This master‘s thesis deals with the design of horizontal heat recovery steam generators (HRSG) with two pressure levels after a combustion turbine. In the introduction part is performed thermal calculation and proposal of a heat transfer surfaces. Furthermore, are suggested dimensions of the drums and pipes for flooding and transferring. The emphasis is placed on the fulfillment the required parameters of steam and flue gas at HRSG outlet. At the end is calculated loss of boiler draft and made technical documentation a drawing of the boiler.

In der Dissertationsschrift wurden zwei Schwerpunkte untersucht, die sich zum einen mit der Entwicklung einer Bewertungsmatrix zur Erstabschätzung potenzieller Abwärmenutzungen und zum anderen mit der Integration thermoelektrischer Generatoren im Gießereiprozess auseinandersetzten. In der Matrix wurden 4 Modellabwärmequellen definiert, die sich jeweils in 9 verschiedene Betriebszustände unterteilen, um die vielfältigen Prozessbedingungen widerzuspiegeln. Weiterhin wurden 4 Modellwärmesenken festgelegt, die in Abhängigkeit der thermischen Leistung der Abwärmequellen, die Bewertungsreferenz darstellen. Im Ergebnis erfolgte eine Bewertung von 144 unterschiedlichen Abwärmenutzungskonzepten nach den Kriterien: Energieeffizienzsteigerung, Kaskadennutzung, wirtschaftlich maximal vertretbares Budget und erzielte CO2-Einsparung. Die Integration der thermoelektrischen Generatoren erfolgte am Pfannenfeuer, im Formkasten und an der Druckgussmaschine. Die höchsten Durchschnittswerte der elektrischen Leistung wurden mit 45mW im Formkasten erreicht. Damit können Sensornetzwerke energieautark versorgt, die Datenverfügbarkeit erhöht und die Prozesseffizienz gesteigert werden.

The industry sector accounts for a vast amount of the world’s total energy use, as much as 37% during 2018. Using energy in a sustainable way is necessary from both an environmental and an economical perspective, and it is therefore relevant to take measurements that result in a more efficient use of energy. One way for industries to become more energy efficient is to recover the waste heat, which is energy that otherwise would go to waste. This report aims to find a method to recover and reuse the low temperature waste heat available at the life science company Cytiva’s production site in Uppsala, Sweden. The proposed solution will be to use the waste heat for heating a vertical greenhouse. The study will examine whether this is feasible, and also how installing photovoltaics affects the energy use. Furthermore, the environmental impact of operating the greenhouse with waste heat is also investigated by calculating the CO2 equivalent. The low temperature waste heat that Cytiva provides relevant for this study is 6683 kW, which will be used to heat up the greenhouse. Simulations in the software IDA ICE will be used to construct and simulate a model of the vertical greenhouse. Results from the simulations show that the chosen size, 25 x 50 x 35.5 meters, gives a good approximation according to the wanted temperature range, 18.3-32.2°C. Furthermore, the results imply that the total energy use, 790 652 kWh, and average power, 90.26 kW is less than the available waste heat and there is a large amount that still is unused. The CO2 equivalent is calculated to be 29 317 kg. A sensitivity analysis is made to evaluate the window-to-wall ratio as well as the size of the entire greenhouse. It showed that both parameters are critical and makes a big difference in the simulations.

The proposal follows up on the undergraduate semester work which dealt with a topic of data centers - a lifestyle based on data circulation. Growing needs of city dwellers, coupled with the demand of constant connectivity, are reflected in the transformation of the landscape which is being occupied by gigantic data centers. Those data centres in the loopback reconfigure the environment of cities that use their instant and "unlimited" computing power. The landscape is becoming the engine room of digital urban life. The thesis develops social and environmental issues of "continuity between a city and a country” and outlines a problem of self-sufficiency and awareness of the energy intensity of current urban lifestyle. In my work I focus on one of the by-products of data centers. That is waste heat, which has a negative effect on the quality and lifespan of electronic components - it is undesirable. Data center entrepreneurs have found a way to divert unfavourable attention from the debate about the energy demand of big data. They transform waste into a desired commodity by replacing conventional forms of heating with a system newly based on the supply of waste heat. Therefore, they are becoming significant suppliers of thermal energy. The phenomenon of heat recycling neutralizes external criticism of big data by making urban life literally dependent on it. The sustainable future of data center operations takes place largely without critical debate. On the contrary, it confirms data production as a process that literally drives everyday life. This new wave of green techno-optimism and related implementations is shrouded in a discourse of innovation, environmental friendliness and smart data processing. The diploma thesis deals with the phenomenon of commodification of waste heat of a specific data center, and its potential for symbolic and material transformation of the urban environment. The critical dimension of this transformation allows visitors to literally experience first-hand the manipulation of the climate of a specific location - the new city market in Brno. Other issues arise in connection with the recycling of waste heat. What will happen when big data streams become a raw material to replace older forms of energy supply in an urbanized world? What will be the impact on the city´s heating, the economic and symbolic importance of data center entrepreneurs?

