•The ball-milling process could increase solar reflectivity from 75.8% to 95.8%.•Larger glass bubbles can be used to make high-performance radiative cooling paints.•The larger glass bubbles are over ...60% cheaper than the original glass bubbles.
Radiative cooling technology potentially can be applied to buildings to reduce cooling energy consumption. One general approach to making radiative cooling paints is to mix polymers with reflective materials. However, the high cost of materials has limited the large-scale application of radiative cooling in real scenarios. In this work, we propose another method to make high-performance radiative cooling paint, at a lower cost. This method entails ball-milling larger glass bubbles instead of the commonly used small glass bubbles. Glass bubbles with a median particle size of 47.9 μm were chosen as the component. After only 5 min of ball-milling, the median particle size was reduced to 9.7 μm. The solar reflectivity of paint made from glass bubbles after 5 min of ball-milling increased from 75.8 % (without ball-milling) to 95.8 %. In field tests, radiative cooling paint made from unground 47.9 μm glass bubbles was found to be 9.4 °C warmer than the ambient temperature at noon, while the paint made by 5 min of ball-milling of these glass bubbles achieved a temperature close to that of ambient air. Moreover, the price per unit of weight of 47.9 μm glass bubbles is only 40 % that of the previous 16.1 μm glass bubbles.
Numerical models have been used to predict the efficacy of ultraviolet (UV) lamps in disinfecting indoor bioaerosols. However, detailed experimental data on both air and surface viral inactivation ...for model validation are lacking. This study aimed to experimentally validate a computational fluid dynamics (CFD)-Lagrangian model for disinfection of airborne and surface viruses with far-UVC light. The susceptibility constants (Z-value) of MS2 virus in the air and on surfaces irradiated by 222 nm far-UVC light were measured. The UVC irradiance distribution, the airborne MS2 concentrations as a function of time, and the surface MS2 count in a full-scale chamber with a 222 nm far-UVC lamp were also measured. The comparison between simulation and experiments showed that the numerical model can predict the inactivation of airborne and surface viruses reasonably well. The validated numerical model was then used to calculate the disinfection of airborne and deposited SARS-CoV-2 in a dental clinic and a shared office. It was found that far-UVC lamps can effectively inactivate airborne and surface SARS-CoV-2 simultaneously in both the clinic and the office. The experimental results can be used as a benchmark for model validation, and the case studies can improve our understanding of far-UVC disinfection in real-life indoor environments.
•The Z-values of airborne and surface MS2 exposure to far-UVC light was measured.•The numerical model was validated by the airborne and surface MS2 virus data.•Effect of far-UVC disinfection of SARS-CoV-2 in a clinic and office was calculated.
