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Journal of Flow Visualization and Image Processing

ISSN Print: 1065-3090
ISSN Online: 1940-4336

Journal of Flow Visualization and Image Processing

DOI: 10.1615/JFlowVisImageProc.v17.i3.60
pages 255-266

THE EFFECT OF A SWIRLER ON THE HEAT TRANSFER COEFFICIENT OF FLOW IN A RECTANGULAR DUCT USING THERMOCHROMIC LIQUID CRYSTALS

Ayudh Mapairoje Paleebut
Department of Mechanical Engineering, Graduate School, Kasetsart University, Bangkok 10900 Thailand
Chawalit Kittichaikarn
Department of Mechanical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 Thailand

ABSTRACT

This paper presents a study on the heat transfer coefficient of flow in a rectangular duct with a swirler using thermochromic liquid crystals. The experiments were conducted in the purpose- built perspex rectangular duct with an aspect ratio of 1:5. One side of the duct was heated by an electrical heater which generated a uniform constant heat flux over the surface. The variation of the Reynolds number was 13,000−24,000. Thermochromic liquid crystals were sprayed on the top of the duct surface forming a temperature sensitive layer. Swirlers with vane angles of 30°, 45°, and 60° to the flow axis were used in the experiment. From the results obtained, it was found that the thermal performance of the air flow through the rectangular duct with a 60°−swirler is the best among those used in this study.