In the wake of global warming and fossil fuel depletion, renewed attention has been paid to shifting away from the use of petroleum based fuels. The world?s energy demand is commencing its dependency on alternative fuels. Such alternative fuels in use today consist of bio-alcohols (such as ethanol), hydrogen, biomass, and natural oil/fat derived fuels. However, in this study, the focus will be on the alternative fuel derived from natural oils and fats, namely biodiesel. The following study characterizes the performance of a medium-duty diesel engine fuelled with biodiesel and conventional diesel. The objective is accomplished by taking measurements of manifold pressure and temperature, fuel flow, air flow, and torque. The study first characterizes a John Deere 4.5 liter 4 cylinder direct injection engine with exhaust gas recirculation (EGR), common rail fuel injection, and variable turbo-charging with conventional petroleum diesel to set a reference for comparison. The study then proceeds to characterize the differences in engine performance as a result of using biodiesel relative to conventional diesel. The results show that torque decreases with the use of biodiesel by about 10%. The evaluation of engine performance parameters shows that torque is decreased because of the lower heating value of biodiesel compared to conventional diesel. The insignificant difference between the other performance parameters shows that the ECM demands the same performance of the engine regardless of the fuel being combusted by the engine.

Multithreaded processors are now common in the industry as they offer high performance at a low cost. Traditionally, in such processors, the assignation of hardware resources between the multiple threads is done implicitly, by the hardware policies. However, a new class of multithreaded hardware allows the explicit allocation of resources to be controlled or biased by the software. Currently, there is little or no coordination between the allocation of resources done by the hardware and the prioritization of tasks done by the software.This thesis targets to narrow the gap between the software and the hardware, with respect to the hardware resource allocation, by proposing a new explicit resource allocation hardware mechanism and novel schedulers that use the currently available hardware resource allocation mechanisms.It approaches the problem in two different types of computing systems: on the high performance computing domain, we characterize the first processor to present a mechanism that allows the software to bias the allocation hardware resources, the IBM POWER5. In addition, we propose the use of hardware resource allocation as a way to balance high performance computing applications. Finally, we propose two new scheduling mechanisms that are able to transparently and successfully balance applications in real systems using the hardware resource allocation. On the soft real-time domain, we propose a hardware extension to the existing explicit resource allocation hardware and, in addition, two software schedulers that use the explicit allocation hardware to improve the schedulability of tasks in a soft real-time system.In this thesis, we demonstrate that system performance improves by making the software aware of the mechanisms to control the amount of resources given to each running thread. In particular, for the high performance computing domain, we show that it is possible to decrease the execution time of MPI applications biasing the hardware resource assignation between threads. In addition, we show that it is possible to decrease the number of missed deadlines when scheduling tasks in a soft real-time SMT system.

Indiana University-Purdue University Indianapolis (IUPUI) / Evolutionary testing (ET) techniques (e.g., mutation, crossover, and natural selection) have been applied successfully to many areas of software engineering, such as error/fault identification, data mining, and software cost estimation. Previous research has also applied ET techniques to performance testing. Its application to performance testing, however, only goes as far as finding the best and worst case, execution times. Although such performance testing is beneficial, it provides little insight into performance characteristics of complex functions with multiple branches. This thesis therefore provides two contributions towards performance testing of software systems. First, this thesis demonstrates how ET and genetic algorithms (GAs), which are search heuristic mechanisms for solving optimization problems using mutation, crossover, and natural selection, can be combined with a constraint solver to target specific paths in the software. Secondly, this thesis demonstrates how such an approach can identify local minima and maxima execution times, which can provide a more detailed characterization of software performance. The results from applying our approach to example software applications show that it is able to characterize different execution paths in relatively short amounts of time. This thesis also examines a modified exhaustive approach which can be plugged in when the constraint solver cannot properly provide the information needed to target specific paths.

