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    Advanced exergoeconomic evaluation of a heat pump food dryer
    (Academic Press Inc Elsevier Science, 2014) Erbay, Zafer; Hepbasli, Arif
    In this study, the results of conventional and advanced exergoeconomic analyses of the performance of a pilot scale air-source heat pump food dryer were compared for the first time. The contributions of the components of the drying system to the exergetic cost effectiveness of the dryer were evaluated, and the effects of changing the inlet drying temperature were determined. The most important system component was determined to be the heat recovery unit, followed by the condenser with respect to the reducing potentials for the total costs of the overall system. Decreasing temperature caused an increase in the cost performance of drying. The modification of the system components for improving the efficiency of the system can be effectively determined through advanced exergoeconomic approach by stating the realistic potential improvements and the priorities in the system. (c) 2014 IAgrE. Published by Elsevier Ltd. All rights reserved.
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    Application of conventional and advanced exergy analyses to evaluate the performance of a ground-source heat pump (GSHP) dryer used in food drying
    (Pergamon-Elsevier Science Ltd, 2014) Erbay, Zafer; Hepbasli, Arif
    Inefficiencies in an energy system can be quantitatively determined through conventional exergy analysis while sources of the irreversibilities and real improvement potential can be deducted using a relatively new method named as advanced exergy analysis. For the first time, an advanced exergy analysis is applied to a ground-source heat pump (GSHP) drying system used in food drying for evaluating its performance along with each component in this study. The results indicate that the most important system component is the condenser due to the design standpoint. The inefficiencies within the compressor could particularly be improved by structural improvements of the whole system and the remaining system components. Furthermore, the inefficiencies of other system components except for the condenser and the evaporator are mainly affected by the internal operating condition. Both the equipment design and system components' interactions of the condenser and the evaporator have a significant effect on their inefficiencies. The conventional and modified (advanced) exergy efficiency values are calculated to be 77.05% and 93.5%, respectively. (C) 2013 Elsevier Ltd. All rights reserved.
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    Assessment and optimisation of ultrasound as a pretreatment in the production of enzyme-modified cheese
    (Elsevier Sci Ltd, 2023) Yilmaz, Ebru; Kurban, Mithat; Erbay, Zafer
    Ultrasound (US) technology has the potential to modify protein structures and accelerate enzymatic reactions through the application of low-frequency high energy. This study aimed to produce enzyme -modified cheese (EMC), which has a concentrated cheese flavour, using US pretreatment in a two -stage process involving proteolysis followed by lipolysis. The optimisation of the proteolysis stage was performed by adjusting the US power, US processing time, and proteolysis time. Optimal conditions were determined to be 46.28 W US power, 9.8 min US pretreatment, and 10.49 h proteolysis. These conditions resulted in a 12.5% reduction in the proteolysis time and produced an EMC comparable with one pro-duced without US pretreatment for 12 h proteolysis. The characteristics of the final EMC were evaluated after the lipolysis stage and it was found that the free fatty acid and volatile content were primarily determined by lipolysis, which was not influenced by US pretreatment applied prior to proteolysis.(c) 2023 Elsevier Ltd. All rights reserved.
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    Assessment of cost sources and improvement potentials of a ground-source heat pump food drying system through advanced exergoeconomic analysis method
    (Pergamon-Elsevier Science Ltd, 2017) Erbay, Zafer; Hepbasli, Arif
    Advanced exergoeconomic analysis, the so-called new exergetic approach combined with the economic analysis, is applied to a ground-source heap pump (GSHP) drying system in this study. The thermodynamic inefficiencies and cost performance of the system components are evaluated in parts. Moreover, the results of the advanced exergoeconomic analysis are compared to those of the conventional exergoeconomic analysis. The results show that total costs in the overall system are 4.008 $/h whereas 2.569 $/h of the total costs are avoidable. The avoidable investment costs are significantly lower than avoidable destruction costs. Advanced exergoeconomic analysis indicates that the most important system components are the drying duct and the condenser with respect to reducing the costs. It is possible to reduce 34.6% of the total costs by developing improvement strategies focused on the drying duct and the condenser. It may be concluded that the conventional exergoeconomic analysis is an effective approach to specify the components, in which costs are accumulated while the advanced exergoeconomic approach is essential to determine the cost sources and to develop cost effective improving strategies. (C) 2017 Elsevier Ltd. All rights reserved.
