Study On The Temperature Field Of LNG Bunkering Vessel For Type C

With generalizing of LNG as the ship fuel,the bunkering technology gets more focuses of international community.So it has vast forward-looking in application and developing space.The working condition of LNG bunkering vessel is very complicated,which would cause unreasonable distribution of temperature.This leads to a major difference of internal and external temperature,which can have an adverse effect on structural strength and stability.This thesis targets to LNG bunkering vessel for type C independent tank,analyze and research the distribution of temperature.First of all,dividing the spatial structure according to the architectural feature,work environment and boundary condition of LNG bunkering vessel for type C independent tank.For the structure under water,heat convection between shell and sea water should be considered.For the structure above water,both heat convection and heat radiation between shell and air should be considered.Then get the initial hypothetical temperature through one-dimensional simplified calculation.Put the initial hypothetical temperature in the heat transfer coefficient calculation formula of every area respectively and get the initial heat transfer coefficient.After that,set up the heat balance equation according to the conservation of energy,in which we put initial heat transfer coefficient.Obtain the temperature of structure after the first iterative calculation.Do the iterative calculation as above until the temperature stable and get the heat transfer coefficient of every area in that case.Put the heat transfer coefficient and environment temperature in the three-dimensional finite element model.Calculation and get the distribution of the temperature field,according to which to select structural steel grade.Ordinary steel should be selected on the deck zone.The temperature of slope plate of lower hopper tank is under-5℃.Grade above B steel should be selected in this zone.The temperature of other zone is all above-5℃.Ordinary steel should be selected according to regular practice.The method of this thesis could be useful for the structural design of LNG bunkering vessel for type C independent tank.