Transitioning to circular flows is essential to economize the planet’s resources. One of the most important resources on earth is water as it is vital for all living things. However, water purification methods have proven to be very energy intensive, and increasing the circular water flows is therefore challenging. Volvo Construction Equipment (VCE) in Hallsberg is a manufacturing industry that produces cabs and tanks for VCE’s machines. The factory needs a lot of water in the pre-treatment process, and a falling film evaporator is currently used to purify most of the process water. VCE is considering investing in another evaporator to add to the existing water treatment system as a second stage to concentrate the process water further. The aim of this project was to investigate how to increase the energy efficiency of the water treatment system at VCE in Hallsberg and the planned extension of that system. The aim was also to analyze the water treatment system as it is today to get a better understanding of the current situation. The method was divided into two main parts. First, the current water treatment was investigated through measurements of electricity, temperatures and mass flows. A few mass and energy balances were also set up, and the excess steam recirculation of the current evaporator was investigated. Secondly, an investigation of potential future water treatment systems was made. The second part consisted of a comparison of different types of evaporators and combinations of these with a focus on energy performance and technical aspects. The second part also included investigating which heating and cooling sources could be used if the second-stage evaporator was to be running on waste heat. The result showed that the electricity demand of the water treatment facility at VCE Hallsbergis approximately 72.7 kWh/ m3 distillate. Measurements also showed that the falling film evaporator used today purifies approximately 0.71 m3/h. Furthermore, the results showed that only 3 % of the energy demand in the falling film evaporator could be exchanged to waste heat, and the waste heat would need temperatures of 100 °C or above. In a second-stage evaporator, the waste heat could be used to replace a larger proportion of the electricity use. There is sufficient power from the ovens to be used as waste heat in the second-stage evaporator. District heating could also be used as a heat source, but only for the low-temperature evaporator. For cooling, a new source would be needed where a compromise between energy use and water consumption of the cooling system needs to be made. This thesis is our degree project for the master of science in energy-environment-management atLinköping University. The project was carried out during the spring semester of 2023.

Lithium-ion batteries are an increasingly popular source of power for many electric applications. Applications range from electric cars, driven by thousands of people every day, to existing and future air vehicles, such as unmanned aircraft vehicles (UAVs) and urban air mobility (UAM) drones. Therefore, robust modeling approaches are essential to ensure high reliability levels by monitoring battery state-of-charge (SOC) and forecasting the remaining useful life (RUL). Building principled-based models is challenging due to the complex electrochemistry that governs battery operation, which would entail computationally expensive models not suited for prognosis and health management applications. Alternatively, reduced-order models can be used and have the advantage of capturing the overall behavior of battery discharge, although they suffer from simplifications and residual discrepancy. We propose a hybrid solution for Li-ion battery discharge and aging prediction that directly implements models based on first-principle within modern recurrent neural networks. While reduced-order models describe part of the voltage discharge under constant or variable loading conditions, data-driven kernels reduce the gap between predictions and observations. We developed and validated our approach using the NASA Prognostics Data Repository Battery dataset, which contains experimental discharge data on Li-ion batteries obtained in a controlled environment. Our hybrid model tracks aging parameters connected to the residual capacity of the battery. In addition, we use a Bayesian approach to merge fleet-wide data in the form of priors with battery-specific discharge cycles, where the battery capacity is fully available (complete data) or only partially available (censored data). The model's predictive capability is monitored throughout battery usage. This way, our proposed approach indicates when significant updates to the hybrid model are needed. Our Bayesian implementation of the hybrid variational physics-informed neural network can reliably predict the battery's future residual capacity, even in cases where previous battery usage history is unknown.

