Engineering Commons^™

Optimization Of Advanced Building Integrated Photovoltaic And Thermal System With Dual Working Fluid, Barilelo E. Nghana

Electronic Thesis and Dissertation Repository

A direct exchange building integrated photovoltaic and thermal (BIPV/T) heat pump system is proposed where the heat extracted from the BIPV is used to drive the heat pump. To ensure a more stable diurnal system performance, especially at low solar conditions, air flow is instituted in the cavity between BIPV façade and the insulated inner wall. The airflow is directed from the heated or cooled space into the air channel and can be exhausted or returned to the space depending on the building operating conditions. The flow and geometrical parameters of the BIPV/T façade are optimized such that more than …

Cluster Acceleration And Stabilization In Downflow Catalytic Reactors: Experimental And Cpfd Simulation Studies, Cesar Alejandro Medina Pedraza

Electronic Thesis and Dissertation Repository

Particle cluster dynamics in downflow reactors are of great importance for the implementation of large scale, environmentally friendly catalytic processes. Studies should address particle cluster velocities, solids holdups, and individual cluster sizes to establish reliable models for the unit scale up.

In this PhD dissertation, the individual characteristics of particle clusters, such as cluster size, velocity, and particle volume fraction, were measured in the feeding, intermediate, and fully developed flow sections of a cold-flow model unit using CREC-GS-Optiprobes. The downer unit employed in this research had a 0.051 m ID and a 2 m high acrylic column. The feeding section …

Cfd Simulations Of Bubble Column Equipped With Bundles Of Concentric Tubes, Glen C. Dsouza

Electronic Thesis and Dissertation Repository

Bubble column reactors are multiphase contactors that have found several industrial applications owing to various attractive features including excellent thermal management, low maintenance cost due to simple construction and absence of moving parts. In order to attain desired performance for a given application, these reactors are usually equipped with internals such as vertical tube bundles to facilitate heat transfer. The column hydrodynamics and turbulence parameters are altered when the column is occluded with internals which adds to the complexity of the problem. The use of Computational Fluid Dynamics (CFD) tools for the study of multiphase flows has gained a lot …

The Effect Of Free-Stream Turbulence On Turbulent Boundary Layers And Convective Heat Transfer From Flat Plates, Ivian Carolina Alfaia De Magalhaes

Electronic Thesis and Dissertation Repository

The present work investigates the effect of free-stream turbulence (FST) on turbulent boundary layers and forced convective heat transfer from flat plates. High resolution, 2-D and 3-D, steady Reynolds-Averaged Navier-Stokes (RANS) simulations using Computational Fluid Dynamics (CFD) techniques were performed to analyze the influence of different free-stream conditions, such as turbulence intensity (TI), integral length scale (L_u) and free-stream velocity (U_o) on local and total skin friction and convective heat transfer coefficients (CHTC), as well as on turbulent boundary layer parameters (boundary layer thickness and momentum thickness). The present study shows that …

Numerical And Semi-Analytical Estimation Of Convective Heat Transfer Coefficient For Buildings In An Urban-Like Setting, Anwar Demsis Awol

Electronic Thesis and Dissertation Repository

Urban building arrangements such as packing density, orientation and size are known to influence the microclimate surrounding each building. Studies on the impact of urban microclimatic changes on convective heat transfer coefficient (CHTC) from a stock of buildings, however, have been rare in surveyed literature. The present study focuses on numerical and analytical investigation of CHTC from building-like models with homogeneous set of equal and unequal planar and frontal densities. Consequently, the study discusses the CHTC response in relation to broader changes in the urban surface form. Part of the process involves the development of a simplified one-dimensional semi-analytical CHTC …

Dynamics Of The Phase Coupling For Flow, Heat And Mass Transfer In Conjugate Fluid/Porous Domains, Mahmoud Mohamed Mostafa Elhalwagy

Electronic Thesis and Dissertation Repository

Porous media prevail in industry e.g. heat transfer equipment, drying, food storage and several other applications. Integrated in engineering, they form conjugate Fluid/Porous domains. Physical modelling requires characterizing the microscale heat and mass (moisture) transfer interstitially within porous media and their macroscale counterparts across regional interfaces. Characterizing turbulence and its effects on phase coupling is often needed too. The modeling literature survey shows phase coupling assumptions depending on empiricism, phase equilibrium and lack of generality. Modeling of the dynamic variations for the modes of phase exchanges, i.e. heat, mass and heat accompanying mass exchanges, on both scales and generic turbulent …

A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi

Electronic Thesis and Dissertation Repository

As part of the Western Cold and Flu aerosol (WeCoF) studies, the present study provides Computational Fluid Dynamics (CFD) modelling of human cough flow. The cough flow is characterized in two different aspects, the flow field and the droplets. In the study of the flow field of coughing, various dynamic characteristics, including the velocity variation, streamwise penetration and power spectral density, are examined. CFD simulations using two different approaches, the unsteady Reynolds Averaged Navier-Stokes (URANS) and the large eddy simulation (LES), are performed for comparison purposes. The numerical results are validated by the experimental data obtained from the measurements by …

A Numerical Tool For Predicting The Spatial Decay Of Freestream Turbulence., Dwaipayan Sarkar

Electronic Thesis and Dissertation Repository

The present numerical work is an attempt towards modelling of freely decaying homogeneous isotropic turbulence with its application in experimental modelling of the effect of incident turbulence on flow around 2D and 3D bluff-bodies. Both steady, Reynolds Averaged Navier Stokes (RANS) and unsteady, Large Eddy Simulation (LES), 3-D numerical computational fluid dynamics (CFD) techniques have been employed to characterise the inviscid decay of large-scale turbulence in terms of the characteristic r.m.s turbulent velocity fluctuations ( ) and the local integral length scale (L_u). The large-scale turbulent properties extracted from the current numerical simulations are inter-related and are shown …

Numerical Simulations Of Two-Phase Flows In The Liquid Solid Circulating Fluidized Bed, Hao Luo

Electronic Thesis and Dissertation Repository

The liquid-solid circulating fluidized bed (LSCFB) has many potential applications in biochemical and petroleum industries, as well as in wastewater treatments, given its higher contact efficiency and being able to accommodate two reactions under one system. With extensive experimental results becoming available, there is clearly a need for computational fluid dynamics (CFD) modeling to expand our understandings of LSCFBs and to predict the hydrodynamic behaviors of the two-phase flows within LSCFB.

In this research, the Eulerian-Eulerian two-phase model combined with the kinetic theory for the granular phase is applied to simulate the two-phase flows in LSCFBs. The key factors affecting …

Numerical Simulation Of Liquid-Solid Circulating Fluidized Beds, Abbas Dadashi

Electronic Thesis and Dissertation Repository

Liquid-solid circulating fluidized bed (LSCFB) reactors are obtaining extensive attraction in the extraction process of functional proteins from industrial broth. A typical LSCFB is comprised of a riser, a downcomer, a liquid-solid separator, a top solids-return pipe and a bottom solids-return pipe. In light of the literature review conducted in this research, a detailed modeling of the protein extraction using an LSCFB ion-exchange system requires a microscopic study including hydrodynamic field, mass transfer and kinetics reactions.

A computational fluid dynamics (CFD) model was developed to simulate the hydrodynamics of the two phase flow in an LSCFB riser. The model is …