The Observation of the Glasshouse by the Use of Warm Water Films on the Roof and Wall

Abstract

Cooling water from a steam power plant was found to be useful as a heat source in heating the glasshouse. The experiments were made at the glasshouse with 19.5m long and 6.0m wide. The water with temperature 12 to 22°C was sprinkled on the roof top ty the amount from 13 to 19m3 per hour. Figs 1, 2, and 3 show the temperature and humidity regimes in the glasshouse, respectively. It was found that heat was always upwards i.e., from the glasshouse to the water film, for the daylight period. When the sprinkling was ceased, more heat was tranferred from the glasshouse to the outside air. This denotes that the sprinkling of warm water on the roof protects the glasshouse from cooler outside conditions. Fig. 5 shows charateristic in heat transfer between the glasswall and water film at the nighttime. The heat transfer at the side wall was from water film to glasswall, while one at the roof was from glasswall to the water film.Heat budget equations for both the water film and the glasshouse for the nighttime are expressed respectively by Eqs. (7) and (8), finally by Eqs. (10) and (13). Eq. (13) denotes that the glasshouse temperature is given as a function of mean water temperature and of soil temperature. The relationship between glasshouse and mean water temperatures is shown in Fig. 6.