Master of Science / Department of Mechanical and Nuclear Engineering / Akira T. Tokuhiro / The Secure Transportable Autonomous Reactor – Liquid Metal system combines a Generation IV nuclear reactor with an advanced Supercritical Carbon Dioxide (S-CO[subscript]2) Brayton power conversion cycle. The Brayton cycle was selected as the power conversion cycle due to its high efficiency, small turbomachinery size, and competitive cost due to reduced complexity as compared to a traditional Rankine cycle. Overall system thermal efficiency is closely tied to the performance of the precooler and recuperators. The Printed Circuit Heat Exchanger (PCHE) manufactured by Heatric is being considered for use as both the precooler and recuperator in the STAR-LM system due to its high effectiveness, wide temperature and pressure operating range, small size, and low cost. PCHEs have been used primarily in the hydrocarbon processing industry to date, and are relatively new in being considered for nuclear applications. In this study, a PCHE is investigated using S-CO[subscript]2 and water as the heat transfer media in conditions relevant to the precooler in the STAR-LM system. Experiments conducted with small temperature differences across the PCHE revealed that the heat transfer coefficient is strongly correlated with the temperature-dependent specific heat near the pseudocritical point. The STAR-LM precooler outlet temperature is near the pseudocritical point, making this region of interest to this work. Testing was conducted to determine the effect of property variation near the precooler outlet in conditions with large temperature differences in the PCHE. These tests revealed that maintaining the precooler outlet temperature near the pseudocritical point does not have a significant effect on heat transfer coefficients in the PCHE under large temperature difference test conditions. Computational Fluid Dynamics (CFD) models were developed to simulate fluid flow and heat transfer in the PCHE. A 2D, 4-channel, zig-zag model was found to reproduce the outlet temperatures to within approximately 15% relative error. The 3D straight channel model reproduced the experimental data to within 3% relative error for the cases simulated. Both of these models predicted the water side outlet temperatures to within 20% relative error.

This paper examines the model-based design of thermal systems in mobile machines with a focus on heat exchanger design. An industry project is described in which the vapor compression cycle for the air-conditioning system was modeled using the software SimulationX. By modeling heat exchanger sections separately, multiple flow arrangements could be tested without the need for physical prototypes. The paper presents this work in the context of the full model-based design process including extensions for hardware in the loop (HiL) testing of control units and operator training using virtual machines.

The global energy usage have been growing and is expected to grow in the forthcoming years. The negative effects of increased energy use are greatly depending on the type of base raw materials required for converting the energy and the negative consequences those have on the environment. From the energy used, fossil fuels stands for the largest part. Excess use of fossil fuels have been shown to have considerable negative effects on the environment, including, but not limited to global warming. Renewable energy is today the world’s fastest growing energy source limiting the negative consequences of growing energy use. The commercial and residential buildings stands together for about 40 % of the total energy usage. Residential buildings alone stands for 20 % of the total world delivered energy consumption by end-use sector. In EU the average residential energy use amounts to 25 % and for individual countries like Sweden and Finland it is 21 %. The EU energy efficiency directive from year 2012 sets a target to save 20 % of the unions primary energy usage by year 2020 compared to the year 1990. The EU countries also agreed in October 2014 on a new energy efficiency target of at least 27 % by the year 2030. To reach this goal, improved energy efficiency are required in all sectors. Finland’s energy efficiency law for buildings from 2013 greatly reduces the minimum energy usage allowed for new buildings. Finland is also preparing for a new law that would by 2020 require all new buildings to be zero or close to zero energy buildings. This is defined by the Ministry of the Environment as buildings that have very high energy efficiency, where the already greatly reduced energy demand is satisfied extensively by renewable energy. As part of the goal to greatly increase buildings energy efficiency, this work focus on heat exchangers for showers. The purpose of this project is to investigate how two different heat exchangers works for shower cabins. This is done by testing a system where the heat exchangers are linked together. The system works by transferring heat from the drainage water and the moist air to the incoming colder drinking water before the cold water is heated in the mixerto desired shower temperature. The measurements are taken for different simulated shower situations. The Heat exchangers efficiency are calculated and the energy savings are examined with annual energy savings. The payback time shows that the system is not currently viable. The efficiency need to be improved, the main issue being the constituent materials heat transfer attributes between cold and hot water. The results are discussed and it is concluded that the system would be viable with improved heat exchanger efficiency and adequate shower use, which depends on the user and the amount of people using the shower. The main issue with increased heat transfer efficiency is the greater risk of contamination between the incoming cold drinking water and the outgoing dirty drainage water.

