Wind pumps for irrigating greenhouse crops

Agriculture is a major consumer of energy in many countries of the world. Only a few of these countries are self-sufficient in conventional energy sources, which are also exhaustible. Fortunately, there are other sources of energy, such as wind, which has experienced recent developments in the area of wind power generation. From irrigation projects to power supply in remote farms, wind power generation can play a vital role. A simple methodology for technical evaluation of windmills for irrigation water pumping has been developed in this study to determine the feasibility per unit amount of water supplied and the levels of daily irrigation demand satisfied by windmill irrigation system at various levels of risk (probability of failure). For this purpose, a series of three hourly wind-speed data over a period of 38 years at Ciego de Ávila, Cuba, were analyzed to compute the diurnal wind pump discharge at varying levels of risk. The sizes of reservoirs required to modulate fluctuating discharge and to satisfy the levels of irrigation demand, on function of crop development dates, cultivated area and water elevation height, were computed by cumulative deficit water budgeting. An example is given illustrating the use of the methodology on tomato crop Licopersicon esculentum Mill) under greenhouse.

The use of wind pumps for greenhouse microirrigation: a case study for tomato in Cuba.

Crop irrigation is a major consumer of energy. Only a few countries are self-sufficient in conventional non-renewable energy sources. Fortunately, there are renewable ones, such as wind, which has experienced recent developments in the area of power generation. Wind pumps can play a vital role in irrigation projects in remote farms. A methodology based on daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. For this purpose, several factors were included: three-hourly wind velocity (W3 h, m/s), flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration as a function of crop planting date. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors. An example is given illustrating the use of this methodology on tomato crop (Lycopersicon esculentum Mill.) under greenhouse at Ciego de Ávila, Cuba. In this case two different W3 h series (average and low wind year), three different H values and five tomato crop planting dates were considered. The results show that the optimum period of wind-pump driven irrigation is with crop plating in November, recommending a 5 m3 volume tank for cultivated areas around 0.2 ha when using wind pumps operating at 15 m of height elevation.

Brief Announcement: Node Sampling Using Centrifugal Random Walks.

We propose distributed algorithms for sampling networks based on a new class of random walks that we call Centrifugal Random Walks (CRW). A CRW is a random walk that starts at a source and always moves away from it. We propose CRW algorithms for connected networks with arbitrary probability distributions, and for grids and networks with regular concentric connectivity with distance based distributions. All CRW sampling algorithms select a node with the exact probability distribution, do not need warm-up, and end in a number of hops bounded by the network diameter.

Node sampling using random centrifugal walks

Sampling a network with a given probability distribution has been identified as a useful operation. In this paper we propose distributed algorithms for sampling networks, so that nodes are selected by a special node, called the source, with a given probability distribution. All these algorithms are based on a new class of random walks, that we call Random Centrifugal Walks (RCW). A RCW is a random walk that starts at the source and always moves away from it. Firstly, an algorithm to sample any connected network using RCW is proposed. The algorithm assumes that each node has a weight, so that the sampling process must select a node with a probability proportional to its weight. This algorithm requires a preprocessing phase before the sampling of nodes. In particular, a minimum diameter spanning tree (MDST) is created in the network, and then nodes weights are efficiently aggregated using the tree. The good news are that the preprocessing is done only once, regardless of the number of sources and the number of samples taken from the network. After that, every sample is done with a RCW whose length is bounded by the network diameter. Secondly, RCW algorithms that do not require preprocessing are proposed for grids and networks with regular concentric connectivity, for the case when the probability of selecting a node is a function of its distance to the source. The key features of the RCW algorithms (unlike previous Markovian approaches) are that (1) they do not need to warm-up (stabilize), (2) the sampling always finishes in a number of hops bounded by the network diameter, and (3) it selects a node with the exact probability distribution.

The use of wind pumps for greenhouse microirrigation: A case study for tomato in Cuba

A methodology based on daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. For this purpose, several factors were included: three-hourly wind velocity (W3 h, m/s), flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration as a function of crop planting date. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors.

