热泵系统用二氧化碳混合制冷剂的理论分析与实验研究
发布时间：2019-05-18 09:33
【摘要】：以CO2（R744）与“零ODP”、“低GWP”人工制冷剂组成的混合制冷剂为研究内容，扬长避短，发挥制冷剂各自的优势，提高CO2系统效率，降低CO2系统排气压力，减小人工制冷剂充灌量和可燃性。采用理论分析和实验研究相结合的研究方法，以CO2水-水热泵系统实验台和制冷剂燃烧极限测试实验台为基础，研究混合制冷剂的燃烧特性、添加剂对CO2水-水热泵系统性能的影响及用CO2混合制冷剂的热泵系统性能。 以R744/R32混合制冷剂为重点，分析R744/R32、R744/R41和R744/R161混合制冷剂的物性参数，将NIST混合制冷剂参数与实验数据对比分析，采用Helmholtz状态方程对R744/R32混合制冷剂参数进行了优化，优化后的最大误差由6%降低到3.4%，计算精度显著提高。 对R744/R32，R744/R41，R744/R161，R744/R152a，R744/R290和R744/R1270共6组混合制冷剂进行热力学理论分析。当CO2的质量分数高于0.95时，循环为跨临界循环；随着CO2含量的降低，当CO2的质量分数低于0.95时，循环由跨临界循环过渡到亚临界循环。纯CO2以及CO2混合制冷剂的热泵循环存在最大COP及对应的最优排气压力。当CO2质量分数小于0.85时，R744/R32的系统效率最大，CO2质量分数大于0.85时，R744/R161的系统效率最大。 对R744/R32、R744/R41和R744/R161混合制冷剂燃烧下限（LFL）进行实验研究，分析惰性气体对燃烧下限（LFL）的影响，结果表明：随着CO2含量的增加燃烧下限（LFL）逐渐升高。当混合制冷剂中CO2的体积比接近50%时，与纯质的R32、R41和R161相比，燃烧下限（LFL）分别提高了0.5%、0.4%和0.45%。 基于跨临界CO2水-水热泵实验台，在充灌量一定的基础上，对含R32、R41和R161三种添加剂（添加剂质量分数小于5%）的跨临界CO2水-水热泵系统及R32添加剂对膨胀机的影响进行实验研究，对CO2水-水热泵系统用R744/R32，R744/R41，R744/R161三种混合制冷剂（R32、R41和R161质量分数5～50%）的性能进行实验研究。研究结果表明： 添加R32、R41和R161添加剂后，在部分工况下，COPh和COPc明显提高，COPh和COPc提高幅度R32R161R41。 在CO2水-水热泵系统用R744/R32，R744/R41，R744/R161三种混合制冷剂中，制热工况下，推荐使用R744/R32和R744/R41组成的混合制冷剂，最大COPh时，R32含量和R41含量分别为50%和40%，与纯质CO2相比，COPh对应提高20.4%和11.9%。制冷工况下，推荐使用R744/R32和R744/R41混合制冷剂，，最大COPc时，R32含量和R41含量分别为40%和40%，与纯质CO2相比，COPc对应提高20.8%和18.5%。R744/R32和R744/R41混合制冷剂随着R32和R41含量的增加，排气压力显著降低，与纯质CO2相比，R744/R32混合制冷剂的排气压力最大降低幅度达37.9%，R744/R41混合制冷剂的排气压力最大降低幅度达15%。由于滑移温度过大，制热量和制冷量显著减小，不推荐使用R744/R161混合制冷剂。
[Abstract]:The mixed refrigerants composed of CO2 (R744), "zero ODP" and "low GWP" artificial refrigerants are taken as the research content. The advantages and disadvantages of the refrigerants are given full play to improve the efficiency of the CO2 system and reduce the exhaust pressure of the CO2 system. Reduce the filling amount and flammability of artificial refrigerants. The combustion characteristics of mixed refrigerants were studied by using the combination of theoretical analysis and experimental research, based on the CO2 water-water heat pump system test bench and the refrigerants combustion limit test bench. The effect of additives on the performance of CO2 water-water heat pump system and the performance of heat pump system with CO2 mixed refrigerants. With emphasis on R744/R32 mixed refrigerants, the physical parameters of R744 / R32, R744 / R41 and R744/R161 mixed refrigerants are analyzed, and the parameters of NIST mixed refrigerants are compared with the experimental data. The Helmholtz equation of state is used to optimize the parameters of R744/R32 mixed refrigerants. The maximum error is reduced from 6% to 3.4%, and the calculation accuracy is significantly improved. Thermodynamic theoretical analysis of six groups of mixed refrigerants, R744 R42, R744 R161, R744 R152A, R744 R290 and R744/R1270, was carried out for R744 R32, R744 R41, R744 R161, R744 R152A, R744 R290 and R744 R290. When the mass fraction of CO2 is higher than 0.95, the cycle is transcritical cycle, and with the decrease of CO2 content, when the mass fraction of CO2 is less than 0.95, the cycle changes from transcritical cycle to subcritical cycle. The heat pump cycle with pure CO2 and CO2 mixed refrigerants has the maximum COP and the corresponding optimal exhaust pressure. When the mass fraction of CO2 is less than 0.85, the system efficiency of R744/R32 is the highest, and when the mass fraction of CO2 is greater than 0.85, the system efficiency of R744/R161 is the highest. The combustion lower limit (LFL) of R744 / R32, R744 / R41 and R744/R161 mixed refrigerants was studied experimentally. the effect of noble gas on the combustion lower