[ES] En un contexto de creciente preocupación por el calentamiento global y de políticas energéticas internacionales, en el cual los sistemas de climatización de los edificios suponen una parte importante del consumo energético global, los sistemas de bombas de calor son considerados como opciones muy interesantes debido a su alta eficiencia y por ser fuentes de energía renovables. En este sentido, una caracterización precisa de estos equipos es de vital importancia con el objetivo de mejorar su diseño y, en aquellos casos dónde este tipo de unidades se integren como parte de sistemas más complejos, implementar estrategias de control eficientes. En este contexto, esta tesis doctoral se centra en el modelado de bombas de calor con el fin de obtener modelos que permitan conocer con precisión el desempeño global de estas unidades en todo el rango de trabajo. En la primera parte del trabajo, se han realizado numerosos ensayos experimentales utilizando un nuevo prototipo de bomba de calor dual, obtenidos dentro del marco de trabajo del proyecto europeo GEOTeCH. Debido a la tipología hibrida de esta unidad, los resultados experimentales obtenidos incluyen datos de desempeño para las principales tecnologías de bombas de calor: las bombas de calor aerotérmicas y geotérmicas. Haciendo uso de toda esta información experimental, esta primera parte del trabajo se centra en obtener modelos polinómicos para la predicción del consumo eléctrico y las capacidades de calefacción y refrigeración en función de las variables externas a la unidad. Dichas variables son fáciles de obtener y suelen medirse en instalaciones reales. Por tanto, estos modelos caracterizan a la bomba de calor como un único componente, simplificando su implementación en modelos globales de sistemas más complejos donde se instalan estas unidades. Además, seleccionado un enfoque empírico para el modelado, en esta parte también se analizan algunos aspectos relevantes, como los términos a incluir en el polinomio, o cómo conformar las matrices experimentales de ensayo necesarias, es decir, cuántos puntos experimentales realizar y dónde situarlos en el rango de operación. Por último, la segunda parte de la tesis doctoral está dedicada a modelar uno de los componentes principales en estas unidades, el compresor. En este caso, el desarrollo de una extensa base de datos que incluye numerosos ensayos calorimétricos de las dos principales tecnologías de compresores, pistón y scroll, ha permitido el análisis detallado de las superficies de respuesta del consumo eléctrico y el caudal másico de refrigerante en función de las temperaturas de evaporación y condensación. A partir de esta información y siguiendo un enfoque similar al utilizado previamente, en esta segunda parte se revisan los modelos incluidos en la norma actual de caracterización de compresores, el estándar AHRI 540 (2020), para comprobar si son adecuados o si, por el contrario, debemos utilizar otro tipo de expresiones polinómicas. También se analizan en profundidad cuestiones críticas como el número de puntos necesarios para caracterizar cada tecnología de compresor, dónde situarlos en el dominio experimental, cómo evitar un posible sobreajuste del modelo minimizando problemas de extrapolación o interpolación, o cómo extrapolar los resultados para predecir con otros refrigerantes u otras condiciones de aspiración. / [CA] En un context de creixent preocupació per l'escalfament global i de polítiques energètiques internacionals, en el qual els sistemes de climatització dels edificis suposen una part important del consum energètic global, els sistemes de bombes de calor són considerats com a opcions molt interessants a causa de la seva alta eficiència i perquè són fonts d'energia renovables. En aquest sentit, una caracterització precisa d'aquests equips és de vital importància amb l'objectiu de millorar el seu disseny i, en aquells casos on aquest tipus d'unitats s'integren com a part de sistemes més complexos, implementar estratègies de control eficients. En aquest context, aquesta tesi doctoral se centra en el modelat de bombes de calor per obtenir models que permitisquen conèixer amb precisió el funcionament d'aquestes unitats a tot el rang de treball. A la primera part del treball, s'han realitzat nombrosos assajos experimentals utilitzant un nou prototip de bomba de calor dual, obtinguts dins del marc de treball del projecte europeu GEOTeCH. A causa de la tipologia hibrida d'aquesta unitat, els resultats experimentals obtinguts inclouen dades de funcionament per a les principals tecnologies de bombes de calor: les bombes de calor aerotèrmiques i geotèrmiques. Fent ús de tota aquesta informació experimental, aquesta primera part del treball se centra a obtenir models polinòmics per a la predicció del consum elèctric i les capacitats de calefacció i refrigeració en funció de les variables externes a la unitat. Aquestes variables són fàcils d'obtenir i se solen mesurar en instal·lacions reals. Per tant, aquests models caracteritzen la bomba de calor com un únic component, simplificant-ne