摘要
在超临界CO2布雷顿循环系统中,由于超临界流体特殊的热物性,并联受热管路中易发生流量分配不均现象,从而易产生热偏差和热应力,严重威胁着换热设备的安全稳定运行。针对并联受热通道内超临界CO2流量分配不均现象开展实验研究,探究流量分配不均的产生机理、影响规律及其抑制方法。采用两根加热长度280 mm,内径2 mm的不锈钢圆管组成并联通道,采用电加热方式分别控制两个并联支路的加热热流。实验参数范围:压力p=7.5-9.2 MPa,热流密度q=0-100 kW/m^2,总进口质量流量m=100-185 g/min,进口温度T=20℃。结果表明,热偏差是流量分配不均的主要因素,且热偏差程度越大,则流动分配不均现象越显著;提高压力及增大进口质量流量,流量偏差程度减弱;采用进口节流装置是一种抑制超临界CO2流量偏差的有效措施,节流程度越大,则流量偏差抑制效果越明显。研究成果为超临界CO2布雷顿循环流动换热系统的设计及优化提供理论基础与技术支撑。
Due to the special thermo-physical properties of supercritical fluids,the phenomenon of nonuniform flow distribution is likely to occur in parallel heated channels in the supercritical CO2 Brayton cycle,which threatens the safe and stable operation of heat exchange equipments owing to induced thermal stress.In this paper,experiments are performed to study on the nonuniform distribution of supercritical CO2 flowing in parallel heated channels.The occurrence mechanism,influencing factors and suppression method for nonuniform flow distribution are explored.Two circular stainless steel tubes are adopted as the parallel test section,with an inner diameter and a heated length of 2 mm and 280 mm,respectively.The heat fluxes for the two parallel channels are controlled by electric heating method.The ranges of test parameters are as follows:system pressure p=7.5-8.5 MPa,heat flux q=0-100 kW/m^2,total mass flow m=100-185 g/min and inlet fluid temperature T=20℃.The results show that the thermal deviation is the main factor for nonuniform flow distribution,and the flow deviation is more obvious with increasing thermal deviation.The flow deviation is suppressed with increasing the system pressure and total mass flow.It is effective to weaken the nonuniform flow distribution by using the strategy of inlet throttling,and the effect of suppressing the flow deviation is more obvious under a greater degree of throttling.The results provide a theoretical basis and technical support for the design and optimization of heat exchanger system in supercritical CO2 Brayton cycle.
作者
颜建国
郑书闽
郭鹏程
白晨光
刘寿春
YAN Jian-guo;ZHENG Shu-min;GUO Peng-cheng;BAI Chen-guang;LIU Shou-chun(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi’an University of Technology,Xi’an 710048,China)
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
2019年第6期713-719,共7页
Chinese Journal of Hydrodynamics
基金
陕西省自然科学基础研究计划(2019JQ-185)
国家自然科学基金项目(51839010)
陕西省重点研发计划(2017ZDXM-GY-081)
中国博士后科学基金资助项目(2018M633546)~~
关键词
超临界流体
流量分配
流量偏差
并联通道
Supercritical fluid
Flow distribution
Flow deviation
Parallel channel
