Ice rinks are energy intense industrial applications. A typical single sheet ice rink in Sweden uses about 1000 MWh/season. A state-of-the art ice rink systems can use less than 500 MWh/season, indicating the potential for improvements. According to several investigations CO2 refrigeration system with heat recovery has proven to be energy-efficient and cost-effective solution in ice rinks.To further improve the efficiency, geothermal function may be added feature. The objective of this study is to evaluate the geothermal function from techno-economic perspective for a typical ice rink in Sweden. Modelling of several scenarios has been performed. Obtained results suggest that CO2 refrigeration system with 2-stage heat recovery, if upgraded with geothermal function, can save between 1.7 to 6.8% of energy annually. In the best case, this study suggests the geothermal function would pay back in 16.4 years. / Ishallar är energikrävande industriella applikationer. En typisk ishall i Sverige använder cirka 1000 MWh / säsong. Ett toppmodernt ishallsystem kan använda mindre än 500 MWh / säsong, vilket indikerar stora förbättringsmöjligheter. Enligt flera undersökningar har CO2-kylsystem med värmeåtervinning visat sig vara energieffektivt och kostnadseffektivt i ishallar.För att ytterligare förbättra effektiviteten kan geotermisk funktion läggas till. Syftet med denna studie är att utvärdera den geotermiska funktionen ur ett tekno-ekonomiskt perspektiv för en typisk ishall i Sverige. En modellering av flera scenarier har utförts. Resultaten antyder att CO2-kylsystem med 2-steg värmeåtervinning, om det uppgraderas med geotermisk funktion, kan spara mellan 1,7 och 6,8% energi årligen. I bästa fall antyder denna studie att den geotermiska funktionen skulle betala tillbaka om 16,4 år.

This master thesis has been conducted at Forsmark nuclear power plant. In nuclear power plants, safety is one of the most important tasks. After the Fukushima-accident, Forsmarks Kraftgrupp AB investigated the possibility to have additional emergency cooling systems. This thesis aims to investigate the use of cooling towers as mobile emergency cooling system for decay heat removal for the nuclear reactors at Forsmark NPP. The advantages and disadvantages of different cooling tower types were looked at. To achieve mobility, some restraints were considered such as dimensions and weight. In the design of cooling towers, experimental values are used. As these crucial data are missing, a backfitting from actual designs was done to derivate the missing data. The results of this thesis show that wet cooling towers are in this case more effective than dry cooling towers. The wet cooling towers cover in the best scenario up to 38MW which is 10 times higher than what can be achieved with the dry cooling tower. That covers the maximal decay heat released in the reactor F3 12 hours after a shutdown.

Supermarkets have a high energy demand where almost half of the energy is used within the refrigeration system. The refrigeration system utilises a cycle where heat is taken and rejected. The rejected heat could be recovered and utilised for other purposes, such as covering internal heating demand or be exported to other facilities. Implementation of heat recovery could create business opportunities between the supermarket and other actors involved. The aim of this thesis was to investigate the potential for heat export from the refrigeration system insupermarkets to neighbours. Case studies were conducted on three different supermarkets in Sweden. This project evaluated field measurements for the current heat recovery within the systems, investigated heat recovery during optimal operation conditions as well as a techno-economic analysis of the heatrecovery system. All three supermarkets within the study recovered heat in the current configuration. In both CG Ytterby and CG Eskilstuna, the recovered heat covered the majority of the internal heating demand. Nevertheless, there was a great potential to recover more heat, since most of the heat was rejected through the gas cooler. The system was also limited by the discharge pressure and the return temperature in the heat recovery unit. The techno-economic analyses indicated that all supermarkets had the potential to cover both internal heating demand with the recovered heat, as well as produce excess to export. It was observed to be more profitable to disconnect from the DHN and become self-sufficient. Heat export from supermarkets would create new innovative business models which can be profitable for both the supermarket and the heat consumer. To produce excess heat, the system had to operate at optimal conditions, increasing electricity usage and hence associated operational costs. This demonstrated the importance of revenues to make it an economically feasible solution. / Livsmedelsbutiker har ett högt energibehov där nästan hälften av energin används i kylsystemet. Kylsystemen använder sig av en cykel där värme tas upp och avges. Den värme som avges kan återvinnas och användas för andra ändamål, till exempel för att täcka internt värmebehov eller exporteras till andra fastigheter och därmed skapa affärsmöjligheter för livsmedelsbutiken. Syftet med examensarbetet var att undersöka potentialen för export av värme från kylsystemet i livsmedelsbutiker. Fallstudier genomfördes för tre olika livsmedelsbutiker i Sverige. Projektet utvärderade fältmätningar för aktuell värmeåtervinning inom systemen, undersökte värmeåtervinning under optimala driftförhållanden samt utförde en teknisk-ekonomisk analys av värmeåtervinningsystemet. Livsmedelsbutikerna i studien återvann värme i den nuvarande konfigurationen. I både CG Ytterby och CG Eskilstuna täckte den återvunna värmen större delen av det interna värmebehovet och det fanns en stor potential att återvinna mer värme, eftersom majoriteten av värmen släpps ut genom gaskylaren. Systemet begränsades även av trycket efter kompressorerna och returtemperaturen i värmeåtervinningsenheten. De teknoekonomiska analyserna visade att alla livsmedelsbutiker hade potential att täcka internt värmebehov med den återvunna värmen, samt producera överskott för export. Det var även observerat att vara mer lönsamt att koppla från fjärrvärmenätverket och bli självförsörjande. Export av värme från livsmedelsbutiker skapar nya innovativa affärsmodeller som kan vara lönsamma för både livsmedelsbutiker och värmekonsumenter. För att producera överskottsvärme var systemet tvunget att drivas under optimala förhållanden, vilket ökade elanvändningen och därmed tillhörande driftskostnader. Detta visade på vikten av intäkter för att göra det till en ekonomiskt genomförbar lösning.

