Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Magnetic resonance imaging studies of forced and free convective heat transfer in packed beds and fluid columns(Montana State University - Bozeman, College of Engineering, 2021) Skuntz, Matthew Eric; Chairperson, Graduate Committee: Ryan Anderson; This is a manuscript style paper that includes co-authored chapters.Prediction of fluid flow and associated energy transport is an essential component in many engineering applications where analytical solutions are not possible. In these systems experimentation and numerical simulations are a necessary part of the design process. This work focuses on the experimental study of mass and energy transport in packed beds and pure fluids under forced and natural convection using nuclear magnetic resonance (NMR) imaging (MRI) techniques. It further evaluates the efficacy of commercial computational fluid dynamics (CFD) software to simulate these processes. The study of heat transfer via NMR has proven difficult historically, despite sensitivity of NMR parameters to temperature. Here, a novel experimental setup is pioneered, which enables the study of heat transfer in packed beds. The method employs fluorinated pore-filling fluid and hydrogen-rich core-shell packing particles. Hydrogen and fluorine are NMR-active chemicals that can be imaged with the same experimental equipment by adjusting the resonance frequency; providing means to image the two domains separately. Pore- fluid velocities and particle-wax melting are observed in the same packed bed, at sub-millimeter resolutions, presenting a more complete picture of the conditions in these hard-to-measure systems. In the presented studies, this methodology is demonstrated under forced convection and proven capable in identifying and correlating spatial variations in heat transfer to pore-fluid velocity. The technique is then employed to assess the accuracy of a CFD model in the commercial software package, STAR CCM+, using the melt to quantify energy absorbed by the bed. In natural convection studies of a pure fluid and packed bed in the Rayleigh-Bénard configuration, the axial circulation pattern is found to change with axial position in the long narrow cylinder, a result that is rarely discussed in literature. A CFD model is shown to match well with these experimental findings. In porous media convection with sub-, near- and super- critical fluid, the rapidly changing thermal diffusivity was captured by the rate the particles absorb energy. Finally, a correlation is developed allowing particle-wax T 2 relaxation time to be converted into temperature.Item Assessment of district energy integration between buildings(Montana State University - Bozeman, College of Engineering, 2021) Oladeji, Oladayo; Chairperson, Graduate Committee: Kevin AmendeDistrict heating or cooling is a system for distributing heat or chilled water in a centralized location through various systems which is intended for residential and commercial heating or cooling requirements. Montana State University (MSU) is looking at implementing a future energy district in form of a distributed heat pump model. Implementing such system will help in reducing carbon emissions in the atmosphere, provide energy savings and ensuring energy is being used efficiently. In the summer season, there is a lack of substantial heat sinks in which heat could be utilized and in the winter season there is a lack of substantial heat sources available due to the extreme cold weather. This project identifies systems that serves as heat sinks and sources in buildings and provides substantial energy. This project also looks into the feasibility of connecting such systems together in a building to follow a recirculating heat pump model which operates in the temperature range of 60°F - 90°F. If this model provides much energy saving opportunities, it could be incorporated in buildings on campus here at MSU and connected to the future energy district. The project scope was limited to Barnard Hall, in which heat sources opportunities identified include the building exhaust air system and the process cooling system while heat sink opportunities identified include the domestic hot water system and the outdoor air that needs to be pre heated majority of the time in Bozeman, Montana. Energy calculations were done for each system and imputed into TRNSYS, an extremely flexible graphically based software used to simulate the behavior of transient systems. The heat pump model was then designed and simulated for a time frame of 8760 hours (A year). The researched showed that this provided some energy savings opportunities and yields no profit in general.Item Energy modeling development and calibration for a mini district energy loop assessment comprised of a set of campus buildings(Montana State University - Bozeman, College of Engineering, 2019) Hays, Joshua Koplyay; Chairperson, Graduate Committee: Kevin AmendeDistrict energy loops are comprised of a network of buildings connected in a water-source loop with utilization of heat pumps to allow for buildings to share thermal energy. To assess the feasibility of creating a district energy loop, the heat sharing capabilities of the proposed interconnected buildings needs to be analyzed. This paper develops a method to assess a mini-district energy loop from historical utility data. Energy modeling was used to create a simple building model from building construction specifications and given inputs from the University Services Engineers on Montana State University's campus. With the energy model developed, the historical utility data was compared to the hourly heat demand and electricity consumption for the building on an outdoor temperature basis. Calibration techniques for heat demand were comprised of increasing or decreasing the outdoor air ventilation requirement and the base heat demand. Electricity consumption was calibrated by altering the equipment plug load in the spaces. The simulated data was validated with metered hourly heat demand data for a high-energy use laboratory building on MSU's campus. This simple energy model was reconfigured to represent another building at MSU by altering building envelope dimensions, and then re-applying