GREENHOUSE HEATING WITH EXHAUST GASES

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 NO_x and no SO₂. Coal fired flue gases leave the stack at 121°C and contain about 12% CO₂, 600 ppm NO_x 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.

Symposium on Potential Productivity in Protected Cultivation

E.A. Maginnes, G.H. Green

https://doi.org/10.17660/ActaHortic.1978.87.37