Latent heat storage applied to horticulture

Abstract

A new concept of solar heat storage applied to horticulture has been tested through a full heating season in a professional greenhouse. This experiment is run in a 500 m 2 multi-span, single-glazed greenhouse of traditional geometry devoted to rose production. The solar heat available inside the greenhouse is transferred and stored by recycling the air through an underground network of flat heat exchangers filled with a phase change material. In an attempt to reach quasi autonomy in a mild climate, the glass is doubled on the inside with an insulating polyethylene Air-Cap ( R) film. The solar greenhouse compartment is compared with a traditional greenhouse compartment of identical geometry bearing the same plantation. The cover of this control compartment is single glazed. Thermal and cultural performances were analysed from December 1979 to April 1980. The solar compartment achieved 80 per cent savings in propane gaz, compared with the control compartment run at the same temperature. Compared with a control compartment doubled with Air-Cap polyethylene, the savings would reduce to 60 per cent. The electrical consumption of the fans of the solar system amount to less than 10 per cent of the basic heating loads. The solar prototype cost twice as much as the control compartment which compares favorably with other solar prototypes known at this time.