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Influence of Membrane on Airflow in Historical Attic Spaces: The First Principles Study Using CFD Models
Poljak, Michal ; Ponechal, Radoslav ; Krušinský, Peter
This paper conducts an initial analysis of the impact of a vapour permeable membrane on airflow within triangular attic spaces, resembling the shape and dimensions of medieval sanctuaries found in historical rural churches in our region. The first principles study, using Computational Fluid Dynamics (CFD) based on the simulation models, aims to identify potential challenges and research directions regarding how the application of this membrane may affect the microclimatic conditions in the attic spaces and the durability of the historical timber trusses. One significant outcome of the study reveals that on a simulated extremely hot summer day, the application of the vapour permeable membrane reduced airflow by 10 to 15 per cent, thus affecting the overall microclimate in the attic.
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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna ; Bílek, Vojtěch ; Haidl, Jan ; Isoz, M. ; Pivokonský, Martin
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
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Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna ; Bílek, V. ; Haidl, J. ; Isoz, Martin ; Pivokonský, M.
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
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Modelling the Oil Lubrication System of Turbocharger
Breckl, Lukáš ; Hliník, Juraj (referee) ; Novotný, Pavel (advisor)
The diploma thesis contains a research part focused on turbocharger construction, engine lubrication system and turbocharger, basic physical properties of lubricating oils and hydrodynamics. The purpose of this thesis is to create analytical and CFD computational model of turbocharger lubrication system. Output pressures and the loss of specific energy are determined.
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Design of modular tubular heat exchanger
Marx, Sven ; Turek, Vojtěch (referee) ; Jegla, Zdeněk (advisor)
Hlavním cílem této práce je seznámit se s požadavky specifické procesní aplikace a návrhem výměníku tepla s křížovým tokem pracovních látek a zhodnotit návrh předmětného výměníku pomocí simulačního softwaru. Nejprve jsou v práci prozkoumány provozní podmínky rekuperace odpadního tepla a obecné možnosti návrhu a jsou uvedeny základní rovnice pro tepelný a hydraulický výpočet. Hlavní část práce se zaměřuje na modulární trubkový výměník tepla s křížovým tokem pracovních látek navržený pro experimentální výzkum rekuperace tepla a zanášení ze znečištěných spalin produkovaných spalováním alternativních paliv na VUT v Brně (VUT) na Ústavu procesního inženýrství (UPI). Nejprve je stručně představena situace v testovací laboratoři. Poté je popsán postup návrhu předmětného tepelného výměníku pomocí softwaru HTRI a výsledky jsou shrnuty a porovnány s cílovými požadavky. Následně je analyzována distribuce toku vody v trubkovém prostoru uvnitř jednoho ze čtyř identických modulů výměníku tepla užitím softwaru CDF pomocí tří různých simulačních přístupů. Jsou popsány dva přístupy využívající model turbulence k--SST a jeden přístup využívající model turbulence k--Realizable turbulence. Nakonec jsou diskutovány rozdíly mezi přístupy a výsledky simulací distribuce toku.
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Simulation of air valves and difusers
Bombera, Jiří ; Rubinová, Olga (referee) ; Uher, Pavel (advisor)
The aim of the diploma thesis is the simulation of air valves and difusers using CFD. The goal of this thesis is to determinate the type of air valve and diffusor, which would ventilate the room of a detached house the best – considering the speed of the airflow and the age of the air. Outcome of this work is the design of the air conditioning system for a detached house with application of the air valve and difuser which is evaluated as the ideal option for the ventilation in the room.
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Inlet recirculation of centrifugal pump
Heinz, Pavel ; Štefan, David (referee) ; Rudolf, Pavel (advisor)
This diploma thesis deals with the phenomenon appearing in hydrodynamic pumps at the sub-optimal flow rate. This phenomenon is inlet recirculation, which is an undesirable phenomenon in the suction of the pump. This recirculation causes cavitation, pressure pulsations and may cause clogging of the suction line. The main goal of the diploma thesis is CFD simulation for the recirculation mode, identification of the flow phenomena, and designs of possible measures to suppress inlet recirculation.
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