Aufgrund von steigenden Energiekosten und einer sukzessive steigenden öffentlichen sowie politischen Forderung nach Umweltbewusstsein und Nachhaltigkeit, ist die Effizienzsteigerung von Gesamtsystemen einer der treibenden Kräfte für innovative, technologische Neuheiten geworden. Besonders bei der Entwicklung von verbrennungsmotorisch angetriebenen Fahrzeugen wurden z.B. durch die Hybridisierung von Antriebssträngen, die die Rekuperation von kinetischer Energie ermöglichen, Technologien zur Energieeinsparung etabliert. Da bei Verbrennungsmotoren ein hoher Anteil der im Kraftstoff gespeicherten Energie technologiebedingt als Abwärme im Abgas verloren geht, bietet die Wärmerekuperation ein weiteres hohes Potential für weitere Einsparungen. Diese ist z.B. mit Hilfe von thermoelektrischen Generatoren (TEG) möglich, die einen Wärmestrom direkt in elektrische Energie umwandeln. Zur effizienten TEG-Systemgestaltung ist ein hoher Temperaturgradient über dem thermoelektrisch aktivem Material notwendig, der wiederum zu kritischen thermomechanischen Spannungen im Bauteil führen kann. Diese werden zum einen durch die unterschiedlichen Temperaturausdehnungskoeffizienten der verschiedenen Materialien und zum anderen durch die mechanische Anbindung auf der heißen und kalten Seite des TEG verursacht. Somit liegt ein Zielkonflikt zwischen dem thermoelektrischen Systemwirkungsgrad und der mechanischen Festigkeit des Bauteils vor. In dieser Arbeit wird mit Hilfe einer mehrkriteriellen Parameteroptimierung eines vollparametrisierten FE-Modells des TEG in ANSYS WORKBENCH eine Methode vorgestellt, den thermoelektrischen Wirkungsgrad bei gleichzeitiger Reduktion der thermomechanischen Spannungen zu optimieren. Zur Optimierung kommt dabei ein genetischer Algorithmus der MATLAB GLOBAL OPTIMIZATION TOOLBOX zum Einsatz. Der Modellaufbau wird in ANSYS WORKBENCH mit der Makro-Programmiersprache JSCRIPT realisiert. Als Ziel- und Bewertungsfunktionen wird die mechanische Belastung jedes Bauteils im TEG ausgewertet und dessen elektrische Leistungsdichte berechnet. Die Ergebnisse zeigen, dass mit Hilfe der vorgestellten Methodik eine paretooptimale Lösung gefunden werden kann, die den gestellten Anforderungen entspricht.

Integrating the electrical and thermal community buildings' energy systems can play an important role in harvesting wasted energy resources and reduction of carbon emissions from buildings and electricity generation sectors. It also increases demand management flexibility by minimizing the curtailed electricity on the grid through electrified heating without increasing the electricity peak demand. The current work examines Integrated Community Energy and Harvesting systems (ICE-Harvest), a new generation of distributed energy resources systems (DERs). They prioritize the harvesting of community waste energy resources—for example, heat rejected from cooling processes and distributed peak electricity fossil-fuel-fired generators, as well as energy from curtailed clean grid electricity resources—to help in satisfying the heating demands of commercial and residential buildings. As such, ICE-Harvest systems provide a solution that can minimize greenhouse gas emissions from high-energy-consumption buildings in cold-climate regions such as North America and Northern Europe. In the current research, a thermal energy sharing model was developed to provide a dynamic characterization of the potential benefits of integrating and harvesting energy within a community of any number of buildings. The proposed model estimates the amount of rejected heat from cooling and refrigeration systems that can be simultaneously collected and used to heat other nearby buildings connected with a low temperature microthermal network (MTN). It also determines the proper timing and quantity of electricity used by the heat pumps in low-temperature MTNs as well as the reduction of both GHG emissions and the energy required from the EMC relative to conventional stand-alone systems. For an energy-balanced community cluster, the model showed that, over the course of a year, the energy harvesting would reduce this node’s GHG emissions by 74% and cover approximately 82% of the heating requirements compared to the BAU system. The results also revealed that the diversity in thermal demand between the connected buildings increases the harvesting potential. This research develops two clustering methods for the ICE-Harvest system. The proposed methods are clustering around anchor building and density-based (DB) clustering with post-processing by adding the closest anchor building to each cluster that focuses on the diversity of the buildings in each cluster. The energy sharing model is used to examine these techniques in comparison with the density-based clustering technique, the commonly used technique in the literature on a large database of 14000 high energy consumption buildings collected in Ontario, Canada. The results of this case study reveal that DB clustering with post-processing resulted in the largest emission reduction per unit piping network length of 360 t CO2eq /km/year. In addition, this research identified seven different cluster categories based on the total and simultaneous cooling-to-heating ratios of each cluster. The ICE harvest system integrates the thermal and electrical networks to add more flexibility to the electricity grid and schedule the electrification of heating (EoH). Current research provides a reduced model for the ICE-Harvest system to study its impact for over 1100 clusters of different categories on a provincial scale on the GHG emission and electricity demand from the grid. The use of ICE-Harvest systems at this scale can displace the energy required from the gas-fired heating resources by 11 TWh, accounting for over 70% of the clusters’ total heating requirements. This results in a 1.9 Mt CO2eq reduction in total GHG emissions, which represents around 60% of the clusters’ emissions. Operating conditions of the thermal network (TN) in the integrated community energy systems affect the ability to harvest waste energy and the reduction of GHG emissions as well as the electricity peak demand and consumption. In the current research, modeling of different thermal distribution network operating scenarios was performed for the different community energy profile clusters. These operation scenarios include low-temperature (fourth generation), ultra-low (fifth generation), a binary range-controlled temperature modulating thermal network operating between Low and Ultra-low temperatures (ICE-Harvest), and a new proposed scenario wherein a continuous range-controlled temperature modulating micro-thermal network. The continuous range-controlled temperature scenario shows the most benefits with the large implementation on the identified clusters. It adds more flexibility to balance the electricity grid as well as results in large GHG emission savings while controlling the increase in site electricity peak demand. The load profile of the cluster affects the selection of the most beneficial energy integrated system. This research shows that, for most of the heating-dominated clusters, it is better to employ the continuous range-controlled temperature TN with peak control and CHP on sites to serve the high heating demands along with short term and seasonal thermal storage. For the majority of balanced and /or cooling-dominated clusters, it is better to implement more carbon-free resources to the electricity grid or on-site that produce electricity but are not associated with heat such as wind, hydro, and solar PV panels. Parametric studies were performed in this research including changing the CHP size, the CHP utilization efficiency, and the grid gas-fired generators usage conditions to show their impact on the GHG emissions reduction from the clustered buildings. The analysis was implemented on a fleet of 1139 sites in Ontario and the results showed that the CHP size and operating hours have a measurable impact on GHG emission saving. The system can reach up to 58% and 66.5% emission savings of the total sites’ emissions with 93% and 39% operating hours respectively following the Ontario grid natural gas peaking power plants for the years of 2016 and 2017 with larger CHP sizes. The largest share of GHG emission saving in 2016 is by the CHP (61%) as opposed to 30% in 2017. The reduced models introduced in this research for the thermal energy sharing, the ICE-harvest system operation and sizing, and the MTN operation aid the investigation of the impact of the large implementation of the ICE-Harvest systems on the GHG emissions and electricity grid. / Thesis / Doctor of Philosophy (PhD)

