to predict appropriately the thermal conductivity for a variety of nanofluids. In the present paper using the Vaschy-Buckingham theorem new correlations for predicting the thermal conductivity of nanofluids were developed based on the existing experimental data. The new correlation proposed took into account the Brownian motion the variation of volume fraction the temperature and the size distribution of nanoparticles. The expression developed successfully predicts the thermal conductivity of a variety of nanofluids TiO2 Al2O3 Al Cu Fe MWCNTs/EG Al2O3 SiO2/methanol TiO2 Al2O3 CuO MWCNTs/water Al2O3/radiator coolant Al2O3/R141b Al CNTs/Engine Oil and Cu/Therminol 66 and suits the data with a mean and standard deviation of 2.74% 3.63% respectively. The correlation was derived from 196 values of nanofluids thermal conductivity 86% of them are correlated within a mean deviation of ±5% while 98% of them belong to an interval of ±10%. Moreover the proposed correlation has been tested on 284 values of thermal conductivity of different nanofluids and the predicted values have been found in excellent agreement with the experimental ones with a mean deviation of 3%. The mean deviation between the correlated and the tested point found to be 2.94%. The present correlation will be a good tool for engineers in preparing the nanofluid for different applications in heat exchangers and thermal solar collectors. © 2015 Elsevier B.V. All rights reserved.
A numerical approach to exergy-based sustainability and environmental assessments of solar energy-powered district cooling systems using actual operational data
(Institution of Chemical Engineers, 2024) Huseyin Gunhan Ozcan; A. Hepbasli; Aysegul Abusoglu
The demand for cooling in buildings has been increasing at a higher rate than heating and more energy is expected to meet this demand. Solar energy can be vital in fulfilling this energy requirement based on its unique renewable energy features. The solar thermal powered absorption cooling (STAC) and solar electrical assisted vapor compression cooling (SEVC) systems are assessed in this study by conducting the conventional and advanced exergy analyses and environmental assessment. Determining the unavoidable part of exergy destruction as in this study provides a unique convenience in design problems where the thermodynamic performances of distinct systems are compared. Under current technological conditions removing the thermodynamically optimized parameters of the designed systems from the minima-maxima dichotomy and rationally evaluating the avoidable part of exergy destruction will protect the researcher from the arbitrariness of the design. The obtained results based on conventional exergy analysis in a component manner showed that priority should be given to solar technologies due to their lowest exergy efficiencies (0.16 for a photovoltaic (PV) and 0.19 for a collector) and sustainability indices (1.20 for the PV and 1.24 for the collector). Advanced exergy analysis results revealed that the exergy destruction significantly originated from the unavoidable part of the total exergy destruction of the components for the solar technologies (93.02 % for the collector and 96.41 % for the PV) cooling (92.12 % for the absorption and 98.42 % for the vapor compression) and overall system (99.92 % for the SEVC and 99.99 % for the STAC). The initial estimated carbon dioxide emissions from the STAC were 0.28 kg CO2-eq attributed to pump power consumption. However these emissions varied dynamically for the SEVC ranging from 0 (when the solar PV field meets the total power) to 5.58 kg CO2-eq (when radiation is not available) depending on the power-consuming components (compressor and pumps). © 2024 Elsevier B.V. All rights reserved.
A parametric study of a piston-prop aircraft engine using exergy and exergoeconomic analysis methods
(Taylor and Francis Inc. 325 Chestnut St Suite 800 Philadelphia PA 19106, 2015) Onder Altuntas; Hikmet Tahir Karakoc; A. Hepbasli
In this study exergetic and exergoeconomic analysis methods are applied to a four-cylinder spark ignition (SI) naturally aspirated and air-cooled piston-prop aircraft engine in the cruise phase of flight operations. The duration of cruise is selected to be 1 h. Three parameters altitude rated power setting (PS) and air-to-fuel ratio (AF) are varied by the calculation of the max-min values of exergy analysis. Based on the results of energy analysis the values for the maximum energy efficiency and fuel consumption flow rate are calculated to be 21.73% and 28.02 kg/h respectively at 1000-m altitude and 75% PS. The results of exergy analysis indicate that all exergetic values vary from 65% to 75% PS while this increase is not seen in exergoeconomic analysis. While the maximum exergy input rate is obtained to be 405.60 kW exergy efficiency has the minimum value with 14.43% and exergy destruction rate has the maximum value with 168.48 kW. These values are achieved at 3000-m altitude and 18 AFs. The maximum average exergy cost of the fuel is calculated to be 130.77 $/GJ at 1000-m altitude 13 AF ratios and 65% PS. At this point while the minimum cost rate associated with the exergy destruction is obtained to be 40.29 $/h the maximum exergoeconomic factor is found to be 19.98%. © 2014 Elsevier B.V. All rights reserved.