Baigiamajame magistro darbe nagrinėjamos grunto ir atliekinės pastato šilumos panaudojimo galimybės mažaenergiame pastate, Vilniaus mieste, Lietuvoje. Suskaičiuoti keturi pastato energijos balansų variantai, naudojant ”CASAnova” kompiuterinę skaičiavimo programą, su skirtingais atitvarų šilumos perdavimo koeficientais. Pastate taikomos dvi energijos taupymo priemonės. Pirmoji yra gruntinis šilumokaitis naudojamas šviežio oro pirminiam pašildymui mechaninio vėdinimo sistemoje, kurio skaičiavimai atliekami ”GAEA” programa. Antroji yra nuotekų šilumos atgavimo šilumokaitis, naudojamas į pastatą tiekiamo šalto vandens pirminiam pašildymui, atgaunant dalį šilumos iš duše susidariusių nuotekų. Pastatui reikiamas metinis šilumos ir vėsos energijos kiekis gaminamas šilumos siurbliu su vertikaliu gręžiniu grunte, kurio skaičiavimams naudojama ”EED” programa. Gręžinių gyliai yra suskaičiuoti kiekvienam pastato energijos balansų variantui. Atlikti ekonominiai skaičiavimai rodo gruntinio ir nuotekų šilumos atgavimo šilumokaičių įdiegimo pastate ekonominę naudą. Pateikti rezultatai rodo kiekvieno varianto energijos poreikius ir gręžinio grunte gylį priklausomai nuo pastato varianto atitvarų šiluminių savybių bei taikomų energijos taupymo sprendimų. Darbą sudaro 9 dalys: įvadas, 6 skyriai, išvados ir pasiūlymai, literatūros sąrašas. Darbo apimtis – 64 psl. teksto, 41 paveikslai, 14 lentelės, 31 bibliografinis šaltinis. / The final master thesis presents technical analysis of low-energy residential building in Vilnius, Lithuania. Building has low temperature floor heating, mechanical ventilation with heat recovery unit and hot water preparation with buffer tank systems. Using “CASAnova” software is calculated fourth energy balances of building according fourth different heat transfer coefficients of the walls. All heating and cooling energy demand of a building is generated from the ground. It is made by using a heat pump with single borehole. A calculation of borehole sizing is made with “EED” software. Two energy saving technologies are analysed for a building. The first idea is to reduce heat energy consumption of hot water preparation. There is calculated benefit of waste water heat recovery heat exchanger which function is to pre-heat hot water using waste water from the shower. Second idea is to reduce heat energy consumption for fresh air heating in air handling unit. There is calculated benefit of earth-to-air heat exchanger using “GAEA” software. Final result of all calculations shows influence of heat transfer coefficient and energy saving technologies to building annual energy balance and depth of borehole. Economic benefit of using energy saving technologies is calculated. Structure: introduction, 6 chapters, conclusions and suggestions, references. Thesis consists of 64 p. of text, 41 figures, 14 tables and 31 bibliographical entries.

The purpose of this research project is the design and optimization of complex chemical engineering problems, by employing evolutionary algorithms (EAs). EAs are optimization techniques which mimic the principles of genetics and natural selection. Given their population-based approach, EAs are well suited for solving multiobjective optimization problems (MOOPs) to determine Pareto-optimal solutions. The Pareto front refers to the set of non-dominated solutions which highlight trade-offs among the different objectives. A broad range of applications have been studied, all of which are drawn from the chemical engineering field. The design of an industrial packed bed styrene reactor is initially studied with the goal of maximizing the productivity, yield and selectivity of styrene. The dual population evolutionary algorithm (DPEA) was used to circumscribe the Pareto domain of two and three objective optimization case studies for three different configurations of the reactor: adiabatic, steam-injected and isothermal. The Pareto domains were then ranked using the net flow method (NFM), a ranking algorithm that incorporates the knowledge and preferences of an expert into the optimization routine. Next, a multiobjective optimization of the heat transfer area and pumping power of a shell-and-tube heat exchanger is considered to provide the designer with multiple Pareto-optimal solutions which capture the trade-off between the two objectives. The optimization was performed using the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) on two case studies from the open literature. The algorithm was also used to determine the impact of using discrete standard values of the tube length, diameter and thickness rather than using continuous values to obtain the optimal heat transfer area and pumping power. In addition, a new hybrid algorithm called the FP-NSGA-II, is developed in this thesis by combining a front prediction algorithm with the fast and elitist non-dominated sorting genetic algorithm-II (NSGA-II). Due to the significant computational time of evaluating objective functions in real life engineering problems, the aim of this hybrid approach is to better approximate the Pareto front of difficult constrained and unconstrained problems while keeping the computational cost similar to NSGA-II. The new algorithm is tested on benchmark problems from the literature and on a heat exchanger network problem.

