The closed solar greenhouse technology and evaluation of energy harvesting under summer conditions.

摘要

Closed and semiclosed greenhouses are used to collect thermal solar energy and for cooling technology. Other than the problem of long-term energy storage in closed greenhouses, the assembly and capacity of cooling and heating systems and the operational control of the microclimate and energy management system are the focus of research and development. A new prototype of solar greenhouse was constructed at Humboldt University, Berlin. In a 300 m2 Venlo-type greenhouse, a cooling fin system under the roof was connected to a heat pump and a low temperature storage tank. Several operational modes are possible for heating and/or cooling the greenhouse and to charge or discharge thermal storage using new technology for integration of the heat pump into the hydraulic pipe system. First results of operational behavior are shown by using typical evaluation parameters such as cooling capacity, collector efficiency, and the coefficient of performance for the heating and cooling operation. With the cooling fin system (cooling surface 1900 m2), the cooling capacity increased to 400 W m-2. The latent to sensible heat exchange ratio was about 40%. The maximum amount of water that condensed on the fin surface was 1.2 L (m2 day)-1. During the experimental interval from May to October 2010, the collector efficiency of the solar greenhouse was 0.55-0.8. The heat pump worked for greenhouse cooling with a seasonal energy efficiency ratio (SEER) of 4.9 and for heating with a heating season performance factor (HSPF) of 4.6.