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    Assessment of Sustainability in the Supply Chain of Sweet Red Pepper Paste Production With Exergy and Life Cycle Analyses
    (Wiley, 2024) Adal, Samiye; Erbay, Zafer
    This study examines cumulative energy (CEnC), exergy (CExC), CO2 emissions (CCO2C), and life cycle assessment of sweet red pepper (SRP) paste production. A whole system approach in five improvement scenarios including different packaging materials and precision farming encompasses the supply chain from farm to fork and cradle to gate. The largest impact on SRP farming is caused by the use of diesel oil, the excessive use of chemical fertilizers, and the use of electricity. In SRP farming step, the CEnC is mainly caused by 86.5% fertilizer and 11% diesel usage. Hotspot impact categories were determined as abiotic (fossil) depletion potential, global warming potential, and human toxicity potential. The base case scenario has the greatest values for CEnC, CExC, and CCO2C and impact assessment results. A CEnC value reduction of 48.6%, 50%, and 30% in the factory processing, packaging-transportation step and whole process, respectively, is observed when the biodiesel scenario is performed. With a 40% reduction in global warming potential value, the combination of polyethylene terephthalate packaging, biodiesel, and precision farming scenario yielded the best results for each impact category analyzed in this study.
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    Assessment of Whole Milk Powder Production by a Cumulative Exergy Consumption Approach
    (Mdpi, 2023) Ucal, Esmanur; Yildizhan, Hasan; Ameen, Arman; Erbay, Zafer
    The production of food is a sector that consumes a significant amount of energy and encompasses both agricultural and industrial processes. In this study, the energy consumption of whole milk powder production, which is known to be particularly energy-intensive, was examined. The study used a cumulative exergy consumption approach to evaluate the overall production process of whole milk powder, including the dairy farm (raw milk production) and dairy factory (powder production) stages. The results showed that raw milk production dominated energy and exergy consumption and carbon dioxide emissions. An amount of 68.3% of the total net cumulative exergy consumption in the system was calculated for raw milk production. In the dairy factory process, the highest energy/exergy consumption occurred during spray drying, followed by evaporation and pasteurization. In these three processes, 98.3% of the total energy consumption, 94.6% of the total exergy consumption, and 95.7% of the total carbon dioxide emissions in powder production were realized. To investigate the improvement potentials in the system, replacing fossil fuels with renewable energy sources and using pasture feeding in animal husbandry were evaluated. While using alternative energy sources highly influenced powder production, pasture feeding had a high impact on consumption in raw milk production. By using renewable energy and pasture feeding, the exergy efficiency, cumulative degree of perfection, renewability index, and exergetic sustainability index values for the overall process increased from 40.5%, 0.282, -0.22, and 0.68 to 68.9%, 0.433, 0.65, and 2.21, respectively.
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    Bioactive potential of ripened white cheeses manufactured in different geographical regions of Turkey
    (Wiley, 2023) Keyf, Pelin; Ugurlu, Ozlem; Erkin, Ozgur Cem; Aydemir, Levent Yurdaer; Erbay, Zafer
    This study investigated the potential bioactive properties of white cheeses produced in different regions of Turkey, including their potential antioxidant, antihypertensive, antidiabetic, antimicrobial, and anticancer activities. The cheese samples were analyzed both before and after in vitro digestion. The study found that all cheese samples exhibited significant angiotensin-converting enzyme inhibition activity both before (45.5%-70.1% for 0.03 g cheese/mL) and after in vitro digestion (25.5%-63.5% for 0.0167 g cheese/mL), whereas alpha-amylase inhibition activity was present in all samples (in the range of 5.1%-50.0% for 3.0 x 10(-5) g cheese/mL) but disappeared after digestion, and alpha-glucosidase inhibition activity was only detected after in vitro digestion (from 20.5% to 60.4% for 5.6 x 10(-5) g cheese/mL), indicating potential antidiabetic properties. However, antimicrobial and anticancer activities were not observed in any of the samples. The results also suggest that the bioactivity potential of white cheese may vary depending on the region of production, as cheeses from the Marmara region exhibited high alpha-glucosidase inhibition activity after digestion. In conclusion, while white cheese is a valuable addition to the diet due to its high nutritional value and potential health benefits. This study revealed the bioactive potential of ripened white cheese and in vivo investigations of the cheese components would better show their possible benefits.