A parametric study of a renewable energy based multigeneration system using PEM for hydrogen production with and without once-through MSF desalination
(Elsevier Ltd, 2022) Ahmet Bozgeyik; Lutfiye Altay; A. Hepbasli
The importance of renewable energy compared to fossil fuels is increasing due to growing energy demand and environmental challenges. Multi-generation systems use one or more energy sources and produce several useful outputs. The present study aims at investigating and comparing solar energy based multi-generation systems with and without once-through MSF desalination unit from the thermodynamic point of view. Firstly hydrogen electricity and hot water for space heating and domestic usage are produced using the system which consists of a parabolic trough collector an organic Rankine cycle (ORC) and a PEM electrolyzer and heat exchanger as sub-systems. The performance of the entire system is evaluated from the energetic and exergetic points of view. Various parameters affecting hydrogen production rate and efficiency values are also investigated with the thermodynamic model implemented in the Engineering Equation Solver (EES) package. The system can produce hydrogen at a mass flow rate of 20.39 kg/day. The results of the study show that the energy and exergy efficiency values of the ORC are calculated to be 16.80% and 40% while those for the overall system are determined to be 78% and 25.50% respectively. Secondly once-through MSF desalination unit is integrated to the system between ORC evaporator and heat exchanger producing domestic hot water in the solar cycle in order not to affect hydrogen production rate while thermodynamic values are compared. Fresh water production capacity of the system is calculated to be at a volumetric flow rate of 5.74 m3/day with 10 stages. © 2022 Elsevier B.V. All rights reserved.
Citation - WoS: 12
Citation - Scopus: 12
A parametric study on energy exergy and exergoeconomic assessments of a modified auto-cascade refrigeration cycle supported by a dual evaporator refrigerator
(Elsevier Ltd, 2024) Ibrahim Karacayli; Lutfiye Altay; A. Hepbasli; Karacayli, Ibrahim; Hepbasli, Arif; Altay, Lutfiye
This paper presents an evaluation of the energetic exergetic and exergoeconomic performances of a modified auto-cascade refrigeration (MACR) cycle integrated with a dual evaporator refrigerator (DER) to determine optimum operating conditions. DER facilitates a reduction in the compression ratio allowing the low-boiling-point component to release more heat before entering the evaporator. In this study the R170/R290 refrigerant mixture which has a low global warming potential but an explosion risk was used. The main purpose of this study is to eliminate the risk of explosion by reducing the compressor discharge temperature and at the same time to enhance the overall cycle performance. To achieve this DER is used instead of air-cooled coils which have limited cooling performance. Despite an ambient temperature of 35°C the MACR cycle achieved a remarkable 51.29 % reduction in compressor discharge temperature when the separator inlet temperature was reduced to 10°C by the DER. It also results in a 72.73% reduction in compression work rate and a significant 137.02% increase in cooling effect compared to the conventional auto-cascade refrigeration cycle. Furthermore the MACR cycle exhibits notable improvements in total exergy destruction rate and exergy destruction cost rate with a 75.23% and a 76.07% reduction respectively. Simultaneously the exergy efficiency and the exergoeconomic factor increased by 266.67% and 179.15% respectively. The MACR cycle achieves optimum energy and exergy performance with a 60% R170 mass fraction and 0.50 vapor quality resulting in 1.429kW compression work rate a COP of 0.70 and an exergy efficiency of 26.66 %. The optimum exergoeconomic performance is achieved with a 40% R170 mass fraction and 0.50 vapor quality. © 2024 Elsevier B.V. All rights reserved.
