Mecit Sivrioğlu - Academia.edu (original) (raw)

Papers by Mecit Sivrioğlu

International Communications in Heat and Mass Transfer, Mar 1, 2008

The main aim of this investigation is to discover the effects of clearance parameters on the stea... more The main aim of this investigation is to discover the effects of clearance parameters on the steady-state heat transfer. In order to solve the three-dimensional elliptic governing equations, a finite volume based CFD code was used. The clearance gap between fin tips and shroud, the base and fin temperatures and the size and configuration of the finned surfaces were varied during the parametric study. The numerical results have been compared to existing experimental values from the literature and the comparison shows a good agreement. It is found that the heat transfer coefficient increases with the increase in the clearance parameter and it approaches to the value of heat transfer coefficient obtained for unshrouded fin arrays.

Applied Thermal Engineering, Jul 1, 2012

Abstract The influence of the clearance gap between fin tips and the top surface of channel on la... more Abstract The influence of the clearance gap between fin tips and the top surface of channel on laminar mixed convection heat transfer from longitudinal fins has been experimentally and numerically investigated. A conjugate analysis has been carried out in which the conservation of mass, momentum and energy equations for the fluid in the two fin enclosure are solved together with the heat conduction equation in the fin and the base plate. Average heat transfer coefficients were obtained for modified Grashof numbers 5 × 10 7 Gr * 9 , and dimensionless fin spacing was varied from S / H = 0.04 to S / H = 0.18 and clearance parameter was varied from c / H = 0.20 to c / H = 0.75, to determine the effect of the clearance gap. The velocity of fluid entering the channel was varied between 0.02 ≤ w in ≤ 0.23 m/s so that experiments were conducted for Reynolds numbers 250 Re

Energy Conversion and Management, 2014

Steady state natural convection and radiation heat transfer from various shaped thin fin-arrays o... more Steady state natural convection and radiation heat transfer from various shaped thin fin-arrays on a horizontal base plate has been numerically investigated. A conjugate analysis has been carried out in which the conservation equations of mass, momentum and energy for the fluid in the two fin enclosure are solved together with the heat conduction equation in the fin and the base plate. Heat transfer by radiation is also considered in analysis. The heat transfer coefficient has been determined for each of the fin array considered in the present study at the same base and the same total area. The results of the analysis show that there are some important geometrical factors affecting the design of fin arrays. Taking into consideration these factors, an optimum fin shape that yields the highest average heat transfer coefficient has been determined.

International Communications in Heat and Mass Transfer, 2005

... This outcome can also be observed from the variation of the row-averaged Nusselt number showi... more ... This outcome can also be observed from the variation of the row-averaged Nusselt number showing an increase towards the exit. ... 2. As can be seen from this figure 25×25 mm copper blocks (k=386 W/m K, =0.3) were used tightly fit to the Teflon substrate. ...

Heat and Mass Transfer, Aug 19, 1997

Heat and Mass Transfer, Feb 1, 2002

Abstract Mixed convection heat transfer in rectangular channels has been investigated experimenta... more Abstract Mixed convection heat transfer in rectangular channels has been investigated experimentally under various operating conditions. The lower surface of the channel is subjected to a uniform heat flux, sidewalls are insulated and adiabatic, and the upper surface is exposed to the surrounding fluid. Experiments were conducted for Pr=0.7, aspect ratios AR=5 and 10, inclination angles 0° ≤ θ ≤ 30°, Reynolds numbers 50 ≤ Re ≤ 1000, and modified Grashof numbers Gr*=7.0 × 105 to 4.0 × 107. From the parametric study, local Nusselt number distributions were obtained and effects of channel inclination, surface heat flux and Reynolds number on the onset of instability were investigated. Results related to the buoyancy affected secondary flow and the onset of instability have been discussed. Some of the results obtained from the experimental measurements are also compared with the literature, and a good agreement was observed. The onset of instability was found to move upstream for increasing Grashof number and increasing aspect ratio. On the other hand, onset of instability was delayed for increasing Reynolds number and increasing inclination angle.

Renewable & Sustainable Energy Reviews, Oct 1, 2017

A general model (sugar production processes) was developed based on data provided by a real plant... more A general model (sugar production processes) was developed based on data provided by a real plant and provided an exergy analysis. It was explored for a techno-economical turbine power plant and the improvement of performance indicators was achieved through thermoeconomic analysis. Unit cost for the turbine power plant is found to be 3.142 [$ / kW]. The simple payback period of the turbine power plant is calculated as 4.32 years. The purpose of this study is to reduce the cost of power plant. At the same time, this study poses a thermoeconomic analysis to increase turbine power.

