Spatial Distribution and Code Revision of Solar-induced Temperature Difference of Hyperbolic Thin-Walled Structures Based on Field Measurements

The distribution principles for solar-induced temperature differences in hyperbolic cooling towers differ in different countries. The current Chinese code about solar-induced temperature difference in cooling towers, originating from 1980s measurements of a singular 105-meter structure at Qinling Power Plant, fails to account for regional climatic variances and dimensional scaling effects. A non-contact 3D thermographic monitoring framework was developed through infrared thermography, with calibration protocols validated via solar irradiation experiments on precast concrete slabs to address this limitation. Subsequently, continuous diurnal monitoring of solar-induced temperature difference was performed on five geometrically distinct hyperbolic cooling towers in China's "cold and severely cold areas". Using statistical analysis of the measured data, the gradient distribution, time-domain evolution, spatial distribution patterns, and characteristics of the sunlit inner wall were identified. After that, the meridional distribution, the circumferential distribution, and the maximum temperature difference were quantified. Finally, The distribution rules of solar-induced temperature difference of the large hyperbolic cooling tower considering the sunward inner wall were refined. It is found that solar-induced temperature differences should be considered in "cold and severely cold areas" in China. The distribution rules of solar-induced temperature difference of large hyperbolic cooling tower are three-section gradient distribution along the thickness, approximately constant along the meridional direction, semicircle asymmetric trigonometric distribution along the circumferential direction on the outer wall, and negative temperature difference at the sunward inner wall. The comparative analysis demonstrated a 1.73-5.00% escalation in structural reinforcement when applying measured solar-induced temperature difference data versus conventional code specifications. The conclusion deepens the understanding of the solar-induced temperature difference distribution of large hyperbolic cooling towers, which also provides the measured basis for revising the cooling tower codes.