abstract: Limited access to clean water due to natural or municipal disasters, drought, or contaminated wells is driving demand for point-of-use and humanitarian drinking water technologies. Atmospheric water capture (AWC) can provide water off the centralized grid by capturing water vapor in ambient air and condensing it to a liquid. The overarching goal of this dissertation was to define geographic and thermodynamic design boundary conditions for AWC and develop nanotechnology-enabled AWC technologies to produce clean drinking water. Widespread application of AWC is currently limited because water production, energy requirement, best technology, and water quality are not parameterized. I developed a geospatial climatic model for classical passive solar desiccant-driven AWC, where water vapor is adsorbed onto a desiccant bed at night, desorbed by solar heat during the day, and condensed. I concluded passive systems can capture 0.25–8 L/m2/day as a function of material properties and climate, and are limited because they only operate one adsorption-desorption-condensation cycle per day. I developed a thermodynamic model for large-scale AWC systems and concluded that the thermodynamic limit for energy to saturate and condense water vapor can vary up to 2-fold as a function of climate and mode of saturation. Thermodynamic and geospatial models indicate opportunity space to develop AWC technologies for arid regions where solar radiation is abundant. I synthesized photothermal desiccants by optimizing surface loading of carbon black nanoparticles on micron-sized silica gel desiccants (CB-SiO2). Surface temperature of CB-SiO2 increased to 60oC under solar radiation and water vapor desorption rate was 4-fold faster than bare silica. CB-SiO2 could operate >10 AWC cycles per day to produce 2.5 L/m2/day at 40% relative humidity, 3-fold more water than a conventional passive system. Models and bench-scale experiments were paired with pilot-scale experiments operating electrical desiccant and compressor dehumidifiers outdoors in a semi-arid climate to benchmark temporal water production, water quality and energy efficiency. Water quality varied temporally, e.g, dissolved organic carbon concentration was 3 – 12 mg/L in the summer and <1 mg/L in the winter. Collected water from desiccant systems met all Environmental Protection Agency standards, while compressor systems may require further purification for metals and turbidity. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

This master thesis deals with the basic problems of solar thermal systems, which are using heat transfer medium. At the beginning this thesis describes basic components of the solar system, especially their meaning and attributes. Further in the thesis are mentioned heat transfer liquids for commercial usage which are used in those systems, their basic properties and dependence on temperature. There is described the physical nature of liquid viscosity and also ways how to measure them. The same is for measurement of liquid density and thermal conductivity. At the end was made measurement of dynamic viscosity of heat transfer liquids for commercial usage at different temperatures. In practical part of the thesis were mixed samples of alternative heat transfer mediums. It was measured their thermal and physical attributes, like for example density, dynamic viscosity and coefficient of volumetric expansion. Each measurement was compared and evaluated.

The transparent conductive oxide (TCO) SnO2:Ta is developed as a selectively solar-transmitting coating for concentrated solar power (CSP) absorbers. Upon covering with an antireflective layer, a calculated absorptivity of 95% and an emissivity of 30% are achieved for the model configuration of SnO2:Ta on top of a perfect black body (BB). High-temperature stability of the developed TCO up to 1073 K is shown in situ by spectroscopic ellipsometry and Rutherford backscattering spectrometry. The universality of the concept is demonstrated by transforming silicon and glassy carbon from non-selective into solar-selective absorbers by depositing the TCO on top of them. Finally, the energy conversion efficiencies of SnO2:Ta on top of a BB and an ideal non-selective BB absorber are extensively compared as a function of solar concentration factor C and absorber temperature TH. Equal CSP efficiencies can be achieved by the TCO on BB configuration with approximately 50% lower solar concentration. This improvement could be used to reduce the number of mirrors in a solar plant, and thus, the levelized costs of electricity for CSP technology.