Energy Conversion and Management, May 1, 2011

Bu makalede yatay bir kanal içerisine çıkıntılı olarak yerleştirilmiş ayrık ısıtıcılardan laminer... more Bu makalede yatay bir kanal içerisine çıkıntılı olarak yerleştirilmiş ayrık ısıtıcılardan laminer akış şartlarında karışık konveksiyon yolu ile ısının uzaklaştırılması durumu sayısal olarak incelenmiştir. Kanal alt ve üst yüzeylerine 8 4 lük dizi şeklinde yerleştirilen ısıtıcılara eşit ısı akıları uygulanmıştır. Elde edilen sonuçlar artan sayısıyla ısıtıcı yüzey sıcaklıklarının arttığını özellikle doğal konveksiyon ile ısı transgerinin ağırlıklı olduğu (/ 1) bölgede yüksek sayılarında ısıtıcı sıcaklıklarının çok yükseldiğini göstermiştir. Bu bölgede üst ısıtıcılardaki sıra ortalama sayıları sıra numarası ile azalırken alt ısıtıcılardaki sıra ortalama sayıları belirli bir sıraya kadar azalmaktadır. Bu sıradan sonra ise sıra ortalama sayılarında doğal konveksiyon etkisi ile bir artış görülmüştür. Bunun sonucunda üst ısıtıcılarda ısıtıcı sıcaklığı sıra numarası ile artmış alt ısıtıcılarda ise belirli bir ısıtıcı sırasından sonra azalmıştır.

International Journal of Heat and Mass Transfer, Apr 1, 2010

Mixed convection heat transfer from longitudinal fins inside a horizontal channel has been invest... more Mixed convection heat transfer from longitudinal fins inside a horizontal channel has been investigated in the natural convection dominated region for a wide range of Rayleigh numbers and different fin heights and spacings. An experimental parametric study was made to investigate effects of fin spacing, fin height and magnitude of heat flux on mixed convection heat transfer from rectangular fin arrays heated from below in a horizontal channel. The optimum fin spacing to obtain maximum heat transfer has also been investigated. During the experiments constant heat flux boundary condition was realized and air was used as the working fluid. The velocity of fluid entering channel was kept nearly constant (0.02 6 w in 6 0.025 m/s) using a flow rate control valve so that Reynolds number was always about Re = 250. Experiments were conducted for modified Rayleigh numbers 3 Â 10 7 < Ra * < 6 Â 10 8 and Richardson number 600 < Ri < 15,000. Dimensionless fin spacing was varied from S/H = 0.04 to S/H = 0.018 and fin height was varied from H f /H = 0.25 to H f /H = 0.80. The results obtained from experimental study show that the dimensionless optimum fin spacing which yields the maximum heat transfer is between S/H = 0.08 and S/H = 0.12. Results also show that optimum fin spacing depends on modified Rayleigh number and fin height. For high modified Rayleigh numbers (Ra * P 5 Â 10 8) and low values of fin height (such as H f /H = 0.25) the optimum fin spacing has taken greater values in comparison to the cases of smaller modified Rayleigh numbers.

Springer eBooks, 1987

Ataturk Organized Industrial District (AOID) is located near Izmir and will comprise 500 small an... more Ataturk Organized Industrial District (AOID) is located near Izmir and will comprise 500 small and medium sized factories. The factories require process steam, hot water, hot air, electricity and energy for space heating. The total peak electricity and heat demand is expected to reach to 600 MW within ten years. Production of heat individually by the factories, central production of heat and cogeneration system alternatives for heat and electricity production are investigated technically and economically to meet the energy demand of AOID as well as the heat demand of the 20000 flats under construction nearby. Pulverized lignite fined cogeneration power plant was found to be the most economical solution which is also favorable from the point of view of environmental protection. Marginal cost of electricity produced by the plant is approximately one-third of the normal purchase price of electricity from the national network. The use of this system conserves the national energy sources by saving considerable amount of fuel during its life time.

Cumhuriyet Science Journal, Sep 30, 2020

In this study, three dimensional mixed convection heat transfer from discrete heat sources placed... more In this study, three dimensional mixed convection heat transfer from discrete heat sources placed in a horizontal rectangular channel has been investigated numerically. 8x4 flushmounted discrete heat sources were mounted on the lower and upper surfaces of the channel. Air is used as working fluid (Pr0.7). The heaters at the bottom and at the top wall were kept at a constant heat flux. Side walls, upper and lower walls are insulated and considered adiabatic. Nusselt number distributions and the effect of the Grashof number (5.8x10 6 ≤ Gr* ≤ 2.3x10 7) and Reynolds number (150 ≤ Re ≤ 971) on the buoyancy-driven secondary flow have been investigated. Distributions of velocity vectors and temperature contours have been determined by the numerical method, and the results have been presented in detail. Governing equations were solved by the control volume method using suitable boundary conditions. The numerical parametric study was made for aspect ratio of AR=8, at various Reynolds and Grashof numbers.

