Wind loads on residential and large-scale solar collector models

Previous studies on solar water heaters have mainly focused on the thermal efficiency of various types of solar collectors, and there has been limited work done on the aerodynamic characteristics of solar collectors or their supporting structure. However, typhoons are among the natural hazards that have a costly impact on residential construction and solar water heaters are usually installed on the flat roofs of buildings for hot water production. Thus, the safety of solar water heaters under severe wind load during typhoon season is a critical issue in the promotion of solar water heaters. In this study, an experimental program was conducted to examine the aerodynamic characteristics of solar collector models (residential and large-scale solar water heaters). The unit sectional uplift coefficient with or without a guide plate is also addressed. Measurements of mean longitudinal and spanwise surface pressure were performed. The data show that the presence of a water storage tank (or a horizontal cylinder) tends to reduce the suction force on the upper surface within the first half of the tilt flat panel (solar collector). Stronger negative longitudinal differential mean pressure is observed for the test case of a tilt flat panel only, which corresponds to strong wind load. The inverted U-shape of mean spanwise pressure distributions is also noted. With a guide plate, less wind load and more uniformity of spanwise differential mean pressure distributions are associated with a larger projected area of a guide plate on the lower surface of a tilt flat panel. This is essentially attributed to the attenuation of corner vortices and a decrease in uplift force.