The emergence of Thermally Driven Cooling system has received more attention recently due to its ability to utilize low grade heat from engine, incinerator or simple flat plate solar collector which are considered as renewable energy sources. ClimateWell AB located in Stockholm has been developing this cooling system based on its patented chemical heat pump technology. The heat pump with its tube shape is put under the absorber as in simple flat plate solar collector making it possible be directly attached on the roof without any additional solar collector. A high performance heat exchanger is needed by its reactor to absorb the energy efficiently during the desorption process as well as to recover heat during the absorption process. Current heat exchanger design has direct contact with the tube’s surface, yet air gaps between the tube and heat exchanger result in alower amount of heat transferred and non-uniform heat distribution across this surface. Moreover, a special treatment which cannot be done by machinery has to be performed in attaching the tube with this heat exchanger. It becomes a problem during mass production since a lot of man power is needed. A new heat exchanger design was proposed to overcome those limitations. This design has annulus which is filled with thermal fluid inside. This fluid will make perfect contact to the heat pump tube’s surface and eliminate the air gap. Furthermore, the need of man power in its production can be minimized. Even though perfect contact can be achieved, the fluid in this new design will increase thermal resistance in the radial direction. Therefore, an investigation has to be conducted to evaluate the performance of this new heat exchanger design based on heat transfer coefficient under steady state condition. The performance investigation also included the influence of various thermal fluids which will be used for this new heat exchanger. The work performed by doing simulation in COMSOL continued with validation of the result with experiment in laboratory. New heat exchanger design efficiency was only 50% while the current one was 82% during the desorption process. In this process, the fluid’s thermal conductivity was the most influencing fluid property. During absorption process, two heat recovery methods are used. First is by flowing the fluid inside the annulus and second is by using additional heat recovery pipe that is attached outside the heat exchanger surface. The first method gave the highest UA value around 34 W/K while the second one gave almost the same value as the current design which is around 11 W/K. In the first method, the thermal fluid’s viscosity strongly influenced its UA value while the second method is greatly influenced by fluid’s heat conductivity.

With the increasing awareness of global warming and the need for limiting greenhouse gas emissions, several sectors are witnessing comprehensive transformations towards sustainable generation and consumption. The European Union can be considered the home for most of these transformations given the union’s efforts to enable decarbonization through regulatory frameworks and initiatives. However, one overlooked source of carbon emissions is the industrial heating sector which is heavily dependent on fossil fuel. Emerging technologies such as solar thermal could provide a solution for limiting the greenhouse gases emitted by this sector. This study examines the factors influencing the diffusion of solar thermal technology and its potential for substituting natural gas in the industrial heating sector. Specifically, the study examines the thermal energy supply side as being a potential facilitator for the diffusion of solar thermal technology. Certain elements from Everett Rogers’ (1995) work on the diffusion of innovations are applied to solar thermal technology along with the concept of lead users by Hippel (1986). The study follows a qualitative approach in collecting and analyzing data through interviews and document analysis. Experts from the energy sector were interviewed along with examining public documents of two major utility companies. The findings suggest that utility companies examined, despite their evident decarbonization efforts, do not represent a suitable vehicle for the diffusion of solar thermal technology. Instead, a business model based on energy efficiency could be the possible breakthrough for this technology. Finally, the study concludes with suggestions for possible actions to expedite the diffusion of solar thermal in the industrial sector.

This study investigates the feasibility and performance of a hybrid system integrating photovoltaic (PV) and solar thermal technologies for industrial process heat. By analyzing various parameters including cost, income, energy production, and system specifications, valuable insights are obtained. The study explores the potential of solar heating (SH) systems as a renewable thermal energy source for industrial processes, overcoming challenges of high costs and limited fossil fuel usage in industrial facilities through hybrid configurations. Data analysis includes cost analysis, income generation, energy balance, and system specifications such as temperature ranges, collector sizes, and efficiencies. While acknowledging limitations in simulation simplifications and the use of a single load profile, the study presents conclusions on the system's economic viability, technical capabilities, and potential applications. The findings highlight the importance of hybrid PV and solar thermal systems in enhancing energy efficiency and promoting renewable energy adoption in industrial process heating.

