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Advanced Exergy Analysis of a Heat Pump Drying System Used in Food Drying
(Taylor & Francis Inc, 2013) Erbay, Zafer; Hepbasli, Arif
Exergy analysis has been used as a powerful tool to study and optimize various types of energy systems. However, the methodology of splitting the exergy destructions (the so-called advanced exergy analysis) allows for a further understanding of the exergy destruction values to improve the system efficiency. In this study, advanced exergy analysis was applied to a pilot-scale heat pump drying system used in food drying for the first time to evaluate its performance at different drying temperatures. The results showed that inefficiencies within the compressor and condenser were mainly due to the internal operating conditions and the efficiencies in the evaporator and heat recovery system could be improved by structural improvements of the whole system and remaining system components.
Beyaz peynir tozu üretiminde peynir suyu ve maltodekstrin kullanımının ürün kalitesi ve depolama stabilitesi üzerine etkileri
(Ege Üniversitesi, 2013) Erbay, Zafer; Koca, Nurcan
Cheese powder, Whey, Maltodextrin, Storage, Spray drying.;Peynir tozu, Peynir suyu, Maltodekstrin, Depolama, Püskürtmeli kurutma.;Peynir tozu; patates cipslerinde, çerez kaplamalarda, pizzalarda, bisküvilerde, soslarda, tuzlu çeşnilerde, çorbalarda, makarna ve sufle-kek türü ürünlerde kullanılmakta olan, maliyetli bir üründür. Bu çalışmada, ülkemizde yaygın olarak tüketilen bir peynir çeşidi olan beyaz peynirden püskürtmeli kurutma ile elde edilen beyaz peynir tozunun ürün maliyetini düşürmek ve kalite özelliklerini geliştirmek için, üretiminde peynir suyu ve maltodekstrin ilavesi denenmiştir. Bu amaçla, 174.2 °C giriş sıcaklığı, 353.8 kPa atomizasyon basıncı ve 68.1 °C çıkış sıcaklığındaki işlem koşullarında pilot çaplı püskürtmeli bir kurutucu sistem kullanılarak 3 farklı beyaz peynir tozu üretilmiş ve peynir suyu ile maltodekstrin ilavesinin toz ürün kalitesi üzerine etkileri saptanmıştır. Aynı zamanda, üretilen tozlar PET/Al/LDPE ile ambalajlanmış, 12 ay boyunca 20 °C'de, yaklaşık %40-50 bağıl nem koşullarında depolanmış ve depolama süresince toz kalite özelliklerindeki değişim saptanmıştır. Maltodekstrin ilavesi ile üretilen beyaz peynir tozunun fiziksel-fonksiyonel özelliklerinin belirgin şekilde geliştiği, ancak duyusal beğenisinin düştüğü saptanmıştır. 12 aylık depolama süresince, tozların kalite özelliklerinde kimi değişiklikler olmakla beraber, tüketilebilir olma niteliğinde bir değişim gözlemlenmemiştir. Sonuçta, beyaz peynir tozunun maliyetini düşürmek ve kalitesini özelliklerini yükseltmek için üretimde maltodekstrin kullanımı umut verici sonuçlar vermiştir.
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.
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.
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.
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.
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.
Energetic, Exergetic, and Exergoeconomic Analyses of Spray-Drying Process during White Cheese Powder Production
(Taylor & Francis Inc, 2012) Erbay, Zafer; Koca, Nurcan
In this study, white cheese powder was produced using a pilot-scale spray dryer. Drying experiments were carried out with an inlet drying air temperature range of 160-230 degrees C, an outlet drying air temperature range of 60-100 degrees C, and an atomization pressure range of 294.2-588.4 kPa. The performance of the spray-drying process and the effects of process conditions on the process performance were evaluated using energetic, exergetic, and exergoeconomic analyses. The performance assessment was performed by using energy and exergy efficiencies, improvement potential ((I) over dotP) rate, total cost, and exergoeconomic factor terms. A comprehensive parametric study was conducted to investigate the effect of varying dead-state temperatures on exergetic and exergoeconomic performance parameters for the drying process. Correlations between the performance parameters and dead-state temperatures were developed. Exergetic efficiency values and (I) over dotP rates were found to vary between 2.66 and 6.00% and 7.54 and 10.96 kW, respectively, and total costs and exergoeconomic factors were in the range 7.30-7.82 TL/h (Turkish lira per hour) and 76.09-81.93%, respectively.
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.
ENERGY AND EXERGY ANALYSES ON DRYING OF OLIVE LEAVES (OLEA EUROPAEA L.) IN TRAY DRIER
(Wiley-Blackwell, 2011) Erbay, Zafer; Icier, Filiz
Recently, olive leaves have a high potential for industrial exploitation in the food industry. The main process in olive leaf treatment is drying. Because drying is an energy-intensive process, analyzing and improving the drying systems is important. In this study, olive leaves were dried in a tray drier and the performance of the drying process was evaluated using energy and exergy analyses methods. The effects of the drying air temperature and the velocity on the performance of the drying process were discussed. While the energy utilization ratio values varied between 14.05% and 26.21%, the exergetic efficiencies varied between 55.95% and 75.12%. It was inferred that exergetic efficiencies increased as the drying air temperature decreased and the drying air velocity increased. They were influenced mainly by the drying air temperature.
