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Examination of Different Heat Exchangers and the Thermal Activities of Different Designs

100%
Ipek O., Kan M., Gurel B.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 3
580-584
EN
In this study, instead of gasketed or brazed plate heat exchangers, which are used in various fields of application, a direct metal sintering method is used to design a heat exchanger with its original geometry and with different geometries. Studies of heat exchangers found in published literature were reviewed, and the thermal behaviors of the proposed unique designs were examined. Usually heat exchangers using this design do not use channel spacing angles of 30-45-60-75° for the plate ducts. The thermal behaviors of the fluid-circulating systems were analyzed using ANSYS FLUENT software, and they used the boundary conditions found in the literature for this design. Heat transfer between the heat exchanger channels and channel walls was calculated. The analyses results show that an increase in the amount of heat transfer surface area and also an increase in surface roughness increased the amount of positive heat transfer.
2
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Effect of Aspect Ratio on Natural Convection in a Cavity with Wavy Walls

100%
Arici M., Kan M., Karabay H.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2B
B-197-B-200
EN
In this study, flow characteristics and natural convection in a cavity with two wavy walls is studied numerically. The wavy walls of the cavity are isothermal and at different temperatures while other straight walls are adiabatic. The fluid considered inside the cavity is air having Prandtl number of 0.71. A parametric study is conducted for various aspect ratios (1 ≤ AR ≤ 5), Rayleigh numbers (10³ ≤ Ra_{H} ≤ 10⁶) and inclination angles (0° ≤ θ ≤ 180°). Streamlines, isotherms and local and mean Nusselt numbers are presented to show the effect of the investigated parameters on the flow field and heat transfer.
3
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Numerical Investigation on Hydrodynamic Combustion and NO_x Emission Behavior in 8 MW Circulating Fluidized Bed

100%
İpek O., Gürel B., Kan M.
Acta Physica Polonica A
|
2017
|
vol. 132
|
issue 3
553-557
EN
Multi-phase flow is one of the types of flow which is frequently observed in natural phenomena and engineering applications. Circulating fluidized beds constitute an important application of multi-phase flow. The combustion and emission behaviours in circulating fluidized beds are determined by hydrodynamic of bearing. The most appropriate combustion can be provided with the hydrodynamic structure of bearing, taking into account fuel and operating parameters. Therefore, the hydrodynamic structure of circulating fluidized beds should be displayed with mathematical/physical modelling and simulation approach for its analysis and synthesis. Mathematical analysis in today's conditions is very difficult or impossible because of excessive turbulence, unstable and two-phase flow characteristics of the bed. Therefore, the most effective way to do this is the use the physical modelling and simulation approach. In this study, 8 MW circulating fluidized bed hydrodynamic analysis are made by ANSYS-FLUENT R14 commercial CFD code and then combustion and emissions analysis are made with hydrodynamic analysis results. These analysis results show that combustion chamber exit mean NO_x emission was 38.5 ppm and combustion chamber exit mean temperature was 1123 K.
4
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Numerical Analysis of Pulverised Coal Fired Boiler with Different Burner Geometries

100%
Gurel B., Ipek O., Kan M.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2B
B-43-B-45
EN
Pulverized coal combustion is extensively used in utility boilers, industrial boilers, furnaces, kilns, and other energy conversion appliances. The effective utilization of pulverized coal is the main problem in study of combustion processes, particularly in burning low-grade coal. It is well known that the emission of nitrogen oxides (NO_{x}) during coal combustion is a main environmental problem. In this study, three different pulverised coal burner geometries for a pulverised coal fired boiler have been studied by numerical analysis. GLI-Tunçbilek coal was used as fuel. Three-dimensional numerical analysis was carried out using Ansys Fluent code. Realizable K-ε turbulence method, single rate devolatilization method, multiple char combustion method and second-order upwind discretization method were used during calculations. Coal particle diameter and coal mass flow rate were assumed to be 70 μm and 378 kg/h respectively.
5
Content available remote

Plate Heat Exchangers as a Compact Design and Optimization of Different Channel Angles

100%
Kan M., Ipek O., Gurel B.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 2B
B-49-B-52
EN
In this study, thermal treatments have been investigated for different channel angles and mass flow rates of a compact heat exchanger have been manufactured by direct metal laser sintering technique instead of a sealed and brazed one used in many areas. Boundary conditions of available heat exchanger experimental test have been used in laboratory. In this study, we have designed for compact heat exchanger of 30°, 45° and 60° channel angle and used three different mass flow rates (0.2, 0.3, and 0.43 kg/s). Heat transfers occurring between heat channels and walls of heat exchangers for different channel angles and efficiency of heat exchangers have been calculated. As a result of the analysis, it has been determined that in order for maximum of heat transfer of a compact heat exchanger, following working conditions ought to be fulfilled: channel angle 30°, hot water input temperature 60°C, cold water input temperature 15°C, and mass flow rate 0.43 kg/s.
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