Utilisation of air and pipe heating systems in Mediterranean greenhouses

Abstract

One of the main objectives of the greenhouse production is to obtain a good performance of the crops, which would not be possible outside due to adverse conditions of the environment. However, to achieve suitable internal air temperature and humidity it is usually necessary to use environmental control techniques, as ventilation or heating.

The objectives of this work were: 1. to study the effect of the different heating systems, pipe and air, in the climatic conditions in a Mediterranean greenhouse and 2. to study the influence of these different heating systems on the occurrence of condensation.

External and internal climatic data were collected as the occurrence of condensation on internal surface of the cover material. All data were registered in a Data Logger each 5 minutes, during several days. With air heaters, inside relative humidity was lower comparing to pipe heating. Both strategies were compared concerning the energy consumption. For the same outside conditions, pipe heating presented higher levels of energy consumption than air heaters. With air heaters, the condensation rate on the inner surface of the cover was strongly reduced.