Research On The Influence Of The Structures Of LNG Ambient Air Vaporizer On The Bottom Temperature Field

Influenced by the COVID-19 epidemic in 2020,the imbalance between supply and demand in the global LNG market has further deepened.The continuously low LNG current price provides a rare opportunity for the development of China’s LNG market.LNG ambient air vaporizer,as a kind of green and environment-friendly heat exchange equipment,has been developed more widely under the current policy of advocating low carbon energy.However,the research on LNG ambient air vaporizer in China is not deep enough at present.Regarding the structure of LNG ambient air vaporizer,it still remains in the stage of relying on experience design,and no sound and mature industry design standards and specifications have been established.During the operation of ambient air vaporizer,the structures of the equipment determines its heat transfer capacity,and the bottom of the ambient air vaporizer is in the most unfavorable heat transfer state,and there will be frosting and cold fog in serious cases.However,there are few studies on the influence of the structure of the ambient air vaporizer on the temperature field at the bottom of the equipment.Therefore,in view of the influence of the structure of the LNG ambient air vaporizer on the bottom temperature field,the influence of various factors on the bottom temperature field was studied from three aspects: the height of the leg,the structure coefficient and the temperature of the outer wall of the finned tube.Based on the heat transfer mechanism inside and outside the finned tube of LNG ambient air vaporizer,the simplified heat transfer geometric model in this paper was analyzed to verify that the heat transfer model in this paper retained the geometric characteristics of LNG ambient air vaporizer,which laid a theoretical foundation for subsequent numerical simulation.The heat transfer between the outer wall of the finned tube of the LNG air temperature gasifier and the surrounding air area was simulated and calculated by using ANSYS software,and the simulation results were analyzed.Proposed LNG ambient air vaporizer impact factor s bottom of temperature field,based on the established temperature field at the bottom of impact factors,to simulate the gasification bottom section temperature field calculation,get the quantity of gasification,the air temperature of evaporator temperature field at the bottom of the impact factor s calculation data,to analyze the data,the quantity of the gasification air temperature type evaporator,The impact factor s increases with the increase of the height of the outerleg,and the increasing trend of the impact factor tends to be gentle after a certain height of the outerleg.According to the distribution trend of s-h data,different fitting formulas were used to fit the data,and the s-h fitting curve was obtained.The evaluation index of the leg height threshold and the corresponding stable interval and length of the leg height were proposed to obtain the leg height threshold,stable interval and length of the leg height of the ambient air vaporizer under each gasification amount.It was found that the leg height threshold increased with the increase of the gasification amount.The length of the stable interval of the corresponding leg height decreases with the increase of the gasification amount.The structure coefficient k of LNG ambient air vaporizer was proposed,and the s-h fitting curve of LNG ambient air vaporizer with different structure coefficients was analyzed.The gasifier with the same structure coefficient was obtained.At the height of the same leg,the influence factor was proportional to the amount of gasification.The mathematical expression of the influence factor increment between the structure coefficient and the temperature field at the bottom is constructed,and it is concluded that the influence factor increment is a power function relationship with the gasification quantity,and the power value is related to the structure coefficient.When the temperature of the outer wall of the finned tube of the ambient air vaporizer is uniformly distributed along different temperatures,the influence factor of the bottom temperature field is the most sensitive to the temperature range of the outer wall of the finned tube in the two-phase region.The sensitivity analysis of the influencing factors of the bottom temperature field(the height of the outerleg,the structural coefficient and the temperature of the outer wall of the finned tube)was carried out,and the order of the sensitivity of the influencing factors was obtained.