This dissertation studies power control of microgrids utilizing multi-agent systems (MASs) concept and technology. The major focus of this work is in addressing proportional power sharing of inverter-based Distributed Generators (DGs) in AC microgrids under variations in maximum power capacity of the DGs. A microgrid can include renewable energy resources such as wind turbines, solar panels, fuel cells, etc. The intermittent nature of such energy resources causes variations in their maximum power capacities. DGs are cyber-physical systems which can be regarded as multi-agent systems. Considering these factors, a consensus algorithm is designed to have the DGs generate their output power in proportion to their maximum capacities under capacity fluctuations. A change in power capacity of a DG triggers the consensus algorithm which uses a communication map at the cyber layer to estimate the corresponding change in a distributed manner. Convergence rate of the algorithm is analytically established and bounds on allowable capacity fluctuations are derived based on practical constraints. During the transient time of reaching a consensus, the delivered power may not match the load power demand. To eliminate this mismatch, a control law is augmented that consists of a finite-time consensus algorithm embedded within the overarching power sharing consensus algorithm. The effectiveness of the distributed controller is assessed through simulation of a microgrid consisting of a realistic model of inverter-based DGs. Details of the microgrid model, its controller structures, and a comprehensive list of parameters are provided. Next, the problem of load power fluctuations in DC microgrids is considered and the consensus algorithms developed for the AC microgrids is extended to this scenario. Here, the DGs reach a consensus on the load power under fluctuations, leading to a distributed tracking algorithm. Another aspect of power control in microgrids is the latency or delays of some renewable energy resources such as fuel-cells, in response to changes in the load demand which results in load and power generation mismatch. To address this issue Energy Storage Systems (ESSs) are incorporated in microgrids. To this end, we systematically study shaping the transient step response of nonlinear systems to satisfy a class of integral constraints. Such constraints are inherent in hybrid energy systems consisting of energy sources and storage elements. While typical transient specifications aim to minimize overshoot, this problem is unique in that it requires the presence of an appreciable overshoot to satisfy the foregoing constraints. The problem was previously studied in the context of linear systems and this dissertation extends that work to nonlinear systems. A combined integral and feedforward control, that requires minimal knowledge of the plant model, is shown to make the system amenable to meeting such constraints. Broadly, the compensation is effective for nonlinear plants with stable open-loop step response and a positive DC gain. However, stability of the resulting closed-loop system mandates bounds on the integral gain. In this regard, we state and prove generalized stability theorems for first and higher-order nonlinear plants. Finally, the proposed compensation is applied on a realistic DG using MATLAB Simscape toolbox.

As the demand for more powerful and smaller electronics rise, the need for creative cooling solutions to prevent burnout becomes increasingly paramount. In response to recent cooling needs, new cooling techniques, such as jet impingement cooling, spray cooling, and heat pipes, have risen in popularity for their simple design and efficiency in thermal transport. This interest has risen in both industry and academia, where research has been conducted to optimize the heat transfer performance for these systems and how these systems can be implemented in new technologies. One method that has risen in interest is affecting the surface, through physical and chemical treatments, and how these different treatments can enhance the heat removal rate for different systems. This dissertation presents two main regions of research that, when combined, can enhance understanding of cooling rates for different surface treatments. The first region is utilizing time domain thermoreflectance (TDTR) to measure the heat transfer coefficients in a microchannel experiencing jet impingement cooling. This current study presents the findings of experiments that measure the heat transfer coefficients on surfaces exposed to hot-spot heating and cooled using water jet impingement at Reynolds numbers up to 6432. The heat transfer coefficients were found using TDTR with a water jet on a fused silica (FS) glass substrate coated with a thin-film Hafnium-alloy (Hf). The heat transfer coefficient data are based on a local, micron-sized hot-spot region (generated by the TDTR pump laser) that is translated at different locations relative to the stagnation point. The study shows that at different microchannel regions (relative to the stagnation point) and for different Reynolds numbers for the jet that the TDTR method can detect changes in the heat transfer coefficient. Along with a novel method to measure the heat transfer coefficients using TDTR, several studies on different surface conditions are presented in the dissertation. Physical changes in wetting performance is analyzed through soft wetting materials and the impact the stiffness has on the hemwicking performance. Through a novel, in house stamping apparatus, polydimethylsiloxane (PDMS) samples were created of varing stiffness of 0.338 MPa to 1.98 MPa. Through analyzing the hemiwicking velocity, hemiwicking diffusion, and initial hemiwicking wicking velocity of ethanol, isopropyl alcohol, and isooctane, it was observed that the stiffness of soft materials can play a significant impact on the overall wicking performance. Furthermore, a deformation model is presented based on pillar deformations observed with PDMS/ExoFlex hybrid samples as the working fluids evaporated from the wicking arrays. The chemical impact on the overall wetting performance is also analyzed and presented in this dissertation. Two main methods were implemented to track the changes in wetting through surface chemistry; through the application of a polyvinyl alcohol (PVA) self-assembled monolayer (SAM) and applying a spiropyran (SPCOOH) to a microstructured gold surface. The changes in hemiwicking velocity and meniscus extension with the PVA SAM displayed an important aspect of chemical interactions with respect to hemiwicking performance, which affects the heat transfer performance of a microstructured surface. The SPCOOH studies revealed a change in wetting behavior which further emphasized the importance of intermolecular interaction on wetting performance, but also revealed a controlling aspect the PVA SAM experiments did not exhibit. Along with these studies, a preliminary study of controlling the intermolecular interactions of metamaterials through strain to change the surface wetting is presented in this dissertation. Through the use of a simple, uni-axial strain instrument, different metamaterials composed of hafnium dioxide, titanium nitride, and tungsten deposited on Kapton tape were subjected to strains up to 8%. While under strain, significant changes in the advancing, receding, and equilibrium contact angle were observed for both polar and non polar fluids on the surface. These changes are attributed through changes in the intermolecular forces and verified through changes in the reflectivity while strain is applied to the metamaterials.