Wind pumps for irrigating greenhouse crops: Comparison in different socio-economical frameworks

A methodology is applied for economic evaluation of water pumping technologies. Different socioeconomic frameworks are considered for Spain, Cuba and Pakistan. The levelised cost of energy is used to determine the best technology. Wind speed, distance to grid, water storage size and elevation are considered. The water elevation has greater influence on wind pumps than on solar PV pumping.

Wind pumps for irrigating greenhouse crops: comparison in different socio-economical frameworks

Wind power can play an interesting role in irrigation projects in different areas. A methodology can determine the feasibility of the technology and the levels of daily irrigation demand satisfied by windmills at different levels of risk, using tomato (Lycopersicon esculentum Mill) as greenhouse crop. The present work compared the feasibility of the technology and the critical factors involved in three different countries: Cuba, Spain and Pakistan. The study considered as factors the wind speed level, the energy cost, the tomato prices, the reliability and distance to the electrical grid, and the crop development dates, determining the economic feasibility for each combination of factors in each country.

Gobernar la complejidad urbana desde la sostenibilidad. Evaluación del gobierno de la gestión visible utilizando indicadores de gobernanza (Venezuela)

Se evalúa con indicadores de gobernanza urbana la sostenibilidad de las formas de hacer ciudad hibrida compleja del gobierno de la gestión visible (GGV). Argumenta que el GGV hace ciudad para legitimarse por desempeño y fortalecer la gobernanza local, en un contexto de mutaciones múltiples y radicales que tienden a diluir y centralizar el poder local y fractalizar la ciudad, profundizando la segregación sociopolítica-territorial y la ingobernabilidad genética de la ciudad hibrida, poniendo en riesgo el Estado federal descentralizado, el derecho a la ciudad, al gobierno local y la gobernanza urbana y multinivel (hipótesis). La estrategia de evaluación de gobernanza innovadora (EEG+i) diseñada para evaluar la relación entre las formas de hacer ciudad hibrida (variables espaciales) y gobernanza (variable a-espacial) es transversal, multidimensional y se construye desde la complejidad, el análisis de escenarios, formulación de constructos, modelos e indicadores de gobernanza, entretejiendo tres campos de conocimiento, gobierno, ciudad y sostenibilidad, en cuatro fases. La Fase 1, contextualiza la gobernanza en la dramática del siglo XXI. La Fase 2, desarrolla la fundamentación teórico-práctica, nuevos conceptos y un abordaje analítico propio ‘genética territorial’, para analizar y comprehender la complejidad de la ciudad hibrida de países en desarrollo, tejiendo ontogenética territorial y el carácter autopoiético del gen informal. En la Fase 3, se caracterizan las formas de hacer ciudad desde la genética del territorio, se formulan modelos e indicadores de gobernanza con los que se evalúan, aplicando un delphi y cuestionarios, los genes tipológicos-formas de hacer ciudad y validan las conclusiones. En la Fase 4, se correlacionan los resultados de los instrumentos aplicados con la praxis urbana del GGV, durante cuatro periodos de gobierno (1996-2010). Concluyendo que, la estrategia de evaluación comprobó las hipótesis y demostró la correlación transversal y multinivel existente entre, las mutaciones en curso que contradicen el modelo de gobernanza constitucional, el paisaje de gobernanza latinoamericano y venezolano, la praxis de los regímenes híbridos ricos en recursos naturales, las perspectivas de desarrollo globales y se expresa sociopolíticamente en déficit de gobernanza, Estado de derecho y cohesión-capital social y, espaciolocalmente, en la ciudad hibrida dispersa y diluida (compleja) y en el gobierno del poder diluido centralizado. La confrontación de flujos de poder centrípetos y centrífugos en la ciudad profundiza la fragmentación socioespacial y política y el deterioro de la calidad de vida, incrementando las protestas ciudadanas e ingobernabilidad que obstaculiza la superación de la pobreza y gobernanza urbana y multinivel. La evaluación de la praxis urbana del GGV