新型LNG汽化器传热性能分析及相关液膜传热实验研究

发布时间：2018-05-07 01:30

本文选题：液化天然气(LNG) + 超级开架式汽化器(SuperORV)　；参考：《浙江大学》2014年硕士论文

【摘要】：在环境问题和能源问题日益成为掣肘世界经济发展的大背景下,天然气作为一种清洁又高效的能源,受到了越来越多的重视。液化天然气(简称LNG)相关的贮存和汽化设备也成为了近些年来研发工作的热点。开架式汽化器(Open-Rack Vaporizer,简称ORV)是LNG接收终端中以海水为热源、用于基本负荷的大型汽化装置。由于海水容易在其底部结冰使得该装置的传热性能下降,导致其汽化性能无法得到进一步的提升。超级开架式汽化器(简称SuperORV)正是在此背景下被开发的,它是在传统ORV基础上的改进版本,采用双层结构的传热管可有效改善汽化器管束外的结冰状况并提高换热效率,目前国内对该装置传热性能的研究还比较少。此外,对于水加热型汽化器,由于利用液膜进行加热的传热方式在一般换热设备中很少被利用,热工研究者对液膜用于加热低温介质的传热过程重视程度还不是很够。因此,对该新型汽化器及相关传热机理的研究无论对于丰富降膜传热的内涵,还是对包括LNG行业在内的低温工程领域都具有重要的现实意义。基于理论和实践相结合的研究思路,本文开展了针对SuperORV传热管的换热特性模拟研究以及其关键传热方式之一竖直管外冷却降膜传热特性的实验研究,旨在为该类汽化器的设计、选型和运行管理提供参考。主要开展以下几方面的工作： 1.详细分析SuperORV关键元件—传热管中海水与LNG的换热过程。根据传热机制的不同,对换热区间进行了划分,即传热管加热段内套管中的LNG流体先后经历单相液体对流换热区、欠热沸腾换热区、饱和沸腾换热区和缺液区,而汽化段环状间隙和加热段内的气态天然气经历单相过热气体对流传热区。对不同换热区间可能适用的对流换热实验关联式进行了分析与探讨,总结出一组适用于SuperORV传热管的传热关联式。在此基础上,建立描述传热管整体换热过程的稳态分布参数模型,并对模型的有效性进行验证。 2.利用上述稳态分布参数模型,对SuperORV传热管的换热性能进行详细的分析,主要包括：获得工作条件下流体和管壁的温度分布；分析并比较强化传热措施对传热管传热性能的影响,以及对结冰状况的影响；探讨冰层状况对传热管换热性能的影响。 3.对管外液膜流动传热的实验研究现状进行了调研,在总结了各相关研究中的实验方法、技术方案及实验装置等的特点的基础上,分析实验的对象、原理和研究目标等,从而确定适用于竖直管外被冷却降膜传热的实验方案,并搭建相关实验系统。利用该实验装置,针对雷诺数对竖直管外被冷却降膜传热特性的影响,开展系统的实验研究,并从实验中所获得的结果中归纳出高雷诺数、中雷诺数和低雷诺数三个区间的无量纲平均换热系数的实验关联式。
[Abstract]:As a kind of clean and efficient energy source , natural gas has been paid more and more attention in the context of environmental problems and energy problems . It is a hot spot in the research and development of LNG in recent years .

Based on the combination of theory and practice , this paper has carried out an experimental study on the heat transfer characteristics of SuperORV heat transfer tubes and the experimental study on the heat transfer characteristics of the outer cooling and falling film of one of the key heat transfer modes . The purpose of this paper is to provide a reference for the design , selection and operation management of this type of vaporizer .

1 . The heat transfer process of the seawater and LNG in the superORV critical element - heat transfer pipe is analyzed in detail . According to the different heat transfer mechanism , the heat transfer zone is divided , that is , the LNG fluid in the heating section of the heat transfer pipe is subjected to the single - phase liquid convection heat transfer area , the under - heat boiling heat exchange area , the saturated boiling heat exchange area and the liquid - deficient area , and the annular gap of the vaporizing section and the gaseous natural gas in the heating section are subjected to single - phase superheated gas convection heat transfer area .

2 , using the steady state distribution parameter model , carrying out detailed analysis on the heat exchange performance of the SuperORV heat transfer pipe , and mainly comprises the following steps of : obtaining the temperature distribution of the fluid and the pipe wall under working conditions ;
The effect of heat transfer measures on the heat transfer performance of heat transfer tubes was analyzed and compared .
The effect of ice layer condition on heat transfer performance of heat transfer tubes is discussed .

3 . Based on the research of the experimental research on the flow heat transfer of the outer liquid membrane , the experimental method , the technical scheme and the research object of the experiment are summarized . The experimental results of the experiment are analyzed , and the experimental system is set up . The experimental research is carried out on the effect of the Reynolds number on the heat transfer characteristics of the cooled falling film outside the vertical pipe , and the experimental study on the dimensionless average heat transfer coefficient in three sections of high Reynolds number , medium Reynolds number and low Reynolds number is summarized from the results obtained in the experiment .

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB611

【参考文献】