As global energy sources transition towards renewable energy, the demand for sustainable fuels has never been greater. The sheer scale of this transition will require numerous solutions to accommodate for the diverse and complex situations worldwide. This dissertation will discuss 3 studies: the utilization of CO2 waste gas to produce fuels sustainably, characterizing biofuels for efficient use in automobiles, and developing a solid, emissonless fuel intended for spaceflight but also applicable on Earth. The hydrogenation of CO2 into value-added molecules could reduce greenhouse gas emissions if waste stream CO2 were captured for conversion. We found that atomic vacancies induced in defect-laden hexagonal boron nitride (dh-BN) can activate the CO2 molecule for hydrogenation. Subsequent hydrogenation to formic acid (HCOOH) and methanol (CH3OH) occur through vacancy-facilitated co-adsorption of hydrogen and CO2. Boron and nitrogen are abundant elements, making h-BN an attractive catalyst in the synthesis of value-added molecules, facilitating efforts to reduce GHG emissions. Biofuels could be vital in a sustainable fuel future. However, their implementation into existing engines requires an understanding of their interactions with engine components at temperature. The formation of carbon deposits on hot metal components can reduce engine performance. Using a novel test rig and gasoline and diesel analog compounds, the degree of fuel degradation to form carbon can be measured on various metal surfaces. Thus, we can screen for low soot-forming biofuels as promising candidates surface on the market. Historically, innovations in space exploration have led to immensely beneficial applications on Earth. Currently, various limitations of power sources hinder the capacity for regular and frequent space exploration. The ability to harvest heat for electrical power would reduce the cost of long-distance and long-duration missions. Employing a regulated, self-propagating, exothermic chemical reaction, we have devised a slow-burning reactant system capable of generating heat at a harvestable rate.

Limitations on water utilization are turning into an expanding issue for the power and electricity generation industry. As a contribution to the solution of water consumption problems, utility companies are shifting toward using air-cooled condensers (ACC) in replace to the typical water-cooling methods of once-through cooling and the surface condenser/wet-cooling tower combination. Although the ACC is a dry cooling method, the industry is quite hesitant to switch over to ACC mainly for three reasons: (a) lower power output, (b) higher capital cost, and (c) larger physical footprint. All these drawbacks are because of the high overall thermal resistance of condensing steam to the ambient air compared to condensing it to water. In this study, detailed mathematical equations were derived to model the heat transfer process through the fined tubes of the ACC. The total thermal resistance model was analyzed and investigated theoretically. The model was used to identify the design components with the most significant effect on the overall thermal resistance of the ACC system. This study proposed a feasible cooling system based on heat pipe technology, using a novel disc-shaped heat pipe design. The solution addresses the three problems highlighted in using the air-cooled condensers in steam powerplant condensers. The analysis covered design and manufacturing considerations, in addition to the thermal performance and the limitations of the proposed annular disc-shaped heat pipe. The proposed annular disc-shaped heat pipe was investigated using three analysis techniques. The first is a theoretical investigation of the heat transfer limitations of the proposed annular disc-shaped heat pipe. This analysis was used to predict the capillary and boiling thermal limitations of the proposed heat pipe design. Secondly, an annular disc-shaped heat pipe was designed and built for the experimental investigation using de-ionized water as the working fluid. The results obtained by the parametric analysis were used as the input for the experimental design. Third, A detailed mathematical set of equations was derived to model the heat pipe thermal resistance. The experimental setup was validated by comparing the results to well-referenced experimental results of similar disc-shaped heat pipe with different evaporator configurations. The experimental results were compared to the thermal resistance model developed in this study. The results showed a starting regime of the heat pipe, where the thermal resistance is decreasing until it reaches a steady performance before it starts to increase again when it reaches the heat transfer limits. The experimental results showed a good agreement with the model prediction in the steady-state regime for heat inputs over 300 w. The data identified two thermal performance regimes of the heat pipe, a single-phase, and a two-phase regime. The second regime starts when the vapor region reaches the isothermal state.

