科研之友
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摘要
The use of solar energy for heating greenhouses in the cold period for a Mediterranean climate is an important issue. In this paper, the thermal performance of a new solar air heater using a packed bed of spherical capsules with the latent heat storage system in east-west oriented greenhouse, is analyzed and discussed. The excess heat in the greenhouse was stored in the packed bed through the diurnal period and extracted at night. An experimental comparative study was conducted in two greenhouses installed in the Research and Technologies Centre of Energy (CRTEn) in Tunisia. The greenhouse heat balance in different components of the greenhouse with a heating system (cover, canopy, soil, inside air and packed bed solar collector), has been used to investigate the impact of the phase change material (PCM) on the greenhouse temperature and humidity. Results show that the nocturnal temperature inside the greenhouse equipped by a heating system exceeds the temperature inside the conventional greenhouse by 5 degrees C. The relative humidity was found to be of an average 10-20% lower at night time inside the heated greenhouse. The nighttime recovered heat of the solar system attained 31% of the total requirements of heating. An economic evaluation was made to find the payback period of the new solar air heater, the potential in saving fuel energy and the reducing carbon dioxide emissions.
- 出版日期2014-7
