Forced flow and convective melting heat transfer of clathrate hydrate slurry in tubes

In this study, we presented the forced flow and convective melting heat transfer characteristics of tetrabutylammonium bromide (TBAB) clathrate hydrate slurry (CHS) flowing through straight circular tubes. Pressure drops of TBAB CHS with the volume fraction in the range of 0-20.0 vol% were measured, and the influence of the volume fraction was analyzed. Power-law equation was used to describe the flow behavior of CHS, and the corresponding indicators including flow behavior index and fluid consistency coefficient indicated that TBAB CHS behaved as a pseudo plastic fluid. Based on the modified Reynolds number, it was found that the empirical correlation could be used to predict the flow friction factor of TBAB CHS. Heat transfer experiments were conducted to measure the local heat transfer coefficients of TBAB CHS flow under constant wall heat flux, which were found to be enhanced by the latent heat involved in the solid-liquid phase change. Local heat transfer coefficient decreased along the heating section until the volume fraction was smaller than a certain small value, then it increased in the following section due to the increase of Reynolds number. The effects of heating power, flow velocity, volume fraction on the local heat transfer coefficients were discussed. Correlations for predicting TBAB CHS heat transfer performance were proposed based on the experimental data in laminar, transitional and turbulent flow regions, respectively. (C) 2010 Elsevier Ltd. All rights reserved.