Smooth-and enhanced-tube heat transfer and pressure drop : effect of Prandtl number and the role of transition to turbulence.
Journal Article
·
· Int. J. Heat Exchangers
OSTI ID:949498
An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics in laminar, transitional, and turbulent flow through one smooth tube and twenty-three enhanced tubes. The working fluids for the experiments were air, water, ethylene glycol, and ethylene glycol/water mixtures; Prandtl number (Pr) ranged from 0.7 to 125.3. The smooth-tube experiments were carried out with Pr values of 0.7, 6.8, 24.8, 39.1, and 125.3; Pr values of 0.7, 6.8, and 24.8 were tested with enhanced tubes. Reynolds number (Re) range (based on the maximum internal diameter of a tube) was 200 to 55,000, depending on Prandtl number and tube geometry. The enhanced-tube friction factors are no more than 5.5 times the smooth-tube values. For some tubes, the friction factors are practically the same for 0.7 {<=} Pr {<=} 25, with moderate differences in laminar, transitional, or turbulent flow for some of the tubes. Consistent with the low-pressure-drop characteristics of these enhanced tubes, the increases in heat transfer coefficient are no more than 2.5 times the smooth-tube values for the Re and Pr ranges covered in the study. For most enhanced tubes, heat-transfer coefficients are insensitive to variations in the Prandtl number for liquids. There is a definite connection between the attainable friction or heat transfer and the transition process.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- EE
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 949498
- Report Number(s):
- ANL/ET/JA-41524
- Journal Information:
- Int. J. Heat Exchangers, Journal Name: Int. J. Heat Exchangers Journal Issue: 2 ; Dec. 2002 Vol. 3
- Country of Publication:
- United States
- Language:
- ENGLISH
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