高效宽负荷率超超临界锅炉垂直管圈水冷壁在低质量流速下的传热特性
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摘要
在压力p=21~29.8 MPa、质量流速G=600~1 100kg/(m~2·s)、热负荷q=330~793kW/m~2工况范围内,对低质量流速优化内螺纹管的传热特性进行了实验研究,并根据实验数据得到了近临界压力区和超临界压力区的传热实验关联式.结果表明:在近临界压力区,亚临界部分的传热特性好于超临界部分的传热特性,质量流速增大能推迟传热恶化,热负荷增大则使传热恶化提前发生,内螺纹管抑制膜态沸腾(DNB)的能力有所减弱;在超临界压力区,压力越低,大比热容区内强化传热作用越显著,在其他条件一定时,超临界水的热物性变化对管内传热的作用由质量流速和热负荷共同决定;质量流速不变,继续增大热负荷,大比热容区内的传热将由强化转变为恶化.
Heat-transfer performance of an internally ribbed tube was experimentally studied at low mass flux under the condition of p=21-29.8 MPa,G=600-1 100kg/(m~2·s)and q=330-793kW/m~2,following which relative heat-transfer correlations were derived by sorting out the experimental data in the near and super critical pressure region.Results show that in the near critical pressure region,where the capacity to restrain the DNB of rifled tube is weakened,heat-transfer performance in the subcritical part behaves better than that in the supercritical part;heat-transfer deterioration can be delayed by increasing the mass flux and lowering the heat flux.In the supercritical pressure region,the lower the pressure is,the stronger the heat-transfer enhancement would be in the large specific heat region;keeping all other parameters constant,the influence of thermal physical properties of supercritical water on the heat-transfer processwould be significantly affected by both the mass flux and heat flux;continuously increasing the heat flux while keeping the mass flux unchanged,heat-transfer reduction would take the place of heat-transfer improvement in the large specific heat region.
Heat-transfer performance of an internally ribbed tube was experimentally studied at low mass flux under the condition of p=21-29.8 MPa,G=600-1 100kg/(m~2·s)and q=330-793kW/m~2,following which relative heat-transfer correlations were derived by sorting out the experimental data in the near and super critical pressure region.Results show that in the near critical pressure region,where the capacity to restrain the DNB of rifled tube is weakened,heat-transfer performance in the subcritical part behaves better than that in the supercritical part;heat-transfer deterioration can be delayed by increasing the mass flux and lowering the heat flux.In the supercritical pressure region,the lower the pressure is,the stronger the heat-transfer enhancement would be in the large specific heat region;keeping all other parameters constant,the influence of thermal physical properties of supercritical water on the heat-transfer processwould be significantly affected by both the mass flux and heat flux;continuously increasing the heat flux while keeping the mass flux unchanged,heat-transfer reduction would take the place of heat-transfer improvement in the large specific heat region.
引文
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[5]张大龙,吴玉新,张海,等.低质量流率垂直管圈超临界煤粉锅炉的水动力特性分析[J].中国电机工程学报,2014,34(32):5693-5700.ZHANG Dalong,WU Yuxin,ZHANG Hai,et al.Hydrodynamic characteristics of vertical tubes with low mass flux in supercritical pulverized coal boiler[J].Proceedings of the CSEE,2014,34(32):5693-5700.
[6]王为术,徐维晖,毕勤成,等.垂直上升内螺纹管内流动沸腾传热特性[J].化工学报,2014,65(3):884-889.WANG Weishu,XU Weihui,BI Qincheng,et al.Flow boiling heat transfer characteristics in vertical upward internally ribbed tube[J].CIESC Journal,2014,65(3):884-889.
[7]于猛,俞谷颖,张富祥,等.超临界变压运行锅炉垂直上升内螺纹管的传热特性[J].动力工程学报,2011,31(5):321-324.YU Meng,YU Guying,ZHANG Fuxiang,et al.Heat transfer characteristics of vertical upward internally ribbed tube in supercritical sliding-pressure operation boilers[J].Journal of Chinese Society of Power Engineering,2011,31(5):321-324.
[8]王建国,李会雄.垂直上升管内临界压力区水的传热恶化研究[J].中国电机工程学报,2011,31(23):67-73.WANG Jianguo,LI Huixiong.Investigation on heat transfer deterioration of water in near critical pressure region in vertically upward tubes[J].Proceedings of the CSEE,2011,31(23):67-73.
[9]赵振兴,邓磊,王祥雨,等.内螺纹管内超临界水传热和阻力特性的数值研究[J].热力发电,2015,44(2):24-30.ZHAO Zhenxing,DENG Lei,WANG Xiangyu,et al.Numerical study on heat transfer and flow resistant characteristics of supercritical water in internally ribbed tubes[J].Thermal Power Generation,2015,44(2):24-30.
[10]GU H Y,ZHAO M,CHENG X.Experimental studies on heat transfer to supercritical water in circular tubes at high heat fluxes[J].Experimental Thermal and Fluid Science,2015,65:22-32.
[11]CHEN Weiwei,FANG Xiande.A new heat transfer correlation for supercritical water flowing in vertical tubes[J].International Journal of Heat and Mass Transfer,2014,78:156-160.
[12]潘杰.超临界循环流化床锅炉低质量流速水冷壁传热及水动力研究[D].西安:西安交通大学,2011.