Sistema de instrumentación y control para la optimización energética de una piscina climatizada

El desconocimiento de los mecanismos que provocan las pérdidas térmicas en los vasos de las piscinas climatizadas provoca una fallida e ineficiente estrategia en la operación de las mismas. Una gestión energética más eficiente, junto con la utilización de fuentes de energía renovables como único aporte térmico, pueden producir una reducción considerable en los costes energéticos relativos a su explotación (hasta en un 80%). El objeto de este trabajo consiste en la instalación de un sistema de instrumentación y control que permita conocer todos los flujos energéticos que se dan en una piscina que incorpora dos fuentes de energía renovables distintas: solar y biomasa. Ambos sistemas satisfacen la demanda de cinco puntos de consumo distintos: calefacción de la sala de la piscina, calefacción de vestuarios y otras estancias, calentamiento del vaso de natación, calentamiento del vaso de chapoteo, y calentamiento de agua de las duchas (ACS). Este sistema de instrumentación y control permite validar empíricamente los distintos modelos propuestos en la bibliografía con el fin de optimizar la gestión de este tipo de instalaciones térmicas. La completa instrumentación incorpora 9 caudalímetros, 19 sondas de temperatura y una de humedad relativa, y es capaz de registrar 75 parámetros distintos con lapsos de tiempo de 10 minutos. La arquitectura del sistema está basada en módulos inalámbricos, con una centralita constituida por un computador conectado a internet para favorecer su acceso a distancia mediante ordenador, Tablet o teléfono móvil. Los datos registrados servirán para validar un modelo de simulación dinámica para piscinas climatizadas. De esta manera, se puede optimizar su consumo energético mediante una correcta gestión de sus instalaciones térmicas.Es necesario agradecer al Ayuntamiento de Archena por su incansable lucha en favor de la eficiencia energética de su instalación, así como por decidida apuesta por llevar a cabo esta instalación que tanto conocimiento podrá aportar a la ciencia

Porous Silicon Gas Sensors: The Role of the Layer Thickness and the Silicon Conductivity

We studied the influences of the thickness of the porous silicon layer and the conductivity type on the porous silicon sensors response when exposed to ethanol vapor. The response was determined at room temperature (27 ∘C) in darkness using a horizontal aluminum electrode pattern. The results indicated that the intensity of the response can be directly or inversely proportional to the thickness of the porous layer depending on the conductivity type of the semiconductor material. The response of the porous sensors was similar to the metal oxide sensors. The results can be used to appropriately select the conductivity of semiconductor materials and the thickness of the porous layer for the target gas

Highly Visible Photoluminescence from Ta-Doped Structures of ZnO Films Grown by HFCVD

Tantalum-doped ZnO structures (ZnO:Ta) were synthesized, and some of their characteristics were studied. ZnO material was deposited on silicon substrates by using a hot filament chemical vapor deposition (HFCVD) reactor. The raw materials were a pellet made of a mixture of ZnO and Ta2O5 powders, and molecular hydrogen was used as a reactant gas. The percentage of tantalum varied from 0 to 500 mg by varying the percentages of tantalum oxide in the mixture of the pellet source, by holding a fixed amount of 500 mg of ZnO in all experiments. X-ray diffractograms confirmed the presence of zinc oxide in the wurtzite phase, and metallic zinc with a hexagonal structure, and no other phase was detected. Displacements to lower angles of reflection peaks, compared with those from samples without doping, were interpreted as the inclusion of the Ta atoms in the matrix of the ZnO. This fact was confirmed by energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) measurements. From scanning electron microscopy (SEM) images from undoped samples, mostly micro-sized semi-spherical structures were seen, while doped samples displayed a trend to grow as nanocrystalline rods. The presence of tantalum during the synthesis affected the growth direction. Green photoluminescence was observed by the naked eye when Ta-doped samples were illuminated by ultraviolet radiation and confirmed by photoluminescence (PL) spectra. The PL intensity on the Ta-doped ZnO increased from those undoped samples up to eight times

Effect of the Gaseous Atmosphere in GaAs Films Grown by Close-Spaced Vapor Transport Technique

The effect of the gaseous atmosphere in the growth of gallium arsenide (GaAs) films was studied. The films have been grown by close-spaced vapor transport (CSVT) technique in a home-made hot filament chemical vapor deposition (HFCVD) reactor using molecular hydrogen and molecular nitrogen as the transport agent. An important point about the gaseous atmosphere is the ease in creating volatile compounds when it makes contact with the GaAs source, this favors the transport of material in a CSVT system. Chemical reactions are proposed in order to understand the significant difference produced from the gaseous atmosphere. The films grown with hydrogen are (almost) continuous and have homogeneous layers with preferential orientation (111). The films grown with nitrogen are granular and rough layers with the coexistence of the orientations (111), (220) and (311) in the crystals. The incorporation of impurities in the films was corroborated by energy dispersive spectroscopy (EDS) showing traces of oxygen and nitrogen for the case of the samples obtained with nitrogen. Films grown in a hydrogen atmosphere show a higher band gap than those grown in a nitrogen atmosphere. With the results of XRD and micro-Raman we observe a displacement and broadening of the peaks, characteristic of a structural disorder. The calculations of the FWHM allow us to observe the crystallinity degree and determine an approximate crystallite size using the Scherrer’s equation