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The effect of the ventilation settings on amount of fed air and its distribution in the car cabin
Poláček, Filip ; Fojtlín, Miloš (referee) ; Pokorný, Jan (advisor)
This thesis deals with measuring of the distribution and volume of intake air inside vehicle cockpit under varying outdoor conditions and air conditioning settings. Fan characteristic was developed to determine the volume of air taken inside the cockpit. The measuring was made using speed probes in climatic chamber, where different outdoor conditions could be simulated. Following the measurements there is dependence between the air distribution and the outside temperature. The diploma thesis presents source materials to develop a mathematical model of car cabin.
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Determination of heat transfer coefficients from the surface of the thermal manikin
Fojtlín, Miloš ; Tuhovčák, Ján (referee) ; Fišer, Jan (advisor)
This thesis deals with an experimental determination of heat transfer coefficients from the surface of the thermal manikin. The main focus of the work lies on separating radiative and convective heat fluxes from the surface of the thermal manikin. Both nude and clothed, standing and seated postures were investigated respectively. The tests were conducted in a constant air temperature (cca 24°C) and a constant wind speed (cca 0,05 m.s-1) environment. The major part of the radiative heat flux was eliminated by a low emissivity coating applied to the surface of the nude thermal manikin, and in the case of clothed manikin by a low emissivity two-piece dress. Favorable results were achieved only in the case of the nude manikin measurements. The measurements were performed across 34 zones that logically represent parts of a human body. Experimental work confirms theoretical expectations in the means of a heat transfer. In addition, the results of this work were compared to results of a similar experimental work. The outcomes of this thesis provide essential information in order to create detailed computational models of a thermal environment. Such models require anatomically specific, separate values of convective and radiative heat transfer coefficients.
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Cooling systems in transport vehicles
Andrlík, Ladislav ; Fojtlín, Miloš (referee) ; Tuhovčák, Ján (advisor)
The purpose of this work is to examine currently used types of automobile cooling systems. This examination is presented in the form of a search report. The history of air conditioning is briefly described in the introduction of this work. The work then deals with the classification and description of cooling systems and their partial components which are complemented by pictures for better visualization. The primary focus is on the types and constructions of the compressors since the compressor is the fundamental element of all air conditioning circuit. The work concludes with information about coolants and adequate oil in use in relation to their ecological impact.
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Heat sources for nearly zero-energy buildings
Zábovský, Ján ; Fojtlín, Miloš (referee) ; Hejčík, Jiří (advisor)
This bachelor's thesis deals with the topic of heat sources for nearly zero energy buildings. It is divided into three parts. The first part of the thesis describes the term „nearly zero energy buldings“ and its differences across European union and especially Czech and Slovak republic. The next part summarizes various types of systems and devices, which are directly or indirectly involved in maintaining interior thermal comfort. It also assesses their applicability to buildings with nearly zero energy consumption. The final part of the thesis consists of the design of several input parameters for the selected model house. A suitable heat source is suggested for each of the variants.
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Modern technologies in thermal management of passenger vehicles with alternative drivetrain
Janíčková, Žaneta ; Kopečková, Barbora (referee) ; Fojtlín, Miloš (advisor)
This bachelor thesis is focused on the assessment of the current state of modern technologies in thermal management of passenger vehicles with alternative drivetrain. The main part of the work is based on the research into advanced systems aimed at minimizing the thermal load of the passengers and at ensuring the thermal comfort in the car cabin through various forms of the heat transfer. The study deals with reversible heat pump, photovoltaic solar panels, thermoelectric Peltier device, infrared heating, heat pipe and magnetocaloric cooling. Technologies are described from the point of view of the theoretical principle of operation, further, there are mentioned benefits and limitations of the system and the application of the technology in vehicles. Finally, a calculation of the energy demands of resistance heating as well as reversible and magnetocaloric heat pump for winter and summer operation is created for illustrative purposes. In addition to that, improvements of available systems and the potential use of prototype technologies, that can significantly contribute to reducing energy consumption while providing the required thermal comfort, are proposed at the end of the thesis.
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Analysis of flow from the car vent using thermoanemometric probe
Šeda, Libor ; Fojtlín, Miloš (referee) ; Lízal, František (advisor)
In this master’s thesis there are summarized fundamental findings about air flow velocity measurements and afterwards introduced the measuring track for automobile car vents, measured object and track arrangement and all used components. Velocity field measurement method is how wire anemometry, and apart from 4 main cases measurements of free air jet, there are velocity profiles in piping measured as an input for CFD simulation. Air vent evaluation criteria are described and their assessment is done for specified cases. Further, there is a CFD simulation presented with comparison to experimental data. Uncertainty of flow rate measured and flow rate setting is determined. Improvement points and encountered issues are presented. Visualization and evaluation program coded in MATLAB environment enables easy data display of CTA results and will serve further vent quality assessment.
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Determination of HVAC air distribution within a passenger vehicle cabin
Planka, Michal ; Mlkvik, Marek (referee) ; Fojtlín, Miloš (advisor)
The aim of this bachelor´s thesis is to determine proportional coefficients of air distribution provided by heating, ventilating, and air conditioning system (HVAC) within a passenger vehicle cabin. The focus of this paper is to determine air flow rates from the outlets at predefined outside climatic conditions (ambient temperature and solar load). The simulation of outside climatic conditions was executed by placing the car into a climatic chamber. The air flow rates from outlets were determined by measuring air flow velocity method, specifically by determining mean value of air flow velocity profile and area of outlet crosssection. Hot-wire anemometry was used for air flow velocity measurement. The results of this experimental work are presented in a diagrammatic form and will serve as a groundwork for boundary condition setting for computer modeling of thermal load and thermal comfort within a vehicular cabin.
