Experimental investigation of convection heat transfer of CO2 at supercritical pressures in a vertical circular tube
Experimental investigation of convection heat transfer of CO2 at supercritical pressures in a vertical circular tube
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超临界压力下CO2在垂直圆管内对流传热的实验研究
DOI：
10.1016/j.expthermflusci.2010.04.005
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发表时间：
2010-11-01
影响因子：
3.2
通讯作者：
Zhang, Yu
中科院分区：
文献类型：
--
作者：
Li, Zhi-Hui;Jiang, Pei-Xue;Zhang, Yu
实验研究了超临界CO2在内径为2mm的垂直圆管内，压力为78 ~ 95 bar，进口温度为25 ~ 40℃，进口雷诺数为3800 ~ 20000时的对流换热特性。分析了热流密度、热物性、浮力和热加速度对对流换热的影响。实验结果表明，在高进口雷诺数（Re = 9000）和高热流密度条件下，向上流动有明显的局部换热恶化和恢复，而向下流动则没有。将进口雷诺数从3800到20,000的实验数据与一些众所周知的经验相关性进行比较，发现在换热恶化后又恢复的情况下差异很大。利用实验数据建立了超临界CO2在垂直小圆管内流动的修正局部湍流努塞尔数关系式。(C)2010爱思唯尔公司版权所有。
The convection heat transfer characteristics of supercritical CO2 in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 degrees C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermo-physical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not for downward flows. Comparison of the experimental data for inlet Reynolds numbers from 3800 to 20,000 with some well-known empirical correlations showed large differences especially when the heat transfer deteriorates and then recovers when the effect of buoyancy is significant. The experimental data was used to develop modified local turbulent Nusselt number correlations for supercritical CO2 flowing in vertical small circular tubes. (C)2010 Elsevier Inc. All rights reserved.