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    Casein-Hydrolysate-Loaded W/O Emulsion Preparation as the Primary Emulsion of Double Emulsions: Effects of Varied Phase Fractions, Emulsifier Types, and Concentrations
    (Mdpi, 2023) Salum, Pelin; Ulubas, Cagla; Güven, Onur; Aydemir, Levent Yurdaer; Erbay, Zafer
    Stable primary emulsion formation in which different parameters such as viscosity and droplet size come into prominence for their characterization is a key factor in W/O/W emulsions. In this study, different emulsifiers (Crill (TM) 1, Crill (TM) 4, AMP, and PGPR) were studied to produce a casein-hydrolysate-loaded stable primary emulsion with lower viscosity and droplet size. Viscosity, electrical conductivity, particle size distribution, and emulsion stability were determined for three different dispersed phase ratios and three emulsifier concentrations. In 31 of the 36 examined emulsion systems, no electrical conductivity could be measured, indicating that appropriate emulsions were formed. While AMP-based emulsions showed non-Newtonian flow behaviors with high consistency coefficients, all PGPR-based emulsions and most of the Crill (TM)-1- and -4-based ones were Newtonian fluids with relatively low viscosities (65.7-274.7 cP). The PGPR-based emulsions were stable for at least 5 days and had D(90) values lower than 2 mu m, whereas Crill (TM)-1- and -4-based emulsions had phase separation after 24 h and had minimum D(90) values of 6.8 mu m. PGPR-based emulsions were found suitable and within PGPR-based emulsions, and the best formulation was determined by TOPSIS. Using 5% PGPR with a 25% dispersed phase ratio resulted in the highest relative closeness value. The results of this study showed that PGPR is a very effective emulsifier for stable casein-hydrolysate-loaded emulsion formations with low droplet size and viscosity.
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    Composition, proteolysis, lipolysis, volatile compound profile and sensory characteristics of ripened white cheeses manufactured in different geographical regions of Turkey
    (Elsevier Sci Ltd, 2018) Salum, Pelin; Govce, Gokce; Kendirci, Perihan; Bas, Deniz; Erbay, Zafer
    Turkish white cheese is the most important cheese variety made in Turkey and significant variations are commonly observed in their properties (mainly sensory). White cheese samples were collected from different geographical regions of Turkey and analysed to determine the common characteristics and to investigate the effects of the regional differences arising from differential natural conditions and the natural variations in raw milk. Although the samples showed similar compositional properties, there were significant variations in the ripening parameters and flavour attributes. Forty-five volatile compounds were identified and a descriptive vocabulary consisting of 15 common attributes were used to describe Turkish white cheese. Cheeses with moderate proteolytic ripening degrees and high lipolytic ripening values caused an increase in the preference score. Moreover, the increase in the volatile acid contents positively affected the preference. The most preferred cheeses were manufactured in two neighbouring provinces located in the north-west of the country. (C) 2018 Elsevier Ltd. All rights reserved.
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    Converting Milk Fat into Powder and Cream Powder
    (Sidas Medya A.S., 2019) Himmetağaoğlu, Ahsen Burçin; Erbay, Zafer; Çam, Mustafa
    Milk fat is the main component and a quality-enhancing ingredient for dairy products such as cream and butter. The increase in worldwide milk production and demand of reduced fat products due to changing of dietary habits, create a surplus of butter and milk fat supply. Milk fat is highly perishable with a short shelf life. Butter is stable at room temperature for about 4 weeks and about 6 months at low refrigeration temperature. However, cold storage is expensive compared to drying and drying becomes a low-cost alternative. Milk fat can be transformed into powder form by spray drying. However, even in dried form, some undesired changes such as fat oxidation and Maillard reaction may occur in dairy powders. Through the microencapsulation technique, stable and durable products can be obtained. In this study, the importance of converting milk fat into powder form and cream powder production are explained, and scientific studies on in the field of conversion of milk fat into powder are summarized. © 2019 Authors. All rights reserved.
