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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

A NEW TYPE OF CAST-IRON AIR PREHEATER

Get access (open in a dialog) DOI: 10.1615/IHTC10.940
pages 177-182

Abstract

A new type of cast-iron preheater is introduced in this paper. The heat transfer surface of the air preheater was of finned-tube made of cast iron. The tubeside surface of the air preheater was formed by the internally longitudinal finned-tubes each one of which was inserted with a twisted tape. The outside surface of the finned tube had the form of radial fins.

Experimental studies of heat transfer and friction factor for the internally finned tube with and without twisted tape inserts were conducted for turbulent flow with Re = 3 × 103 - 20 × 103 on a hydraulic diameter basis of the tube. It was found that the enhancement of heat transfer for the combined use of the internally finned tube with twisted tape of twist ratio Yl = 6.1 was excellent.

Experiments were also performed for the investigation of heat transfer and hydraulic characteristics of outside surface in the range of Reynolds number Re = 1.5 × 104- 1.7 × 105. The results of the experiments are presented.

The cast-iron air preheater was designed to provide the industrial boilers with a steam output of 0.28 - 5.6 kg/s (l-20t/h). The industrial experiments of boilers equipped with air preheater for steam output of 0.28 - 2.8 kg/s (l-10t/h) are given in the paper.