SHORT-TERM THERMAL PERFORMANCE OF A BUILT-IN SOLAR STORAGE FOR FROST PREVENTION IN A GREENHOUSE

Built-in solar storage is an alternative to the traditional solar coll ectors. This paper explores the possibility of utilizing such solar st ores for frost prevention in greenhouses. In the study, two identical NE-SW orientated greenhouses with 50 m(2) ground area were erected. Th e total ground area and volume of the water stores used in the solar g reenhouse were about 64 and 5.4% of the total ground area and volume o f the greenhouse. The short-term results showed that at times when the air temperature in the control greenhouse dropped below 0 degrees C, it was about 3.5 degrees C in the solar greenhouse, and sometimes this difference was more than 4.5 degrees C. The average fraction of solar energy storage by the stores was 0.26 fora four day period. (C) 1998 John Wiley & Sons, Ltd.