M. Beniušis „Kelto „Victoria Seaways“ šilumokaičio ir aušinimo vamzdyno virpesių tyrimas“. Laivų projektavimo ir statybos magistratūros studijų programos baigiamasis darbas. Darbo vadovas dr. P. Mažeika, Klaipėdos universitetas: Klaipėda, 2014. Raktažodžiai: virpesiai, laivas, keltas, virpesių tyrimai, šilumokaitis. Baigiamojo darbo teorinėje dalyje aprašoma virpesių klasifikacija, pagrindiniai virpesių žadintojai ir analizuojami įvairūs virpesių lygio mažinimo laive, virpesių skaičiavimo būdai. Eksperimentinėje dalyje pateikiama keltų „Victoria Seaways“ ir „Athena Seaways“ aušinimo sistemos dalies virpesių matavimo metodika. Nagrinėjami reiso Klaipėda-Kylis-Klaipėda metu atliktų matavimų rezultatai, bei nustatomos tiriamos aušinimo sistemos dalies padidintų virpesių lygio priežastys. Paskutinėje darbo dalyje pateikiamos išvados ir rekomendacijos. / M. Beniušis “Vibration research of heat exchanger and cooling piping in Victoria Seaways ferry”. Final work of the master studies of ship design and building program. Academic supervisor Dr. P. Mažeika, Klaipeda University: Klaipėda, 2014. Keywords: vibrations, ship, ferry, vibration research, heat exchanger. The theoretical part of the final work describes the classification of vibration, main excitations of vibration and analyses various methods for reduction of the vibration level on board and vibration calculation. The experimental part presents the vibration measurement methodology in the cooling systems of Victoria Seaways and Athena Seaways ferries. It examines the results of measurements carried out during Klaipėda-Kiel-Klaipėda trip and identifies the reasons for the recent level of vibration in the analysed cooling system. The final part of the work contains the conclusions and recommendations.

Approved for public release, distribution is unlimited / This study concentrates on the empirical characterization of a staggered pin-fin array heat exchanger placed in a modular, rectangular wind tunnel. A full analysis of the heat transfer and pressure drop behavior was conducted on various pin-fin shapes, sizes, and configurations. The study was based on airflow over a wide range of Reynolds numbers in the laminar regime. The empirical data gathered can be used to corroborate and develop better numerical models to characterize the performance of such heat exchangers as well as scale down to the micro level for comparison with micro-heat exchangers. / Lieutenant, United States Navy

The purpose of this thesis is to use a model to optimize the heat exchanger network for process industry and to estimate the minimum cost required for the heat exchanger network without compromising the energy demand by each stream as much as possible with the help of MATLAB programming software. Here, the optimization is done without considering stream splitting and stream combining. The first phase involves with deriving a simple heat exchanger network consisting of four streams i.e... Two hot streams and two cold streams required for the heat exchanger using the traditional Pinch Analysis method. The second phase of this work deals with randomly placing the heat exchanger network between the hot and cold streams and calculating the minimum cost of the heat exchanger network using genetic coding which is nothing but thousands of randomly created heat exchangers which are evolved over series of population.

Given the unstable state of the environment, there is an undeniable need for the development of sustainable technologies. This need affects all areas of everyday life, even the shower. Modern shower systems result in energy waste in the form of heat, which can be minimized through the implementation of a heat exchanger. In cooperation with Consat SES this project developed a system to implement a heat exchanger using an in-shower water transportation pipe. A fitting non-electrical pump and motor were also chosen. To develop these elements a general design methodology of defining the problem, identifying the solution space, developing concepts, testing concepts and proposing a design, was used with adaptations for the component at hand. By following this strategy for each component and then reviewing the system as a whole, a new shower system was developed with a trapezoidal water transport pipe, a wing pump, and a turgo turbine.

Master of Science / Department of Civil Engineering / Dunja Peric / Piles have been used for many years in civil infrastructure as foundations for buildings, bridges, and retaining walls. Energy piles are thermo-active foundation systems that use geothermal energy for heating and cooling of buildings. Ground source heat is a very attractive, economical, efficient and sustainable alternative to current heating practices. Unlike the air temperature, the temperature below the Earth’s surface remains relatively constant throughout the year, somewhere between 10oC to 15oC below a depth of 6 m to 9 m (Kelly, 2011). This provides an opportunity for construction of thermo-active foundation systems with embedded geothermal loops. The main purpose of such thermo-active system is to transfer deep ground heat to a building through the fluid circulating within the geothermal loop. It is because these thermo-active foundation systems enable heat exchange between the deep ground and the building that is called the heat exchanger pile (HEP). The thermal energy supplied by a HEP can then supplement air-pump-based heating/cooling system. Although heat exchanger piles have been successfully implemented in Europe and Asia, their usage in U.S. remains uncommon. One reason for this might be currently limited understanding of the associated soil-structure interaction, thus unfavorably affecting the design procedures. To this end, a study was undertaken to investigate the predictive capabilities of computational models and to gain a better understanding of the load-transfer mechanisms of energy piles. Thus, coupled thermo-hydro-mechanical computational modeling of a single actual end bearing HEP was carried out for different loading scenarios including thermal and mechanical loads by using the finite element code ABAQUS/Standard 6.13-2. The results of the analyses of the heat exchanger pile with two different types of layered soil profile are presented: isotropic and anisotropic. The computational model was validated and verified successfully against field test results for all considered loading scenarios. Additional analyses were performed to gain a deeper insight into the effects of soil layering and on the behavior of energy piles. It was found that changes in the soil stiffness affected primarily the head displacement and vertical stresses and strains in the pile.