Isı Bilimi ve Tekniği Dergisi, Oct 31, 2017

In this study, the effect of the flow routing plates on the laminar mixed convection heat transfe... more In this study, the effect of the flow routing plates on the laminar mixed convection heat transfer in a horizontal channel that has protruded heat sources at the bottom and top surfaces were investigated numerically and experimentally. The air was used as the cooling fluid, and protruded heat sources were equipped as 4x8 rows into the rectangle channel that has insulated walls. The experimental study was applied for two different Reynolds (Re) numbers. A numerical model complying with the experimental results was created, and numerical investigations were performed in different Reynolds and modified Grashof (Gr*) numbers for the 0°, 30°, 60° values of the plate angles (α). The analyses showed that using flow routing plate only increases the heat transfer from the first four heater rows on the bottom surface, and the first and the last heater rows on the top surface. The findings obtained during the experimental and numerical studies were presented in detail as graphics showing the row averaged Nusselt number (Nurow ave.), the heater temperatures, velocity vectors, and temperature contours.

Energy, 2015

This study is related to the energy and exergy analysis of a model sugar factory in Turkey. In th... more This study is related to the energy and exergy analysis of a model sugar factory in Turkey. In this study, energy efficiency issue in food industries are investigated within a general context to provide energy saving by reducing energy – exergy losses in the sugar production process. The aim of this study is to determine the best energy and exergy efficiency with the mass and energy balances according to design parameters for a sugar factory. Energy savings that can be applied in food industries are examined. Appropriate scenarios are prepared, and optimization results are compared. As a result of thermodynamics calculations made according to the 1st and 2nd Laws of Thermodynamics, energy and exergy efficiencies of a factory were calculated. Factory total energy efficiency and exergy efficiency were found to be 72.2% and 37.4%, respectively, and according to these results, energy quality was found to be 0.64. In conclusion, the current turbine power process energy and exergy efficiencies were 46.4% and 27.7%, respectively, and the optimized turbine power process energy and exergy efficiencies were 48.7% and 31.7%, respectively. This study performs an attitude to the problem of exergy optimization of the turbine power plant. An overall assessment of the energy and exergy efficiency calculations is performed and is focused on how they should be.

Data in Brief, 2015

A huge amount of energy is consumed during sugar production in the food industry. The large amoun... more A huge amount of energy is consumed during sugar production in the food industry. The large amount of steam used and the power of the turbine power plant are key factors. This makes energy and exergy analysis important in sugar factories. The data given in the following paper are related to input and output information of the paper entitled Energyexergy analysis and optimisation of a model sugar factory in Turkey by Taner and Sivrioglu (2015) [1]. Factory total energy efficiency and exergy efficiency are found to be η enT ¼72.2% and η exT ¼37.4%, respectively, and according to these results, the total energy quality ∅ T ¼0.64. These results indicate higher efficiency than similar studies

Wäarme- und Stoffübertragung

ICHMT Third International Symposium on Radiative Transfer, 2001

essentially no effect of coal Cl content on corrosion rates, unlike some of the UK results. Possi... more essentially no effect of coal Cl content on corrosion rates, unlike some of the UK results. Possible reasons for these differences are presented and discussed.

Solar Energy, 1996

In this study, an air window collector having vertical black blinds was investigated experimental... more In this study, an air window collector having vertical black blinds was investigated experimentally under actual outdoor conditions. The vertical blind was installed between two 120 x 80 cm glass panes. It can rotate about the vertical axis. The fully open position makes a 90 ° angle with the vertical plane. A commercially available blind made of cloth and coated with black paint was tested. The air circulation in the system is provided by a fan parallel to blinds. Various parameters were measured and recorded using a data acquisition system. The effect of these parameters on the thermal performance of the system were determined experimentally.

International Journal of Thermal Sciences, 2000

A systematic theoretical investigation of the effects of fin spacing, fin height, fin length and ... more A systematic theoretical investigation of the effects of fin spacing, fin height, fin length and temperature difference between fin and surroundings on the free convection heat transfer from horizontal fin arrays was carried out. The three-dimensional elliptic governing equations were solved using a finite volume based computational fluid dynamics (CFD) code. Preliminary simulations were made for cases reported in the literature. After obtaining a good agreement with results from the literature a large number of runs were performed for a detailed parametric study. It has been shown that it is not possible to obtain optimum performance in terms of overall heat transfer by only concentrating on one or two parameters. The interactions among all the design parameters must be considered. Results are presented in graphical form together with optimum values and correlations, and compared with available experimental data from the literature.