El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.

An experimental study was performed on a low frequency transcritical thermoacoustic engine developed at Maurice J. Zucrow Laboratories. The goal of the experiment was to characterize the effects of engine geometry on the thermoacoustic production of the working fluid and to use insights gained to design a power extraction device for the transcritical thermoacoustic engine. The effects of geometry were investigated by parametrically varying the length of the resonator and the diameter of the resonator and measuring the pressure amplitude and frequency of thermoacoustic instabilities developed at varying ∆T and one bulk pressure of P Pcr = 1.1. It was found that increasing resonator length increases pres?sure amplitude, decreases frequency, and increases acoustic power developed. Increasing resonator diameter decreases pressure amplitude, increases frequency, and increases acoustic power developed. It was also experimentally proven that coiled tube sections in the res?onator attenuate the thermoacoustic pressure wave. After testing, the knowledge gained was applied to the design of a bidirectional impulse turbine for eventual integration into a scaled-up version of the current thermoacoustic engine to be used to extract power from the thermoacoustic instabilities developed in the rig.

Bolidens elektrolysverk på Rönnskär hade ett behov av att analysera potentialen för att återvinna och utnyttja spillvärme från kondensat för verket. Ångan som användes för existerande värmeväxlare varåtervunnen från olika processer inom Rönnskär, men även producerad av en oljepanna. Den ännu outnyttjade spillvärme som fanns på elektrolysverket skulle potentiellt kunna assistera existerande värmeväxlare för att minska oljekonsumtionen. Ett av målen var att undersöka om det var möjligt attöka temperaturen på elektrolyten till 63 ℃ med ytterligare en värmeväxlare före den nuvarandevärmeväxlaren. Uppvärmningspotentialen för en värmeväxlare med den kondensatmängd och kondensattemperatur som fanns på elektrolysverket skulle undersökas om temperaturen på kondensatet var lägre än 63 ℃. Projektet analyserade relaterade system inom elektrolysverket och mer specifikt avkoppringens utformning med olika maskiner och system. Analysen inkluderade också rekommendationer inom val av värmeväxlare, dimensionering och beräkningar för konfiguration av rörvärmeväxlaren. Sedan beräknades även kondensatmängd, kondensattemperatur, hållbarhetsanalys och ekonomisk analys. En känslighetsanalys utfördes för de viktigaste variablerna.  Resultaten visade att mängden kondensat var för liten för att motivera ytterligare en värmeväxlare. Detta ledde till två fallstudier för olika scenarion inom elektrolysverket vad gällde mängd kondensat, kondensattemperaturer och uppvärmningspotential för elektrolyten. I första fallet beräknades kravet på kondensattemperaturen för uppvärmning av elektrolyten till 63 ℃. I andra fallet utforskades uppvärmningspotentialen av elektrolyten med den beräknade kondensattemperatur på cirka 60 ℃. För båda fallen så användes varierande volymflöden mellan 53,5 liter/min till 126 liter/min. Det medfördeatt elektrolyttemperaturen kunde värmas upp till ett intervall på mellan 30 och 44 ℃. Elektrolytens uppnådda temperatur var beroende av vilket volymflöde som valdes. För att nå temperaturen 63 ℃ påelektrolyten behövdes en kondensattemperatur på cirka 96 ℃ för maxkapacitet. Bästa valet av värmeväxlare var rörvärmeväxlare. Utformningen av värmeväxlaren gav ett acceptabelt tryckfall och god total värmeöverföringskoefficient. Hållbarhetsanalysen visade att det var gynnsamt med en värmeväxlare för att minska koldioxidutsläppen. Minskade koldioxidkostnader gav en mer gynnsam ekonomi, frånsett eventuella investeringskostnader. Känslighetsanalysen visade att känsliga variabler har låg påverkan på resultatet och att de viktiga variablerna som temperaturer och flöden påverkaderesultatet som förväntat. Slutligen kunde man konstatera att denna lösning inte var gynnsam för tillfället på grund av brist på kondensatmängd, men kan vara relevant för elektrolysverket i framtiden. / Boliden's electrolysis plant at Rönnskär had a need to analyze the potential to reuse waste heat from the condensate. The steam used for existing heat exchangers was recovered by various processes within Rönnskär and/or produced by an oil fired boiler. The waste heat that was available at the electrolysis plant could possibly assist existing heat exchangers to reduce oil consumption. One of the goals was to investigate whether it was possible to increase the temperature of the electrolyte to 63 ℃with an additional heat exchanger before the current heat exchanger. The heating potential of a heat exchanger with the certain amount of condensate and condensate temperature that was present at the electrolysis plant would be investigated if the temperature of the condensate was lower than 63 ℃.The project analyzed related systems within the electrolysis plant and more specifically, the process of interest in terms of design with different machines and systems. The analysis also included recommendations in the selection of heat exchangers, dimensioning and calculations for the configuration of a shell and tube heat exchanger. The amount of condensate, condensate temperature, sustainability analysis and economic analysis were also calculated. The sensitivity analysis was performed on important and sensitive variables. The result showed that the amount of condensate was too small to justify an additional heat exchanger. This led to two case studies for different scenarios within the electrolysis plant in terms of amount of condensate, condensate temperatures and heating potential for the electrolyte. In the first case, the requirement for the condensate temperature for heating the electrolyte to 63 ℃ was calculated. In the second case, the heating potential of the electrolyte with the calculated condensate temperature and the different amounts of condensate were explored. The volume flow varied between 53,5 liters/min to 126 liters/min for the condensate with a temperature of about 60 ℃. This meant that the electrolyte temperature could be heated between a range 30 to 44 ℃. The temperature of the electrolyte was depended on the volume flow chosen. To reach the temperature of 63 ℃ on the electrolyte, a condensate temperature of approximately 96 ℃ was needed for maximum capacity. The best choices of heat exchangers were a shell and tube heat exchanger. The design of the heat exchanger gave an acceptable pressure drop and a good overall heat transfer coefficient. The sustainability analysis showed that it was beneficial to have a heat exchanger to reduce carbon dioxide emissions. By reducing the carbon emissions, it resulted in less cost for EUA (European union allowance), but the investment cost was not included in these calculations. The sensitivity analysis showed that sensitive variables have a low impact on the result and that the important variables such as temperatures and flows affected the result as expected. Finally, it could be stated that this solution was not favorable at the moment due to a lack of condensate but may be relevant for the electrolysis plant in the future.

