K E REBY ROY
Articles written in Sadhana
Volume 45 All articles Published: January 2020 Article ID 0012 Original Article (Mechanical Sciences)
The present study investigates chilldown characteristics of a horizontal copper transfer line with 7.94 mm outer diameter, 0.81 mm wall thickness and 500 mm length. Data presented in this paper is for the experiments conducted with different mass fluxes (66 kg (m².s)⁻¹ to 102 kg (m².s)⁻¹) in a horizontal copper transfer line under terrestrial gravity conditions. Temperature measurements were recorded at six equidistantpoints to a distance of 330 mm from an inlet. Inverse problem solving method is utilized to calculate corresponding heat flux and heat transfer coefficients. Considering the thermal properties of the quenched wall, an empirical relation was developed. It is found that while employing copper transfer lines instead of stainless steel, thermal mass of the section is reduced by a factor of 100, thereby encountering a reduction of 50% in critical heat flux.
Volume 46 All articles Published: 1 February 2021 Article ID 0002
Chilldown of transfer lines is an important phenomenon associated with cryogenic liquid transfer from the storage facility to the location of its intended application. Analysis of heat transfer characteristics during cryogenic chilldown of a helical coil is the focus of this study. In view of the ease in availability and handling compared to other cryogens, Liquid nitrogen is adopted. The cryogen was transmitted through copper helical test sections with 7.94 mm outer diameter, 0.81 mm wall thickness and having helix angles 4°, 6°, 8°, 10°, 12° and 16° with horizontal axes, at three different mass fluxes, that is, 66 kg/m2s, 86 kg/m2s and 102 kg/ m2s under terrestrial gravity conditions. Temperature-time relationships were obtained and the results were compared with that of straight channels. The results of the experiment indicated that the chilldown time for coils of different helix angles were different at a given mass flux. Also, for a given helix angle, chilldown time varied inversely with mass flux. Results suggested the prospect of an optimum helix angle that can serve in minimizing the chilldown time, thereby reducing cryogenic liquid consumption. Finding correlations connecting heat transfer parameters in helical coils would enhance the scope of this study.