高温、强辐射条件下萘升华法测量对流换热系数的适用性研究

Applicability Research of Convective Heat Transfer Coefficients Measured with the Naphthalene Sublimation Method under Conditions of High Temperature and Strong Radiation

为探究萘升华热质比拟技术测量建筑外壁面对流换热系数在高温、强辐射条件下的适用性,本文以南海地区温度、辐射气象参数的统计结果为基础设定实验工况,在风洞实验室采用萘升华法与热平衡法分别进行测试,进行对比实验研究。结果表明:萘升华实验中,四块萘盒测量的对流换热系数结果相近,最大差值为1. 52 W/(m^2·K),可认为萘升华技术的测量结果不会因萘盒制作的细微差异而存在显著不同;萘升华法与热平衡法测量结果基本一致,二者差值的最大百分比为6. 71%,在实验仪器误差的可接受范围内;高温(强辐射)情况下,萘升华法与热平衡法测量结果的差值与低温(低辐射)情况下并无明显差异,萘升华法在高温及强辐射条件下仍然适用;为进一步提高萘升华法测量精度,应保证萘表面与墙壁表面温差不超过5. 3℃。该研究对南海地区低能耗建筑的设计研究及萘升华技术的普及与改进具有一定推动作用。

In order to investigate the applicability of measuring convective heat transfer coefficients of the external wall of buildings with the naphthalene sublimation heat-mass transfer analogy technique under conditions of high temperature and strong radiation,experimental working conditions were set in this paper on the basis of statistics of temperature and radiation meteorological parameters in the South China Sea area to test.The contrast experiments of the naphthalene sublimation method and the heat balance method were conducted respectively in the wind tunnel laboratory.By analyzing data,it can be found that the results of convective heat transfer coefficients measured by four naphthalene boxes are approaching in the naphthalene sublimation experiment with the largest difference of 1.52 W/(m^2•K).It can be considered that the results measured by the naphthalene sublimation method are not changed significantly due to the minor differences in the manufacturing of the naphthalene box.The results measured by the naphthalene sublimation method and the thermal balance method are consistent with the largest percentage of differences of only 6.71%which is within the acceptance error scope of the experiment instruments.And there is no obvious difference in different values of results measured by the two methods in high temperature(strong solar radiation)and in low temperature(low solar radiation).It can be found that the naphthalene sublimation method can be used in the area with extreme climates including high temperature and strong solar radiation.The temperature gap between naphthalene and wall should he no more than 5.3℃ in order to promote the measuring precision of the naphthalene sublimation method.This study can improve the naphthalene sublimation and enhance the design of low energy consumption building in the South China Sea region.