We propose a method for estimating the convective-heat-transfer coefficient (CHTC) distribution on building walls by using the water-evaporation method involving filter paper and three-dimensional laser scanning, and demonstrates consistency with the gravimetric evaporation method. The theory and method are established based on the convective heat- and mass-transfer analogy and a near-infrared laser-scanning system. The equations to remotely estimate the CHTC distribution are obtained empirically, and the proposed method is applied to the walls of a penthouse during winter. The spatial distribution of the surface reflection intensity that determines the evaporation rate is successfully retrieved with 0.2–0.3% accuracy from a measurement distance of 5 m. The comparison of evaporation rates with a gravimetric measurement does not show a statistically significant bias. The results show that the crucial factors for the precision of the CHTC estimation are errors in the laser-scanning system and their amplification when dividing the evaporation rate by the vapour pressure deficit to obtain the convective-mass-transfer coefficient. The estimated CHTC distributions on the target walls have approximately ≤ 2–3 W m−2 K−1 errors in the 95% confidence interval after applying spatial and/or temporal averaging. Although the error in the convective-heat-transfer coefficient is larger in winter during minimal vapour pressure deficits, it is generally well explained in the range of the random error in laser scanning. The correlation between the spatially-averaged convective-heat-transfer coefficient and near-wall wind speed is comparable to existing methods (R = 0.71–0.79), and the regression relation agrees with that obtained in previous studies performed in similar conditions.

中文翻译：

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基于激光扫描的全尺寸建筑墙体对流热传递系数分布估计方法

我们提出了一种通过使用涉及滤纸和三维激光扫描的水蒸发方法来估计建筑物墙壁上的对流传热系数 (CHTC) 分布的方法，并证明了与重量蒸发方法的一致性。该理论和方法是基于对流传热传质类比和近红外激光扫描系统建立的。远程估计 CHTC 分布的方程是根据经验获得的，并且所提出的方法在冬季应用于顶层公寓的墙壁。决定蒸发率的表面反射强度的空间分布以 0.2-0.3% 的精度从 5 m 的测量距离成功检索。蒸发率与重量测量的比较没有显示出统计学上的显着偏差。结果表明，影响 CHTC 估计精度的关键因素是激光扫描系统中的误差及其在将蒸发率除以蒸汽压差以获得对流传质系数时的放大。在应用空间和/或时间平均后，在 95% 置信区间内，目标墙上估计的 CHTC 分布具有大约 ≤ 2–3 W m-2 K-1 误差。虽然在冬季蒸汽压不足的情况下，对流传热系数的误差较大，但在激光扫描的随机误差范围内通常可以很好地解释。