Citation - WoS: 3
Citation - Scopus: 3
A REVIEW ON COMPUTATIONAL FLUID DYNAMICS SIMULATION METHODS FOR DIFFERENT CONVECTIVE DRYING APPLICATIONS
(Serbian Society of Heat Transfer Engineers, 2023) Seda Özcan Çoban; Fatih Selimefendigil; Hakan Fehmi Oztop; A. Hepbasli; Coban, Seda Ozcan; Hepbasli, Arif; Oztop, Hakan Fehmi; Selimefendigil, Fatih
This paper focuses on the CFD studies on one of the commonly used drying processes for different applications. First a brief information about drying is given with determining important properties that effect drying characteristics. Next basic principles of CFD modelling are explained while capabilities of computational processing are presented. A detailed literature survey about CFD studies in convective drying process is then conducted. Finally some sound concluding remarks are listed. It may be concluded that the CFD is a powerful and flexible tool that can be adopted to many different physical situations including complex scenarios results of CFD simulations represent good predictions for fluid-flow heat and mass transfer of various drying methods and those numerical studies can be used for validation and controlling of applicability of new drying systems. © 2023 Elsevier B.V. All rights reserved.
A sub-system design comparison of renewable energy based multi-generation systems: A key review along with illustrative energetic and exergetic analyses of a geothermal energy based system
(Elsevier Ltd, 2022) Ahmet Bozgeyik; Lutfiye Altay; A. Hepbasli
In recent years it has gained a significance importance to decrease ecological footprint so to have a positive contribution to environmental quality. Renewable energy plays a significant role in future trends for efficiency and environmental issues. Efficiency of systems is to be increased to meet future demands in terms of sustainability with increased consumption. There is a need for new and innovative research studies on promising technologies processes and strategies to have sustainable water and energy management in cities. This review paper investigates the use of energy sources in single or multiple forms with different system designs from simple to complex structures. The examined studies were presented in a tabulated form including energy and exergy efficiency values as well as the methods and tools used. The results indicated that the systems with the highest energy and exergy efficiency values had several useful outputs such as hydrogen fresh water drying heating and cooling etc. The maximum exergetic efficiency was determined to be 94% for a multiple energy sourced multi-generation system while the maximum energetic efficiency was calculated to be 111.3% for a solar assisted and heat pump integrated multi-generation system amongst the reviewed studies. To illustrate the obtained results from review a geothermal energy based multi-generation system was considered. Some parametric studies were also undertaken to see the effects of geothermal water temperature and flow rates on efficiency values. For a single production case they were determined to be 13.7% and 50% respectively while they were obtained to be 98.6% and 67.7% for a multi-generation system in which electricity low grade hot water production high temperature hot water production and hydrogen were useful outputs. However it should be noted that there was a threshold about the number of products to have an optimum increase in the efficiency values. © 2022 Elsevier B.V. All rights reserved.
Citation - WoS: 28
Citation - Scopus: 29
A sub-system design comparison of renewable energy based multi-generation systems: A key review along with illustrative energetic and exergetic analyses of a geothermal energy based system
(ELSEVIER, 2022) A. Bozgeyik; L. Altay; A. Hepbasli; Hepbasli, A.; Bozgeyik, A.; Altay, L.
In recent years it has gained a significance importance to decrease ecological footprint so to have a positive contribution to environmental quality. Renewable energy plays a significant role in future trends for efficiency and environmental issues. Efficiency of systems is to be increased to meet future demands in terms of sustainability with increased consumption. There is a need for new and innovative research studies on promising technologies processes and strategies to have sustainable water and energy management in cities. This review paper investigates the use of energy sources in single or multiple forms with different system designs from simple to complex structures. The examined studies were presented in a tabulated form including energy and exergy efficiency values as well as the methods and tools used. The results indicated that the systems with the highest energy and exergy efficiency values had several useful outputs such as hydrogen fresh water drying heating and cooling etc. The maximum exergetic efficiency was determined to be 94% for a multiple energy sourced multi-generation system while the maximum energetic efficiency was calculated to be 111.3% for a solar assisted and heat pump integrated multi-generation system amongst the reviewed studies. To illustrate the obtained results from review a geothermal energy based multi-generation system was considered. Some parametric studies were also undertaken to see the effects of geothermal water temperature and flow rates on efficiency values. For a single production case they were determined to be 13.7% and 50% respectively while they were obtained to be 98.6% and 67.7% for a multi-generation system in which electricity low grade hot water production high temperature hot water production and hydrogen were useful outputs. However it should be noted that there was a threshold about the number of products to have an optimum increase in the efficiency values.
