Estudio de la distribución de temperatura de aire en un invernadero tipo en Almería ("raspa y amagado")

This Doctoral Thesis was born with the aim of studying the thermal environment inside greenhouses and especially the influence it has on the worker, since most similar studies in greenhouses are focused on the crop. In this work the air temperature conditions with respect to the workers are studied, specifically the heterogeneity of air temperature inside a greenhouse is analysed following the methods gathered in ISO 7726. To achieve this goal, a network of wireless sensors and a year-long experimental campaign is carried out in a typical greenhouse in Almer´ia. The results allow the characterization of the air temperature distribution inside a greenhouse and confirms the existence of heterogeneity in air temperature according to the norm ISO 7726, as well identifying patterns in its distribution. Derived from this study, difficulties were found in accurately measuring and with low cost the wind speed inside a greenhouse, which leads to a calibration of a low cost anemometer. The calibration focuses on a hot-wire anemometer, which attempts to solve its main drawback, namely its loss of accuracy when air temperature or ambient temperature changes. This calibration is carried out by means of a Gaussian Regression Process and is validated with real data, reaching the goal of achieving a low-cost device capable of accurately measuring air velocity in a typical air temperature range. Finally, and also as a consequence of the study of the thermal environment, it was observed that greenhouse workers, despite the plastic cover covering such greenhouses, may be susceptible to risks associated to ultraviolet radiation on skin and eyes. For this reason, through a network of sensors, a measurement campaign of ultraviolet radiation is carried out for a year inside a typical greenhouse in Almer´ia. The results indicate that the risk limit established by the World Health Organization is exceeded, so it is confirmed that there exist risk to the health of greenhouse workers by ultraviolet radiation.