Two-phase flow boiling characteristics in plate-fin channels at offshore conditions

Abstract

In order to optimize the plate-fin heat exchangers for floating liquefied natural gas and avoid the degradation of performance at offshore conditions, the flow boiling characteristics in offset strip fins channels of plate-fin heat exchangers under offshore heaving conditions were investigated experimentally, covering the mass fluxes in the range 64–128 kg/(m2·s) and vapor qualities (vapor mass fractions) in the range 0.1–0.8. The results show that the influence of heaving is stronger for vapor quality equal to 0.6, leading to the increment of the heat transfer coefficients by 8.4%. The heat transfer coefficients under heaving conditions vary with the sloshing motion in a sinusoidal-like way. The enhancement of time-average heat transfer coefficients varies in the range of 98.4–108.4% for different heaving conditions. As the vapor quality increases, the relative fluctuation amplitude Ah and sloshing time-average factor Fh of heat transfer coefficients initially increase and then decrease, showing a maximum at a vapor quality of 0.6; for increasing mass flux, Ah decreases and Fh increases; for decreasing sloshing period and increasing sloshing amplitude, both Ah and Fh decrease. A novel correlation model for the heat transfer coefficients under heaving conditions for flow boiling in offset strip fin channels is proposed, and the predicted deviations within ±10%.