ORC系统中板式蒸发器传热特性的研究  

Numerical Study of Evaporator's Heat Transfer Characteristics in ORC System

作　　者：邱长亮 吴俐俊[1] 吴世锋 QIU Chang-liang;WU Li-jun;WU Shi-feng(College of Mechanical and Energy Engineering, Tongji University, Shanghai 201804, China)

机构地区：[1]同济大学机械与能源工程学院,上海201804

出　　处：《节能技术》2020年第1期9-15,37,共8页Energy Conservation Technology

基　　金：国家自然科学基金资助项目(51574179)。

摘　　要：蒸发器作为余热回收有机朗肯循环(Organic Rankine Cycle,ORC)系统的关键部件之一,其传热性能影响着整个系统的传热效率。本文以新型全焊式板式换热器为模型,通过加载蒸发相变UDF进行数值模拟,得出不同的热水流量、热水进口温度、R245fa流量下的传热和流动特性,并通过计算不同工况下j因子和f因子定量评估了蒸发器的综合换热性能。计算结果表明:提高热水进口流量和R245fa流量对ORC系统蒸发器的传热性能有明显的改善作用;随着热水进口流量、热水进口温度以及R245fa入口流量的增加,热水侧压降和工质侧压降随之增大,热水侧压降整体大于工质侧压降,且热水侧j/f分别提高了71.6%,-18.1%,73.3%,工质侧j/f分别提高了29.7%,-13.5%,35.9%。Evaporator is one of the key components of Organic Rankine Cycle(ORC)system for waste heat recovery,and its heat transfer performance affects the heat transfer efficiency of the whole system.In this paper,based on the Mixture multiphase flow model in Fluent,a new type of all-welded plate heat exchanger was used as the evaporator model.By loading a user-defined function(UDF),the variation of heat transfer and flow characteristics of the evaporator were studied under different conditions of hot water flow rate,hot water inlet temperature and R245fa inlet flow rate.And the comprehensive heat transfer performance of evaporator was quantitatively evaluated by calculating j factor and f factor under different working conditions.The results showed that increasing the water inlet flow rate and R245fa inlet flow rate could significantly improve the heat transfer performance of the evaporator in ORC system.The pressure drops of hot water side and R245fa side increased with an increase of hot water inlet flow rate,hot water inlet temperature and R245fa inlet flow rate,the pressure drop of hot water was higher than that of working medium.And the j/f of hot water side increased by 71.6%,-18.1%and 73.3%respectively,the j/f of working medium side increased by 29.7%,-13.5%and 35.9% respectively.

关 键 词：蒸发器 数值模拟 气液相变 传热特性 性能评价 

分 类 号：TK11[动力工程及工程热物理—热能工程]