Experimental investigation of pressure drop and heat transfer for air flow through enhanced tubes
An experimental investigation of the pressure drop and heat transfer characteristics for a smooth tube and various enhanced tubes was made. The working fluid for the experiments was air. The Reynolds number (Re) was varied between 200 and 50000 to provide data for the laminar, transition and turbulent flow regimes. Nine enhanced tubes were tested. For the spirally fluted tubes, it is established that the friction factor and Nusselt number in laminar, transitional and turbulent flow are generally higher than the smooth tube values. Using the corresponding states relations that were given in a previous report (DOE/CE/90029-2), it is established that the reduced heat transfer data for the spirally fluted tubes are coincident with those for the smooth tube. The validity of the frictional law of corresponding states and the existence of a definite connection between transition and the heat transfer enhancement have been verified experimentally. For the three Hitachi Cable enhanced tubes, the results indicate that the behavior with respect to friction or heat transfer is about the same as that for the smooth tube in laminar flow and the transition region. There is hardly any improvement in heat transfer up to a Reynolds number of about 10000 and only very moderate increases occur at higher Reynolds numbers. In turbulent flow, the friction factor is slightly higher than the smooth tube value. The three Wieland enhanced tubes are characterized by transition Reynolds numbers that are considerably greater than those for the Hitachi tubes, the spirally fluted tubes or the value for the present smooth tube. Consequently, the friction factor and Nusselt number are generally lower than the smooth tube values within the transition region, with higher values than the smooth tube data in turbulent flow. 20 refs., 12 figs., 1 tab.
- Research Organization:
- Clarkson Univ., Potsdam, NY (USA). Fluid Mechanics, Heat and Mass Transfer Lab.
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- FG02-89CE90029
- OSTI ID:
- 5860552
- Report Number(s):
- DOE/CE/90029-5; ON: DE91012151
- Country of Publication:
- United States
- Language:
- English
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