Numerical Investigation And Experimental Verification Of Falling Film Flow And Heat Transfer At Shell-Side Of Coil-Would Heat Exchanger Under FLNG Offshore Condition

As the main cryogenic heat exchanger floating LNG(FLNG)platform,Coil-Wound Heat Exchanger(CWHE)cannot be prevented from being influenced by sloshing movement under off-shore condition.And the total liquid yield of FLNG descend caused by deterioration of CWHE performance.It becomes important to ascertain the change regulation of CWHE under off-shore condition to optimize structure parameters.Firstly,the numerical model of the flow and heat transfer characteristics of fluid falling film evaporation in shell-side of CWHE is established The mechanism of the status of shell-side two-phase flow should be analyzed.Then,a model for simulating flow pattern,including the droplet flow,the column flow and the sheet flow,is developed by employing the Volume of Fluid-Continuous Surface Force method;the mass transfer model is developed and mass transfer rate can be predicted on tube surface and liquid-gas interface;then the latent heat during evaporation and condensation can be calculated based on the mass transfer rates.Secondly the applicability of the CWHE shell-side model is enhanced to be applicable to off-shore condition.An off-shore numerical simulation method is proposed based on ship movement form.Then a model for correcting gravity direction and a model for additional sloshing additional are involved in the numerical model,which makes simulation of CWHE performance under off-shore condition possible.The proposed model is validated by the experimental data from the existing experimental results.The flow pattern of simulation results is almost same as the images observed from experiment results.And the validation results show that the predicted data can agree with the experimental data within averaged deviation of±18.3%.The offshore performance of CWHE is numerically analyzed,and the results show that the performance of CWHE is associated with movement form,movement amplitude and movement frequency.Under yawing,rolling and swaying condition the heat transfer performance descends,especially under condition of high frequency and large amplitude.The worst heat transfer area deteriorate by 47%.Under heaving the heat transfer is enhance for half period but gets worse on the whole.The heat transfer is also the worst by increasing frequency and amplitude but trend to be intensified under small amplitude and low frequency condition.