Traditionally, geothermal boreholes have utilized the ground energy for space heating and cooling. In this system, a circulation loop is placed in a small-diameter borehole typically extending to a depth of 200-300 ft. The hole is then backfilled with a mixture of sand, bentonite and/or cement. The loop is connected to a geothermal heat pump and the fluid inside the loop is circulated. The heat energy is fed into the ground for cooling in the summer and withdrawn from the ground for heating in the winter. Geothermal heat pumps work more efficiently for space heating and cooling compared to air-source heat pumps.  The reason is ground-source systems use the ground as a constant temperature source which serves as a more favorable baseline compared to the ambient air temperature. A significant cost associated with any deep geothermal borehole is the drilling required for installation. Because Energy Piles perform the dual function of exchanging heat and providing structural support, and are only installed at sites where pile foundations are already required, these systems provide the thermal performance of deep geothermal systems without the additional drilling costs. Low maintenance, long lifetime, less variation in energy supply compared to solar and wind power, and environmental friendliness have been cited as additional Energy Pile advantages. Case studies show that they can significantly lower heating/cooling costs and reduce the carbon footprint. Energy cost savings for typical buildings outfitted with Energy Piles could be as much as 70 percent. The use of Energy Piles has rapidly increased over the last decade, especially in Europe where more than 500 applications are reported. Primary installations have been in Germany, Austria, Switzerland and United Kingdom. Notable projects include the 56-story high Frankfurt Main Tower in Germany, Dock E Terminal Extension at Zurich International Airport in Switzerland and the One New Change building complex in London U.K. Energy piles have seen very little use in the North America, only a handful of completed projects are known; Marine Discovery Center in Ontario, Canada, Lakefront Hotel in Geneva, New York and the Art Stable building in Seattle, Washington. Energy Piles are typically installed with cast-in-place technology (i.e. drilled shafts, continuous flight auger piles, micropiles etc.) while some driven pile applications are also reported. Other types of geotechnical structures in contact with the ground, such as shallow foundations, retaining walls, basement walls, tunnel linings and earth anchors, also offer significant potential for harnessing near-surface geothermal energy. Energy Pile design needs to integrate geotechnical, structural and heat exchange considerations. Geotechnical characteristics of the foundation soils and the level of the structural loads are typically the deciding factors for the selection and dimensioning of the pile foundations. The geothermal heat exchange capacity of an Energy Pile is a key parameter to be considered in design. Thermal characteristics of the ground as well as the heating and cooling loads from the structure need to be considered for the number of piles that will be utilized as heat exchangers. Therefore, the thermal properties of the site need to be evaluated for an Energy Pile application in addition to the traditional geotechnical characterization for foundation design. Energy Piles bring new challenges to geotechnical pile design. During a heat exchange operation, the pile will expand and contract relative to the soil as heat is injected and extracted, respectively. These relative movements have the potential to alter the shear transfer mechanism at the pile-soil interface.  Furthermore, the range of temperature increases near the pile surface, though limited by practical operational guidelines, can have a significant effect on pore pressures generation and soil strength. This dissertation provides answers for several research questions including the long-term performance of Energy Piles, the applicability of the thermal conductivity tests to Energy Piles.  Furthermore, it presents the results and a detailed discussion about the full scale in-situ thermo-mechanical pile load test conducted at Virginia Tech. / Ph. D.

<p> The objective of this investigation was to examine the potential of the point heat-flux meter in studying the dynamic heat transfer process in a scraped-surface heat exchanger.</p> <p> The heat-flux meters were an integral part of the copper heat exchanger which was steam-heated. Water was passed through the equipment as a thin film. The steam condensate was collected for measurement.</p> <p> Mathematical analysis related the transient differential temperature of the detector with the transient applied heat flux. A mathematical model was found that would estimate the instantaneous heat flux from the heat-flux-meter experimental temperature difference.</p> <p> Instantaneous and time-average local heat fluxes were measured by the heat-flux meter and the condensate respectively. The meter accuracy was -7000 Btu/hr sq ft.</p> <p> The heat-flux meter can be used in studying dynamic heat transfer processes.</p> / Thesis / Master of Engineering (MEngr)

Heat pipe is a passive heat transport device, engineered to harness latent heat of vaporization of contained working fluid to efficiently transfer sensible energy of one fluid stream to another. Heat pipes have observed applications in HVAC, electronics cooling, space equipment cooling, etc. due to their high effective thermal conductivity. Heat pipe heat exchanger (HPHE) employs finned heat pipes for performance enhancement. A mathematical model was developed into a Mathcad based tool for properly sizing and optimizing gravity-assisted HPHE designs. A charging station was setup to fabricate heat pipes under deep vacuum using a liquid nitrogen cold trap. A wind test tunnel was constructed to conduct experiments on a HPHE prototype. The thermal performance testing resulted in 11.4 kW of heat duty with 54% effectiveness of the HPHE. Parametric studies were also conducted for varying input heat and air flow rates, followed by the result comparison with program predictions.

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