evidenció que la correlación entre gobernanza, la producción de genes formales y la ciudad por iniciativa privada tiende a ser positiva y entre gobernanza, genes y producción de ciudad informal negativa, por el carácter autopoiético-autogobernable del gen informal y de los nuevos gobiernos sublocales que dificulta gobernar en gobernanza. La praxis del GGV es contraria al modelo de gobernanza formulado y la disolución centralizada del gobierno local y de la ciudad hibrida-dispersa es socio-espacial y políticamente insostenible. Se proponen estrategias y tácticas de gobernanza multinivel para recuperar la cohesión social y de planificación de la gestión innovadora (EG [PG] +i) para orquestar, desde el Consejo Local de Gobernanza (CLG) y con la participación de los espacios y gobiernos sublocales, un proyecto de ciudad compartido y sostenible. ABSTRACT The sustainability of the forms of making the hybrid-complex city by the visible management government (VMG) is evaluated using urban governance indicators. Argues that the VMG builds city to legitimate itself by performance and to strengthen local governance in a context of multiple and radical mutations that tend to dilute and centralize local power and fractalize the city, deepening the socio-spatial and political segregation, the genetic ingovernability of the hybrid city and placing the decentralized federal State, the right to city, local government and urban governance at risk (hypothesis). The innovative governance evaluation strategy (GES+i) designed to assess the relationship between the forms of making the hybrid city (spatial variables) and governance (a-spatial variable) is transversal, multidimensional; is constructed from complexity, scenario analysis, the formulation of concepts, models and governance indicators, weaving three fields of knowledge, government, city and sustainability in four phases. Phase 1, contextualizes governance in the dramatic of the twenty-first century. Phase 2, develops the theoretical and practical foundations, new concepts and a proper analytical approach to comprehend the complexity of the hybrid city from developing countries, weaving territorial ontogenetic with the autopiethic character of the informal city gen. In Phase 3, the ways of making city are characterized from the genetics of territory; governance indicators and models are formulated to evaluate, using delphi and questionnaires, the ways of making city and validate the conclusions. In Phase 4, the results of the instruments applied are correlated with the urban praxis of the VMG during the four periods of government analyzed (1996-2010). Concluding that, the evaluation strategy proved the hypothesis and showed the transversal and multilevel correlation between, mutations that contradict the constitutional governance model, the governance landscape of Latinamerica and the country, the praxis of the hybrid regimes rich in natural resources, the perspectives of the glocal economy and expresses socio-politically the governance and rule of law and social capital-cohesion deficit and spatial-temporarily the hybrid disperse and diluted city (complex) and the diluted-centralized local government. The confrontation of flows of power centripetal and centrifugal in the city deepens the socio-spatial and political fragmentation and deterioration of the quality of life, increasing citizens' protests and ingovernability which hinders poverty eradication and, multilevel and urban governance. The evaluation of the VMG urban praxis showed the correlation between governance, the production of formal genes and city by private initiative tended to be positive and, between informal genes-city production and governance negative, due to its autopiethic-self governable character that hinders governance. The urban praxis of the VMG contradicts the formulated governance model and thecentralized dissolution of the local government and hybrid city are socio-spatial and politically unsustainable. Multiscale governance strategies are proposed to recreate social cohesion and a management planning innovative method (EG [PG] + i) to orchestrate, from the Local Governance Council (LGC) and with the participation of sublocal governments and spaces, a shared and sustainable city project.

