This work deals with the topic „Heating buildings building resources on different types of fuel in assessing economic benefits“. On this theme is elaborated theoretical part, then the topic is applied to the specified building. The project is design central heating, water heating, water heater design power unit. The project is designed in two versions. In the first variant are the heat source gas boilers. In the second variant are the heat source heat pumps.

In terms of master’s thesis HAM-Tools library designed for MATLAB/Simulink was modified for the use in simulations of houses in the Czech Republic. Modified library and its parts were described in detail and tested by the simulation of the one-zone and two-zones models of the house. The simulations of models with same parameters were also realized in program TRNSYS. The corresponding results achieved in mentioned simulation tools were compared to each other. The one-zone model created by using HAM-Tools library is tested by the simulation of ventilating, heating, cooling, and sources of moisture. A demonstration of the practical use of the simulation is carried out in the thesis, namely by examining the influence of the insulation thickness on the thermal performance of the house (resp. its heat loss) on real atmospheric conditions. Among others, available resources of meteorological data are mentioned and compared to each other. The function for processing of the meteorological data to a file compatible with the HAM-Tools library was created. It was also created a material data file containing commonly used materials of building structures in the Czech Republic and their parameters.

The AK4 rifle serves as the primary weapon for the Home Guard, an integral part of the Swedish Armed Forces. Introduced in 1964, the AK4 is the Swedish version of the Heckler & Koch G3 and functions as a fully automatic assault rifle. Among its components, the handguard holds significant importance, providing stability, improving accuracy and control, and protecting the user from heat generated by the barrel. Recognizing the need for optimization, an employee from the ALTEN Group, possessing military experience and expertise in the AK4, launched a project to enhance the ergonomics and versatility of the handguard in a cost-effective manner. This initiative stems from the excessively high cost of commercially available handguards, making them financially unviable for replacing the original handguard of every AK4 used by the Home Guard personnel. This project aims to design and develop a next-generation handguard for the AK4 rifle that addresses the current limitations of the existing handguard. The primary focus is improving the shooter’s performance by establishing a comfortable shape of the handguard, reducing the weight, and enhancing its compatibility with accessories. Additionally, the aim is to ensure the handguard is cost-effective for mass production and meets the requirements set by the Swedish Defense Materiel Administration. To achieve the aims, interviews and a comprehensive user testing study was conducted, collecting quantitative data in the form of participant ratings and rankings for different design concept while also gathering qualitative data through participant feedback that highlighted specific design features contributing to comfort. Additionally, a systematic material selection process was performed, involving the analysis and ranking of various materials based on properties such as weight, price, and specific mechanical properties. Furthermore, the manufacturing analysis relied mainly on conversations with industry experts possessing expertise in the field of plastic manufacturing. Upon conducting a detailed analysis, it has been determined that the ideal configuration for the final product is an octagonal shape. After careful evaluation, Polyamide 6 reinforced with 30% glass fibers has emerged as the most suitable material choice for the handguard. This material had the optimal balance between mechanical properties, thermal performance, durability, cost-effectiveness, and environmental impact. To produce 50,000 handguard units, the recommended manufacturing method was injection molding due to its compatibility with mass production and the advice received from industry experts. Considering the design and selected material, a substantial number of the requirements outlined by FMV could be fulfilled by conducting both theoretical analyses and practical experiments.

The thesis discusses possibilities of use new thermal insulation materials based on natural renewable resources (primary technical hemp) in development of the new thermal insulation materials. The main task (in the work) is to find modifications of the thermal insulation mats based on natural fibres by chemicals substances to improve the moisture properties, thermal properties and fire resistance.

The diploma thesis deals with warm-air heating and ventilation system of energyefficient family house. The part of thesis is theoretical introduction to low-energy and passive houses, ventilation and heating. The proposal itself is based on the applicable standards and includes all progressive steps, including the calculation of the thermal performance and sizing individual parts of the system. The drawing project documentation is listed in appendixes.