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Design and construction of transparent nozzle for visualization and measurement of the internal flow
Sapík, Marcel ; Fojtlín, Miloš (referee) ; Jedelský, Jan (advisor)
This thesis deals with design and construction of transparent nozzle for research of internal flow of liquids. The objective was to design potential construction of the nozzle and make a manufacturing drawing. The theoretical part deals with basics of atomization including properties of liquids and describes basic optical methods for internal flow in a nozzle. In the research part of this thesis, a number of construction solutions has been picked to serve as an inspiration for the final shape of the nozzle. Its construction is elaborated in the last part along with a description of the process, a manufacturing drawing, and a visual documentation with a 3D model.
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Assesment of the Thermal Environment in Vehicular Cabins
Fojtlín, Miloš ; Khoury, Roch El (referee) ; Havenith, George (referee) ; Jícha, Miroslav (advisor)
Ľudia žijúci vo vyspelých krajinách trávia väčšinu svojho života vo vnútorných prostrediach budov alebo dopravných prostriedkov. Z tohto dôvodu, záujem o výskum kvality vnútorných prostredím rastie, pričom hlavný dôraz je kladený na oblasti výskumu ľudského zdravia, produktivity a komfortu. Jedným z faktorov ovplyvňujúci kvalitu prostredí je ich tepelný aspekt, ktorý je najčastejšie popísaný teplotou vzduchu, radiačnou teplotou, vlhkosťou vzduchu a rýchlosťou prúdenia vzdu-chu. Zatiaľ čo tieto parametre je možné riadiť systémom pre vykurovanie, vetranie a klimatizáciu nezávisle na počasí, takéto zariadenia sa podieľajú na vysokej spotrebe energie a značnej uhlíkovej stope. V prostediach kabín áut a dopravných prostriedkov je riadenie parametrov tepelného prostredia komplikované z dôvodu ich asymetrickej a časovo premenlivej povahy. Táto situácia je obzvlášť kritická vo vozidlách na elektrický pohon s vlastnou batériou, kde je energia na úpravu vnútornej mikroklímy čerpaná na úkor dojazdu vozidla. Pre uvedené dôvody sa hľadajú nové, en-ergeticky účinnejšie spôsoby pre úpravu tepelných prostredí a zabezpečenia tepelného komfortu. Jedným z potenciálnych riešení sú zariadenia dodávajúce človeku teplo alebo chlad lokálne, ako napríklad vyhrievané a vetrané sedadlá a sálavé panely. Vzhľadom na to, že experimentálny výskum vnútorných prostredí je náročný s ohľadom na čas a potrebné vybavenie, trendy výskumu vplyvov takýchto zariadení na človeka smerujú k optimalizačným úlohám vo virtuálnych prostrediach pomocou modelov ľudksej termofyziológie a tepelného pocitu/komfortu. Avšak pre spoľahlivé výsledky modelovania sú potrebné presné vstupné parametre definujúce prostredie, odev, vplyv povrchov v kontakte s človekom (napríklad sedadlá) a pôsobenie systémov na lokálnu úpravu mikroklímy. Cieľom tejto dizertačnej práce je vytvorenie metodológie na hodnotenie tepelných prostredí v kabínach automobilov s ohľadom na pozíciu v sede a využitím technológii na lokálnu úpravu tepelných prostredí. Jedným z požiadavkov na takúto metodológiu je jej aplikovateľnosť vo virtuálnych ale aj reálnych prostrediach. V prípade hodnotenia reálnych prostredí, cieľom je vytvorenie demonštrátora, ktorý by bol využiteľný ako spätná väzba pre riadenie systémov pre úpravu mikroklímy na základe požadovaného tepeleného pocitu. Validita uvedenej metodológie bola demonštrovaná v typických podmienkach kabín automobilov (5–41 °C) a poznatky z tejto práce sú prenesiteľné do širokého spektra inžinierkych aplikácii. V oblasti osobnej dopravy a pracovných prostredí s vyššou tepelnou záťažou je táto metóda užitočná pre identifikáciu možných zdrojov diskomfortu. Navyše je táto metóda vhodná i pre rýchlo rastúci segment elektrických vozidiel, kde je možné sledovať tok energie potrebnej na dosiahnutie určitej úrovne komfortu a riešenie optimalizačných úloh za účelom úspory energie a predĺženie dojazdu. Obdobné aplikácie možno nájsť i v budovách a prostrediach s podobnými charakteristikami.
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Environmental control system of aircraft cabin
Fojtlín, Miloš ; Hejčík, Jiří (referee) ; Fišer, Jan (advisor)
In this research work available information about air-conditioning systems of actual airliners are processed. These systems solve in complexity aircraft cabin microclimate modification into form comfortable and acceptable for the human body (ECS – enviromental control system). The work also covers ECS subsystems description. It explains their function, thermalmechanical principle, different possibilities of their realization and overall ECS function. Examples of ECS negative impact on other aircraft systems are also mentioned. Afterwards, real schemes of ECS built on board are sketched. The paper also presents reasons of ECS introduction, concrete requirements to cabin microclimate out of consideration to safe stay of human bean on board in different flight procedures. Simultaneously technical obstacles and limitations of ECS are shown. In conclusion need of correct ECS function is highlighted.
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