Mälarenergi’s vision is a world where we live and operate together without climate impact. This degree project has examined which opportunities Mälarenergi Elnät has in order to work towards this vision by looking more closely at whether their bigger substations can become self-sufficient in terms of heating, cooling and battery charging. The purpose of this degree project was to investigate how heat recovery from the substations’ transformers and the installation of PV-systems could contribute to both more environmentally friendly and self-sufficient substations. In addition to that, the economics and how this would affect the Swedish power grid regulation were of interest. The thesis was based on current values and data for oil temperatures and installed power in three of Mälarenergi Elnät’s substations. In addition to this, the thesis also includes a literature study, where previous research in heat transfer from power transformers, up-to-date information about PV-installations and the power grid regulation in Sweden were studied. The results of the thesis showed that both PV-installations and heat exchange for heating the station buildings could be of great benefit for Mälarenergi Elnät. In all but one case, the energy saving measures resulted in lower life cycle costs than if no measures were taken. It shows that the measures investigated in the thesis are not only good from an environmental perspective, but also has economic profitability.

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Many industrial processes have low-temperature waste heat sources that cannot be efficiently recovered. Low grade waste heat has generally been discarded by industry and has become an environmental concern because of thermal pollution. This has led to the lookout for technologies which not only reduce the burden on the non-renewable sources of energy but also take steps toward a cleaner environment. One approach which is found to be highly effective in addressing the above mentioned issues is the Organic Rankine Cycle (ORC), which can make use of low- temperature waste heat to generate electric power. Similar in principle to the conventional cycle, ORC is found to be superior performance-wise because of the organic working fluids used in the cycle. The focus of this study is to examine the ORC using different types of organic fluids and cycle configurations. These organic working fluids were selected to evaluate the effect of the fluid boiling point temperature and the fluid classification on the performance of ORCs. The results are compared with those of water under similar conditions. In order to improve the cycle performance, modified ORCs are also investigated. Regenerative ORCs are analyzed and compared with the basic ORC in order to determine the configuration that presents the best thermal efficiency with minimum irreversibility. The evaluation for both configurations is performed using a combined first and second law analysis by varying certain system operating parameters at various reference temperatures and pressures. A unique approach known as topological method is also used to analyze the system from the exergy point of view. Effects of various components are studied using the exergy-wheel diagram. The results show that ORCs using R113 as working fluid have the best thermal efficiency, while those using Propane demonstrate the worse efficiency. In addition, results from these analyses demonstrate that regenerative ORCs produce higher efficiencies compared to the basic ORC. Furthermore, the regenerative ORC requires less waste heat to produce the same electric power with a lower irreversibility.

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