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文中介绍在跨临界CO_2制冷系统中采用的双节流装置,第一膨胀阀用来控制高压侧压力,第二膨胀阀用两相流引射器代替,以回收系统膨胀功。对双节流装置引射制冷系统的性能进行了实验研究,分析了两段式喷嘴几何尺寸和工况变化对引射器性能和系统COP的影响。实验结果表明,在固定工况下,随着第一喷嘴扩张角的增加,引射比和压缩机耗功先增大后减小,而系统制冷量和系统COP呈相反的趋势;随着第一喉部当量直径的增加,引射比和系统COP都先增大后减小。在固定几何尺寸下,蒸发温度为-1℃和-3℃时,系统COP和引射比分别取得最大值;随着气冷器出口压力的升高,引射比逐渐增加,而系统COP逐渐减小。
The article introduces the double throttling device used in the transcritical CO_2 refrigeration system. The first expansion valve is used to control the pressure on the high pressure side. The second expansion valve is replaced by the two-phase flow ejector to recover the system expansion work. Experimental study on the performance of the throttling refrigeration system with double throttling device was carried out. The influence of the nozzle geometry and working conditions on the ejector performance and system COP was analyzed. Experimental results show that with the increase of the first nozzle divergence angle, the injection ratio and compressor work efficiency first increase and then decrease, while the system cooling capacity and system COP show the opposite trend. A throat equivalent diameter increases, the injection ratio and the system COP first increased and then decreased. At fixed geometry, the COP and the emissivity of the system were maximized at -1 ℃ and -3 ℃, respectively. With the increase of the outlet pressure of the air cooler, the injection ratio increased gradually and the COP of the system gradually increased Decrease