Thermal Insulation Characteristics of a Curved Roof Greenhouse with an Internal Curtain for Spraying Water

Abstract

A device for spraying wellwater on the inner roof of a greenhouse (water curtain) was first discribed by one of the authors and its excellent heating characteristics have been established on several multispan greenhouses with double, triple and quadruple roofs. This paper describes the comparative analysis of the thermal characteristics of the curved roof greenhouses with and without the water curtain.
The test house was intermittently sprayed with wellwater and controlled by a simple room thermostat. The control house was installed with tunnels which were covered with double layer films. Both houses were cultivated with strawberry in the flowering stage. The nocturnal ambient mean temperature ranged was 4.4°C to -4.5°C. The test house has successfully maintained the air temperature above 8°C and the soil temperature above 10°C. The water spraying flow rate of 2.7 to 7.2 l/m²hr: floor was able to provide sufficient inside climate conditions for a wide range of outside climate conditions.