Optimización de la succión de sólidos sumergidos utilizando bombas centrífugas con velocidad variable

La acumulación de material sólido en embalses, cauces fluviales y en zonas marítimas hace que la extracción mecánica de estos materiales por medio de succión sea cada vez mas frecuente, por ello resulta importante estudiar el rendimiento de la succión de estos materiales analizando la forma de las boquillas y los parámetros del flujo incluyendo la bomba. Esta tesis estudia, mediante equipos experimentales, la eficacia de distintos dispositivos de extracción de sólidos (utilizando boquillas de diversas formas y bombas de velocidad variable). El dispositivo experimental ha sido desarrollado en el Laboratorio de Hidráulica de la E.T.S.I. de Caminos, C. y P. de la Universidad Politécnica de Madrid. Dicho dispositivo experimental incluye un lecho sumergido de distintos tipos de sedimentos, boquillas de extracción de sólidos y bomba de velocidad variable, así como un elemento de separación del agua y los sólidos extraídos. Los parámetros básicos analizados son el caudal líquido total bombeado, el caudal sólido extraído, diámetro de la tubería de succión, forma y sección de la boquilla extractora, así como los parámetros de velocidad y rendimiento en la bomba de velocidad variable. Los resultados de las medidas obtenidas en el dispositivo experimental han sido estudiados por medio del análisis dimensional y con métodos estadísticos. A partir de este estudio se ha desarrollado una nueva formulación, que relaciona el caudal sólido extraído con los diámetros de tubería y boquilla, caudal líquido bombeado y velocidad de giro de la bomba. Así mismo, desde el punto de vista práctico, se han analizado la influencia de la forma de la boquilla con la capacidad de extracción de sólidos a igualdad del resto de los parámetros, de forma que se puedan recomendar que forma de la boquilla es la más apropiada. The accumulation of solid material in reservoirs, river channels and sea areas causes the mechanical extraction of these materials by suction is becoming much more common, so it is important to study the performance of the suction of these materials analyzing the shape of the nozzles and flow parameters, including the pump. This thesis studies, using experimental equipment, the effectiveness of different solids removal devices (using nozzles of different shapes and variable speed pumps). The experimental device was developed at the Hydraulics Laboratory of the Civil University of the Polytechnic University of Madrid. The device included a submerged bed with different types of sediment solids, different removal nozzles and variable speed pump. It also includes a water separation element and the solids extracted. The key parameters analyzed are the total liquid volume pumped, the solid volume extracted, diameter of the suction pipe, a section of the nozzle and hood, and the parameters of speed and efficiency of the variable speed pump. The basic parameters analyzed are the total liquid volume pumped, the removed solid volume, the diameter of the suction pipe, the shape and cross-section of the nozzle, and the parameters of speed, efficiency and energy consumed by the variable speed pump. The measurements obtained on the experimental device have been studied with dimensional analysis and statistical methods. The outcome of this study is a new formulation, which relates the solid volume extracted with the pipe and nozzle diameters, the pumped liquid flow and the speed of the pump. Also, from a practical point of view, the influence of the shape of the nozzle was compared with the solid extraction capacity, keeping equal the rest of the parameters. So, a recommendation of the best shape of the nozzle can be given.

Estudio energético de renovables en una explotación ganadera

Este trabajo tiene por objetivo el estudio de ahorro energético en una explotación ganadera. Para ello, se contempla la posibilidad de sustituir los sistemas actuales por otros alimentados de energía solar, geotérmica o eólica. La energía obtenida a partir de la producción de metano a través de la utilización de los purines no se contempla, debido a que son utilizados como abono en las parcelas colindantes. PUNTOS TRATADOS Se parte de que, en la explotación, la calefacción es de gas natural y la electricidad es generada por un grupo electrógeno. Estudio de la irradiancia de la zona y de la cantidad de paneles solares y baterías necesarios para hacer la explotación ganadera autosuficiente. Estudio del potencial eólico de la zona y de la cantidad de aerogeneradores y baterías necesarios para hacer la explotación ganadera autosuficiente. Estudio del potencial calorífico de la zona y de la cantidad de tubos, bombas de calor y baterías necesarios para hacer la explotación ganadera autosuficiente. Cálculo de los costes de la instalación solar, eólica y geotérmica. Comparación de los resultados obtenidos anteriormente y breve discusión sobre el sistema elegido. ABSTRACT OBJETIVES This job has got like objective the energetic saving study in a cattle exploitation. For it, it is contemplated the possibility of replacing the current systems with others fed on solar, wind and geothermal power. Energy obtained across production of methane across animal organic wastes it is not contemplated, because they are used as fertilizer on adjacent smallholdings. TREATED POINTS It is parted of that, in the exploitation, heating is propane and electricity is generated by an electrical generator. Study about irradiance on the place and quantity of solar panels and batteries to doing self-sufficient the cattle exploitation. Study about wind potential on the place and quantity of wind generators and batteries to doing self-sufficient the cattle exploitation. Study about calorific potential into ground and quantity of pipes, heat pumps and batteries to doing self-sufficient the cattle exploitation. Calculation about solar, wind and geothermal installation costs. Comparison about results have been obtained and brief discussion about chosen system

