Length effect on entrainment limit of large-L/D vertical heat pipe. (June 2016)

• Record Type: Journal Article
• Authors: Seo, Joseph; Bang, In-Cheol; Lee, Jae-Young
• Is Part Of: International journal of heat and mass transfer. Volume 97(2016:Jun.)
• Page Start: 751
• Page End: 759
• Publication Date: 2016-06
• Subjects: Heat pipe -- L/D ratio -- Entrainment limit -- Thermosyphon -- Heat removal -- Thermal performance; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.02.065
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: The effects of the L / D ratio on the thermal hydraulics of heat pipes are examined. The effects of the L / D ratio on the entrainment limit are also considered. Various entrainment limit correlations are compared against experimental data. Discrepancies between experiment and theory are examined for various L / D values. The need for an entrainment limit correlation with L / D correction is confirmed. Abstract: Heat pipes, which are heat-transfer devices of high thermal conductance, have been studied intensively because of their applicability and efficiency. However, only a small number of studies have been conducted on relatively long heat pipes. Here, the thermal hydraulic characteristics of a long heat pipe are studied. In particular, the thermal performance of the heat pipe and the entrainment limit, one of the important design parameters, are examined, so as to determine their sensitivities to the length-to-inner-diameter ( L / D ) ratio. Experiments are conducted to measure the heat removal performance and limitations of the heat pipe for various length scales. It is found that the heat-pipe performance exhibits a similar trend for various L / D, but with differing values. It is also found that the L / D effect on the entrainment limit for a large- L / D heat pipe differs significantly from the predictions of conventional correlations. Therefore, in order to develop a practical passive heat-pipe-based heat-removal device, an entrainment limit expression incorporating L / D correction is required.