A predominant amount of energy needed in the industrial sector is in the form of heat. A significant number of industries in the world still relies on fossil fuels for meeting their heat requirements. A transition to renewable energy for heating needs is at a snail's pace due to fossil fuel lock-in, cost superiority of conventional fuels, and less government support for renewable technology for thermal requirements. The dairy industry is one of the sectors that need heat energy for its production process. This study deals with a techno-economic analysis on the integration of parabolic trough collectors in the dairy industry. The thesis finds the barriers for solar-thermal collectors to evolve in the dairy sector and the viewpoint of the dairy industry towards the acceptance of solar thermal for meeting their thermal needs. From a literature review, it is observed that the need for dairy product will increase in the coming year. To meet the demand, the production process has to be increased. For sustainable production, companies have to rely on environment-friendly energy sources to meet the thermal demand. In the thesis work, it was also found that for several solar fractions, the LevelizedCost of Heat (LCoH) of solar-assisted heating system is less than the LCoH of the fossil-fueled conventional boiler. Therefore, it is economically viable to integrate solar thermal collectors in the dairy industry. The project also compares the LCoHof solar-assisted heating system when solar integration is done at a) feed water heating, b) direct steam generation, and c) process integration. The effect of integration point on the solar fraction, LCoH, and carbon mitigation potential is presented for a real case dairy unit in Dubai. The simulations are performed using a dynamic simulation tool. Results show that minimum LCoH and solar fraction are achieved for process integration. The process integration results in up to 90 % of the solar fraction. Through process integration, the LCoH of the conventional boiler can be reduced by 60%.

The building sector account for 40 % of the global energy demand, and an increasingly popular way to supply buildings with heat is through the use of heat pumps. Solar thermal (ST) can either be used as a low temperature energy source in the heat pump or to directly supply the building’s heating demand.  The increasing market of PV has made it a favorite for roof-top solar installation. Its physical integration with buildings and HPs is simpler than that of ST and can supply any available electric load associated with the building and not just the HP system. It can also supply any excess power to the grid.  In order to properly compare these two options, key performance indicators (KPIs) were identified for several system boundaries within the building and HP system. Technical KPIs used were seasonal performance factor (SPF), solar fraction (SF) and self-consumption (SC), while internal rate of return (IRR), net present value (NPV), profitability index (PI) and payback time was used to evaluate their economic performance.  For the thesis a multi-family house was modelled in TRNSYS where different system sizes of either ST or PVs was simulated for a year with three-minute intervals. The ST was connected in a parallel configuration thereby supplying the building’s domestic hot water (DHW) through a separate storage tank. The modelled heat pump was a ground source heat pump (GSHP) which utilizes boreholes as the low temperature energy source. The SPF increased for both the ST and PV integration from the reference scenario (no PV/ST integration) but to a varying degree depending on the analyzed system boundary. The economic results suggested that PVs are the more financially sound option over ST for the simulated MFH. The sensitivity analysis also showed the large impact of economic assumptions on the expected profitability for both the PV and ST systems. Based on the results would the simulated MFH with an existing GSHP benefit more from installing PV instead of ST from both a technical, economic and environmental perspective.  It is reasonable that PVs will most likely be an integral part for future buildings in Sweden with or without HPs because of its financial strength and versatility of demand supply, especially compared to ST. / Byggsektorn står för 40% av det globala energibehovet, och ett alltmer populärt sätt att leverera värme till ett hus är genom användning av värmepumpar. Solvärmefångare kan antingen användas som en lågtemperaturenergikälla i värmepumpen eller för att direkt leverera byggnadens värmebehov.  Den ökande marknaden för solceller har gjort den till en favorit för takmonterad solinstallation. Dess fysiska integration med byggnader är enklare än solvärmefångare och kan leverera el till hea byggnaden och inte bara värmepumpssystemet. Solceller kan också leverera till elnätet om produktionen överstiger byggnadens behov. För att korrekt jämföra dessa två alternativ identifierades viktiga indikatorer för flera systemgränser inom byggnaden och värmepumpssystemet. Tekniska indikatorer som användes var årsvärmefaktor, solfraktion och självförbrukning, medan internränta, nuvärde, lönsamhetsindex och återbetalningstid användes för att utvärdera deras ekonomiska resultat. För uppsatsen modellerades ett flerbostadshus med tillgänglig takyta i TRNSYS där olika systemstorlekar (i kvadratmeter) av antingen solvärmefångare eller solceller var simulerade i ett år med tre minuters intervall. Solvärmefångaren var ansluten i en parallell konfiguration med värmepumpen, varigenom byggnadens varmvatten levereras genom en separat lagertank. Den modellerade värmepumpen var en bergvärmepump som utnyttjar borrhål som lågtemperaturenergikälla. Årsvärmefaktorn ökade för både solvärmefångar- och solcells-integrationen från referensscenariot (ingen solteknisk-integration) men i varierande grad, beroende på den analyserade systemgränsen. De ekonomiska resultaten visade att solceller är det mer ekonomiskt sunda alternativet över solvärmefångare för det simulerade flerbostadshuset. Känslighetsanalysen visade också på den stora effekten av ekonomiska antaganden på den förväntade lönsamheten för både solceller och solvärmefångare. Baserat på resultaten skulle det simulerade flerbostadshuset med en befintlig bergvärmepump dra nytta av att installera solceller istället för solvärmefångare från ett tekniskt, ekonomiskt och miljömässigt perspektiv. Det är troligt att solceller kommer vara en del i framtida byggnader i Sverige med eller utan värmepumpar på grund av den ekonomiska styrkan och möjligheten att tillgodose både byggnaden och elnätet vid överproduktion.