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    Design and process optimisation of double emulsions loaded with casein hydrolysate
    (Elsevier Sci Ltd, 2024) Salum, Pelin; Ulubas, Cagla; Guven, Onur; Cam, Mustafa; Aydemir, Levent Yurdaer; Erbay, Zafer
    Water-in-oil-in-water (W1/O/W2) emulsions show promise for encapsulating hydrophilic active substances. However, the low stability of W1/O/W2 hinders its use for encapsulation purposes, and peptide encapsulation has challenges due to its surface-active properties. This study aimed to determine the appropriate formulation based on turbidity and encapsulation efficiency, as well as the optimal production parameters (ultrasound amplitude and time) for double emulsions containing casein hydrolysate, with a focus on the second homogenisation stage. Double emulsions were produced with three different emulsifiers (polysorbates 20, 60, or 80) at different concentrations (0.25%, 1%, or 1.75%) and dispersed phase ratios (10%, 20%, or 30%) using an ultrasound homogeniser. The results indicated that dispersed phase ratios and emulsifier concentrations had higher impact on emulsion properties than emulsifier types. A stable emulsion with high encapsulation efficiency was achieved with 1% polysorbate 20 and a 30% dispersed phase ratio, using sonication at 54% amplitude for 66 s. (c) 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
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    Drying of dairy products
    (Elsevier, 2023) Erbay, Zafer; Salum, Pelin; Bolat, Enise Betül
    Milk is a special raw material in the food industry, with its unique components, these components' valuable properties, ease of fractionation, and susceptibility to change. All these features create important opportunities and grounds for the drying of dairy products. Today, a wide variety of dried dairy products are available in the market, and studies continue to improve their quality and variety. Moreover, researchers have carried out studies to preserve the valuable dairy ingredients during drying and deliver them in their active form to the organs, where they will present their prospective impact. As the drying of dairy products is a comprehensive topic, in this chapter, dried dairy products are summarized, and the recent efforts to overcome the challenges in their production are discussed within the scope of some highlighted issues. © 2023 Elsevier Inc. All rights reserved.
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    Effects of milk types used in Antep cheese production on some cheese organoleptic quality parameters and brine composition during 5-month ripening
    (Wiley, 2023) Ertekin, Mahmut; Ugurlu, Ozlem; Salum, Pelin; Erbay, Zafer
    Antep cheese is a local Turkish cheese characterized by scalding during production and ripened in brine. In this study, Antep cheeses were produced using mixtures of different milk types (cow, sheep, and goat milk) and ripened for 5 months. The composition, proteolytic ripening extension index (REI), free fatty acid (FFA) content, and volatile compounds of the cheeses and the variation of the brines were analyzed for the 5-month ripening period. Low proteolytic activity in cheese during ripening caused the cheeses to have low REI values (3.92%-7.57%), although it was observed that some parts of the water-soluble nitrogen fractions diffused into the brine, causing a lower REI. As a result of lipolysis during ripening, total FFA (TFFA) concentrations in all cheeses were increased, whereas the highest increases were detected in the concentrations of short-chain FFAs. The highest FFA concentrations were determined in cheese produced using goat milk, and the volatile FFA ratio in TFFA exceeded 10% in the third month of ripening. Although it was observed that the milk types used in the production had significant effects on the change of volatile compounds of the produced cheeses and their brines, the impact of the ripening time was more important. Practical ApplicationThis study investigated Antep cheese made with different milk types. Volatile compounds and soluble nitrogen fractions were transferred to the brine by diffusion during ripening. The volatile profile of the cheese varied with milk type, but ripening time was the primary factor influencing volatile compounds. This suggests that the targeted organoleptic properties of the cheese are determined by ripening time and conditions. Additionally, changes in the brine's composition during the ripening process provide insight into how to manage the brine as waste.