Development of a novel autonomous robot for navigation and inspect in oil wells

This paper proposes a novel robotic system that is able to move along the outside of the oil pipelines used in Electric Submersible Pumps (ESP) and Progressive Cavity Pumps (PCP) applications. This novel design, called RETOV, proposes a light weight structure robot that can be equipped with sensors to measure environmental variables avoiding damage in pumps and wells. In this paper, the main considerations and methodology of design and implementation are discussed. Finally, the first experimental results that show RETOV moving in vertical pipelines are analyzed.

Extension of the characteristic equation to absorption chillers with adiabatic absorbers

Various researchers have developed models of conventional H2O–LiBr absorption machines with the aim of predicting their performance. In this paper, the methodology of characteristic equations developed by Hellmann et al. (1998) is applied. This model is able to represent the capacity of single effect absorption chillers and heat pumps by means of simple algebraic equations. An extended characteristic equation based on a characteristic temperature difference has been obtained, considering the facility features. As a result, it is concluded that for adiabatic absorbers a subcooling temperature must be specified. The effect of evaporator overflow has been characterized. Its influence on cooling capacity has been included in the extended characteristic equation. Taking into account the particular design and operation features, a good agreement between experimental performance data and those obtained through the extended characteristic equation has been achieved at off-design operation. This allows its use for simulation and control purposes.

SolarPaces 2013: Innovations on direct steam generation in linear fresnel collectors

Direct Steam Generation (DSG) in Linear Fresnel (LF) solar collectors is being consolidated as a feasible technology for Concentrating Solar Power (CSP) plants. The competitiveness of this technology relies on the following main features: water as heat transfer fluid (HTF) in Solar Field (SF), obtaining high superheated steam temperatures and pressures at turbine inlet (500ºC and 90 bar), no heat tracing required to avoid HTF freezing, no HTF degradation, no environmental impacts, any heat exchanger between SF and Balance Of Plant (BOP), and low cost installation and maintenance. Regarding to LF solar collectors, were recently developed as an alternative to Parabolic Trough Collector (PTC) technology. The main advantages of LF are: the reduced collector manufacturing cost and maintenance, linear mirrors shapes versus parabolic mirror, fixed receiver pipes (no ball joints reducing leaking for high pressures), lower susceptibility to wind damages, and light supporting structures allowing reduced driving devices. Companies as Novatec, Areva, Solar Euromed, etc., are investing in LF DSG technology and constructing different pilot plants to demonstrate the benefits and feasibility of this solution for defined locations and conditions (Puerto Errado 1 and 2 in Murcia Spain, Lidellin Newcastle Australia, Kogran Creek in South West Queensland Australia, Kimberlina in Bakersfield California USA, Llo Solar in Pyrénées France,Dhursar in India,etc). There are several critical decisions that must be taken in order to obtain a compromise and optimization between plant performance, cost, and durability. Some of these decisions go through the SF design: proper thermodynamic operational parameters, receiver material selection for high pressures, phase separators and recirculation pumps number and location, pipes distribution to reduce the amount of tubes (reducing possible leaks points and transient time, etc.), etc. Attending to these aspects, the correct design parameters selection and its correct assessment are the main target for designing DSG LF power plants. For this purpose in the recent few years some commercial software tools were developed to simulatesolar thermal power plants, the most focused on LF DSG design are Thermoflex and System Advisor Model (SAM). Once the simulation tool is selected,it is made the study of the proposed SFconfiguration that constitutes the main innovation of this work, and also a comparison with one of the most typical state-of-the-art configuration. The transient analysis must be simulated with high detail level, mainly in the BOP during start up, shut down, stand by, and partial loads are crucial, to obtain the annual plant performance. An innovative SF configurationwas proposed and analyzed to improve plant performance. Finally it was demonstrated thermal inertia and BOP regulation mode are critical points in low sun irradiation day plant behavior, impacting in annual performance depending on power plant location.