With more restrictions regarding the use of refrigerants with high GWP-values, refrigeration systems that uses R744 (Carbon dioxide) as a refrigerant increases. Supermarkets are energy intense facilities where the refrigeration system utilize a significant part of the total utilized energy. Heat recovery have been proven beneficial and reduces the total energy utilization for the building.  This master thesis evaluates an existing R744 refrigeration system with heat recovery, for the purpose to find an optimal system configuration and control strategy that minimizes the operational costs. Today the refrigeration system uses a water-cooled condenser/gas cooler that during the period from February to November 2021 consumed 8 194 m3 of cooling water, that resulted in high water costs for the supermarket. With the development of a model that takes historical data as input can different system configurations and control strategies be tested and compered to the historical analysis of the existing refrigeration system. Four system configurations with different heat recovery solutions were evaluated.  The result of this study shows that the operational cost can be reduced by 31% (55 400 SEK) with a control strategy that adapts the discharge pressure to the facility’s heating demand. With maximized heat recovery the condenser/gas cooler load decreases and therefore the cooling water flow decreases too. With an additional heat exchanger in the supermarkets ventilation exhaust duct can the water consumption further be reduced, compared with similar system without an additional heat exchanger. The additional heat exchanger reduced the cooling water consumption by 1 400 m3 for the investigated period and reduced the total operational cost by 9 800 SEK. However, it is recommended to first apply the control strategy that adapts the discharge pressure to the heating demand, and from there evaluate the benefits of a heat exchanger in the exhaust duct. / Med ett allt strängare regelverk angående användandet av köldmedier med höga GWP-värden, ökar antalet kylanläggningar som använder R744 (Koldioxid) som köldmedium. Livsmedelsbutiker är energikrävande där kylsystemen är en stor del av den totala energimängd som nyttjas. Studier visar att värmeåtervinning för dessa system kan med fördel användas för att minska energianvändningen i fastigheten.  Detta masterexamensarbete utvärderar en befintlig R744-kylanläggning med värmeåtervinning, i syfte att finna en optimal systemkonfiguration och styr-strategi som minimerar driftkostnaderna. Idag används en vattenkyld kondensor/gaskylare som under perioden februari till november 2021 förbrukade 8 194 m3 kylvatten, vilket resulterade i höga vattenkostnader för butiken. Genom att utveckla en modell som använder historisk mätdata som indata kan olika systemlösningar och styr-strategier testas och jämföras med analysen av det befintliga kylsystemet. Fyra systemkonfigurationer med olika grad av värmeåtervinning utvärderades. Studiens resultat visar att driftkostnaderna kan reduceras genom att anpassa kylsystemens högtryck till fastighetens värmebehov. Genom att maximera värmeåtervinningen minskar nyttjandet av kondensorn/gaskylaren och därmed flödet av kylvatten. Med en extra värmeväxlare i butikens frånluftskanal kan vattenförbrukningen reduceras ytterligare jämfört med liknande system utan denna värmeväxlare. Dock rekommenderas att initialt nyttja en styrstrategi som anpassar högtrycket efter värmebehov, för att sedan utvärdera fördelarna med en värmeväxlare i ventilationens frånluftskanal.

