LNG卡车空调冷能利用系统设计及气化器分析

发布时间：2017-12-28 06:25

本文关键词：LNG卡车空调冷能利用系统设计及气化器分析　出处：《山东大学》2016年硕士论文　论文类型：学位论文

【摘要】：世界能源环境危机促进了LNG(液化天然气)汽车的发展。LNG的存储温度是-162℃,需要将天然气温度升温至10～40℃才能供入发动机。天然气在气化升温过程中会释放巨大的冷能,本文所涉及的LNG汽车空调系统即利用天然气气化升温过程中释放的冷能。LNG气化装置是该空调系统的核心装置,气化器的气化性能直接决定了天然气发动机供气的可靠性,探究气化器的换热性能极为必要。本文在广泛阅读文献,了解国内外研究现状,综合利用理论分析、数值模拟相结合的方法对空调系统进行设计仿真,并对不同结构气化器进行数值计算得到各结构下的换热性能和压降特性。LNG冷能用于汽车空调系统需要冷媒对来进行冷量的传递,本文结合实际确定合适的冷媒,实现利用LNG冷能为驾驶室供冷。LNG的存储温度为-162℃,易导致空调系统管道结冰,并且LNG的流量随汽车行驶工况变化而变化,因而在对空调系统设计时综合考虑了管道结冰,LNG流量不均匀的情况,以确保空调系统的可靠性。气化器是该空调系统的重要部件,本文利用CFD软件对气化器换热情况进行计算。LNG在气化器中存在相变,在计算过程加入相变函数,以保证计算的真实性。分析了在LNG最大流量下,改变系统中冷媒流量得到系统管道不结冰的临界工况,确定保证系统正常运行的最小冷媒流量,为系统的安全工作和泵的选型提供依据。核算了二级气化器的气化性能,探讨空调系统对发动机供气的影响。根据扭曲管换热器的思想,设计出扭曲螺旋管换热器。对不同导程和横截面参数的扭曲螺旋管进行计算,得到各管换热性能和压降性能,比较不同扭转螺旋管的综合性能,得到相较于原气化器螺旋管的优化方案；并针对不同方案计算结果拟合得到扭曲螺旋管的换热性能和流动特性无量纲关系式。利用一维软件确定空调系统的实际送风量,并根据一维计算得到得到空调换热器冷媒流量和冷媒入口温度的关系。根据三维计算得到的冷媒流量和一维计算得到的送风量,搭建整个空调系统模型,验证方案可行性,并优化参数设计。
[Abstract]:The crisis in the world's energy environment has promoted the development of LNG (liquefied natural gas) vehicles. The storage temperature of LNG is -162 C, and the temperature of natural gas needs to be heated to 10~40 C in order to supply the engine. Natural gas will release huge cold energy during the process of gasification and heating. The LNG automotive air conditioning system in this paper is the cold energy released from natural gas gasification and heating process. The LNG gasification device is the core device of the air conditioning system. The gasification performance of the gasifier directly determines the reliability of the gas supply of the natural gas engine, and it is extremely necessary to explore the heat transfer performance of the vaporizer. In this paper, we read extensively the literatures and understand the research status at home and abroad. Combined with theoretical analysis and numerical simulation, we design and simulate the air conditioning system, and calculate the heat transfer performance and pressure drop characteristics of different structures under different structures. LNG cold energy can be used for vehicle air conditioning system to transfer refrigerating volume to refrigerant pairs. In this paper, combined with the actual situation, the suitable refrigerant is determined, and the LNG cold energy can be used to cool the cab. The storage temperature of LNG is -162 degrees, which is easy to cause the icing of air conditioning system, and the flow of LNG varies with the driving cycle. Therefore, when the design of air conditioning system is considered, the situation of pipeline icing and uneven LNG flow is taken into account, so as to ensure the reliability of air conditioning system. The gasifier is an important part of the air conditioning system. In this paper, the CFD software is used to calculate the heat transfer of the gasifier. LNG has a phase transition in the gasifier, and the phase transition function is added in the calculation process to ensure the authenticity of the calculation. Based on the analysis of the maximum flow rate of LNG, the critical condition of refrigerant system is obtained by changing the refrigerant flow rate in the system, and the minimum refrigerant flow to ensure the normal operation of the system is determined, which provides a basis for safety work and pump selection. The gasification performance of two stage gasifier is calculated and the influence of air conditioning system on engine gas supply is discussed. The twisted tube heat exchanger was designed according to the thought of the twisted tube heat exchanger. Twisted spiral on the different lead and cross-section parameters of the tube are calculated, the pipe heat transfer and pressure drop performance, comprehensive performance comparison of different reverse spiral tube, are compared with the optimization scheme for the original spiral pipe; and according to the different calculation schemes results fitted the twisted spiral tube heat transfer and flow the characteristics of the dimensionless relation. One dimension software is used to determine the actual air supply of the air conditioning system, and the relationship between the refrigerant flow rate and the inlet temperature of the refrigerant is obtained by one dimension calculation. According to the refrigerant flow rate and the air volume calculated by one-dimensional calculation, the whole air conditioning system model is built, and the feasibility of the scheme is verified, and the parameter design is optimized.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U463.851

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