The goal of this dissertation is to fabricate wires made of Cu/CNT and Al/CNT composites with good mechanical strength and super thermal/electrical conductivities using powder compaction and wire extrusion manufacturing processes. Powder compaction was studied using both test and simulation. Cold compaction, hot compaction and vibration assisted (cold) compaction tests were conducted to achieve different density ratios. Hot compaction tests improved about 6% compared with cold compaction under the same compression pressure. Although the relative density ratio does not obviously improve at vibration assisted (cold) compaction, the strength of the specimens made under vibration loading is much better than those of cold compaction. Additionally, finite element models with well calibrated Drucker Prager Cap (DPC) material constitutive model were built in Abaqus/Standard to simulate powder compaction processes. The results of finite element model have excellent correlations with test results up to the tested range, and finite element models can further predict the loading conditions required in order to achieve the higher density ratios of the materials. Two exponential formulas for predicting density ratio were obtained by combining the test data and the simulation results. A new analytical solution was first time developed to predict the axial pressure versus the density ratio for powder compaction according to DPC material model. The results between analytical solution and simulation model have an excellent match. Extrusion method was adopted to produce wires of aluminum (Al), copper (Cu) and copper/carbon nanotubes (Cu/CNTs) composites. A new analytical solution was developed to predict magnitude of extrusion force, where friction effects between die and sample were considered. The analytical solution achieved a much better result than the classical slip line theory and other existing analytical solutions. Extensive finite element (FE) models were built to validate the analytical solution under different extrusion conditions. FE simulation cases were run for different die angles (including 30°, 45° and 60°) and different extrusion area ratios (including 16:1 and 4:1). The comparison results showed a good match between analytical solutions and finite element models. Both Eulerian and Lagrangian methods were set up and compared in finite element models in order to predict the extrusion force during the extrusion process. Four wire extrusion tests of metals and metal/CNTs composites were successfully conducted under elevated temperatures ranging from 300°C to 703°C. Test results further validated the accuracy of the analytical solution.

Energy sources powering space missions range from highly energetic nuclear reactions to short-lifetime and low-output batteries. The proper selection of a power system is dependent on the mission duration and destination and oftentimes energy sources that may be optimal for the former may be unsuitable for the latter. Various limitations of these power sources hinder the capacity for regular and frequent space exploration. However, the ability to harvest heat for electrical power generation would allow for long-distance and long-duration missions at a reduced cost. By employing a regulated, self-propagating, exothermic chemical reaction between solid fuel and oxidizer, we hope to devise a slow-burning reactant system capable of generating heat at a harvestable rate. Eighteen energy-dense fuel and oxidizer combinations were selected to assess for their slow-propagating potential. One ceramic and one graphite propagation cell were designed to monitor combustion along a linear length of pyrolant powder and to measure reaction temperatures. Each reaction was ignited through heating of a nichrome wire placed at one end of the pyrolant mixture and four thermocouples were placed at 1 cm intervals along the length of powder following the wire. In addition to the propagation cell, a multi-step selection process was devised to evaluate each pyrolant. By this process, the pyrolant mixture between lithium peroxide and boron was selected, and the best propagation rate achieved by this system was measured to be 1.49 cm/s.