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.
Exergetic analysis and evaluation of a new application of gas engine heat pumps (GEHPs) for food drying processes
(Elsevier Sci Ltd, 2011) Gungor, Aysegul; Erbay, Zafer; Hepbasli, Arif
In this study, three medicinal and aromatic plants (Foeniculum vulgare, Malva sylvestris Land Thymus vulgaris) were dried in a pilot scale gas engine driven heat pump drier, which was designed, constructed and installed in Ege University, Izmir, Turkey. Drying experiments were performed at an air temperature of 45 degrees C with an air velocity of 1 m/s. In this work, the performance of the drier along with its main components is evaluated using exergy analysis method. The most important component for improving the system efficiency is found to be the gas engine, followed by the exhaust air heat exchanger for the drying system. An exergy loss and flow diagram (the so-called Grassmann diagram) of the whole drying system is also presented to give quantitative information regarding the proportion of the exergy input dissipated in the various system components, while the sustainability index values for the system components are calculated to indicate how sustainability is affected by changing the exergy efficiency of a process. Gas engine, expansion valve and drying ducts account for more than 60% amount of exergy in the system. The exergetic efficiency values are in the range of 77.68-79.21% for the heat pump unit, 39.26-43.24% for the gas engine driven heat pump unit, 81.29-81.56% for the drying chamber and 48.24-51.28% for the overall drying system. (C) 2010 Elsevier Ltd. All rights reserved.
Exergetic performance assessment of a pilot-scale heat pump belt conveyor dryer
(Wiley-Blackwell, 2010) Erbay, Zafer; Icier, Filiz; Hepbasli, Arif
In this study, olive leaves were dried in a pilot-scale heat pump (HP) belt conveyor dryer as a thin layer. Drying experiments were carried out at the drying air temperature range of 45-55 degrees C with the drying air velocity range of 0.5-1.5 m s(-1). The performance of the system and the process was evaluated using exergy analysis method. The exergy loss and flow diagram (the so-called Grassmann diagram) of the dryer system was presented to give quantitative information regarding the proportion of the exergy input that is dissipated in the various system components. Effects of the drying air temperature and the velocity on the performance of the drying process were discussed. The actual coefficient of performance values were obtained to be 2.37 for the HP unit and 2.31 for the overall system, respectively. The most important component of the system for improving the efficiency was determined to be the compressor. Exergetic efficiencies of the drying of olive leaves were in the range of 67.45-81.95%. It was obtained that they increased as the drying air temperature decreased and the drying air velocity increased. Copyright (C) 2009 John Wiley & Sons, Ltd.
Exergoeconomic (Thermoeconomic) Analysis and Performance Assessment of a Gas Engine-Driven Heat Pump Drying System Based on Experimental Data
(Taylor & Francis Inc, 2012) Gungor, Aysegul; Erbay, Zafer; Hepbasli, Arif
Exergoeconomic analysis has been used as a powerful tool to study and optimize various types of energy-related systems. In this study, we use the specific exergy cost (SPECO) method to calculate exergy-related parameters and display cost flows for all streams and components in a gas engine-driven heat pump drying system based on the experimental data. We analyze and evaluate the performance of the drying system components and the drying process for three different medicinal and aromatic plants from an exergoeconomic point of view. We also investigate the effect of varying dead (reference) state temperatures on exergoeconomic performance parameters for the drying system components and drying process. Although the condenser and drying chamber of the gas engine-driven heat pump dryer were significantly affected by the ambient temperature, the gas engine was slightly influenced by the ambient temperature. At low ambient temperatures, the exergy rates increased and the most effective performance obtained from this dryer was at 0 degrees C. The performance of the drying process also increased at low ambient temperatures. This study demonstrated that exergoeconomic analysis can provide more information than exergy analysis, and the results obtained from the exergoeconomic analysis provided cost-based information, suggesting potential locations for drying system improvement.
Exergoeconomic analyses of a gas engine driven heat pump drier and food drying process
(Elsevier Sci Ltd, 2011) Gungor, Aysegul; Erbay, Zafer; Hepbasli, Arif
Exergoeconomic analysis of a pilot scale gas engine driven heat pump (GEHP) drying system is performed based on the experimental values using Exergy, Cost, Energy and Mass (EXCEM) analysis method in this study. The performance of the drying system components is discussed, while the important system components are determined to improve the system efficiency. The performance of the drying process is also analyzed for three different medicinal and aromatic plants from the exergoeconomic point of view. A comprehensive parametric study is conducted to investigate the effect of varying dead (reference) state temperatures on exergoeconomic performance parameters for both drying system components and drying process. The correlations between the performance parameters and dead state temperatures are developed. The results have indicated that the dead state temperature affects the performance parameters, particularly the drying process parameters. Rising the dead state temperature leads to an increase in the exergy efficiencies of the drying process and a decrease in the ratio of the thermodynamic loss rate to the capital cost (<(R)over dot>(ex)) values in a polynomial form. <(R)over dot>(ex), values of the drying process are obtained to be very higher compared to those of the drying system components. (C) 2011 Elsevier Ltd. All rights reserved.