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    Effects of spray drying process conditions on the quality properties of microencapsulated cream powder
    (Elsevier Sci Ltd, 2019) Himmetagaoglu, Ahsen Burcin; Erbay, Zafer
    Effects of spray drying conditions including inlet drying temperature (150, 170 or 190 degrees C), feed flow rate (9.0, 19.5 or 30 mL min(-1)), and aspiration rate (50, 75 or 100%) on the composition, water activity, reconstitution, density, colour, morphology, surface fat and free fatty acid content of microencapsulated cream powder were evaluated. The variation in the wettability, bulk and tapped densities, surface fat and volatile fatty acid contents of the powders showed similar tendencies with the spray drying parameters. In contrast, moisture content, fat content, water activity, solubility, and colour properties were not influenced by the processing conditions. High inlet drying temperature, low or high aspiration rates, and high feed flow rate caused undesirable powder properties. According to the results, processing conditions that cause high drying rates should not be applied for production of a high-quality microencapsulated cream powder. (C) 2018 Elsevier Ltd. All rights reserved.
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    Effects of spray-drying conditions on the chemical, physical, and sensory properties of cheese powder
    (Elsevier Science Inc, 2015) Koca, Nurcan; Erbay, Zafer; Kaymak-Ertekin, Figen
    Dairy powders are produced to increase the shelf life of fresh dairy products and for use as flavoring agents. In this study, 24 cheese powders produced under 7 different conditions were used to investigate the effects of spray-drying parameters (e.g., inlet air temperature, atomization pressure, and outlet air temperature) on the quality of white cheese powder. Composition, color, physical properties, reconstitution, and sensory characteristics of white cheese powders were determined. The results revealed that the white cheese powders produced in this study had low moisture content ratios and water activity values. High outlet air temperatures caused browning and enhanced Maillard reactions. Additionally, high outlet air temperatures increased wettability and dispersibility and decreased the solubility of white cheese powders. Free fat content was positively correlated with inlet air temperature and negatively correlated with outlet air temperature and atomization pressure. Sensory analyses revealed that white cheese powder samples had acceptable sensory characteristics with the exception of the sample produced at an outlet air temperature of 100 degrees C, which had high scores for scorched flavor and color and low scores for cheese flavor.
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    Effects of using whey and maltodextrin in white cheese powder production on free fatty acid content, nonenzymatic browning and oxidation degree during storage
    (Elsevier Sci Ltd, 2019) Erbay, Zafer; Koca, Nurcan
    Use of maltodextrin and whey improves the physical properties of spray-dried cheese powder and, as cheese replacers, they decrease the raw material costs. However, it is necessary to evaluate their effects on the chemical quality and sensory properties of the product. Three powders, control (CON), whey-added cheese powder (WACP), and maltodextrin-added cheese powder (MACP) were produced to determine free fatty acid (FFA) content, degree of nonenzymatic browning, oxidation, and sensory (flavour) changes during 12 months' storage. In the emulsion preparation and drying process, total volatile FFAs decreased up to 9% and 53.5%, respectively, with higher decrease in CON than in WACP or MACP. Although whey increased oxidation degree of powder, oxidised flavour could not be perceived until the ninth month of storage. Maltodextrin slightly decreased cheese flavour and overall impression scores. There was no difference detected in the powders for scorched flavour. (C) 2019 Published by Elsevier Ltd.
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    Effects of whey or maltodextrin addition during production on physical quality of white cheese powder during storage
    (Elsevier Science Inc, 2015) Erbay, Zafer; Koca, Nurcan
    There is an increasing demand for cheese as a food ingredient, especially as a flavoring agent. One of the most important cheese flavoring agents is cheese powder. To obtain an intense cheese flavor, ripened cheese is used as a raw material in cheese powder but this increases production costs. Moreover, use of natural cheese decreases the physical quality of powder because of its high fat content. In this study, we evaluated opportunities to use whey or maltodextrin for improving the physical quality of powders in production of white cheese powder. We produced cheese powders with 3 different formulations control (CON), whey-added (WACP), and maltodextrin-added (MACP) and determined the effects of formulation on cheese powder quality. Physical quality parameters such as color, densities, reconstitution properties, free fat content, particle morphology, and sensory characteristics were investigated. The different cheese powders were stored for 12 mo at 20 degrees C and we evaluated the effect of storage on powder quality. Addition of maltodextrin to cheese powder formulations significantly improved their physical quality. The densities and reconstitution properties of cheese powder were increased and free fat content was decreased by use of maltodextrin. The MACP particles were spherical with a uniform distribution and larger particle sizes, whereas CON and WACP particles were wrinkled, irregularly shaped with deep surface dents, and variable in size. Although caking was observed in scanning electron micrographs after 12 mo of storage, it was not detected by sensory panelists. The color of cheese powders changed very slowly during storage but browning was detected. The results of this study show that it is possible to use maltodextrin or whey in production of white cheese powder to reduce production costs and improve the physical quality of powders.
