Ibrahim Yildiz and Hakan Caliskan
The purpose of this study is to evaluate the energy and exergy prices and carbon emission equivalents of the jet kerosene (Jet A-1) fuel considering 12 months data for an air…
Abstract
Purpose
The purpose of this study is to evaluate the energy and exergy prices and carbon emission equivalents of the jet kerosene (Jet A-1) fuel considering 12 months data for an air craft used in the air transport sector in Turkey.
Design/methodology/approach
In the selection of the energy resources, one of the most important factors besides the need is the price of the energy resources. To use and save the energy resources efficiently, the prices should be evaluated in terms of exergy too. In this context, the exergy prices and carbon emission equivalents of the jet kerosene fuel have been examined.
Findings
According to analysis results, after January 2020, a steady decline in energy prices has been obtained until April 2020. In this regard, directly proportional changes have been obtained in exergy prices. The minimum exergy price of the fuel is calculated as 74.36 US cents/kWh for April 2020, while the maximum exergy price of the fuel is calculated as 150.02 US cents/kWh for September 2019. The minimum exergy price based carbon emission equivalents for the jet kerosene fuel is determined as 1,099.98 US cents/kg for April 2020, while the maximum exergy price based carbon emission equivalents for the jet kerosene fuel is found to be 2,219.29 US cents/kg for September 2019.
Originality/value
The new contribution has been made to the open literature by examining the energy and exergy prices of the jet kerosene fuel. In addition, the carbon emission equivalents of the jet kerosene fuel have been determined not only energy but also exergy methods.
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Salim Caliskan and Hakan Akyuz
This study aims to investigate the effect of speckle pattern on displacement measurements using different speckle diameters and coverage ratios.
Abstract
Purpose
This study aims to investigate the effect of speckle pattern on displacement measurements using different speckle diameters and coverage ratios.
Design/methodology/approach
In order to compare the coverage ratio and speckle diameter during the evaluation of the correlation of digital images (DIC) study, template speckle plates were produced on a computer numerical control (CNC) punch press with 600 punches per minute. After the speckle plates were manufactured, the speckled pattern was randomly painted on a plain white side through the manufactured template plates, and then tensile tests were performed under the same loading conditions for each sample to observe displacement variation via correlation parameters.
Findings
During the manufacturing of templates with thin plates, a punch diameter of less than 1.7 mm will cause tool failure; therefore, uniform speckle size can be assessed before operation. A higher coverage ratio resulted in more accurate and reliable results in displacement data. With smaller coverage, the facet size should be increased to achieve favorable results.
Research limitations/implications
If thick template plates are selected, speckle painting cannot be done properly; therefore, template thickness shall also be assessed before operation.
Practical implications
For randomly distributed DIC templates, increasing coverage beyond 50% does not make sense due to difficulties in the production process in the punch press.
Originality/value
Evaluating DIC results via templates manufactured in a punch press with different speckle diameters and coverage ratios is a new topic in literature.
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Cuneyt Caliskan and K. Hakan Altintas
The purpose of this paper is to evaluate the time, place and ambulance types specified on the ambulance patient registry forms for cases transferred through 112 EMS in the…
Abstract
Purpose
The purpose of this paper is to evaluate the time, place and ambulance types specified on the ambulance patient registry forms for cases transferred through 112 EMS in the Bozcaada and Gökçeada island districts of the province of Çanakkale.
Design/methodology/approach
The universe of the descriptive – cross-sectional epidemiological study was composed of the ambulance patient registration forms of the cases which were transferred from Bozcaada and Gökçeada islands between January 1, 2009 and December 31, 2013.
Findings
Of the transfers made, 28.1 percent were in the year 2012, 39.5 percent were in summer, 16.6 percent were in July, 17.9 percent were on Monday, 37.1 percent were between 12.00 and 17.59 h and 61.5 percent were from Gökçeada island. Ground ambulances were more common in the transfers from Bozcaada island, while ambulance boat and helicopter ambulance were more common for transfers from Gökçeada island. Helicopter-Emergency Medical Service (HEMS) (p<0.001), which is commonly preferred for patient transfers, inversely affects the use of Ambulance Boat-Emergency Medical Service (BEMS) and ground ambulances. Transfers from Bozcaada island were found to be shorter in duration, and the number of transfers from Bozcaada island between 00.00 and 05.59 h were found to be higher than from Gökçeada island (p<0.001), while the number of transfers via ground ambulance between 00.00 and 05.59 h were found to be higher than the other ambulance types (p<0.001).
Practical implications
This study reveals the current state of the various referral routes from the islands.
Originality/value
This paper is the first study to demonstrate the characteristics of patients referred from the island belongs to Turkey.