Global energy consumption has been increasing continuously every year. Many energy sources are utilized. Conventional fossil fuels are not sustainable, and their environmental impacts are more apparent than ever before. For heating purposes, most of the heat still comes from combustion of both non-renewable and renewable energy sources. According to IEA (2019), only 10% of heat supply in industrial sectors and buildings comes from renewable sources. Hence, 40% of the carbon emission in the energy sector comes from heat. Therefore, shifting from non-renewable to renewable energy sources is essential in reducing the environmental impact from heat production. Sweden has a long tradition of solar thermal in district heating for cities. Therefore, this study tried to look at the application of solar thermal energy for heat production to supply the District Heating (DH) system and compare its environmental performance to other types of energy sources. The system that was examined in this study is the solar thermal collector field from Absolicon in Härnösand. A Life Cycle Assessment (LCA) was conducted to evaluate the life cycle environmental impacts of this solar collector field. The assessment was done by collecting primary data provided by Absolicon and its suppliers and secondary data from the literatures. The results showed that Absolicon solar thermal collector field generated less overall environmental impacts than conventional energy sources in heat production. Moreover, the result for carbon footprint of the solar collector is 4.4 kg CO2/MWh, which is at least 3-4 times less lifetime emissions when compared to other solar energy technologies. / Den globala energiförbrukningen har ökat kontinuerligt varje år. Många energikällor används. Konventionella fossila bränslen är inte hållbara och deras miljöpåverkan är mer påtaglig än någonsin tidigare. För uppvärmningsändamål kommer det mesta av värmen fortfarande från förbränning av både icke-förnybara och förnybara energikällor. Enligt IEA (2019) kommer endast 10 % av värmeförsörjningen i industrisektorer och byggnader från förnybara källor. Därför kommer 40 % av koldioxidutsläppen i energisektorn från värme. Därför är en övergång från icke-förnybara till förnybara energikällor väsentligt för att minska miljöpåverkan från värmeproduktion. Sverige har en lång tradition av solvärme inom fjärrvärme för städer. Därför försökte denna studie titta på tillämpningen av solvärmeenergi för värmeproduktion för att försörja fjärrvärmesystemet (DH) och jämföra dess miljöprestanda med andra typer av energikällor. Systemet som undersöktes i denna studie är solfångarfältet från Absolicon i Härnösand. En livscykelanalys (LCA) genomfördes för att utvärdera livscykelns miljöpåverkan av detta solfångarfält. Bedömningen gjordes genom att samla in primärdata från Absolicon och dess leverantörer och sekundärdata från litteraturen. Resultaten visade att Absolicon solfångarfält genererade mindre total miljöpåverkan än konventionella energikällor vid värmeproduktion. Dessutom är resultatet för solfångarens koldioxidavtryck 4,4E kg CO2/MWhvilket är minst 3-4 gånger mindre livstidsutsläpp jämfört med andra solenergitekniker.

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