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    Energy and exergy analyses of a fluidized bed coal combustor steam plant in textile industry
    (Elsevier Sci Ltd, 2016) Ozdil, N. Filiz Tumen; Tantekin, Atakan; Erbay, Zafer
    In this study, the analyses of first and second laws of thermodynamic are presented for a 6.5 MW power plant located in Adana, Turkey. The system components, examined in the present study, are listed as a fluidized bed coal combustor (FBCC), a heat recovery steam generator (HRSG), an economizer (ECO), fans, pumps, a cyclone and a chimney. All of the system components are examined one by one and the energy and exergy analyses are carried out for all of the system components. The highest value of irreversibility is observed in the FBCC, about 93% of the entire system irreversibility tracked by HRSG and ECO with 3% and 1%, respectively. The high excess air value, which is the primary origin of irreversibility, causes the heat losses from the FBCC, due to the increment in mass flow rate of the combustion gas. Moreover, the high excess air value gives rise to occurrence of low combustion efficiency in FBCC which can be decreased through decreasing flow rate of air with decreasing oxygen. Secondly, changes in the energy and exergy efficiencies are examined employing different ambient temperature. As the ambient temperature increases, the second law efficiencies of FBCC and HRSG increases but efficiency of ECO decreases. (C) 2016 Elsevier Ltd. All rights reserved.
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    Energy and exergy analyses of spray drying of a fruit puree (cornelian cherry puree)
    (Inderscience Enterprises Ltd, 2015) Saygi, Gulsefa; Erbay, Zafer; Koca, Nurcan; Pazir, Fikret
    In this study, a fruit powder was produced from the mixture of cornelian cherry puree (CCP)/maltodextrin by spray drying. The performance of spray drying process and the drying system was evaluated by energy and exergy analyses. Experiments were carried out with an inlet drying air temperature range of 130-160 degrees C, an outlet drying air temperature range of 65-85 degrees C and CCP/maltodextrin ratio was chosen as 60/40, 50/50, and 40/60 (w/w). While the energetic and exergetic efficiencies for the drying process were calculated between 3.2-17.3% and 0.7-4.1%, the exergetic efficiencies of the spray dryer and overall system were found to vary between 27.0-39.1% and 26.7-32.9%, respectively. Results showed that high inlet and low outlet air temperatures caused high effectiveness for drying process. However, maltodextrin concentration of the feed did not have significant effects on the process performance.
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    Enhanced exergetic analysis of an olive oil refining plant: evaluation of the first and second level of exergy destructions
    (Inderscience Enterprises Ltd, 2019) Bozoglan, Elif; Erbay, Zafer; Hepbasli, Arif; Gunerhan, Huseyin
    Enhanced exergy analysis is built up as a novel modality to specify the origins of irreversibilities and to concentrate substantial improvement potential of components. The scope of this paper is to apply the enhanced exergy analysis to an olive oil refinery plant operated in Izmir, Turkey, that is conducted for the first time to agree the first level (endogenous/exogenous) and the second level (combination of the endogenous/exogenous and unavoidable/avoidable parts studied before) of destructions for exposing substantial efficiencies. Results showed that the components in the plant mostly have endogenous exergy destructions. Besides, the distillation unit has the highest endogenous exergy destruction value of 150.9 kW as the avoidable and unavoidable endogenous sections are 76.85 and 74.08 kW, respectively. Furthermore, the shell and tube economiser has the highest modified (enhanced) exergetic efficiency of 99.9% while the modified performances of plate-heat exchanger and pump (VII) are calculated as 73% and 71.24%, respectively.