Sage Journals: Discover world-class research

Abstract

An experimental study of local flow characteristics within cowled finned systems has been carried out using laser Doppler anemometry (LDA). Such systems are used to control axial temperature profiles within the barrel of an extrusion process. During the experiments, a perspex model was used to simulate the actual system. The inlet Reynolds number within the air cowl was 1.72 × 10⁴. The local flow between fins was characterized by the flow in the curved duct formed by the fin base tube, fin surfaces and air cowl around the outer diameter of the fins.

The flow pattern between the fins was measured at the sight windows on the air cowl wall. The local flow characteristics and its effect on heat transfer behaviour on fin surfaces were discussed. It was highlighted that the heat transfer through fin surfaces can be greatly influenced by the local flow characteristics. The mean heat transfer coefficient in the curved duct was estimated using both empirical equations and experimental results. The mean coefficient was also predicted using a computational fluid dynamics (CFD) package, and was underestimated by 12 per cent when compared with that found using the empirical relationships.

Keywords

cowled finned systems local flow between fins LDA heat transfer enhancement

Get full access to this article

View all access options for this article.

References

Lin

Griffiths

A. J.

Review of parameters affecting barrel extruder temperature profiles. In Proceedings of Second Biennial European Joint Conference on Engineering Systems Design and Analysis, London, August 1994, pp. 711–720.

Neal

S. B.H.C.

Hitchcock

J. A.

A study of the heat transfer processes in the banks of finned tubes in cross flow, using a large scale model technique. In Third International Heat Transfer Conference, Chicago, Illinois, Vol.3, 1966, pp. 290–298.

Kruckels

Kottke

Investigation of the local heat transfer on finned tubes and modelling. Chemie. Ing. Tech., 1970, 42, 355–362.

Legkiy

V. M.

Pavlenko

V. P.

Makarov

A. S.

Zheludov

Y. S.

Investigation of local heat transfer in a tube with annular fins in transverse air flow. Heat Transfer: Soviet Res., 1974, 6 (6), 101–107.

Sparrow

E. M.

Chastain

S. R.

Effect of angle of attack on the heat transfer coefficient for an annular fin. Int. J. of Heat and Mass Transfer, 1986, 29 (8), 1185–1191.

Jacobi

A. M.

Local heat transfer behaviour and its impact on a single-row, annularly finned tube heat exchanger. Trans. ASME, J. Heat Transfer, 1993, 115 (2), 66–74.

Lin

Griffiths

A. J.

CFD simulation of cooling air flows within shrouded finned heater/cooler systems used on barrel extruders. In Proceedings of Joint ASME/JSME Fluid Engineering Annual Conference, Hilton Head Island, South Carolina, 13–18 August 1995.

Bates

C. J.

The use of laser Doppler anemometry for the study of water flow pipes. PhD thesis, University of Wales College of Cardiff, 1977.

Kreith

Black

W. Z.

Basic Heat Transfer, 1980, Ch. 5 (Harper, New York).

10.

Sung

H. J.

Yang

J. S.

Park

T. S.

Local convective mass transfer on circular cylinder with transverse annular fins in crossflow. Int. J. of Heat and Mass Transfer, 1996, 39 (5), 1093–1101.

11.

White

F. M.

Heat and Mass Transfer, 1988, Ch. 1 (Addison-Wesley, Reading, Massachusetts).

12.

Rohsenow

W. M.

Hartnett

J. P.

Handbook of Heat Transfer, 1973, Sec. 7 (McGraw-Hill, London).

Local flow characteristics and its effect on cowled finned systems

Abstract

Abstract

Keywords

Get full access to this article

References