Limits of Reyonolds Number for Effective Use of Heat Transfer Promoters

Twisted tape and static mixer

Abstract

Heat transfer coefficients in a pipe with heat transfer promoter are compared with those in round pipe for the same pumping power. The ratio of the heat transfer coefficient of the former to the latter is measured. Limiting Reynolds number where the above ratio of the heat transfer coefficient exceeds unity is indicated graphically as a guide for effective use of heat transfer promoters. Both twisted tape and static mixer give the highest coefficient ratios, 2.13.2, for Reynolds numbers 300550. Further, the static mixer gives high coefficient ratios, 1.8 2.1, even for especially low Reynolds numbers 150.