Browsing by Author "Yamali, Cemil"

Now showing 1 - 5 of 5

Citation - WoS: 74
Citation - Scopus: 86
Adsorption properties of a natural zeolite-water pair for use in adsorption cooling cycles
(Elsevier Sci Ltd, 2010) Solmus, Ismail; Yamali, Cemil; Kaftanoglu, Bilgin; Baker, Derek; Caglar, Ahmet; Manufacturing Engineering; 06. School Of Engineering; 01. Atılım University
The equilibrium adsorption capacity of water on a natural zeolite has been experimentally determined at different zeolite temperatures and water vapor pressures for use in an adsorption cooling system. The Dubinin-Astakhov adsorption equilibrium model is fitted to experimental data with an acceptable error limit. Separate correlations are obtained for adsorption and desorption processes as well as a single correlation to model both processes. The isosteric heat of adsorption of water on zeolite has been calculated using the Clausius-Clapeyron equation as a function of adsorption capacity. The cyclic adsorption capacity swing for different condenser, evaporator and adsorbent temperatures is compared with that for the following adsorbent-refrigerant pairs: activated carbon-methanol; silica gel-water; and, zeolite 13X-water. Experimental results show that the maximum adsorption capacity of natural zeolite is nearly 0.12 kg(w)/kg(ad) for zeolite temperatures and water vapor pressures in the range 40-150 degrees C and 0.87-738 kPa. (C) 2009 Elsevier Ltd. All rights reserved.
Citation - WoS: 58
Citation - Scopus: 66
Experimental Investigation of a Natural Zeolite-Water Adsorption Cooling Unit
(Elsevier Sci Ltd, 2011) Solmus, Ismail; Kaftanoglu, Bilgin; Yamali, Cemil; Baker, Derek; Manufacturing Engineering; 06. School Of Engineering; 01. Atılım University
In this study, a thermally driven adsorption cooling unit using natural zeolite-water as the adsorbent-refrigerant pair has been built and its performance investigated experimentally at various evaporator temperatures. The primary components of the cooling unit are a shell and tube adsorbent bed, an evaporator, a condenser, heating and cooling baths, measurement instruments and supplementary system components. The adsorbent bed is considered to enhance the bed's heat and mass transfer characteristics; the bed consists of an inner vacuum tube filled with zeolite (zeolite tube) inserted into a larger tubular shell. Under the experimental conditions of 45 degrees C adsorption, 150 degrees C desorption, 30 degrees C condenser and 22.5 degrees C, 15 degrees C and 10 degrees C evaporator temperatures, the COP of the adsorption cooling unit is approximately 0.25 and the maximum average volumetric cooling power density (SCR,) and mass specific cooling power density per kg adsorbent (SCP) of the cooling unit are 5.2 kW/m(3) and 7 W/kg, respectively. (C) 2011 Elsevier Ltd. All rights reserved.
Citation - WoS: 2
Magnetically Geared Direct Drive Wind Generator Thermal Analysis
(Ieee, 2017) Zeinali, Reza; Ertan, H. Bulent; Yamali, Cemil; Tarvirdilu-Asl, Rasul; Electrical-Electronics Engineering; 06. School Of Engineering; 01. Atılım University
This paper considers Dual Stator Spoke Array Vernier Permanent Magnet (DSSA-VPM) generator for the direct drive wind-electric energy conversion. The structure of the generator is described. Although how this design is optimized is not discussed, dimensions of the designed generator are given. In electrical machine design thermal performance is naturally of utmost importance. In this paper thermal performance of the design and how its temperature can be kept within the temperature limit imposed by its insulation class and the permanent magnets used is investigated. It is found that when air flow within the generator is not permitted, at rated load condition the generator temperature reaches very high levels. To lower the operating temperature, ventilation holes are introduced to the end plates of the frame. Also some blades are placed on the rotor to help flow of air over the end windings. A model is introduced to calculate the air speed in the region where air flows. Using the calculated air speed a new heat transfer coefficient is determined for the region where air flows. It is found out that with the mentioned modifications to the structure of the generator the designed generator temperature rise can be kept within the value permitted for its insulation class. Therefore, the power density of the design can be safely compared with the power density of other types of designs for direct drive turbines. It is found that DSSA-VPM generator topology offers a clear advantage over other types of generators considered in the literature.
Citation - WoS: 5
Measurement of Solar Radiation in Ankara, Turkey
(Turkish Soc thermal Sciences Technology, 2013) Caglar, Ahmet; Yamali, Cemil; Baker, Derek K.; Kaftanoglu, Bilgin; Basic Sciences; Manufacturing Engineering; 06. School Of Engineering; 08. Medical School; 01. Atılım University
The solar energy potential of Ankara, Turkey, (39.89 degrees N, 32.78 degrees E) has been investigated using the measurements of global and beam radiation over the period May 2008 to May 2009. Surface air temperature was also measured and variation in clearness index evaluated over this period. Global and beam radiations have been analyzed using hourly, daily and monthly averages obtained from 1-minute averages of recorded data. Results show that annual average daily global and beam radiations were 17.04 and 15.72 MJ/m(2)/day, respectively, for this period. The results are compared with the data available for several other cities in Turkey. The study shows that Ankara has a large solar potential. The consistency of these data with that from the State Meteorological Service (SMS) weather station in Ankara was analyzed. Significant differences between these 2 stations were found and are attributed to measurement error at the SMS station. New radiation-measurement stations should be established to create a better national radiation database for Turkey.
Citation - WoS: 43
Numerical Investigation of Coupled Heat and Mass Transfer Inside the Adsorbent Bed of an Adsorption Cooling Unit
(Elsevier Sci Ltd, 2012) Solmus, Ismail; Rees, D. Andrew S.; Yamali, Cemil; Baker, Derek; Kaftanoglu, Bilgin; Manufacturing Engineering; 06. School Of Engineering; 01. Atılım University
In this study, the influence of several design parameters on the transient distributions of temperature, pressure and amount adsorbed in the radial direction of a cylindrical adsorbent bed of an adsorption cooling unit using silica gel/water have been investigated numerically. For this purpose, a transient one-dimensional local thermal non-equilibrium model that accounts for both internal and external mass transfer resistances has been developed using the local volume averaging method. For the conditions investigated, the validity of the local thermal equilibrium and spatially isobaric bed assumptions have been confirmed. To improve the performance of the bed considered, efforts should be focused on reducing heat transfer resistances and intra-particle (interior) mass transfer resistances but not inter-particle (exterior) mass transfer resistances. (C) 2011 Elsevier Ltd and IIR. All rights reserved.