Aplicación de energía geotérmica de muy baja entalpia para la climatización de un edificio de oficinas en Alcorcón, Madrid

El presente Proyecto tiene como propósito el estudio de la viabilidad de la implantación de energía geotérmica de muy baja entalpia para la climatización de un edificio empresarial en Madrid. Para ello se emplearon cálculos teóricos y simulaciones realizadas mediante programas informaticos especializados con el fin de estimar los parámetros técnicos necesarios para su viabilidad. Se estimo el suministro de la potencia necesaria a través de tres bombas de calor tipo agua-agua que sustituyen a las bombas de calor aire-agua individuales anteriormente instaladas. El intercambio de calor se realiza a través de sondas geotérmicas U-Simple. Se dimensionaron los colectores, bombas de circulación, deposito de inercia y vaso de expansión necesarios para funcionamiento del sistema. El estudio económico determino la necesidad de una alta inversión inicial, con una rentabilidad a medio plazo. Además de los beneficios económicos se realizo un estudio de las emisiones de gases de efecto invernadero demostrando la reducción de los mismos, lo que refleja que además de ser una tecnología económicamente viable es una energía limpia. ABSTRACT The objective of the present project is to evaluate the viability of the imposition of a low-enthalpy geothermal energy system for air conditioning in a business building in Madrid. In this study, both theoretical calculations and numerical simulations in specialized programs were used in order to estimate the technical parameters needed for its viability. We estimated the necessary power supply, which is delivered by three heat water-water pumps that substitute the individual heat air-water pumps previously installed. The heat exchange is achieved through geothermal vertical simple-U probes. Also in this work we have measured the collectors, flow pumps, inertia deposit and the water expansion vessel needed for the proper operation of the system. The economic study determined the need of a high initial investment with mid-term profit. In addition to the economic benefits, the greenhouse gases emissions were evaluated, finding that the geothermal energy system implies a reduction of these emissions. This reflects the fact that, in addition to being economically viable, the geothermal energy is considered a clean energy.

Analysis of crystallographic slip and grain boundary sliding in a Ti-45Al-2Nb-2Mn (at%)-0.8 vol%TiB2 alloy by high temperature in situ mechanical testing

This work aims to contribute to a further understanding of the fundamentals of crystallographic slip and grain boundary sliding in the γ-TiAl Ti–45Al–2Nb–2Mn (at%)–0.8 vol%TiB2 intermetallic alloy, by means of in situ high-temperature tensile testing combined with electron backscatter diffraction (EBSD). Several microstructures, containing different fractions and sizes of lamellar colonies and equiaxed γ-grains, were fabricated by either centrifugal casting or powder metallurgy, followed by heat treatment at 1300 °C and furnace cooling. in situ tensile and tensile-creep experiments were performed in a scanning electron microscope (SEM) at temperatures ranging from 580 °C to 700 °C. EBSD was carried out in selected regions before and after straining. Our results suggest that, during constant strain rate tests, true twin γ/γ interfaces are the weakest barriers to dislocations and, thus, that the relevant length scale might be influenced by the distance between non-true twin boundaries. Under creep conditions both grain/colony boundary sliding (G/CBS) and crystallographic slip are observed to contribute to deformation. The incidence of boundary sliding is particularly high in γ grains of duplex microstructures. The slip activity during creep deformation in different microstructures was evaluated by trace analysis. Special emphasis was placed in distinguishing the compliance of different slip events with the Schmid law with respect to the applied stress.