Prediction methods for single-phase turbulent flow inside tubes with wire-coil inserts
Wire-coil inserts provide an efficient and inexpensive way to enhance the thermal performance of heat-exchanger tubes. For applications that require frequent cleaning, their easy-to-retrofit characteristic offers a significant advantage over integrally enhanced-tube types. However, the lack of suitable prediction methods is a major reason why wire-coil inserts are not more frequently used by industry. Heat-transfer and friction-factor comparisons of predicted values and experimental data for 39 different coil configurations taken from seven sources are presented. Two prediction methods are considered; the empirical correlations of Ravigurgurajan and Bergles (1986) and the mechanistic predictions methods of James et al. (1993). Favorable agreement existed between the predictions and the heat-transfer data. The average and root-mean-square (RMS) errors were 4 and 14, with the correlation of Ravigurgurajan and Bergles and 16 and 20 percent, with the prediction method of James et al. The Ravigurgurajan and Bergles is therefore recommended for tubes with coil inserts when the coil geometries conform to the restrictions considered in the development of the correlations. Substantially more scatter existed with the friction-factor data, and it reached a factor of two for some tubes with essentially the same coil geometry. Three possible causes are (1) the pressure drop is also a function of the tube inside diameter (lower f values obtained with the large diameters), (2) a loose fit sometimes existed between the coil and base tube, and (3) experimental error.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10154912
- Report Number(s):
- ANL/ES/CP-81833; CONF-940625-5; ON: DE94012642
- Resource Relation:
- Conference: 6. AIAA/ASME thermophysics and heat transfer conference,Colorado Springs, CO (United States),20-23 Jun 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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