基于传热窄点分析的跨临界CO2系统稳态性能研究  

Steady state performance of transcritical CO2 system based on pinch point analysis

作　　者：朱超男 陈蕴光[1] Zhu Chaonan;Chen Yunguang(School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院

出　　处：《低温与超导》2019年第11期55-61,共7页Cryogenics and Superconductivity

摘　　要：基于传热窄点研究了固定气体冷却器进出口水温时,高低不同的进水温度、不同的出水温度、排气压力、蒸发温度、过热度以及换热面积对于系统性能的影响。结果表明:随着进出口水温的升高和换热面积的减小,系统COP逐渐减小,并且最优高压压力逐渐升高;随着蒸发温度的升高,系统COP逐渐增加,最优高压压力逐渐升高;增加过热度只会在排气压力较低时提高系统的COP。当处于部分负荷工况时,冷端温差随负荷率的增加而减小;对于气冷器进出口水温温差大的工况,当负荷率小于1时传热窄点会位于换热器中间位置。在负荷率到达1时,传热窄点恰好移动到冷端。当负荷率大于1时,传热窄点一直稳定在冷端;对于气冷器进出口水温温差小的工况,当负荷率小于1时,传热窄点就已经到达冷端,并随着负荷率的增大一直稳定在冷端;部分负荷下的COP总是小于设计负荷下的COP,实际负荷偏离设计负荷越远,系统的COP越小。Based on pinch point analysis, the effects of inlet water temperature, outlet temperature, discharging pressure, evaporation temperature, superheat and heat transfer area on the performance of CO2 heat pump system were studied. The results show that with the increase of inlet and outlet water temperatures and the decrease of heat transfer area, the COP gradually decreases, and the optimal discharging pressure gradually increases;With the increase of evaporation temperature, the COP gradually increases and the optimal discharging pressure gradually increases;Increasing the superheat will increase the COP under the condition of low discharging pressure.The approach temperature difference of the gas cooler decreases with the increase of the load rate under the conditions of partial load;For the conditions where the inlet and outlet water temperature difference is large, when the actual load rate is less than 1, the pinch point locates in the middle of the gas cooler. When the actual load rate reaches 1, the pinch point just moves to the cold end. When the actual load rate is greater than 1, the pinch point always locates at the cold end. For the conditions where the inlet and outlet water temperature difference is small, when the actual load rate is less than 1, the pinch point has already moved to the cold end of the gas cooler, and it always locates at the cold end with the increase of load rate;The COP under partial load is always less than the COP under the design load, and the more the actual load deviates from the design load, the smaller the COP is.

关 键 词：CO2跨临界循环 COP 传热窄点 冷端温差 部分负荷 

分 类 号：TB657.2[一般工业技术—制冷工程]