Effects of the Passive Use of Nocturnal Radiative Cooling in Fresh Vegetable Cooling

Abstract

Net radiation flux density of about 40 to 60 W/m² is obtained during the clear-sky night in autumn, and by the following morning, lettuces exposed to the atmosphere are cooled down to a temperature almost the same as that achieved by ordinary precooling. In a simple facility that provides shelter from wind or sunlight, this nocturnal radiative cooling effect may be enhanced. Using the net radiation flux density estimated from the temperature difference between the dry bulb temperature and the globe temperature as an index, it is possible to properly open and close the covering.