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[ES] Se plantea la aplicación del ciclo Brayton inverso para la generación de temperaturas criogénicas por su capacidad de funcionamiento usando como fluido de trabajo únicamente aire, sin requerir el empleo de fluidos refrigerantes de mayor impacto ambiental en el proceso. Dentro de este proyecto se incluye la realización de ensayos de rendimiento del ciclo mediante una instalación experimental, la caracterización de un modelo informático del ciclo a partir de resultados experimentales y la implementación de posibles mejoras a la eficiencia global del sistema, con el objetivo de obtener prestaciones atractivas comercialmente. Adicionalmente se incluyen un estudio de viabilidad de este sistema frente a las soluciones actuales en distintas aplicaciones industriales, [EN] The application of an Inverted reverse Brayton cycle is proposed due to its ability to operate using only air as the working fluid, without requiring the use of refrigerant fluids with greater environmental impact. This project includes conducting a series of cycle performance tests through an experimental installation, the characterization of a computer model of the cycle based on experimental results and the implementation of possible upgrades to the overall efficiency of the system with the aim of developing a commercially attractive design. Additionally, a feasibility study of this system is included compared to current solutions in different industrial applications., [CA] En aquest Treball Final de Màster s’estudiarà el desenvolupament i implementació d’un cicle Brayton invers avançat que permeta obtindre temperatures inferiors a les aconseguides pels sistemes actuals de va fregir mecànic i que s’aproximen a les obtingudes mitjançant l’ús de líquids criogènics com el nitrogen liquide. Presentant a més el benèfic afegit d’emprar com a fluid de treball aire ambient, sense requerir de l’ús de fluids refrigerants de major impacte ambiental la legislació del qual s’encamina a majors restriccions. Aquest treball inclou els resultats de múltiples campanyes d’assaig realitzades sobre una instal·lació experimental i el desenvolupament i caracterització d’un model informàtic del cicle en el programari VEMOD. Discutint-se la implementació de possibles millores a l’eficiència global del sistema de cara a futures aplicacions, realitzant-se un estudi de viabilitat comercial d’aquest sistema enfront de les solucions actuals en l’àmbit industrial i sanitari.

[ES] El presente Trabajo de Fin de Máster parte de la necesidad de mejorar el proceso de combustión de una empresa fabricante de fritas, esmaltes y colores cerámicos de la provincia de Castellón. Una frita es una mezcla de sustancias inorgánicas obtenida mediante un enfriamiento rápido de una masa fundida. Para lograr fundir las sustancias de partida es necesario alcanzar temperaturas de 1600 °C. El proceso de fusión de la frita se lleva a cabo mediante hornos de alimentados con gas natural. La combustión del gas realizada fuera de los parámetros estequiométricos y utilizando aire como comburente produce un aumento de los gastos en combustible y en las emisiones. El aporte controlado de oxígeno mediante una fuente externa permite optimizar el proceso de combustión para ser más eficiente y menos contaminante. Dado que el proceso de fusión se realiza de forma continua, debe garantizarse el suministro de oxígeno. Para ello se debe diseñar e instalar un depósito criogénico de 50 metros cúbicos en el que se almacenará el oxígeno en forma líquida a -185 °C. Desde este depósito, el oxígeno se pasa a un evaporador desde el que se envía en fase gas a los a los quemadores de los hornos. El TFM incluye el diseño mecánico básico del depósito según normativa europea EN y el proyecto de las medidas de seguridad necesarias para su instalación en el emplazamiento de la empresa., [EN] This Master's Thesis is based on the need to improve the combustion process of the furnaces of a company that manufactures frits, enamels and ceramic colors in the province of Castellón. A frit is a mixture of inorganic substances obtained by rapid cooling of a melt. To melt the starting substances, it is necessary to reach temperatures of 1600 ° C. The frit melting process is carried out by furnaces fired with natural gas. Combustion outside the ideal stoichiometric parameters results in increased fuel consumption and emissions. The controlled supply of oxygen through an external source will allow optimizing the combustion process to be more efficient and less polluting. Since the melting process is carried out continuously, the supply of oxygen must be ensured. For this, a 50 cubic meter cryogenic tank must be designed and installed in which oxygen will be stored in liquid form at -185 ° C. From this tank, the oxygen will be passed to an evaporator from which it will be sent in the gas phase to the burners of the furnaces. The Master's Thesis includes the basic mechanical design of the tank using design codes for pressure equipment and the project of the security measures necessary for its installation at the company's site.

Those scientific and industrial equipment that require a very low temperature cooling system to operate often require continuous maintenance and constant control of the cryogenic liquid level. For this reason, some plants are equipped with remote surveillance systems based on “ad hoc” developed technologies for very low temperatures. We present a patented technical solution to be able to use, in cryogenic conditions, a common ultrasound sensor that costs 4 euros. This cap for dewar tanks, due to its particular shape, allows to obtain this result. Consequently, it also offers the possibility of being able to use other lowcost technologies, such as the microcontrollers of the Arduino series. This allows an unlimited range of developments ranging from remote monitoring to the total automation of the ordinary maintenance of the cooling system. With this idea an “active cap” for Dewar was created at very low cost. It monitors the level of liquid nitrogen and provides online measurements updated in real time, the forecast of intervention for topping up and any alarm messages. A simple upgrade can allow automatic refilling of the liquid in the dewar. This solution, for inexpensiveness, can also represent an alternative to closedcircuit cooling and recycling systems., Le apparecchiature scientifiche e industriali che per funzionare richiedono un impianto di raffreddamento a bassissima temperatura hanno spesso bisogno di continua manutenzione e del controllo costante del livello del liquido criogenico. Per questo motivo alcuni impianti vengono dotati di sistemi di sorveglianza remota basati su tecnologie realizzate ad hoc per le bassissime temperature. Viene presentata una soluzione tecnica brevettata per poter impiegare in condizioni criogeniche un comune sensore a ultrasuoni del costo di 4 euro. Questo tappo per serbatoi dewar, grazie alla sua particolare forma, consente di ottenere questo risultato offrendo di conseguenza la prospettiva di poter impiegare altre tecnologie a basso costo, come i microcontrollori della serie Arduino. Ciò favorisce un’illimitata gamma di sviluppi che vanno dal monitoraggio remoto fino all’automazione totale della manutenzione ordinaria dell’impianto di raffreddamento. Grazie a questa idea è stato realizzato a bassissimo costo un tappo attivo per vasi di Dewar che sorveglia il livello dell’azoto liquido e invia al personale addetto le misure aggiornate in tempo reale, la previsione di intervento per il rabbocco ed eventuali messaggi di allarme. Un semplice upgrade può consentire il rabbocco automatico del liquido nel dewar. Per la sua economicità, questa soluzione può rappresentare anche un’alternativa ai sistemi di raffreddamento e riciclo a circuito chiuso.

Radiation hardness is a critical design constraint for current and future generation silicon detectors, which are foreseen to undergo radiation fluences higher than 1×1014 cm−2 1-MeV neutron equivalent. Recently, low-temperature operating conditions have been suggested as an effective means to recover the negative effects of radiation damage on silicon detector collection properties. In order to investigate such an effect, simulations have been carried out using the ISE-TCAD DESSIS device simulator. The simulated results are compared with charge collection spectra obtained with 1064 nm laser pulses on devices irradiated with 23 GeV protons as a function of detector bias voltage. Thousands of simulation results have been cross-checked with the experimental data. The results obtained so far indicate that the “three-level model” can be successfully extended to predict irradiated detector behavior at least down to a temperature of 190 K.