[pt] Diante dos constantes avanços da tecnologia os dispositivos eletrônicos vêm passando por um processo de miniaturização, ao mesmo tempo em que sustentam um aumento de potência. Essa tendência se mostra um desafio para seu gerenciamento térmico, uma vez que os sistemas de resfriamento típicos para eletrônicos utilizam ar como fluido de trabalho, e o seu baixo coeficiente de transferência de calor limita sua capacidade de atender às necessidades térmicas da indústria atual. Nesse sentido, o resfriamento bifásico tem sido considerado uma solução promissora para fornecer resfriamento adequado para dispositivos eletrônicos. Circuitos de termossifão bifásico combinam a tecnologia de resfriamento bifásico com sua inerente natureza passiva, já que o sistema não requer uma bomba para fornecer circulação para seu fluido de trabalho, graças às forças da gravidade e de empuxo. Um dissipador de calor de microcanais, localizado bem em cima do dispositivo eletrônico, dissipa o calor gerado. Isto o torna uma solução de baixo custo e energia. Além disso, ter um circuito de termossifão operando com um refrigerante de baixo GWP, como o R-1234yf, resulta em baixo impacto para o meio ambiente, uma vez que é um refrigerante ecologicamente correto e o sistema tem baixo ou nenhum consumo de energia. Este trabalho fornece um modelo numérico detalhado para a simulação de um circuito de termossifão bifásico, operando em condições de regime permanente. O circuito compreende um evaporador (chip e dissipador de calor de micro-aletas), um riser, um condensador refrigerado a água de tubo duplo e um downcomer. Equações fundamentais e constitutivas foram estabelecidas para cada componente. Um método numérico de diferenças finitas, 1-D para o escoamento do fluido por todos os componentes do sistema, e 2-D para a condução de calor no chip e evaporador foi empregado. O modelo foi validado com dados experimentais para o refrigerante R134a, mostrando uma discrepância em relação ao fluxo de massa em torno de 6 por cento, para quando o sistema operava sob regime dominado pela gravidade. A pressão de entrada do evaporador prevista apresentou um erro relativo máximo de 4,8 por cento quando comparada aos resultados experimentais. Além disso, a maior discrepância da temperatura do chip foi inferior a 1 grau C. Simulações foram realizadas para apresentar uma comparação de desempenho entre o R134a e seu substituto ecologicamente correto, R1234yf. Os resultados mostraram que quando o sistema operava com R134a, ele trabalhava com uma pressão de entrada no evaporador mais alta, assim como, com um fluxo de massa mais alto. Por causa disso, o R134a foi capaz de manter a temperatura do chip mais baixa do que o R1234yf. No entanto, essa diferença na temperatura do chip foi levemente inferior a 1 grau C, mostrando o R1234yf como comparável em desempenho ao R134a. Além disso, o fator de segurança da operação do sistema foi avaliado para ambos os refrigerantes, e para um fluxo de calor máximo do chip de 33,1 W/cm2, R1234yf mostrou um fator de segurança acima de 3. Isso significa que o circuito de termossifão pode operar com segurança abaixo do ponto crítico de fluxo de calor. Dada a investigação sobre a comparação de desempenho dos refrigerantes R134a e R1234yf, os resultados apontaram o R1234yf como um excelente substituto ecologicamente correto para o R134a, para operação em um circuito de termossifão bifásico. / [en] Given the constant advances in technology, electronic devices have been going through a process of miniaturization while sustaining an increase in power. This trend proves to be a challenge for thermal management since commonly electronic cooling systems are air-based, so that the low heat transfer coefficient of air limits its capacity to keep up with the thermal needs of today s industry. In this respect, two-phase cooling has been regarded as a promising solution to provide adequate cooling for electronic devices. Two-phase thermosyphon loops combine the technology of two-phase cooling with its inherent passive nature, as the system does not require a pump to provide circulation for its working fluid, thanks to gravity and buoyancy forces. A micro-channel heat sink located right on top of the electronic device dissipates the heat generated. This makes for an energy and cost-efficient solution. Moreover, having a thermosyphon loop operating with a low GWP refrigerant such as R-1234yf results in low impact for the environment since it is an environmentally friendly refrigerant, and the system has low to none energy consumption. This work provides a detailed numerical model for the simulation of a two-phase thermosyphon loop operating under steady-state conditions. The loop comprises an evaporator (chip and micro-fin heat sink), a riser, a tube-in-tube water-cooled condenser and a downcomer. Fundamental and constitutive equations were established for each component. A finite-difference method, 1-D for the flow throughout the thermoysphon s components and 2-D for the heat conduction in the evaporator and chip, was employed. The model was validated against experimental data for refrigerant R134a, showing a mass flux discrepancy of around 6 percent for when the system operated under gravity dominant regime. The predicted evaporator inlet pressure showed a maximum relative error of 4.8 percent when compared to the experimental results. Also, the chip temperature s largest discrepancy was lower than 1 C degree. Simulations were performed to present a performance comparison between R134a and its environmentally friendly substitute, R1234yf. Results showed that when the system operated with R134a, it yielded a higher evaporator inlet pressure as well as a higher mass flux. Because of that, R134a was able to keep the chip temperature lower than R1234yf. Yet, that difference in chip temperature was slightly lower than 1 C degree, showing R1234yf as comparable in performance to R134a. In addition, the safety factor of the system s operation was evaluated for both refrigerants, and for a maximum chip heat flux of 33.1 W/cm2, R1234yf showed a safety factor above 3. This means the thermosyphon loop can operate safely under the critical heat flux. Given the investigation on the performance comparison of refrigerants R134a and R1234yf, results pointed to R1234yf being a great environmentally friendly substitute for R134a for the two-phase thermosyphon loop.