【作者】 苏健；

【导师】 张绍志；

【作者基本信息】 浙江大学 ， 制冷及低温工程， 2011， 硕士

【摘要】 自复叠制冷系统使用单级油润滑压缩机,具有结构简单、低温端无运动部件的特点,在—40℃～—160℃广阔的温区都有较高的效率,在低温电子、低温医学、冷冻干燥、气体液化领域具有良好应用前景。工质成份的优化对自复叠制冷系统至关重要,好的配比可以改善回热器高低压水当量匹配特性,使回热器的传热状况明显改善,大大减少回热过程和节流过程的不可逆损失,使系统性能明显改善。优化手段有数值模拟和实验等两种。由于多元混合工质的物性数据缺乏,使得数值模拟优化得到的结果与实际情况差别较大。目前,自复叠制冷系统工质成份的优化还是以实验为主。由于不同流程形式、不同应用场合的系统差别大,系统可调变量多,使得充注工质的优化过程费时费力。为了提高自复叠制冷系统的调试效率,本文设计了一套多元混合工质自动充注装置,并在自复叠制冷系统试验台上进行了工质的自动优化实验研究。论文主要进行了如下工作：1.总结了国内外有关制冷剂充注装置和自复叠制冷系统工质优化的研究进展。2.设计了一套多元混合工质制冷剂的自动充注装置,保证自复叠系统工质优化过程中制冷剂精确可控的加入,避免手动调试给充注过程带来干扰。3.结合自动充注装置,在现有自复叠制冷装置上进行了三元、四元工质的充注实验研究,建立不同沸点工质成份对系统运行的影响规律。4.进行了三元工质R50/R23/R600a和四元工质R50/R23/R600a/R1150在不同起始充注量下的优化实验,发现在不同的起始充注量下都可以达到相近的优化充注量,四元工质优化实验,得到的系统效率比采用三元工质时提高8-12%。更多还原

【Abstract】 The auto—cascade refrigeration system is a kind of refrigeration system, in which refrigerant mixture is employed and only one single—stage compressor with oil lubrication is required. Since auto—cascade refrigeration system is simple, having no moving parts working at low temperature, and highly efficient in temperature range of—40℃～—160℃, it has been widely used in the fields of electronics, medicine, freeze drying and gas liquefaction.The optimization of the composition of refrigerant mixture is important for the auto—cascade refrigeration system. Appropriate composition will facilitate the matching of water equivalences of high and low pressure side and reduce the irreversible loss in heat transfer and throttling processes. Usually numerical simulation and experimental test are used to optimize the composition. Due to the lack of property data of multi-component refrigerant mixture, the results of numerical simulation are different to the performance of actual system. Therefore, experimental tests is the primary means to obtain the ideal composition. Due to the variation of system and application, and the number of adjustable variable, the debugging of the charging process is hard and time-consuming. In order to raise the efficiency of debugging of auto-cascade refrigeration system, in this paper, an automatic charging device was designed and tested on an existing auto-cascade system. The main work carried out are listed as follows:1. domestic and foreign work about refrigerant charging device and composition optimization of refrigerant mixture for auto-cascade refrigeration system were summarized.2. an automatic charging device was designed to charge refrigerants automatically and accurately for the composition optimization process, avoiding the disturbance and inaccuracy caused by the manual operation. 3. based on the automatic charging device, experiments that utilized ternary and quaternary refrigerant mixture were done to study the impacts of refrigerants with different boiling points on the system running.4. composition optimization experiment were conducted from several initial charging states for ternary refrigerant mixture R50/R23/R600a and quaternary refrigerant mixture R50/R23/R600a/R1150. It was found that similar charging quantities were achieved after optimization. Compared with the system efficiency for the case of ternary refrigerant mixture, the system efficiency for the case of quaternary refrigerant mixture was increased by 8-12%.更多还原