Heat Transfer Characteristics of the Single-Phase, Elbow Thermosyphon

This paper describes the results of single-phase experiments on a right-angled, or elbow, thermosyphon with the cooled section upright and the heated section horizontal. For diameter-based Rayleigh numbers less than 10^7.6, the data indicate the existence of two flow regimes: fully mixed and impeded. A flow model is used to suggest how the cooled section and heated section flow patterns are coupled together. This model satisfactorily explains the effect of geometry on heat transfer, as revealed in the usual plots of Nusselt number versus Rayleigh number. Thermal performance was found to be comparable to that of the linear thermosyphon.