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中南大学学报(自然科学版)

Journal of Central South University

第49卷    第3期    总第283期    2018年3月

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文章编号:1672-7207(2018)03-0741-06
水平微肋管内有机工质R245fa的沸腾换热性能
王志奇1,刘力文1,贺妮1,夏小霞1, 2,彭德其1,张建平1,明镇洋1

(1. 湘潭大学 机械工程学院,湖南 湘潭,411005; 2. 中南大学 能源科学与工程学院,湖南 长沙,410083)

摘 要: 为增强有机朗肯循环发电系统中蒸发器的传热能力,对水平微肋管内新型有机工质R245fa的沸腾换热性能进行实验研究。研究结果表明:R245fa沸腾换热系数随质量流速增大而提高,随饱和温度和热流密度增大而减小;随着干度增大,沸腾换热系数先增大后降低,存在1个临界干度;在实验条件下,临界干度约为0.4,并与实验工况有关;超过临界干度时,质量流速对R245fa沸腾换热系数的强化作用增大,而饱和温度对沸腾换热的抑制作用增大;在4种常用关联式中,KANDLIKAR关联式对R245fa沸腾换热性能的预测较精确,预测值与91.6%的实验值偏差在±25%以内,绝对平均偏差为11.2%,能满足工程设计要求。

 

关键词: 微肋管;R245fa;沸腾换热;预测关联式

Flow boiling heat transfer characteristics of R245fa in horizontal micro-fin tube
WANG Zhiqi1, LIU Liwen1, HE Ni1, XIA Xiaoxia1, 2, PENG Deqi1, ZHANG Jianping1, MING Zhenyang1

1. Institute of Mechanical Engineering, Xiangtan University, Xiangtan 411005, China; 2. School of Energy Science and Engineering, Central South University, Changsha 410083, China

Abstract:To intensify the heat transfer process of evaporator in organic Rankin cycle (ORC), flow boiling heat transfer characteristics of R245fa in a horizontal micro-fin tube were tested. The results show that boiling heat transfer coefficient increases with the increase of mass velocity of R245fa, while it decreases with the increase of saturation temperature and heat flux density. With the increase of vapor quality, boiling heat transfer coefficient reaches the maximum at a critical vapor quality. The critical vapor quality is about 0.4, and it is varied according to the operating conditions. When vapor quality is larger than the critical value, heat transfer coefficient can be promoted more remarkably at higher mass velocity or lower saturation temperature. Among the four widely used correlations, KANDLIKAR correlation has high forecast accuracy, the deviation between the forecast value and 91.6% of experimental values is within ±25%, and the absolute mean deviation is 11.2%.The correlation is more precise to predict boiling heat transfer coefficients, and it can be used for the design of evaporator in ORC.

 

Key words: micro-fin tube; R245fa; flow boiling; prediction correlations

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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