Citation - WoS: 7
Citation - Scopus: 6
Achieving ultra-high coefficient of performance in a novel solar-assisted trigeneration system integrating absorption and Rankine cycles
(Elsevier Ltd, 2025) Aslı Tiktaş; A. Hepbasli; Huseyin Gunerhan; Hepbasli, Arif; Gunerhan, Huseyin; Tiktas, Asli
A novel solar-driven trigeneration system was developed and thermodynamically assessed integrating an absorption heat transformer (AHT) a Rankine cycle (RC) and an absorption cooling cycle (ACC) into a unified configuration. The innovation lay not only in the use of an AHT to power the RC—an uncommon integration in itself—but more significantly in the full thermodynamic loop architecture that employed a single working fluid pair (LiBr–H2O) shared by both absorption subsystemswhile also driving a steam-based Rankine subsystem. This tightly coupled single-loop design enabled internal thermal cascading and eliminated the need for separate working fluids auxiliary heating or intermediate heat exchangers— unlike conventional hybrid or cascade systems which (i) rely on multiple working fluid loops for power and cooling (ii) require fossil-fueled auxiliary heaters to drive RCs or (iii) incur high irreversibility losses due to fluid-to-fluid heat exchange between subsystems. Based on the simulation results a net electrical power output of 457.90 kW an overall exergetic efficiency of 74.40 % and a RC energy efficiency of 56.30 % were obtained. The cooling coefficient of performance (COP) reached 7.03 significantly outperforming conventional single-effect absorption systems. The system was fully powered by flat-plate solar collectors (FPSCs) without requiring any fossil-based auxiliary energy. A comprehensive validation was performed using component-level comparisons with experimental studies covering pressure drops internal irreversibility and the influence of working fluid properties on performance metrics. Additionally detailed thermo-economic assessments were carried out. The total investment cost was approximately US$8.54 million with a remarkably short payback period (PP) of 2.56 years and an internal rate of return (IRR) of 24.43 %. Levelized costs of electricity cooling and heating were calculated as US$0.20/kWh US$0.024/kWh and US$0.024/kWh respectively. Comparative analysis against literature benchmarks proven that the proposed system offered superior thermodynamic and economic performance especially in cooling and heating outputs. This study showed a new design paradigm for low-grade renewable energy utilization providing both a scalable solution for high efficiency multigeneration and a practical framework for future sustainable energy systems. © 2025 Elsevier B.V. All rights reserved.
Advanced exergoeconomic analysis of a gas engine heat pump (GEHP) for food drying processes
(Elsevier Ltd, 2015) Aysegul Gungor; George Tsatsaronis; Huseyin Gunerhan; A. Hepbasli
Exergetic and exergoeconomic analyses are often used to evaluate the performance of energy systems from the thermodynamic and economic points of view. While a conventional exergetic analysis can be used to recognize the sources of inefficiencies the so-called advanced exergy-based analysis is convenient for identifying the real potential for thermodynamic improvements and the system component interactions by splitting the exergy destruction and the total operating cost within each component into endogenous/exogenous and unavoidable/avoidable parts. In this study for the first time an advanced exergoeconomic analysis is applied to a gas-engine-driven heat pump (GEHP) drying system used in food drying for evaluating its performance along with each component. The advanced exergoeconomic analysis shows that the unavoidable part of the exergy destruction cost rate within the components of the system is lower than the avoidable part. The most important components based on the total avoidable costs are drying ducts the condenser and the expansion valve. The inefficiencies within the condenser could particularly be improved by structural improvements of the whole system and the remaining system components. Finally it can be concluded that the internal design changes play a more essential role in determining the cost of each component. © 2015 Elsevier B.V. All rights reserved.
Advanced exergoeconomic analysis of a trigeneration system using a diesel-gas engine
(Elsevier Ltd, 2014) Emin Açıkkalp; Haydar Aras; A. Hepbasli
In this paper a trigeneration system was analyzed using an advanced exergy analysis. The trigeneration system is located in the Eskisehir Industry Estate Zone in Turkey. The exergy efficiency of the system is 0.354 and the total exergy destruction of the system is 16.695 MW. The total exergoeconomic factor of the system is 0.069 and unit electricity generating cost is 56.249 $/GJ. The exergy destruction and investment cost rates within the facility's components are generally divided into four parts: endogenous exogenous avoidable and unavoidable exergy destruction. Through this analysis the improvement potential of the costs of the components and the investment and the overall system were determined along with the economic relationships between the components. The results of the analysis indicate that the combustion chamber high pressure steam turbine and condenser exhibit significant economic improvement potential because of their high exergy destruction costs. Similarly the heat recovery steam generator and condenser exhibit significant potential to reduce their investment costs. In addition suggestions for improving system economical parameters are provided. © 2014 Elsevier Ltd. All rights reserved. © 2014 Elsevier B.V. All rights reserved.

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