Articles
EVALUATION OF AN AIR CONDITIONING WATER CHILLER/HEAT PUMP SYSTEM WITH HEAT STORAGE FOR SOLAR HEATING OF GREENHOUSES
Two double-poly greenhouses of nominally 1100 m2 have been constructed utilizing state-of-the-art energy conservation technology.
The new generation system uses a heat pump/chiller unit which reclaims thermal energy (sensible and latent) from the air within the greenhouse during periods of high solar insolation.
This energy is stored in a 45 000 litre water storage tank buried beneath the greenhouse floor.
When heating is required, during low solar insolation, the chiller reverses the heat pump operation and transfers heat from the storage tank to the greenhouse.
Conventional ventilation methods and auxiliary steam heating are used as back-up to provide a proper growing environment during periods when the chiller/heat recovery system is unable to meet cooling and heating requirements.
Both greenhouses are presently being monitored for energy consumption, temperature, humidity, solar radiation and carbon dioxide levels using automated data acquisition techniques.
These parameters will be correlated with actual return from the sale of product, and capital maintenance and operating costs to ascertain system efficiencies, benefits and cost pay-back periods relative to conventional glass greenhouses.