This master's thesis explores the role of bespoke air handling units in enhancing energy efficiency in existing buildings. The context for the study is set against the backdrop of global initiatives, including the United Nations' Sustainable Development Goals, specifically Goal 7, which emphasizes the need to improve energy efficiency to combat climate change. The significance of enhancing energy efficiency is well-established, evident both at the EU level and in national policies and regulations. Buildings represent a significant portion of the energy utilization puzzle, with substantial potential for enhancing energy efficiency, although it is often underutilized. One of the contributing factors to inefficiency is outdated ventilation systems, which lead to high thermal losses. This challenge can be addressed by retrofitting these systems with modern, efficient air handling units, thus contributing to energy conservation and cost savings. This study focuses on the adoption of bespoke air handling units adjusted to the site and capable of accommodating constraints related to factors such as space limitations in machine rooms, existing ductwork layouts, and the location of shafts. The primary goal is to empower engineers to move beyond conventional approaches, enabling them to optimize technology choices based on local conditions, specific system performance requirements, and the economic viability of each project. The aim of this study is twofold: first, to develop a methodology for designing bespoke air handling units; and second, to demonstrate the practical application of this methodology in the context of two distinct renovation projects. In line with the aim of the thesis, a design methodology for site-tailored units equipped with a two stage flat crossflow heat exchanger and an indirect evaporative cooling system was developed. The methodology delves into different aspects of data analysis, 3D modeling, and the conduct of performance calculations.The established methodology was applied in two reconstruction projects in central Stockholm, where bespoke air handling units were designed in compliance with provided technical specifications. In both scenarios, a viable option emerged for accommodating a tailored unit within the technical room situated on the first floor. For both units, the energy performance metrics signify a notable achievement in terms of heat recovery efficiency, coupled with relatively modest requirements for heating and cooling power capacity from the combined heating and cooling aircoil. However, the calculated maximum specific fan power for a single unit with heat recovery exceeded the stipulated value specified in the technical specifications, which was accepted by the client. The results of the study included air handling unit product drawings, ventilation blueprints of the technical room with the integrated air handling unit, component specifications, unit flowcharts, performance calculations, and control operating pictures. The results of this work indicate that the improvement of the building's energy efficiency is rendered feasible through the installation of bespoke air handling units in the studied reconstruction projects.

The rise in green-house gases emissions is an overall problem nowadays, in order to achieve the European goals by 2030, several changes are needed. Supermarkets are responsible of 3% of the emissions in Sweden, which makes them a clear target to reduce emissions. By using heat recovery systems, supermarkets can recover part of the heat excesses and use it for ambient or water heating. This can generate a reduction in heat demand, however, to be able to recover heat excess, more electricity is consumed. In the case study conducted, the heat recovery system of a supermarket in Matorp, Sweden has been analyzed. Studying the performance of the system, it has been seen that the COP values are around 2, low values compared with other case studies. The reason for this low performance is because of low discharge pressure, that also leads to a low amount of heat recovered. In the techno economic analysis, the operational costs of the heat recovery system are compared to the ones that a floating condensations system would have had. In the operational costs, both the electricity and the heating costs are considered. The results show that the overall floating condensation costs are only 1.86% higher than the heat recovery costs. This is a small value, but it has to be taken into account that the performance of the system and the heat recovered is low. Finally, in the environmental analysis the CO2 emissions savings by using a HR instead of a FC one is calculated, showing a reduction of 2.3 tons of CO2 per year. / Ökningen av utsläpp av växthusgaser är ett övergripande problem nuförtiden, och för att uppnå de europeiska målen till 2030 behövs flera förändringar. Supermarkets står för 3% av utsläppen i Sverige, vilket gör dem till en tydlig målgrupp för att minska utsläppen. Genom att använda värmeåtervinningssystem kan livsmedelsbutiker återvinna en del av överskottsvärmen och använda den för uppvärmning av lokaler eller vatten. Detta kan minska värmebehovet, men för att kunna återvinna överskottsvärme förbrukas mer elektricitet. I den genomförda fallstudien har värmeåtervinningssystemet i en livsmedelsbutik i Matorp, Sverige analyserats. Genom att studera systemets prestanda har man sett att COP-värdena ligger runt 2, vilket är låga värden jämfört med andra fallstudier. Anledningen till denna låga prestanda är det låga avluftningstrycket, vilket också leder till en låg mängd återvunnen värme. I den tekno-ekonomiska analysen jämförs driftskostnaderna för värmeåtervinningssystemet med de som ett flytande kondensationssystem skulle ha haft. I driftskostnaderna beaktas både el- och uppvärmningskostnader. Resultaten visar att de totala kostnaderna för flytande kondensation endast är 1,86% högre än kostnaderna för värmeåtervinning. Detta är ett litet värde, men det måste beaktas att systemets prestanda och den återvunna värmen är låg. Slutligen, i den miljömässiga analysen beräknas minskningen av CO2-utsläpp genom att använda ett HR istället för ett FCsystem, vilket visar en minskning med 2,3 ton CO2 per år.

