GCRIS

Now showing 1 - 2 of 2

Numerical Optimization of a Finned Tube Gas To Liquid Heat Exchanger
(Izmir Institute of Technology, 2009) Bilir, Levent; İlken, Zafer
The optimization of the fin and protrusion dimensions and shapes of finned tube gas to liquid heat exchangers are performed numerically in this thesis. The dimensions of a commercially available heat exchanger of a combi boiler apparatus are taken as basic dimensions and various parameters about plate fin and three different protrusions, namely balcony, winglet and imprint, are examined step by step. The study is realized within the geometrical dimension range used in actual applications. The numerical analyses of several heat exchangers are performed using Fluent CFD software. The boundary conditions used in the numerical investigation are taken from the actual operating conditions of the combi boiler heater apparatus. Firstly, the best plate fin geometry is determined. Secondly, the best protrusion dimensions are obtained. Finally, the effects of three protrusion placement on plate fin surface are examined. The fin I5B2W3 is determined as the best among the investigated fins. The use of actual operating conditions as boundary conditions and the investigation of the individual and cumulative effects of three different protrusions are the novelties of the study. In order to validate the numerical models, a comparison with a computational and experimental study performed by Wu and Tao is also made. The results of the models created for comparison purpose show good agreement with the results given by Wu and Tao. It is also observed that results obtained from the two alternatives for the modeling, one with symmetrical and the other with periodic boundary condition, are very close. According to these results, it is concluded that the numerical outcomes obtained in the present study are reliable.
Simulation of the Heater Test Room Defined by En 442 Standard and Virtual Testing Og Different Type of Heaters
(Izmir Institute of Technology, 2011) Erdoğmuş, Abdullah Berkan; İlken, Zafer
Heat outputs of radiators are determined experimentally in specific conditions. Many standards have been developed to identify test conditions. EN442 standard specifies test room properties, temperature measurements and heat output calculations for radiators. In this study, the heat dissipation capabilities of three different panel radiators were determined by using numerical methods. The height and length of the tested radiators were 600 mm and 1000 mm, respectively. An experimental study was conducted in the standard test room in order to determine boundary conditions for computational study and verify numerical results. Tests were carried out in three different operating conditions. Twelve measurements were performed in each condition when test room reached steady state. Turbulent typed air flow in the test room and water flow inside the tested radiators were simulated. Temperature and velocity contours in virtual test room are also investigated in this study. Non uniform temperature distribution on the front surface of tested radiators was observed. It is seen that the symmetricity in velocity contours is distorted by using more complex radiator models and increasing excess temperature. The difference between experimental and computational heat output fluctuates between 0.4% and 13.6% for the simplest model, 3.4% and 11.1% for the second radiator, 4.5% and 12.9% for most complicated model investigated in this study. Good results are obtained for the excess temperature of 50oC and 60oC. For the lowest excess temperature, results are also in acceptable range. The study shows that computational methods can be applicable in the design of new heater types.

Phd Degree / Doktora

Browse

Filters

Settings

Sort By

Results per page

Search Results