Sādhanā | 2021
Experimental investigation on heat transfer characteristics in cryogenic chilldown of a helically coiled tube
Abstract
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/m 2 s, 86 kg/m 2 s and 102 kg/m 2 s 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.