Browsing by Author "Tiktas, Asli"

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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.
Citation - WoS: 13
Citation - Scopus: 13
Exergoeconomic optimization of a proposed novel combined solar powered electricity and high-capacity cooling load production system for economical and potent generation via utilization of low-grade waste heat source
(ELSEVIER, 2024) Asli Tiktas; Huseyin Gunerhan; Arif Hepbasli; Hepbasli, Arif; Gunerhan, Huseyin; Tiktas, Asli
A novel system for combined electricity and cooling generation was introduced integrating Flat Plate Solar Collectors (FPSC) Absorptional Heat Transformer (AHT) Organic Rankine Cycle (ORC) and Absorption Cooling Cycle (ACC) systems to utilize low-grade solar energy. The ability to use low-grade waste heat sources (70 degrees C-90 degrees C) via FPSC system for high-capacity integrated cooling and electricity generation in a more economical way a feature not commonly addressed in conventional systems and previous literature studies was a key advancement. The need for additional generators boilers and high-temperature heat sources was eliminated resulting in substantial cost savings and a simplified system design. The FPSC-AHT integration identified as having significant advantages over separate electricity and cooling load production was comprehensively evaluated for its combined exergoeconomic and environmental benefits in multigeneration system design. The modeling was performed using Engineering Equation Solver (EES) and Transient System Simulation Software (TRNSYS) in Izmir Turkey with the aim of achieving the heightened economic efficiency and superior Coefficient of Performance (COP) values without high-temperature waste heat sources. Three configurations were examined with the third demonstrating superior technoeconomic performance due to the increased thermal efficiency of solar hybrid photovoltaic-thermal (PV-T) systems. The higher cost per unit area in the PV-T system was effectively offset by the substantial electricity consumption contributing to energy savings. Economic indicators for the third configuration included an initial investment of US$9.91 million annual operational costs of US$1.29 million a payback period of 4.2 years an annual energy cost gain of US$9.25 million a levelized cost of cooling (LCC) of US$0.014/kWh and an electricity cost (LCE) of US$0.015/kWh. Through exergy analysis toluene was identified as the optimal working fluid revealing a total exergy destruction rate of 13245.46 kW. The performance of the proposed system was tested under different operation conditions and based on these results a sensitivity analysis and a comparison with the real-word studies were performed. In comparison to real- world data the proposed system exhibits superior performance metrics especially in terms of COP and exergy efficiency values. The optimal configuration established using single and multiobjective optimization approaches based on exergoeconomic parameters indicated annual electricity and cooling load production of 40000 MWh and 300 GWh respectively. The system's efficiency in producing 1000 kW of electricity power and 4000 kW of cooling load at a comparable cost to systems generating only one output was highlighted. To determine the technoeconomic performance improvement of the proposed integrated system the optimal configuration of the novel integrated system was compared to a reference plant for similar-scaled integrated power and cooling generation (UCI Trigeneration Plant). Compared to the UCI Trigeneration Plant the proposed system demonstrated significant improvements in technoeconomic performance. Specifically the proposed system achieved a 164.13 % increase in annual electricity production a 97.38 % increase in annual cooling duty a 60.36 % reduction in initial investment a 57 % reduction in annual operational costs and a 47.5 % reduction in payback period. Additionally the levelized costs of electricity and cooling were 40 % and 22.22 % lower respectively. Significantly higher electricity and cooling output highlights the system's ability to meet demanding energy needs. Lower initial investment and operational costs coupled with a reduced payback period make the system financially attractive. Lower levelized costs for electricity and cooling increase the system's competitiveness and affordability. The innovative integration of technologies provides new insights into the design of multigeneration systems setting a new benchmark for sustainable energy solutions.
Citation - WoS: 9
Exergy and sustainability-based optimisation of flat plate solar collectors by using a novel mathematical model
(INDERSCIENCE ENTERPRISES LTD, 2023) Asli Tiktas; Huseyin Gunerhan; Arif Hepbasli; Hepbasli, Arif; Gunerhan, Huseyin; Tiktas, Asli
A novel mathematical model was used to estimate optimum tilt and azimuth angles considering exergoeconomic and sustainability aspects. This approach made the solar collector's performance evaluation independent of experimental precision. The optimal angles of 41.191degree celsius 10.038degree celsius for Izmir maximised the total surface radiation exergetic efficiency exergetic sustainability index and minimised the destruction and cost rates due to the enhanced useful exergy stream. However for thermal efficiency maximisation useful collected solar energy and total surface radiation competed leading to lower tilt and azimuth angles (0 -0.008). A multi-objective optimisation process chose the pair (0 259.428) to maximise first law efficiency and exergoeconomic factor.
