A. Madueño

Influence of Water and Air Flow on the Performance of Cellulose Evaporative Cooling Pads Used in Mediterranean Greenhouses

Evaporative cooling systems are a widely used technique in Mediterranean greenhouses. In this study, the cellulose evaporative cooling pads most commonly used in this region were tested in the laboratory using a new methodology in a wind tunnel to determine the water flow on the pad and air flow through it, as well as the water consumption and pressure drop caused by each pad as a function of air speed. Greater water flow increased the pressure drop, but the main effect on performance was caused by modifying the air flow through the pad. We recommend a range of air speeds through the pad of 1 to 1.5 m s-1, at which the pressure drop was between 3.9 and 11.25 Pa, depending on the type of pad and the water flow applied. On the other hand, saturation efficiency ranged between 64% and 70%, while the amount of evaporated water varied between 1.8 and 2.62 kg h-1 K-1 per square meter of pad area.

Low-frequency characterisation of mesocarp electrical conductivity in different varieties of olives (Olea europaea L.)

An AC of 50Hz was found to be suitable for characterizing the MI of olives.An ADC of 10bits was sufficient for measuring the conductivity properly.The conductivity increased while the hardness decreased during maturation.Olive varieties have an average value of conductivity from ripening to maturation.Electrical conductivity can be easily applied in the olive groves. Measurement of the electrical conductivity of various agrifood products is used to determine different parameters of foods, such as the moisture content and germinability of seeds or the resistance of fruits to frost. Recent studies have established the measurement of electrical impedance asa technique for assessing the maturity stage and fruit quality. In this study, we developed an experimental conductivity meter of alternating current (AC) at 50Hz frequency, controlled by a microprocessor PIC18F2550 linked to aPC via a USB port. This device was used to measure the electrical conductivity in the mesocarp of olives (Olea europaea L.), which are used in oil production, at different stages of maturity. The measurements of electrical conductivity (expressed in % of full scale) were then used to establish an objective fruit maturity index and to determine the optimal timing of collection based on parameters such as oil yield and quality. The evolution of electrical conductivity in the mesocarp of the fruit was measured in four different cultivars, Picual, Manzanilla de Sevilla, Hojiblanca, and Gordal Sevillana. Our findings showed that the conductivity increased according to the stage of ripeness. Similarly, each variety had a characteristic average value for the latter stages of ripening and maturation.