ISHS Acta Horticulturae 268: IV International Symposium on CO2 in Protected Cultivation
CO2 ENRICHMENT WITH NATURAL GAS FIRED HOT-AIR HEATERS |
| Author: | A. Kiel |
| Abstract:
When greenhouses are heated by means of hot-air blowers not only CO2 but NOx is blown into the greenhouse. Using a physical model based on the NOx emission from the hot-air blower, the ventilation rate of the greenhouse, and absorption of NOx by the crop it was shown to be possible to predict a concentration gradient in the greenhouse which matched the gradient actually measured. The model was used to establish a relationship between the average outside temperature and the NOx concentration in the greenhouse, given a certain cultivation temperature. This enables prediction of the NOx concentration in greenhouses during very cold spells, when hot-air blowers are used for long periods. The results show that even a 'low-NOx' hot-air blower with an NOx emission of only 8 ppm can produce NOx levels in the greenhouse which exceed a possible crop damage threshold of 250 ppb. | |
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