Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis

This study investigates the temperature reduction capacity and water consumption of a fan-pad system installed in a greenhouse located in the coastal regions of Almería. The suitability of this system for coastal zones with high environmental humidity during the summer is analyzed. Historical temperature and relative humidity series are studied, obtaining the thermal difference and maximum, medium, and minimum monthly water consumption of the pads based on the operation data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a decrease of 5.92 ºC in the mean temperature and a water consumption of 13.55 l/h per square meter of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel and compared with that of a new pad of the same model. Over time and with low maintenance, the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of the pad increases by 6.6% due to the greater contact time between the air and the waterMinisterio de Economía y Competitividad de España AGL2015-68050-RUnión Europea (FEDER) AGL2015-68050-

Energy Efficiency in Greenhouse Evaporative Cooling Techniques: Cooling Boxes versus Cellulose Pads

Evaporative cooling systems using a combination of evaporative pads and extractor fans require greenhouses to be hermetic. The greatest concentration of greenhouses in the world is located in southeast Spain, but these tend not to be hermetic structures and consequently can only rely on fogging systems as evaporative cooling techniques. Evaporative cooling boxes provide an alternative to such systems. Using a low-speed wind tunnel, the present work has compared the performance of this system with four pads of differing geometry and thickness manufactured by two different companies. The results obtained show that the plastic packing in the cooling unit produces a pressure drop of 11.05 Pa at 2 m·s−1, which is between 51.27% and 94.87% lower than that produced by the cellulose pads. This pressure drop was not influenced by increases in the water flow. The evaporative cooling boxes presented greater saturation efficiency at the same flow, namely 82.63%, as opposed to an average figure of 65% for the cellulose pads; and also had a lower specific consumption of water, at around 3.05 L·h−1·m−2·°C−1. Consequently, we conclude that evaporative cooling boxes are a good option for cooling non-hermetic greenhouses such as those most frequently used in the Mediterranean basin

Cimentaciones a tracción para invernaderos

La importancia socioeconómica de los cultivos protegidos en amplias zonas de la cuenca mediterránea, justifica la proliferación de invernaderos. La causa de colapso de las mismas suele ser la acción del viento a succión, por lo que las cimentaciones deben trabajar a tracción. Sin embargo, éstas actualmente no se calculan y es la propia experiencia del constructor, o el deseo del agricultor, lo que marca el número de las mismas, la separación entre ellas y sus dimensiones. En este trabajo se analiza el comportamiento de dicho elemento estructural mediante el método de los elementos finitos (a través del programa informático ANSYS 5.6); realizando previamente ensayos de modelos de cimentaciones a escala en laboratorio, y ensayos de prototipos a escala real en campo.La comparación de los resultados reales obtenidos en campo con los obtenidos mediante simulación por elementos finitos, demuestra que el uso de ésta técnica de cálculo puede utilizarse para el dimensionado de las cimentaciones a tracción que usualmente se instalan en los invernadero

Design and Testing of a Structural Monitoring System in an Almería-Type Tensioned Structure Greenhouse

Greenhouse cultivation has gained a special importance in recent years and become the basis of the economy in south-eastern Spain. The structures used are light and, due to weather events, often collapse completely or partially, which has generated interest in the study of these unique buildings. This study presents a load and displacement monitoring system that was designed, and full scale tested, in an Almería-type greenhouse with a tensioned wire structure. The loads and displacements measured under real load conditions were recorded for multiple time periods. The traction force on the roof cables decreased up to 22% for a temperature increase of 30 °C, and the compression force decreased up to 16.1% on the columns or pillars for a temperature and wind speed increase of 25.8 °C and 1.9 m/s respectively. The results show that the structure is susceptible to daily temperature changes and, to a lesser extent, wind throughout the test. The monitoring system, which uses load cells to measure loads and machine vision techniques to measure displacements, is appropriate for use in different types of greenhouses

Basket-Handle Arch and Its Optimum Symmetry Generation as a Structural Element and Keeping the Aesthetic Point of View

The arches were a great advance in construction with respect to the rigid Greek linteled architecture. Its development came from the hand of the great Roman constructions, especially with the semicircular arch. In successive historical periods, different types of arches have been emerging, which in addition to their structural function was taking aesthetic characteristics that are used today to define the architectural style. When, in the construction of a bow, the rise is less than half the springing line, the semicircular arch is no longer used and the segmental arch is used, and then on to another more efficient and aesthetic arch, the basket-handle arch. This study examines the classic geometry of the basket-handle arch also called the three-centered arch. A solution is proposed from a constructive and aesthetic point of view, and this is approached both geometrically and analytically, where the relationship between the radius of the central arch and the radius of the lateral arch is minimized. The solution achieved allows the maximum springing line or clear span to be saved with the minimum rise that preserves the aesthetic point of view, since the horizontal thrust of a bow is greater than the relationship between the springing line of the arch and the rise. This solution has been programmed and the resulting software has made it possible to analyse existing arches in historic buildings or constructions to check if their solutions were close or not from both points of view. Thus, it has been possible to verify that in most of the existing arches analyzed, the proposed solution is reached

