In this paper, experimental work has been performed to analyze the heat transfer and flow characteristics in spirally fluted tube annuli with large variations of the fluid properties. The objective of this paper is to develop a Nusselt number correlation considering the property variation effect on the heat transfer performance. This paper investigates the effects of property variations not only in radial direction but also in axial direction on the heat transfer rate. The effect of property variation on the heat transfer rate increased as the Prandtl number increased. The property variation effect on heat transfer rate was more significant in laminar flow than in turbulent flow. A new correlation of the Nusselt number that considered the property variation effect with ±20% error bands was developed for annulus flow with a fluted inner tube. The correlation can be applied for the cases in which the fluid property changes significantly: i.e., Pr range of 2-32, the temperature difference between the wall and the bulk fluid up to 40 °C, and the axial temperature variation up to 73 °C.
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanical Engineering
- Fluid Flow and Transfer Processes