Browsing by Author "Gungor, Aysegul"

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Citation - WoS: 64
Citation - Scopus: 75
Advanced exergoeconomic analysis of a gas engine heat pump (GEHP) for food drying processes
(PERGAMON-ELSEVIER SCIENCE LTD, 2015) Aysegul Gungor; George Tsatsaronis; Huseyin Gunerhan; Arif Hepbasli; Tsatsaronis, George; Hepbasli, Arif; Gunerhan, Huseyin; Gungor, Aysegul
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. (C) 2014 Elsevier Ltd. All rights reserved.
Citation - WoS: 2
Citation - Scopus: 2
Enhanced exergy analyses of a gas engine heat pump (GEHP) dryer for medicinal and aromatic plants
(INDERSCIENCE ENTERPRISES LTD, 2015) Aysegul Gungor; Arif Hepbasli; Huseyin Gunerhan; Hepbasli, Arif; Gunerhan, Huseyin; Gungor, Aysegul
In this study the performance of a gas engine heat pump (GEHP) drying system is evaluated using both conventional and advanced (or enhanced) exergetic analysis methods. The results indicated that the inefficiencies within the compressor and the drying ducts are mainly due to the internal operating conditions while the efficiency of the condenser could be improved by structural improvements of the whole system and the remaining system components. High levels of endogenous exergy destruction show that the component interactions do not contribute significantly to the thermodynamic inefficiencies. Thus one should focus on how to reduce the internal inefficiency rates of the components. On the overall system basis the value for the conventional exergetic efficiency is in the range of 79.71-81.66% while that for the modified exergetic efficiency varies between 84.50 and 86.00% through improving the overall components.
Citation - WoS: 46
Citation - Scopus: 49
Splitting the exergy destruction into avoidable and unavoidable parts of a gas engine heat pump (GEHP) for food drying processes based on experimental values
(Pergamon-Elsevier Science Ltd, 2013) Aysegul Gungor; Zafer Erbay; A. Hepbasli; Huseyin Gunerhan; Erbay, Zafer; Hepbasli, Arif; Gunerhan, Huseyin; Gungor, Aysegul
Some limitations in a conventional exergy analysis may be significantly reduced through an advanced exergy analysis. In this regard the latter is a very useful tool to assess the real potential for improving a system component by splitting the exergy destruction into unavoidable and avoidable parts. This may provide a realistic measure to deduct the improvement potential for the thermodynamic efficiency of a component. For this purpose improvement efforts are then made by focusing only on these avoidable parts. In this paper a gas engine heat pump (GEHP) drying system was analyzed using both conventional and advanced exergy analyses. Three medicinal and aromatic plants (Foeniculum vulgare Malva sylvestris L. and Thymus vulgaris) were dried in a pilot scale GEHP drier which was designed constructed and installed in Ege University Izmir Turkey. Drying experiments were performed at an air temperature of 45 C with an air velocity of 1 m/s. For each system component avoidable and unavoidable exergy destructions modified exergy efficiency values and modified exergy destruction ratios were determined. Except for the compressor the evaporator and the drying cabinet most of the exergy destructions in the system components were avoidable and these avoidable parts can be reduced by design improvements. For the HP unit and the overall drying system the values for exergy efficiency were obtained to be in the range of 82.51-85.11% and 79.71-81.66% while those for the modified exergy efficiency were calculated to be in the range of 85.70-89.26% and 84.50-86.00% respectively. © 2013 Elsevier Ltd. All rights reserved. © 2013 Elsevier B.V. All rights reserved.