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This study aims to evaluate variation of performance metrics involving specific fuel consumption (SFC), thrust, thermal efficiency and overall efficiency values of turboprop…
Abstract
Purpose
This study aims to evaluate variation of performance metrics involving specific fuel consumption (SFC), thrust, thermal efficiency and overall efficiency values of turboprop engine used in regional aircraft according to varying altitude of 0–9 km and 0.3–0.6 Mach ranges. Moreover, influences of design parameters such as overall pressure ratio (OPR) ranging between 12 and 15 and turbine inlet temperature (TIT) ranging between 1,200 K and 1,400 K regarding the engine are dealt with by using ideal and real codes of parametric cycle equations.
Design/methodology/approach
This study is performed based on thermodynamic analysis for real and ideal conditions by means of MATLAB software.
Findings
When considering influences of flight conditions, SFC of the PW127-E changes between 6.4 g/kNs and 13.75 g/kNs at ideal conditon whereas changes between 6.9 g/kNs and 14.64 g/kNs at real conditions. Moreover, overall efficiency of the engine varies between 28.3% and 35.5% at ideal, whereas it is found between 12.8% and 18.5% at real condition owing to varying altitude and Mach. On the other hand, with effects of design variables, SFC of the engine changes between 9.59 g/kNs and 10.38 g/kNs at ideal however 11.74 g/kNs and 12.76 g/kNs at real. Lastly, overall efficiency of the engine resides between 30.61% and 33.13% at ideal whereas between 14.37% and 18.61% at real due to varying OPR and TIT variables.
Practical implications
It is expected that this study helps in understanding how to vary performance metrics of the engine according to internal variables and external conditions. Namely, the approach used in present study could benefit the determination of the on-design and off-design performance of the engine in theoretical manner.
Originality/value
The novelty of this study is to present performance analysis of the three-shaft PW127-E turboprop by considering the effect of design parameters and flight conditions on engine performance in ideal and real conditions.
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Hamidou Benzenine, Rachid Saim, Said Abboudi, Hakan F. Öztop and Nidal Abu-Hamdeh
The purpose of this paper is to present a three-dimensional (3D) analysis of the laminar flow of air and the conjugate heat transfer in a pipe of rectangular cross-section with a…
Abstract
Purpose
The purpose of this paper is to present a three-dimensional (3D) analysis of the laminar flow of air and the conjugate heat transfer in a pipe of rectangular cross-section with a solid or perforated deflector inserted on the lower wall.
Design/methodology/approach
To this end, by using the finite volume method, the conservation equations for mass, momentum and energy are solved numerically. Two cases of “single and double” perforation were studied and compared with that of the solid case for a range of Reynolds numbers ranging from 140 to 840. The velocity and temperature profiles were plotted and interpreted on three different sections placed sequentially upstream, mid-stream and downstream of the deflector. Total heat exchange at the bottom wall, outlet fluid temperature, perforated PFE deflector performance and pressure loss is presented for different cases studied and for different Reynolds numbers.
Findings
The results show that although the perforated deflector improves the heat transfer, it also results in additional pressure losses; the study also showed the existence of a limiting velocity beyond which the perforation effect on the improvement of the heat exchange decreases until the same performance of the solid deflector is achieved.
Originality/value
The main originality of this work is to show a 3D analysis for a perforated baffle as heat exchanger application.
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The objective of this study is to explore and compare intellectual capital (IC) and its three components in deposit, investment and participation banks operating in Turkey’s…
Abstract
Purpose
The objective of this study is to explore and compare intellectual capital (IC) and its three components in deposit, investment and participation banks operating in Turkey’s banking sector, and to analyze empirically the relationship between intellectual capital and financial performances of the banks.
Design/methodology/approach
The study uses a panel data of 46 banks operating in the Turkish banking system during the period of 2005–2019. To measure intellectual capital, value-added intellectual coefficient (VAIC) is used, consisting of the efficiency of a firm’s three types of capital – that is human, structural and employed capitals. To examine the proposed research hypotheses for each bank type separately, multiple regression analysis methods are used.
Findings
The findings of this paper reveal a positive and statistically significant relationship between IC and financial performance of the banks. Specifically, two of the components of IC, namely, employed and human capital efficiencies, are the most influential value drivers for the financial profitability of the banks, whereas structural capital efficiency has less importance in the profitability of the banks. The financial performance of the banks in Turkey is affected mostly by human capital. Therefore, if banks plan to increase their profitability, they need to pay more attention to human capital than structural and employed capitals.
Originality/value
The current study can be considered as one of the most comprehensive studies on analyzing the relationship between intellectual capital and financial performances of businesses in the Turkish banking sector. The previous studies analyzed either the banks individually or all banks as one group. The paper provides a valuable framework for executives, managers and policymakers in managing IC within the Turkish context as the most comprehensive study in the relevant literature.