calibration techniques to generate hourly heating and cooling data. Converting the model to be heat-pump compatible allowed for internal thermal energy sharing within the building to occur. Hourly heat demand and hourly heat availability were determined for external thermal energy sharing for a high-energy use laboratory building. After which, heat sources, heat sinks, and thermal energy storage tanks were assessed to determine the feasibility of a district energy loop.Item Heat transfer and flow in packed beds with nuclear magnetic resonance microscopy and computational fluid dynamics(Montana State University - Bozeman, College of Engineering, 2017) Perera, Dinal; Chairperson, Graduate Committee: Sarah L. Codd; Ryan Anderson (co-chair)Fluid flow and heat transfer characteristics in packed beds are studied extensively due to its importance in different fields. The macroscopic and continuum approaches used for analysis require a degree of empiricism and theoretical assumptions. Pore-scale models drive out the need for empiricism and theoretical assumptions but cannot be validated due the lack of accurate pore-scale experimental methods. This thesis presents a novel method that utilizes Nuclear Magnetic Resonance (NMR) techniques to map the pore scale melt fraction and velocities within packed beds, non-invasively. An initial experiment was conducted where heated Nitrogen was flowed through a packed bed filled with PCMs. The increasing signal intensities due to the melting of these PCMs were captured using a 1H tuned coil. Another experiment was conducted where heated Fluorinert was flowed through a packed bed filled with PCMs. The melt front of the PCMs and the velocity of the Fluorinert was imaged using a 1 H/19 F dual tuned coil. Discrete Element Modelling (DEM) was used for the generation of randomly packed beds that mimic the experimental packed beds. These numerical packed beds were modelled under the same inlet conditions as in experimental work to yield models that showed similarities to the processes seen in experimental results. Numerical work analyzed the effects of particle size and geometry on flow, heat transfer and pore structure. Three models were developed: a packed bed of monodisperse spheres, a bed of spherical particles with a Gaussian distribution in diameters and a bed of non-spherical particles with a Gaussian distribution in diameters. It was concluded that the beds of spherical and non-spherical particles with a Gaussian distribution in diameters yielded the best complementary results to the experimental work. These numerical models and the experimental work yielded maximum velocities in the range of 6 mm/s to 8 mm/s, while showing similar attributes such as intra-particle melt gradients, preferential flow pathways and channeling effect. Experimental work shows a melt front of 60 mm in 41 minutes while models yielded a melt front of 18 mm in the same time.Item Green's function simulation method for earth-air heat exchangers(Montana State University - Bozeman, College of Engineering, 2015) Denowh, Chantz Michael; Chairperson, Graduate Committee: David A. Miller; Kevin Amende (co-chair)Earth-air heat exchangers (EAHXs), or earth-tubes, decrease building heating/cooling loads by pre-conditioning supply air in underground pipes. Air circulates underground to exchange heat with the surrounding soil before entering the building. The concept is fairly simple, but the field currently lacks fundamental information of the energy interactions in common EAHX installations. This identifies the need of a model framework inclusive of all EAHX design considerations, time-dependent climate conditions, and EAHX types to support the completion of this fundamental information. The EAHX types in this study include installations under locations free of structures (under yard) and under foundational slabs (under slab). This research develops the groundwork of this framework through a versatile model using the Green's Function method and numeric integration. The Green's Function method incorporates the majority of time-dependent heat transfer mechanisms surrounding EAHXs through long and short time solution components. The long time component calculates the initial soil temperature distribution in the under yard, non-radiant under slab, and radiant under slab installations. The under yard simulations were successfully validated using experimental soil temperature data from around the United States. The non-radiant under slab temperatures produced unrealistic results in some locations, but the novel Green's Function method in this location has significant potential for under slab EAHX applications. Results from the long time solution feed into the short time solution as a space-dependent initial condition. The short time solution uses a finite difference approach to calculate the heat transfer along the EAHX length. This method was validated using computation fluid dynamics with good agreement. The two components work together to quickly simulate a large number of EAHX installations. The research includes an example optimization procedure to demonstrate the framework's versatility. It successfully optimized the EAHX lengths for 95% effectiveness in cooling on the hottest day of the year in 15 locations around the United States.Item Thermal simulation of an experimental high temperature fixed bed cored brick regenerative air preheater(Montana State University - Bozeman, College of Engineering, 1977) Ameel, Timothy AllenItem Natural convection heat transfer between bodies and their enclosures(Montana State University - Bozeman, College of Engineering, 1975) Warrington, Robert O'NeilItem Natural convection heat transfer between a fixed array of cylinders and its cubical enclosure(Montana State University - Bozeman, College of Engineering, 1977) Crupper, GordonItem Thermal model of highway overpass bridge(Montana State University - Bozeman, College of Engineering, 2003) Bunger, Tylar Paul; Chairperson, Graduate Committee: Edward E. AdamsItem Instrumentation requirements and design of a facility for turbulent natural convection studies(Montana State University - Bozeman, College of Engineering, 1983) Pracht, David Allyn
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