Design, Fabrication and Preliminary Testing of a Laboratory-scale Air Pre-heater with Annular Fins

Author : San Agustin, Celeste Guevarra
Major Adviser : Demafelis, Rex B.
Committee Members :
Year : 1991
Month : October
Type : Thesis
Degree: BS
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An air pre-heater with annular fins was designed and fabricated at the Josiah International Machines, Inc. and the Department of Agricultural Machinery and Engineering Technology (AMET), CEAT, UPLB, College, Laguna. The equipment was designed primarily to supply hot air to a continuous rotary dryer. Ambient air blown across the tube banks was heated by steam that condensed inside the tubes. The preliminary testing was conducted at Unit Operations Laboratory of the Department of Chemical Engineering.

Three fan speed settings were subjected to three trials each. The parameters that were tested include the inlet and outlet temperatures, steam pressure and the mass flow rates of steam and air. The behavior of the overall heat transfer coefficient at varying air stream velocities was also investigated upon.

The results show that the equipment was able to raise the temperature from an average of 93.2 °F to an average of 148.4 °F. The maximum efficiency attained based the ratio of the amount of heat absorbed by air to that released by steam was found to be 83.55% on the average. The theoretical and actual overall heat transfer coefficients were also evaluated and compared. An average maximum difference of 17.84% was obtained. It was found that the overall heat transfer coefficient increased with air velocity. The recommendations geared improve the performance of the air pre-heater were also given.

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