Exergoeconomic performance assessment of a pilot-scale spray dryer using the specific exergy costing method
(Academic Press Inc Elsevier Science, 2014) Erbay, Zafer; Koca, Nurcan
In this study, exergoeconomic analysis was performed to evaluate the performance of a pilot scale spray dryer during white cheese powder production by the specific exergy costing (SPECO) method. Drying experiments were carried out at an inlet drying air temperature range of 160-230 degrees C, an outlet drying air temperature range of 60-100 degrees C and an atomisation pressure range of 294.2-588.4 kPa. The components of drying system were separately analysed and the effects of operating conditions on system components and the overall system were discussed. Improvements for the drying cabinet should be focused on for process optimisation, whereas structural improvements of the atomiser should strongly be considered for reducing investment costs. Furthermore, investment costs for the feed pump used in the drying system should be decreased or the feed pump should be replaced with a cheaper one. While results showed high inlet and low outlet air temperatures caused high effectiveness for the overall system performance, the operating costs were the most important variable due to expenses. (c) 2014 IAgrE. Published by Elsevier Ltd. All rights reserved.
Investigating the effects of operating conditions on the exergetic performance of a pilot-scale spray-drying system
(Inderscience Enterprises Ltd, 2012) Erbay, Zafer; Koca, Nurcan
In this study, performance of a pilot scale spray drier was evaluated by exergy analysis method. Performance parameters were investigated for the components of the drying system and overall system. Furthermore, the effects of process conditions such as atomisation pressure, inlet and outlet drying air temperatures on the performance of the spray drier were analyzed. While the most effective system component was determined as heater, atomizer was the most important component with the highest improvement potential rate. Results showed that high inlet and low outlet air temperatures caused high effectiveness for overall system performance.
Kinetics of Total Phenolic Content and Total Color Difference During Liquid Smoking of Kashar Cheese
(Taylor & Francis Inc, 2013) Erbay, Zafer; Koca, Nurcan
Since the late 1800s, smoking has been used for giving color, taste, and aroma to foods, as well as for developing new products. Due to health, technical, and economic reasons, one of the widely used smoking techniques preferred by manufacturers is smoking with liquid smoke. In this study, fresh Kashar cheese slices were smoked by immersion in liquid smoke at concentrations (10, 20, 30%), smoking temperatures (20, 30, 40 degrees C) and smoking times (30, 60, 120, 180, 300 s). The appropriate equation and kinetic parameters were determined for the variation of total phenolic content and total color difference. A pseudo-first-order kinetic model was obtained, and activation energy values were calculated as 10.7 kJ/mol and 24.3 kJ/mol, respectively.
Optimization of Drying of Olive Leaves in a Pilot-Scale Heat Pump Dryer
(Taylor & Francis Inc, 2009) Erbay, Zafer; Icier, Filiz
Recently, the interest in olive leaf has increased due to its high phenolic content. It has a high potential for industrial exploitation in food industry and the main process in olive leaf treatment is drying. Drying affects the product quality and is an energy-intensive process, so the use of heat pumps in drying processes that have low operating cost has attracted the attention of the investigators. In this study, response surface methodology was used to optimize operating conditions of drying of olive leaves in a pilot-scale heat pump conveyor dryer. The independent variables were air temperature, air velocity, and process time, and the responses were total phenolic content and antioxidant activity loss, final moisture content, and exergetic efficiency. Optimum operating conditions were found to be temperature of 53.43C, air velocity of 0.64 m/s, process time of 288.32min. At this optimum point, total phenolic content loss, total antioxidant activity loss, final moisture content, and exergetic efficiency were found to be 9.77%, 44.25%, 6.0% (w.b.), and 69.55%, respectively.
Optimization of hot air drying of olive leaves using response surface methodology
(Elsevier Sci Ltd, 2009) Erbay, Zafer; Icier, Filiz
Recently, the interest in olive leaves has increased due to its high phenolic content. Olive leaves have a high potential for industrial exploitation in the food industry and drying is the main process in olive leaf treatment. In this Study, response surface methodology was used to optimize operating conditions of the drying of olive leaves in a tray drier and desirability function used as the methodology for the optimization. Optimization factors were air temperature (40-60 degrees C), air velocity (0.5-1.5 m/s) and process time (240-480 min) while investigated responses were total phenolic content (PC) and antioxidant activity loss (AC), final moisture content (MC), and exergetic efficiency (eta). The optimum conditions for drying of olive leaves in a tray drier were determined to obtain the criteria; minimum PC and AC, and maximum eta for MC value below 6% and the optimum condition was found to be the temperature of 51.16 degrees C with the air velocity of 1.01 m/s for the process time of 298.68 min. At this optimum point, PC, AC, MC and eta were found as 10.25%, 41.88%, 6.0% and 65.50%, respectively. (C) 2008 Elsevier Ltd. All rights reserved.

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