la implementació en models globals de sistemes més complexos on s'instal·len aquestes unitats. A més, seleccionat un enfocament empíric per al modelatge, en aquesta part també s'analitzen alguns aspectes rellevants, com els termes a incloure al polinomi, o cóm conformar les matrius experimentals d'assaig necessàries, és a dir, quants punts experimentals realitzar i on situar-los al rang d'operació. Per acabar, la segona part de la tesi doctoral està dedicada al modelat d'un dels components principals d'aquestes unitats, el compressor. En aquest cas, el desenvolupament d'una extensa base de dades que inclou nombrosos assajos calorimètrics de les dues principals tecnologies de compressors, pistó i scroll, ha permès l'anàlisi detallat de les superfícies de resposta del consum elèctric i el cabal màssic de refrigerant segons les temperatures d'evaporació i de condensació. A partir d'aquesta informació i seguint un enfocament similar a l'utilitzat prèviament, en aquesta segona part es revisen els models inclosos a la norma actual de caracterització de compressors, l'estàndard AHRI 540 (2020), per comprovar si són adequats o si, per contra, cal utilitzar un altre tipus d'expressions polinòmiques. També s'analitzen en profunditat qüestions crítiques com el nombre de punts necessaris per caracteritzar cada tecnologia de compressor, on situar-los al domini experimental, cóm evitar un possible sobreajust del model minimitzant problemes d'extrapolació o interpolació, o cóm extrapolar els resultats per predir amb altres refrigerants o altres condicions d'aspiració. / [EN] In a context of global warming concerns and global energy policies, in which heating and cooling systems in buildings account for a significant amount of the global energy consumption, heat pump systems are widely considered as a really interesting option for enabling high efficiency and also for being renewable energy sources. In this sense, an accurate characterization of these units is of vital importance to improve their design and implement efficient control strategies, when the unit is integrated in more complex systems. Against this background, this PhD thesis focuses on heat pump modelling in order to create map-based models able to accurately characterize the global performance of these units for the entire working range. In the first part of this work, many experimental tests have been obtained for a new Dual Source Heat Pump prototype tested in the framework of the European project GEOTeCH. Due to the dual typology, the experimental results include performance data for the two main heat pump technologies: Air Source Heat Pumps and Ground Source Heat Pumps. By using all this experimental information, this first part focuses on obtaining empirical polynomial models capable of accurately predicting energy consumption and heating and cooling capacities as a function of external variables. Such variables are easy to measure and are usually recorded in real installations. Therefore, these models characterize the heat pump as a single component, simplifying its implementation in global models of more complex systems where these units are installed. Furthermore, selecting the empirical model approach, this part also includes some critical aspects, such as how to obtain the best polynomial expression, or how to perform the required experimental test matrices, i.e., how many tests should be conducted and where in the operating range. Finally, the second part of this PhD thesis is dedicated to modelling one of the main components of these units, the compressor. In this case, the development of an extensive database including numerous calorimetric tests on the two main compressor technologies, reciprocating and scroll compressors, has allowed the detailed analysis of the response surfaces of their performance parameters, i.e., the energy consumption and mass flow rate as a function of the evaporation and condensation temperatures. Using this information, and following an approach similar to that used in the first part, this second part reviews the models included in the current compressor characterization standard, the AHRI 540 (2020), in order to check whether they are appropriate or, on the contrary, whether we should use of other types of polynomial expression. Critical issues such as the number of points needed to characterize each compressor technology, where to place them in the experimental domain, how to prevent possible overfitting in the model adjustment to minimize extrapolation or interpolation problems, or how to extrapolate results for predicting other refrigerant or suction conditions, are discussed in depth. / I would like to acknowledge the financial support that has made this PhD thesis possible. The doctoral fellowship FPU15/03476 was founded by “Ministerio de Educación, Cultura y deporte” inside the program “Formación de Profesorado Universitario”, and the GEOTeCH project (No 656889) founded by the European Union under the “Horizon 2020 Framework Programme for European Research and Technological Development” / Marchante Avellaneda, J. (2023). Study of Response Surface Models for the characterization of the performance in Refrigeration Equipments and Heat Pumps [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/192653