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Murat Özdemir, Hilal Buyukgoze, Yener Akman, Hakan Topaloğlu and Kenan Çiftçi
Teachers' expressing candid and natural emotions during teaching and learning processes is of vital importance for the quality and content of education. Because of that reason, it…
Abstract
Purpose
Teachers' expressing candid and natural emotions during teaching and learning processes is of vital importance for the quality and content of education. Because of that reason, it is necessary to explore factors that have a role in teachers' emotional labour. Therefore, the current study aims to test a novel model developed to explore the direct and indirect relations among distributed leadership, teacher autonomy and emotional labour.
Design/methodology/approach
The study data came from 1,007 teachers working at 81 state high schools located in 12 different regions in Turkey. To test the proposed model, the authors conducted a mediation analysis of structural equation modelling.
Findings
The analysis confirms that teacher autonomy is a prominent mediator in the relationship between distributed leadership and emotional labour.
Originality/value
This study is expected to contribute to the body of research focusing on the effects of leadership on teachers' emotional labour.
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Fatih Selimefendigil and Hakan F. Oztop
This study aims to examine the effects of cross-flow and multiple jet impingement on conductive panel cooling performance when subjected to uniform magnetic field effects. The…
Abstract
Purpose
This study aims to examine the effects of cross-flow and multiple jet impingement on conductive panel cooling performance when subjected to uniform magnetic field effects. The cooling system has double rotating cylinders.
Design/methodology/approach
Cross-flow ratios (CFR) ranging from 0.1 to 1, magnetic field strength (Ha) ranging from 0 to 50 and cylinder rotation speed (Rew) ranging from −5,000 to 5,000 are the relevant parameters that are included in the numerical analysis. Finite element method is used as solution technique. Radial basis networks are used for the prediction of average Nusselt number (Nu), average surface temperature of the panel and temperature uniformity effects when varying the impacts of cross-flow, magnetic field and rotations of the double cylinder in the cooling channel.
Findings
The effect of CFR on cooling efficiency and temperature uniformity is favorable. By raising the CFR to the highest value under the magnetic field, the average Nu can rise by up to 18.6%, while the temperature drop and temperature difference are obtained as 1.87°C and 3.72°C. Without cylinders, magnetic field improves the cooling performance, while average Nu increases to 4.5% and 8.8% at CR = 0.1 and CR = 1, respectively. When the magnetic field is the strongest with cylinders in channel at CFR = 1, temperature difference (ΔT) is obtained as 2.5 °C. The rotational impacts on thermal performance are more significant when the cross-flow effects are weak (CFR = 0.1) compared to when they are substantial (CFR = 1). Cases without a cylinder have the worst performance for both weak and severe cross-flow effects, whereas using two rotating cylinders increases cooling performance and temperature uniformity for the conductive panel. The average surface temperature lowers by 1.2°C at CFR = 0.1 and 0.5°C at CFR = 1 when the worst and best situations are compared.
Originality/value
The outcomes are relevant in the design and optimization-based studies for electric cooling, photo-voltaic cooling and battery thermal management.
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Usage of gas turbine engines has increased by day due to rising demand for military and civil applications. This case results in investigating diverse topics related to energy…
Abstract
Purpose
Usage of gas turbine engines has increased by day due to rising demand for military and civil applications. This case results in investigating diverse topics related to energy efficiency and irreversibility of these systems. The purpose of this paper is to perform a detailed entropy assessment of turbojet engines for different flight conditions.
Design/methodology/approach
In this study, for small turbojet engines used in unmanned aerial vehicles, parametric cycle analysis is carried out at (sea level-zero Mach (hereinafter phase-I)) and (altitude of 9,000 m- Mach of 0.7 (hereinafter phase-II)). Based on this analysis, variation of performance and thermodynamic parameters with respect to change in isentropic efficiency of the compressor (CIE) and turbine (TIE) is examined at both phases. In this context, the examined ranges for CIE is between 0.78 and 0.88 whereas TIE is between 0.85 and 0.95.
Findings
Increasing isentropic efficiency decreases entropy production of the small turbojet engine. Moreover, the highest entropy production occurs in the combustor in the comparison of other components. Namely, it decreases from 2.81 to 2.69 kW/K at phase-I and decreases from 1.44 to 1.39 kW/K at phase-II owing to rising CIE.
Practical implications
It is thought that this study helps in understanding the relationship between entropy production and the efficiency of components. Namely, the approach used in the current analysis could help decision-makers or designers to determine the optimum value of design variables.
Originality/value
Due to rising isentropic efficiencies of both components, it is observed that specific fuel consumption (SFC) decreases whereas specific thrust (ST) increases. Also, the isentropic efficiency of a compressor affects relatively SFC and ST higher than that of the turbine.