Global warming and associated role of energy consumption across various sectors is a well-researched topic in recent years. Understanding current urban energy consumption patterns will allow us to understand how future energy consumption patterns will evolve. With electrification of vehicles and potentially altering culture of work from home, the energy usage at regional level would see a significant change in the future. The current PhD dissertation contributes to energy consumption analysis of a region by analyzing residential energy consumption, commercial energy consumption and transportation energy use by households. The aggregation of these energy consumption within a region contributes to the total energy consumption of a region. As the share of electric vehicles increases, the proposed modeling frameworks provides the current consumption that serves as a baseline estimate. Specifically, for the energy consumption, we examine the choice of energy sources and the energy consumption by source. The share of electrical vehicles is currently increasing. As the share of electric vehicles increases within our transportation infrastructure, the spatio-temporal nature of current electricity demand is likely to alter with increased household electricity consumption for vehicle charging. To develop a future estimate of urban demand with electric vehicles, a model system of current consumption serves as a baseline estimate. The analysis of energy use in residential buildings and commercial buildings is conducted using Residential Energy Consumption Survey (RECS) and Commercial Building Energy Consumption (CBECS) datasets. The transportation energy use is analyzed using National Household Travel Survey (NHTS) and MPG of the vehicles taken from Vehicle Fuel Economy Estimates. Multiple Discrete Continuous Extreme Value (MDCEV) model and Joint Binary Logit - Fractional Split Model (Joint BLFSM) are used to analyze residential energy consumption. While Bi level MDCEV is used for commercial energy use and spatial weighted regression models are used to analyze transportation energy use.

In Sweden, district heating is the most common way to heat apartment buildings and premises. It is most common for properties to use district heating as the only heating source, but there are now trends in which more and more properties combine district heating with another energy source such as an exhaust air heat pump or geothermal heating. This report is a case study on how an exhaust air heat pump can be combined with district heating in an apartment building compared to if the house uses only district heating for heating. The background to the study is that Gävle Energi AB wants to investigate the return temperature to the district heating network from a facility that has an exhaust air heat pump and district heating in combination compared to a normal facility that only has district heating. The focus of this thesis is on investigating two structurally identical properties in Gävle with two different ventilation systems and heating systems. The first property, Property 1, has an exhaust and supply air ventilation system with a heat exchanger and only district heating for heating. The other property, Property 2, has a mechanical exhaust air ventilation system with exhaust air heat pump and district heating in combination. The method used during the analysis has been a compilation of collected data from Gävle Energi AB and of own measurements with a measurement period of one week. The analysis compares two different heating systems based on three different factors, energy use (kWh), supply and return temperature to the district heating network (°C) and operating costs (SEK/Year). Results show that, Property 2 (exhaust air heat pump in combination with district heating) has 31% lower district heating use on average. However, electricity uses for the property increased by 20%. The total energy use for property 2 was thus reduced by 15%. The reduction in energy use in Property 2 corresponds to a reduction in operating costs of 5.4%.However, the operating cost of Property 2 does not include the investment in the heat pump or the maintenance cost. Both the investment in the district heating center and the maintenance cost are included in the district heating price. COP calculated varying between 1.8 and 3.8. COP measured varied between 2.2 and 3.8. COP value for Property 2 was 3 on average for both COP measured, and COP calculated.   District heating in combination with an exhaust air heat pump gives a higher return temperature than district heating alone, the difference was about 10 °C during the measurement carried out for a week in April 2022. The difference was also verified by the volume-weighted return temperature, which was calculated to be 1.0 °C higher. The conclusion is that an exhaust air heat pump in combination with district heating seems to have a lower operating cost resp district heating and mechanical supply and exhaust air with heat recovery ventilation for the user in the studied types of building, but it also creates an elevated return temperature in the district heating network. Environmentally, an exhaust air heat pump together with district heating can be positive if electricity is produced from renewable energy sources with low carbon dioxide emissions, such as solar energy and wind power, but consideration must be given to system effects in the district heating network, such as how the production of electricity is affected, this varies between different district heating systems.