Tesis por compendio / [ES] La tecnología de bombas de calor se ha vuelto estratégica en Europa, está extendiéndose rápidamente y se planea que reemplace las calderas de gas en un futuro cercano. Sin embargo, aún enfrenta desafíos, como encontrar refrige-rantes nuevos viables y altamente eficientes, y mejorar aún más el rendimiento del sistema. Para abordar este último problema, han surgido las bombas de calor de velocidad variable que prometen reducir el consumo anual e incremen-tar el confort adaptando la potencia suministrada a las necesidades cambiantes. Esta tecnología se está implementando ya, pero carece de una metodología estandarizada para diseñar y seleccionar sus componentes. Esta tesis tiene como objetivo establecer pautas de diseño generales para la selección y diseño de componentes de bombas de calor de velocidad variable, y ofrecer información valiosa que se pueda traducir en herramientas para asistir en la simulación, diseño, selección y detección de fallas en estos dispositivos. El contenido del estudio se puede dividir en tres áreas temáticas: En una primera parte, se estudian los compresores de velocidad variable. El compresor es el primer componente que se selecciona en una bomba de calor, modula la capacidad y es el principal consumidor de energía. Sin embargo, no existen metodologías bien establecidas para modelar su comportamiento. En esta parte, se realizan ensayos de caracterización de compresores de velocidad variable y sus inversores para comprender su comportamiento y proporcionar correlaciones compactas para modelar su rendimiento. En la segunda parte, se propone una metodología para dimensionar los intercambiadores de calor en bombas de calor de velocidad variable. Nor-malmente, se diseñan para una potencia fija y temperaturas de trabajo constan-tes, sin embargo, en las bombas de velocidad variable, la capacidad y las tempe-raturas de trabajo fluctúan significativamente con el tiempo. En esta parte, se estudia la evolución del rendimiento de los intercambiadores de calor con la capacidad (velocidad del compresor) y se propone una metodología de selec-ción/dimensionamiento que considera la evolución de la capacidad requerida y de las condiciones climáticas externas a lo largo del año. Por último, se evalúa la circulación del aceite en las bombas de calor de velocidad variable. Gestionar la lubricación en los compresores de velocidad variable es un problema típico ya que, para tener suficiente lubricación a bajas velocidades, el compresor termina bombeando un exceso de aceite a altas velo-cidades. En esta parte se estudia la evolución de las tasas de circulación de acei-te con la velocidad y se analiza teóricamente su efecto en el rendimiento de la bomba de calor. / [CA] La tecnologia de les bombes de calor s'ha tornat estratègica a Europa, s'està estenent ràpidament i es preveu que substituïsca les calderes de gas en un futur pròxim. Tanmateix, encara s'enfronta a desafiaments com trobar refrigerants nous viables i altament eficients, i millorar encara més el rendiment del sistema. Per abordar aquest darrer problema, han sorgit les bombes de calor de velocitat variable que prometen reduir el consum anual i incrementar el confort adaptant la potència subministrada a les necessitats variables. Aquesta tecnologia ja s'es-tà implementant, però manca d'una metodologia estandarditzada per dissenyar i seleccionar els seus components. Aquesta tesi té com a objectiu establir pautes de disseny generals per a la se-lecció i disseny de components de bombes de calor de velocitat variable, i oferir informació valuosa que es pugui traduir en eines per ajudar en la simulació, disseny, selecció i detecció de fallades d'aquests dispositius. El contingut de l'estudi es pot dividir en tres àrees temàtiques: En una primera part, s'estudien els compressors de velocitat variable. El compressor és el primer component seleccionat d'una bomba de calor, modula la capacitat i és el principal consumidor d'energia. Tanmateix, no hi ha metodo-logies ben establides per modelar el seu comportament. En aquesta part, es realitzen assajos de caracterització de compressors de velocitat variable i els seus inversors per comprendre el seu comportament i proporcionar correlaci-ons compactes per modelar el seu rendiment. En la segona part, es proposa una metodologia per dimensionar els inter-canviadors de calor en bombes de calor de velocitat variable. Normalment, es dissenyen per a una potència fixa i temperatures de treball constants, no obs-tant això, en les bombes de velocitat variable, la capacitat i les temperatures de treball fluctuen significativament amb el temps. En aquesta part, s'estudia l'evo-lució del rendiment dels intercanviadors de calor amb la capacitat (velocitat del compressor) i es suggereix una metodologia de selecció/dimensionament que considera