limit (LFL) was analyzed. The results show that the combustion lower limit (LFL) increases gradually with the increase of CO2 content. When the volume ratio of CO2 in the mixed refrigerants is close to 50%, compared with the pure R32, R41 and R161, the combustion lower limit (LFL) is increased by 0.5%, 0.4% and 0.45%, respectively. Based on the transcritical CO2 water-water heat pump experimental platform, on the basis of a certain amount of filling, the content of R32, The transcritical CO2 water-water heat pump system with R41 and R161 additives (the mass fraction of additives is less than 5%) and the effect of R32 additives on the expander were studied experimentally. the R744 鈮
本文编号：2479887
[Abstract]:The mixed refrigerants composed of CO2 (R744), "zero ODP" and "low GWP" artificial refrigerants are taken as the research content. The advantages and disadvantages of the refrigerants are given full play to improve the efficiency of the CO2 system and reduce the exhaust pressure of the CO2 system. Reduce the filling amount and flammability of artificial refrigerants. The combustion characteristics of mixed refrigerants were studied by using the combination of theoretical analysis and experimental research, based on the CO2 water-water heat pump system test bench and the refrigerants combustion limit test bench. The effect of additives on the performance of CO2 water-water heat pump system and the performance of heat pump system with CO2 mixed refrigerants. With emphasis on R744/R32 mixed refrigerants, the physical parameters of R744 / R32, R744 / R41 and R744/R161 mixed refrigerants are analyzed, and the parameters of NIST mixed refrigerants are compared with the experimental data. The Helmholtz equation of state is used to optimize the parameters of R744/R32 mixed refrigerants. The maximum error is reduced from 6% to 3.4%, and the calculation accuracy is significantly improved. Thermodynamic theoretical analysis of six groups of mixed refrigerants, R744 R42, R744 R161, R744 R152A, R744 R290 and R744/R1270, was carried out for R744 R32, R744 R41, R744 R161, R744 R152A, R744 R290 and R744 R290. When the mass fraction of CO2 is higher than 0.95, the cycle is transcritical cycle, and with the decrease of CO2 content, when the mass fraction of CO2 is less than 0.95, the cycle changes from transcritical cycle to subcritical cycle. The heat pump cycle with pure CO2 and CO2 mixed refrigerants has the maximum COP and the corresponding optimal exhaust pressure. When the mass fraction of CO2 is less than 0.85, the system efficiency of R744/R32 is the highest, and when the mass fraction of CO2 is greater than 0.85, the system efficiency of R744/R161 is the highest. The combustion lower limit (LFL) of R744 / R32, R744 / R41 and R744/R161 mixed refrigerants was studied experimentally. the effect of noble gas on the combustion lower limit (LFL) was analyzed. The results show that the combustion lower limit (LFL) increases gradually with the increase of CO2 content. When the volume ratio of CO2 in the mixed refrigerants is close to 50%, compared with the pure R32, R41 and R161, the combustion lower limit (LFL) is increased by 0.5%, 0.4% and 0.45%, respectively. Based on the transcritical CO2 water-water heat pump experimental platform, on the basis of a certain amount of filling, the content of R32, The transcritical CO2 water-water heat pump system with R41 and R161 additives (the mass fraction of additives is less than 5%) and the effect of R32 additives on the expander were studied experimentally. the R744 鈮
本文编号：2479887
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