Pressure drop and heat transfer characteristics of tetra-n-butyl ammonium bromide clathrate hydrate slurry during flow melting and generating in a double-tube heat exchanger

Abstract

This study presents the flow and heat transfer characteristics of tetra-n-butyl ammonium bromide (TBAB) aqueous solution and clathrate hydrate slurry (CHS) in a double-tube heat exchanger (DHE). Both the TBAB aqueous solutions at the supercooling state and normal state were tested to understand the influence of supercooling state on the flow and heat transfer of TBAB aqueous solution. Pressure drops of 5–25wt% TBAB CHS flowing through DHE without heat exchange were measured and the corresponding flow friction factor was obtained, while the pressure drops of the flow melting and generating of TBAB CHS were also obtained. Single side heat transfer coefficients of the flow melting of 10–25wt% TBAB CHS in the heat exchanger were presented, and the local heat transfer correlation was developed with the consideration of the effect of latent heat on the heat transfer. Moreover, the heat transfer during TBAB CHS generation process was found to be deteriorated by the adherence of crystals on the heat transfer surface, and the heat transfer improvement by the melting operation was shown.