Ismail Teke

Effects of Bed Height and Particle Size on Drying of a Turkish Lignite

Drying of coarse lignite particles, because of high inherent moisture content, is very important for the lignite user. An effective drying process is necessary to utilize coarse lignite particles effectively. Fixed-bed drying experiments were carried out for a Turkish lignite (Konya-Ilgın). Effects of bed height and particle size were investigated. Drying experiments were carried out at 80, 130, and 150 mm bed heights and 20, 35, and 50 mm particle sizes. It was found that increasing the bed height increased the drying time and decreased the drying rate, and particles of larger sizes have lower drying rates and higher drying times. Additionally, it was also found that Konya-Ilgın lignite does not show a constant drying rate and has a long falling drying rate. As a result of this study, drying characteristics of Konya-Ilgın lignite were presented for different drying conditions.

Optimum distribution of thermal insulation material for constant insulation material volume or a given investment cost

Most of the recent studies based on the alternative energy sources and efficient use of energy due to the rapidly exhausting fossil energy sources. Insulation is one of the solutions applied to decrease heat losses or gains. Present studies require tedious iterations to achieve a solution for optimum distribution of thermal insulation material for the volumes confined with environments at different temperatures such as cold storages. In this study, a general analytical solution for the optimum distribution of thermal insulation material is given for the volumes confined with environments at different temperatures for a given investment cost or constant insulation material volume. Analytical solution technique given in this study eliminates the need for tedious iterations or using a specialized computer software, and can also be combined with economic analysis models to include effects of economical parameters such as fuel price, interest rate, etc. A case study is also given for explanation and application of suggested methodology for a room confined with environments at different temperatures. It is shown that optimum distribution of insulation material easily achieved by one step analytical solution technique.

Investigation of the System Parameters Affecting the Runtime of a Freezer Compartment

In this study, an experimental setup was built to evaluate the energy consumption of a freezer compartment by varying the runtime (i.e. the ratio of the compressor ON time to the total cycle time) of the system with the evaporation temperature and the airflow rate. Evaporation temperature and the normalized airflow rate were varied from −25°C to −28°C and from 0.8 to 1.4, respectively, thus the effects of these parameters on the runtime of the freezer were evaluated in a wide range of operating conditions. In addition, an empirical model that estimates the runtime within ± 4% compared to the experimental data was presented. By using the empirical model, optimum operating conditions (i.e. evaporation temperature and airflow rate) for the freezer were found with an energy saving of %13.8.Copyright

Effects of the Nano Particle Concentration and Type on Natural Convection Heat Transfer From Horizontal Concentric Cylinder Systems Cooling in the Ambient Air

Natural convection heat transfer from horizontal concentric cylinders is studied experimentally and numerically. Concentric cylinder was formed with two cylinders made of copper, and the annulus was filled with water. Concentric cylinder system was located in the ambient air and the inner horizontal cylinder was kept at a constant temperature. Experimental study was carried out in a conditioned room which can be maintained at a stable required value and inside a sufficiently designed test cabin. The inner copper cylinder surface temperatures varied between 30 °C–50 °C and ambient temperature was 20 °C. On the basis of the experimental data average Nusselt numbers for the air side of the concentric cylinders were calculated and compared with numerical results. The effective thermal conductivity of the annulus was calculated by using the experimental data and numerical solution results and compared. Besides, heat transfer enhancement in horizontal annuli has been investigated for different nano particle concentrations. Water based nano fluid containing Al2O3 nano particles have been used. Isotherms and streamlines are presented in the annulus and the air side. Heat transfer rates under steady state conditions for different nano particle concentrations were compared and heat transfer enhancement was determined.Copyright