Exergetic evaluation of high-temperature radiative cooling combined with natural ventilation

This paper describes the possibility of high-temperature radiative cooling combined with natural ventilation. Weset uptwo small wooden experimental buildings:onehas a radiative-cooling system on the ceiling;and the other hasa conventional convective-cooling system.In the room with radiative cooling, we examinedthree patterns of cooling and ventilation: the first is radiative cooling withoutventilation; the second is radiative cooling with natural ventilation; and the third is no radiative cooling but natural ventilation. The ceiling surface temperature of the radiative cooling was controlled at approximately 26OC, which is much higher than conventional radiative cooling panels. Wecalculated exergetic quantities using the measured data: cool/warm radiant exergies emitted from indoor wall surfaces, cool/warm and wet/dry exergies contained by room air. The order ofthe cool radiant exergy emitted from the interior wall surfacesin the case of radiative cooling with natural ventilation was10 to80mW/m2, and the cool/wet exergiescontained by room air were 14J/m3 and8J/m3, respectively. Thesewere much smaller than those in the case of radiative cooling withoutnatural ventilation. If the room air temperature and relative humidity werecontrolled at 26OC50% with a convective cooling system under the outdoor condition of 32.5OC61%, the cool/dry exergies contained by room airwouldturn out to be 88J/m3 and 366J/m3, respectively. The resultobtained from thisexperimental research suggeststhatthe exhaustion of indoor moisture by natural ventilation is of vital importance to realize high-temperature radiative cooling systems, namely low-exergy cooling system.