Liquid-migration based model for predicting the thermal performance of spiral wound heat exchanger for floating LNG

The spiral wound heat exchanger (SWHE) applied on floating liquefied natural gas (FLNG) vessels suffers performance deterioration due to the sloshing effects of lateral liquid migration and partially-dryout falling film evaporation. For predicting the SWHE performance under the sloshing effects, a mathematical model of floating SWHEs is presented in this paper. In the model, the lateral liquid migration is described by an equation of liquid migration mass flow rate deduced from laminar film momentum conservation; the partially-dryout falling film evaporation is calculated by the dryout area ratio using the weighted average method; the SWHE performance under the sloshing effects is predicted by incorporating the liquid migration mass flow rate and dryout area ratio into the mass and energy conservation equations. The comparisons of model predictions with experimental data show that the deviations of heat capacities are within 4.5% under the sloshing amplitudes among 0-9° and the periods among 6-20 s.