适合小管径空调器的分配器分流性能评价与结构优化

为了开发具有最佳流量分配性能的小管径空调分配器,本文采用数值仿真和空气-水实验相结合的方法评价了常用分配器的分流性能,提出分配器的结构优化方法,并利用空调整机实验验证了该结构优化方法的改进效果。对于三种比较适合于小管径空调器的分配器进行的实验和计算表明,插孔式分配器的分流性能最佳,在额定制冷和额定制热工况下流量分配不均匀度均小于6%;实验结果与仿真计算得出的分配器流量分配不均匀度结果吻合,计算结果与实验的偏差都在15%以内。利用验证过的仿真模型,对插孔式分配器进行结构优化,优化后的分配器应用于空调整机后,系统能效提高了2.2%~2.7%。     

新型双温驱动吸收制冷循环性能

针对跨临界CO_2压缩制冷系统制取冷量以消耗高品位能量为代价的问题,本文依据能量梯级利用原理,提出双温低品位热源驱动的新型CO_2-[emim][Tf_2N]吸收式制冷循环的新流程,在构建该制冷循环数学模型的基础上,搭建测试双温驱动吸收制冷循环性能的实验装置,利用模拟和实验方法分析了操作参数对系统性能的影响规律。在定流量的条件下,研究驱动热源温度、冷却水入口温度以及载冷剂入口温度等操作参数对新系统性能的影响规律,结果表明双温驱动新型吸收制冷系统不仅可实现高效制冷,而且最低制冷温度可达到-15.2℃,研究结果为CO_2-离子液体制冷系统的理论设计计算提供实用的数据基础。     

Reliability-based design optimization under stationary stochastic process loads

Time-dependent reliability-based design ensures the satisfaction of reliability requirements for a given period of time, but with a high computational cost. This work improves the computational efficiency by extending the sequential optimization and reliability analysis (SORA) method to time-dependent problems with both stationary stochastic process loads and random variables. The challenge of the extension is the identification of the most probable point (MPP) associated with time-dependent reliability targets. Since a direct relationship between the MPP and reliability target does not exist, this work defines the concept of equivalent MPP, which is identified by the extreme value analysis and the inverse saddlepoint approximation. With the equivalent MPP, the time-dependent reliability-based design optimization is decomposed into two decoupled loops: deterministic design optimization and reliability analysis, and both are performed sequentially. Two numerical examples are used to show the efficiency of the proposed method.