ISHS Acta Horticulturae 87: Symposium on Potential Productivity in Protected Cultivation
GREENHOUSE HEATING WITH EXHAUST GASES |
| Authors: | E.A. Maginnes, G.H. Green |
| Abstract:
Since 1974 three heating systems involving exhaust gases have been constructed. One involved using exhaust gases from a turbine fired with natural gas for heating as well as carbon dioxide enrichment (patented Canada and U.S.A.). The next two utilized exhaust gases from a coal fired steam generator for heating only. Turbine exhaust gases leave the stack at 450°C and contain about 2% CO2, 16 ppm NOx and no SO2. Coal fired flue gases leave the stack at 121°C and contain about 12% CO2, 600 ppm NOx and 300 ppm SO2. In the case of the turbine, exhaust gases were delivered to the greenhouse, mixed with outside air and discharged at 82°C between two layers of polyethylene covering the structure. With exhaust from a coal fired unit, one system involved delivery of hot gases to the greenhouse where they were passed through fibreglass ducts at an average temperature of 95°C, while the other used a closed circuit hot water system involving an air to water heat exchanger in the duct leading to the stack. Hot water leaves the heat exchanger at 120°C and returned at 80°C. These three systems have been used successfully to meet the heating requirement of tomatoes grown in three 96 m2 double-layered polyethylene covered growing areas. A further 96 m2 area heated conventionally served as control. | |
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