Local Heat Transfer and Pressure Drop for Finned-Tube Heat Exchangers Using Oval Tubes and Vortex Generators  

Oleh:

Sohal, Manohar S. ; Wallstedt, Philip C. ; O’Brien, James E.

Jenis: Article from Bulletin/Magazine
Dalam koleksi: Journal of Heat Transfer vol. 126 no. 5 (Oct. 2004), page 826-835.
Topik: generators; local heat transfer; pressure drop; finned - tube; heat exchangers; oval tube; vortes generators

Ketersediaan

Perpustakaan Pusat (Semanggi) Nomor Panggil: JJ90.9 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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This paper presents the results of an experimental study of forced convection heat transfer in a narrow rectangular duct fitted with an elliptical tube and one or two delta - winglet pairs. The duct was designed to simulate a single passage in a fin - tube heat exchanger. Heat transfer measurements were obtained using a transient technique in which a heated airflow is suddenly introduced to the test section. High - resolution local fin - surface temperature distributions were obtained at several times after initiation of the transient using an imaging infrared camera. Corresponding local fin - surface heat transfer coefficients were then calculated from a locally applied one - dimensional semi - infinite inverse heat conduction model. Heat transfer results were obtained over a Reynolds number range based on duct height of 670 – 6300. Pressure - drop measurements have also been obtained for similar elliptical - tube and winglet geometries, using a separate single - channel, multiple - tube - row pressure - drop apparatus. The pressure - drop apparatus includes four tube rows in a staggered array. Comparisons of heat transfer and pressure - drop results for the elliptical tube versus a circular tube with and without winglets are provided. Mean heat transfer results indicated that the addition of the single winglet pair to the oval - tube geometry yielded significant heat transfer enhancement, averaging 38 % higher than the oval - tube, no - winglet case. The corresponding increase in friction factor associated with the addition of the single winglet pair to the oval - tube geometry was very modest, less than 10 % at Re(D)((h)) = 500 and less than 5 % at Re(D)((h)) = 5000.

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