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almería’s greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W∙m−2) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C

Educación sanitaria para mejorar la adhesión al tratamiento y evitar complicaciones en pacientes sometidos a hemodiálisis

La Enfermedad Renal Crónica (ERC) está provocando que aumente el número de pacientes sometidos a Tratamientos Renales Sustitutivos (TRS), entre los que se encuentra la Hemodiálisis (HD), la cual exige cambios en la conducta para alcanzar los objetivos del tratamiento. Tras los resultados obtenidos en diversos estudios sobre los conocimientos que poseen los pacientes sometidos a Hemodiálisis sobre su enfermedad, tratamiento y cuidados, una de las metas de los profesionales de enfermería será conseguir que estos pacientes y sus familias tengan un nivel adecuado de información, evitando así la aparición de problemas potenciales, los cuales serán tratados en un Plan de Cuidados Estandarizado con objetivos e intervenciones basados en la educació

Basket-Handle Arch and Its Optimum Symmetry Generation as a Structural Element and Keeping the Aesthetic Point of View

The arches were a great advance in construction with respect to the rigid Greek linteled architecture. Its development came from the hand of the great Roman constructions, especially with the semicircular arch. In successive historical periods, different types of arches have been emerging, which in addition to their structural function was taking aesthetic characteristics that are used today to define the architectural style. When, in the construction of a bow, the rise is less than half the springing line, the semicircular arch is no longer used and the segmental arch is used, and then on to another more efficient and aesthetic arch, the basket-handle arch. This study examines the classic geometry of the basket-handle arch also called the three-centered arch. A solution is proposed from a constructive and aesthetic point of view, and this is approached both geometrically and analytically, where the relationship between the radius of the central arch and the radius of the lateral arch is minimized. The solution achieved allows the maximum springing line or clear span to be saved with the minimum rise that preserves the aesthetic point of view, since the horizontal thrust of a bow is greater than the relationship between the springing line of the arch and the rise. This solution has been programmed and the resulting software has made it possible to analyse existing arches in historic buildings or constructions to check if their solutions were close or not from both points of view. Thus, it has been possible to verify that in most of the existing arches analyzed, the proposed solution is reached

Application of Semi-Empirical Ventilation Models in A Mediterranean Greenhouse with Opposing Thermal and Wind Effects. Use of Non-Constant Cd (Pressure Drop Coefficient Through the Vents) and Cw (Wind Effect Coefficient)

The present work analyses the natural ventilation of a multi-span greenhouse with one roof vent and two side vents by means of sonic anemometry. Opening the roof vent to windward, one side vent to leeward, and the other side vents to windward (this last vent obstructed by another greenhouse), causes opposing thermal GT (m3 s−1) and wind effects Gw (m3 s−1), as outside air entering the greenhouse through the roof vent circulates downward, contrary to natural convection due to the thermal effect. In our case, the ventilation rate RM (h−1) in a naturally ventilated greenhouse fits a second order polynomial with wind velocity uo (RM = 0.37 uo2 + 0.03 uo + 0.75; R2 = 0.99). The opposing wind and thermal effects mean that ventilation models based on Bernoulli’s equation must be modified in order to add or subtract their effects accordingly—Model 1, in which the flow is driven by the sum of two independent pressure fields GM1=√(∣∣G2T±G2w∣∣) , or Model 2, in which the flow is driven by the sum of two independent fluxes GM2=|GT±Gw| . A linear relationship has been obtained, which allows us to estimate the discharge coefficient of the side vents (CdVS) and roof vent (CdWR) as a function of uo [CdVS = 0.028 uo + 0.028 (R2 = 0.92); CdWR = 0.036 uo + 0.040 (R2 = 0.96)]. The wind effect coefficient Cw was determined by applying models M1 and M2 proved not to remain constant for the different experiments, but varied according to the ratio uo/∆Tio0.5 or δ [CwM1 = exp(−2.693 + 1.160/δ) (R2 = 0.94); CwM2 = exp(−2.128 + 1.264/δ) (R2 = 0.98)]

Dispositivo para medir el comportamiento de cimentaciones ante un esfuerzo de tracción o de comprensión

Número de publicación: ES2221783 A1 (01.01.2005) También publicado como: ES2221783 B1 (16.12.2006) Número de Solicitud: Consulta de Expedientes OEPM (C.E.O.)P200202403 (18.10.2002)Un dispositivo para medir el comportamiento de cimentaciones ante un esfuerzo de tracción o de compresión, que comprende: un bastidor (1, 2); un cilindro hidráulico (3) montado en el bastidor de modo que pueda pivotar alrededor de al menos un eje; medios de acoplamiento mecánico del cilindro hidráulico (3) a la cimentación; medios de medir el esfuerzo ejercido por el cilindro hidráulico sobre la cimentación; medios de medir el desplazamiento de la cimentación bajo el esfuerzo; y medios de alimentación hidráulica del cilindro hidráulico.Universidad de Almería. Universidad de Sevill