To decrease the ecological footprint, humans either have to adjust their lifestyles, or the large scale industries must take corporate social responsibility. This study is based on the well-developed field of energy efficiency in industries by applying technology and organizational-focused proposals. The proposals are based on three different aspects, the economic, the environmental, and the social. These three aspects combined are called the triple bottom line perspective. An original case of the study objects energy balance was determined to develop the conclusions, with the simulation program IDA ICE. The study object was GKN ePowertrain, located in Köping. Energy efficiency cases were simulated in IDA ICE to observe the change in the energy balance. The cases and interviews of the employees were the foundation of the discussion where the improvements were critically reviewed from the triple bottom line perspective. The result shown that the temperature was too high for working conditions, the ventilation system consumes a large quantity of energy, and the internal flow of information is insufficient. In conclusion, GKN ePowertrain would increase their overall value by investing in a cooling system and more efficient heat exchangers for their ventilation system. These investments would notably increase their short term value of environmental sustainability and the social aspect. Furthermore, their economic value would increase in the long term. The cooling system would improve the working environment, and a new ventilation system would increase the heat recovery and decrease the energy consumed, even more than the consumption of the cooling system. Finally, GKN should also be more distinct in their information to the employees in the building regarding energy aims and their working environment, to have a positive gain of value in all the fields.

This master's thesis is an investigation and evaluation of MELCOR (a software tool for severe accident analyses regarding nuclear power plants), or more correctly of the (ASEA-Atom BWR 75) reactor model developed for version 1.8.6 of MELCOR. The main objective was to determine if MELCOR, with the reactor model in question, is able to produce satisfactory results in severe accident analyses compared to results made by MAAP, which is currently the only official software tool for this application in Sweden. The thesis work is related to the RASTEP project. This project has been carried out in several stages on behalf of SSM since 2009, with a number of specific issues explored within an NKS funded R&D project carried out 2011-2013. This investigation is related to the NKS part of the project. The purpose with the RASTEP project is to develop a method for rapid source term prediction that could aid the authorities in decision making during a severe accident in a nuclear power plant. A software tool, which also gave the project its name, i.e. RASTEP (RApid Source TErm Prediction), is therefore currently under development at Lloyd's Register Consulting. A software tool for severe accident analyses is needed to calculate the source terms which are the end result from the predictions made by RASTEP. A set of issues have been outlined in an earlier comparison between MAAP and MELCOR. The first objective was therefore to resolve these pre-discovered issues, but also to address new issues, should they occur. The existing MELCOR reactor model also had to be further developed through the inclusion of various safety systems, since these systems are required for certain types of scenarios. Subsequently, a set of scenarios was simulated to draw conclusions from the additions made to the reactor model. Most of the issues (pre-discovered as well as new ones) could be resolved. However the work also rendered a set of issues which are in need of further attention and investigation. The overall conclusion is that MELCOR is indeed a promising alternative for severe accident analyses in the Swedish work with nuclear safety. Several potential benefits from making use of MELCOR besides MAAP have been identified. In conclusion, they would be valuable assets to each other, e.g. since deviations in the results (between the two codes) would highlight possible weaknesses of the simulations. Finally it is recommended that the work on improving the MELCOR reactor model should continue. / RASTEP

