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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

TRANSITIONAL FLOW REGIME NOMENCLATURE FOR SMOOTH HORIZONTAL TUBES HEATED AT A CONSTANT HEAT FLUX

Get access (open in a dialog) DOI: 10.1615/IHTC16.cov.023021
pages 3327-3334

Аннотация

Although the transitional flow regime has been extensively investigated, the Reynolds number boundaries of the transitional flow regime were in general qualitatively defined and relied on visual observations. The result is that the definitions of the start and end of the transitional flow regime often relied on subjective decisions (which data points to consider as either laminar, transitional and turbulent), which made it challenging to compare transitional flow results of different studies. The purpose of this study was therefore to define new nomenclature to mathematically quantify the boundaries of the transitional flow regime, as well as the heat transfer and pressure drop characteristics in this regime. An experimental set-up was designed, built and validated against literature. Two smooth circular test sections with inner diameters of 4 mm and 11.5 mm, respectively, were used and the maximum length-to-diameter ratios were 1 373 and 872, respectively. Heat transfer and pressure drop measurements were taken at Reynolds numbers between 700 and 10 000 at different heat fluxes. A total of 364 mass flow rate measurements, 36 809 temperature measurements and 2 583 pressure drop measurements were taken. It was found that the boundaries of the transitional flow regime were the same for the pressure drop and heat transfer results. The start of the transitional, quasi-turbulent and turbulent flow regimes were defined mathematically, as well as the width of the transitional flow regime, transition gradient and inflection point, to be able to investigate and compare the heat transfer and pressure drop characteristics in the transitional flow regime.