l'evolució de les càrregues i de les condicions climàtiques externes al llarg de l'any. Finalment, s'avalua la circulació de l'oli a les bombes de calor de velocitat variable. Gestionar la lubricació als compressors de velocitat variable és un pro-blema típic, ja que per tenir suficient lubricació a baixes velocitats, el compres-sor acaba bombejant un excés d'oli a altes velocitats. En aquesta part s'estudia l'evolució de les taxes de circulació d'oli amb la velocitat i s'analitza teòricament el seu efecte en el rendiment de la bomba de calor. / [EN] Heat pump technology has become strategic in Europe, it is rapidly spread-ing, and it is planned to replace gas boilers in the near future. However, they still have challenges to solve, such as finding new viable and highly efficient refriger-ants and further increasing their system performance. For this latter issue, vari-able-speed heat pumps arise, which claim to decrease annual consumption and increase comfort by adapting the delivered capacity to the changing loads. This technology is being implemented but lacks a standardized methodology to de-sign and select its components. This thesis aims to establish comprehensive design guidelines for selecting and designing variable-speed heat pump components and give insights that can translate into valuable information and tools for engineers to assist them in the pump simulation, design, selection and fault detection. The content of the study can be divided into three thematic areas: In the first part, variable-speed compressors are studied. The compressor is the first selected heat pump component; it modulates the capacity and is the primary energy consumer. However, there are no well-established methodolo-gies to model their behavior. In this part, extensive testing of variable-speed compressors and their inverters was carried out to understand their behavior and to provide compact correlations to model their performance. The second part proposes a methodology to size heat exchangers for variable-speed heat pumps. Typically, they are designed for a fixed capacity and constant working temperatures. However, the capacity and working tempera-tures fluctuate significantly overtime in variable-speed pumps. In this part, the performance evolution of heat exchangers with capacity is studied, and a meth-odological selection/sizing technique is proposed that considers the evolution of external climatic conditions and loads over the year. Lastly, the oil circulation in variable-speed heat pumps is assessed. Man-aging lubrication in variable-speed compressors is a typical issue, as a design valid for sufficient lubrication at low compressor speeds will end up pumping excess oil at high speeds. In this final part, the evolution of oil circulation rates with speed is studied, and its effect on heat pump performance is theoretically analyzed. / I am indebted to the Spanish and European governments for their financial support with the grant PRE2018-083535, which made this research possible. Their commitment to academic excellence and research advancement has been crucial in successfully completing this thesis. / Ossorio Santiago, RJ. (2024). Modelling of Heat Pumps Working with Variable-Speed Compressors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203104 / Compendio

<p>There are no commercially available wearable shoe in-sole sensors that are capable of measuring and distinguishing between shear and compression forces. Companies have already developed shoe sensors that simply measure pressure and make general inferences on the collected data with elaborate software [2, 3, 4, 5]. Researchers have also attempted making sensors that are capable of measuring shear forces, but they are not well suited for biomedical applications [61, 62, 63, 64]. This work focuses on the development of a novel wearable sensor system that is capable of identifying and measuring shear and compression forces through the use of capacitive sensing. Custom hardware and software tools such as materials test systems and capacitive measurement systems were developed during this work. Numerous sensor prototypes were developed, characterized, and optimized during the scope of this project. Upon analysis of the data, the best capacitive measurement system developed in this work utilized the CAV444 IC chip, whereas the use of the Arduino-derived measurement system required data filtering using median and Butterworth zero phase low pass filters. The highest dielectric constant reported from optimization experiments yielded 9.7034 (+/- 0.0801 STD) through the use of 60.2% by weight calcium copper titanate and ReoFlex-60 silicone. The experiments suggest certain sensors developed in this work feasibly measure and distinguish between shear and compressional forces. Applications for such technology focus on improving quality of life in areas such as managing diabetic ulcer formation, preventing injuries, optimizing performance for athletes and military personnel, and augmenting the scope of motion capture in biomechanical studies.</p>