The study compared four different cooling systems and analyzed the competitiveness in those systems regarding electricity consumption, environmental impact and life cycle cost analysis. The assignment was given from the consultant company Ramböll who believed in these systems design as a solution to minimize the energy consumption in cooling systems. The purpose of the study was to facilitate the selection of cooling system by finding a key ratio for profitability in terms of energy consumption. This makes it easier to select one of these systems in project planning. A representative building model was built in the energy simulation program IDA ICE. From these result an energy profile was achieved.   The energy profile was then used in another simulation program called Polysun were detailed system regulations could be made. By programing the controllers to regulate the distribution in an efficient way the energy consumption was minimized and matches the building cooling demand. The simulation was done for one full year and the obtained total energy consumption for each system, it was then used to calculate the operational cost. The life cycle cost analysis is a tool that compare each system costs during its lifetime. A depth analysis was also done regarding the sensitivity of changes in the profitability for the systems, by applying different electrical price and cost of capital.   The study shows that the systems with different borehole storage solutions proves to be effective systems for covering the building cooling demand with a significant lower electricity consumption, compared to the system with a chiller. The different borehole storage systems also contribute to cover some parts of the heat demand, since the stored heat needs to be used in order to make the borehole storage functional. By analyzing the cooling systems in a comparative perspective, the most effective solution is identified from an economic and environmental point of view. The cooling system that only contained a borehole storage was the solution that distinguished the most regarding total electricity consumption and environmental impact. This system resulted in being the most profitable cooling system between the compared systems. The combined system with a borehole storage system and a heat pump solution was also proven to be an effective cooling system, additionally with an advantage of providing parts of the hot water demand in the building.

The transportation industry stands for a big chunk of the worlds total carbon emissions. To counter this problem electric vehicles are seen as a good solution. However, these vehicles come at a greater cost and do not offer the same range as their less environmentally friendly counterpart. To lessen costs and development time when optimizing electric vehicles, simulations of the vehicles functionality can be utilized. One way of getting such simulations is to design a digital twin of the physical system. A digital twin is able to mimic the functionality of the physical system and can therefore offer well based indications of how a change in design will change the performance in reality. In this thesis a digital twin of the cooling system of an electric boat is designed with realistic results. Cooling systems in the scope of electric vehicles are of grave importance since the electric driveline becomes hot during use which can hinder performance of the vehicle. This is especially true for the high voltage batteries that tend to have quite a narrow range of temperatures within which performance is optimal. This thesis handles an attempt at optimizing the cooling system, replicated by the digital twin, by the use of a temperature predictive model. Three different machine learning models were tested and the resulting best model achieved a mean absolute error of 2.4 and a mean average percentage error of 5.7. However, the model was unable to foresee sudden temperature spikes and drops. A possible fix, that could not be tested in this thesis, would be to implement further input data such as driver profiles and/or GPS data with speed limits. / Transportindustrin står för en stor del av världens totala koldioxidutsläpp. För att motverka detta problem ses elfordon som en bra lösning. Dessa fordon kommer dock till en högre kostnad och erbjuder inte samma räckvidd som deras mindre miljövänliga motpart. För att minska kostnader och utvecklingstid vid optimering av elfordon kan simuleringar av fordonens funktionalitet användas. Ett sätt att få sådana simuleringar är att designa en digital tvilling av det fysiska systemet. En digital tvilling kan efterlikna det fysiska systemets funktionalitet och kan därför erbjuda välbaserade indikationer på hur en förändring i design kommer att förändra prestandan. I detta examensarbete designas en digital tvilling av kylsystemet i en elbåt med realistiska resultat. Kylsystem i elfordon är av stor betydelse eftersom den elektriska drivlinan blir varm under användning, vilket kan hindra fordonets prestanda. Detta gäller särskilt för högspänningsbatterierna som tenderar att ha ett ganska smalt temperaturintervall för optimal prestanda. Denna avhandling behandlar ett försök att optimera kylsystemet, replikerat av den digitala tvillingen, genom att använda en temperaturförutsende modell. Tre olika maskininlärningsmodeller testades och den resulterande bästa modellen uppnådde ett genomsnittligt absolut fel på 2.4 och ett genomsnittligt procentuellt fel på 5.7. Modellen kunde dock inte förutse plötsliga temperaturspikar och -fall. En möjlig fix, som inte kunde testas i denna avhandling, skulle vara att implementera ytterligare indata såsom förarprofiler och/eller GPS-data med hastighetsbegränsningar.