【作者】 何冰强；

【导师】 梁荣光；

【作者基本信息】 华南理工大学 ， 车辆工程， 2010， 博士

【摘要】 二氧化碳汽车空调系统（The Carbon Dioxide Automotive Air Conditioning System,CO₂-AACS）是一种以CO₂为制冷工质的节能、环保空调系统。本文基于规模化生产具有工程应用价值的高效微通道平行流气体冷却器（The Gas Cooler of Micro-channel with Parallel Flow, GCMCPF）为目标,研究强化CO₂工质在GCMCPF中的换热。在广东省教育部产学研结合产业化示范基地建设项目（No. 2008B090200051）的资助下,本文对CO₂在GCMCPF的流动和传热特性进行了深入的实验研究。论文的主要内容包括如下几方面:首先,基于GCMCPF结构和工质的均质流动与平均温差,建立了“GCMCPF参数化模型”算法。在分析GCMCPF技术目标参数的基础上,求解了矩形微通道、圆形微通道的单元式数值模型。针对GCMCPF在CO₂-AACS中需要高压运行,提出了“刺破翻边”的实物构造技术,构造了能承受高压的实物模型,为研究CO₂的流动和传热奠定了基础。其次,分析了CO₂跨临界制冷循环工作原理,针对CO₂在GCMCPF的超临界状态,利用二氧化碳压缩机（CO₂ Compressor,CO₂-C）和GCMCPF为主要单元,构建了跨临界二氧化碳空调系统（Air Conditioner of Carbon Dioxide in Trans-Critical, CO₂-ACTC）试验平台。完成了基于车辆行驶实际工况的试验平台测试,结果表明:该试验平台满足设计要求,同时适用于研究以二氧化碳为工质的相关系统元器件的结构及性能特性研究。再次,针对影响CO₂流动与换热的主要因素,结合试验平台的功能特性,拟定了研究CO₂流动与传热的实验方案。进行了矩形、圆形单元GCMCPF的流动和传热特性实验。基于实验结果,分析了CO₂在GCMCPF的流动与传热。为深入研究GCMCPF强化传热指明了方向。最后,针对单元式GCMCPF存在流动与传热不均衡的问题,以改善CO₂的流动和强化高效传热为目标,从优化结构出发,构建了圆形微通道的多元式GCMCPF对比研究实物,并进行了对比实验和研究分析。结果表明,该模型达到了高效换热并具有工程应用推广价值。本文建立了适用于本实验条件下的“GCMCPF参数化模型”算法;提出并采用“刺破翻边”技术对GCMCPF进行实物构造;设计并构建了以CO₂-C和GCMCPF为主要单元的CO₂-ACTC试验平台;通过对GCMCPF进行实验研究,分析了主要工况条件对CO₂在GCMCPF中的流动与换热性能的影响。这些研究工作可为GCMCPF的应用提供理论和实验依据,本试验平台同时也适用于以CO₂为工质的相关系统元器件结构及性能特性的研究。更多还原

【Abstract】 The carbon dioxide automotive air conditioning system （CO₂-AACS） is an energy-saving and environment-friendly air conditioning system. It uses CO₂ as work medium in refrigeration. This dissertation focuses on researching the flow and heat transfer characteristics of CO₂, aiming to determine methods for increasing heat transfer efficiency in the gas cooler of micro-channel with parallel flow （GCMCPF）. We expect the findings of this research to contribute to the industrial production of this equipment. Toward these ends, the following measures were taken:First, an algorithm was developed based on the analysis of the GCMCPF structure in homogeneous flow of work medium and mean temperature difference. Using GCMCPF technical data, numerical analysis of both the circle and rectangle micro-channels of the GCMCPF was performed. The CO₂-AACS has to work under high pressure; thus, we developed a structure formation method called pierce and flanging, which can help improve strength in the welding region for construction of collecting tubes that can withstand high pressure in work conductions. This structure lays the foundation for studying CO₂ flow and heat transfer.Second, we studied the principle of refrigeration of CO₂ circulation in trans-critical flow. Considering the characteristics in trans-critical flow, we designed and constructed an experimental platform for a carbon dioxide air conditioner in trans-critical （CO₂-ACTC） flow. This platform uses a CO₂ compressor （CO₂-C） and the GCMCPF as the main components. Experiments were conducted simulating the work conditions of a car. Results show that the platform can work well, and satisfies the requirements of research on the characteristics of a parallel flow cooler that uses CO₂ as work medium.We designed the experimental scheme taking into consideration the main factors influencing flow and heat exchange of CO₂ and the performance of the experimental platform. Performance analysis of flow and heat transfer in the circle and rectangle micro-channels of the GCMCPF was conducted. The results serve as guidelines for further research on intensified heat transfer of the GCMCPF.To solve the problems of fluency and unbalanced heat transfer generated by the single-channel model of the GCMCPF, two multi-channel models of the rectangle and circle micro-channels were designed and constructed in the experiment. Experimental results show that multi-channel GCMCPF can considerably increase the heat transfer efficiency of the GCMCPF and enhance its applicability in engineering.In this dissertation, the GCMCPF was constructed using the pierce and flanging method, and an algorithm was established and applied to the experimental conditions of the GCMCPF. The experimental platform of the CO₂-ACTC using CO₂-C and GCMCPF as the main components was designed and constructed. The influence of different working conditions on flow and heat exchange of CO₂ in the GCMCPF was analyzed based on experiments on the GCMCPF. The work in this dissertation can provide theoretical and experimental support in GCMCPF applications, as well as facilitate research on the characteristics of relevant systems that use CO₂ as work medium.更多还原