Citation - WoS: 14
Citation - Scopus: 11
Extended exergy analysis of a novel integrated absorptional cooling system design without utilization of generator for economical and robust provision of higher cooling demands
(Elsevier Ltd, 2024) Aslı Tiktaş; Huseyin Gunerhan; A. Hepbasli; Emin Açıkkalp; Acikkalp, Emin; Tiktas, Asli; Hepbasli, Arif; Gunerhan, Huseyin
The focus of this study is on designing a novel system for the provision of high-capacity cooling and heating loads (4000 kW) with the utilization of absorption technology to increase economic viability and COP value of existing cooling plants via lower-grade waste heat sources (70 °C-90 °C). To achieve this aim in the novel system an integration including the LiBr-water solution based absorptional heat transformer (AHT) and absorptional cooling cycle (ACC) and flat plate solar collector (FPSC) systems was proposed. In the integration the utilization of the generator in the cooling cycle was avoided with the interaction of the high-temperature LiBr-water solution (120 °C-150 °C) from the AHT system and ACC system evaporator. In this way both the additional cost of the boiler and heat source and the enhancement of economic viability and COP value were achieved. Energy economic traditional and extended exergy sustainability and environmental analyses were implemented in this novel system. The COP value for the cooling system was determined to be 3.10 from energy analysis. This result forms a significant indicator for achieving of the main focus of the current study with the proposed novel system. The annual heating and cooling duty generations with this novel system were computed as 52.37 GWh and 52.40 GWh respectively. In the context of economically comparing the proposed system to other plants with similar scale that already exist the initial overall expenditure yearly operational expenses and the time it takes to recover the investment for the proposed system were set at $4.56 million $3.12 million and 1.75 years respectively. It is worth noting though that these figures fall within the range of $6–8 million $5–7 million and 5–10 years respectively for the currently operational plants. This result indicated that the proposed system provides a robust alternative to the existing cooling-heating cogeneration systems in terms of main output generation and is more economically viable. Also the novel system gained annually US$3.89 million in energy costs. The conventional exergy analysis results were summarized by forming an exergy flow and loss diagram namely the Grassmann diagram. In addition in this current study the novel extended exergy flow diagram indicating extended exergy content components energy carriers of the proposed system and exergy product rate streams was also proposed and drawn for the proposed system. © 2024 Elsevier B.V. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 1
A Key Review of Geothermal Heat Pumps: Exergoeconomic and Environmental Aspects with Prospects for Further Development
(Elsevier, 2026) Hepbasli, Arif; Tiktas, Asli
A comprehensive analysis of geothermal heat pumps (GHPs) was conducted, emphasizing their technoeconomic, exergoeconomic, and environmental aspects apart from previous literature studies. A thorough, extended literature review was performed to identify the latest trends, challenges, and innovations in GHP technology. This study's novelty is in its multifaceted evaluation of GHP systems, integrating exergoeconomic analysis with a broader environmental impact assessment, an area largely underexplored in previous research. Significant improvements in system performance were observed through incorporating additional heat sources like wind turbines, solar thermal panels, and organic Rankine cycle systems. These integrations resulted in notable enhancements in performance efficiency (COP), heating load production, and overall seasonal efficiency, with COP increases of up to 56.92% and heating load improvements of up to 77.8%. Moreover, the environmental impact of hybrid systems was reduced, with substantial decreases in CO2 emissions and other pollutants. A novel modified bibliometric analysis was also developed, revealing gaps in the literature, particularly in the need for advanced exergy analysis and the optimization of hybrid GHP systems for various geographic regions. Interest in GHP research has significantly increased over the past decade. Despite these advances, challenges remain in addressing installation costs, system complexity, and efficiency variations across different climates. This study introduces unique recommendations for optimizing hybrid configurations, reducing installation costs, improving energy storage, and developing adaptive control systems-all of which represent significant contributions to the field.
Citation - WoS: 47
Citation - Scopus: 48
Single and multigeneration Rankine cycles with aspects of thermodynamical modeling- energy and exergy analyses and optimization: A key review along with novel system description figures
(ELSEVIER, 2022) Asli Tiktas; Huseyin Gunerhan; Arif Hepbasli; Hepbasli, Arif; Gunerhan, Huseyin; Tiktas, Asli
The energy crises caused by the rapidly increasing population density around the world and the economic environmental and health threats that have reached significant dimensions emphasize the importance of the concept of sustainable energy more and more every day. For this reason to ensure the sustainability of energy not only sustainable energy sources but also optimum system designs are developed which can be integrated with these sources and where waste heat recovery mechanisms are effective. At this point Rankine cycle systems (RCSs) are an extremely good opportunity to close this gap due to their structural features. In this study we grouped the RCSs existing in the literature and made a comprehensive evaluation of these systems from broad perspectives such as exergo-economics exergoenvironment optimization and system design results and effects. The potential system designs revealed by compiling studies in the literature for the system type in question through the novel general system description figures were drawn with a completely original approach. For comparing the system designs in the studies examined with each other more easily and seeing the possible ef-fects the systems considered were originally and completely drawn by the authors of this paper based on the principle of standardization. We summarized the examined study in terms of system design the applied energy exergy economic analyzes and optimization processes the obtained general results input and output parameters affecting the system and their interaction with system components in a single table with novel flow chart tables. We presented an effective easy-to-understand comparison method based on a strong visualization principle and expect that in this way one can inspire potential studies and understand easily the gaps in the literature. Also we prepared a novel comprehensive comparison table for all types of RCSs in terms of techno-economic and envi-ronmental considerations. The main findings indicated that the maximum power heating and cooling output rates thermal and exergy efficiency values mean total production cost rate payback period and greenhouse gas emission ranges were 1040-329750 kW 15.2-2500 kW 567-22500 kW 12.8-73.8% 51.6-75.5% 85.39 $/h 3.6 years and 0.098 t/MWh respectively for cogeneration RCSs. The mean greenhouse gas emission total production cost rate and payback period values were lower compared to other RCS types with higher exergy efficiencies and production outputs. It may be concluded that in terms of exergoeconomic and environmental perspectives cogeneration RCSs form a better optimum configuration for many cases with utilization of influent waste heat recovery opportunities compared to other choices.