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Heat Transfer Characterization of Shell and Tube Heat Exchangers
Title
Heat Transfer Characterization of Shell and Tube Heat Exchangers.
Creator
Betancourt, Arturo, Curet, Oscar M., Graduate College
Abstract/Description
Shell-and-tube heat exchangers (STHXs) are a popular choice in the petroleum refining industry, chemical industry, food processing industry and in power generation plants. This kind of heat exchanger is made up of an array of baffles that redirects the working fluid to increase heat transfer. The objective of this work is to understand the underlying physics of the heat transfer in a shell-and-tube heat exchanger and its interconnection to the fluid structure associated with their design....
Show moreShell-and-tube heat exchangers (STHXs) are a popular choice in the petroleum refining industry, chemical industry, food processing industry and in power generation plants. This kind of heat exchanger is made up of an array of baffles that redirects the working fluid to increase heat transfer. The objective of this work is to understand the underlying physics of the heat transfer in a shell-and-tube heat exchanger and its interconnection to the fluid structure associated with their design. This research focuses on the steady state three dimensional analysis of the time averaged turbulent flow and heat transfer characterization of the shell side of a small scale single segmented baffle heat exchanger. The study is carried out using the computational fluid dynamics (CFD) software package ANSYS: FLUENT 15.0 on a hybrid unstructured mesh. The CFD results are then compared against experimental results. The Reynolds averaged-Navier-stokes (RANS) based turbulent model realizable is used to model the turbulence inside the heat exchanger. The results obtained from CFD and experiment from the shell side wall outlet temperature differ by 5 %. Based on the computational results it is found that the regions of highest velocity at the inlet and in the core flow lead to a higher local heat transfer enhancement. A better understanding of the complex flow and heat transfer regimes inside a shell and tube heat exchanger given by this work would aid to further the development of more cost efficient and effective heat exchanger designs.
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Date Issued
2015
PURL
http://purl.flvc.org/fau/fd/FA00005869
Format
Document (PDF)
The Effect of Flexibility and Aspect Ratios on Ribbon-Fin-Propulsion
Title
The Effect of Flexibility and Aspect Ratios on Ribbon-Fin-Propulsion.
Creator
Liu, Hanlin, Taylor, Bevan, Lashaw, Evan, Graduate College, Curet, Oscar M.
Abstract/Description
Ribbon-fin-based propulsion has the potential to improve the maneuverability of underwater vehicles in complex environments. In this type of propulsion a series of rays are used to send traveling waves along an elongated fin, which is referred to as ribbon fin. In this work, in order to know the effect of flexural rigidities and aspect ratios on undulating ribbon fin propulsion; we built a robotic ribbon fin, and tested the physical model in a water flume. In a series of experiments we...
Show moreRibbon-fin-based propulsion has the potential to improve the maneuverability of underwater vehicles in complex environments. In this type of propulsion a series of rays are used to send traveling waves along an elongated fin, which is referred to as ribbon fin. In this work, in order to know the effect of flexural rigidities and aspect ratios on undulating ribbon fin propulsion; we built a robotic ribbon fin, and tested the physical model in a water flume. In a series of experiments we measured the propulsive force, power consumption and the free-swimming speed of the robotic fin as a function of wave frequency for fins with different ray stiffness and aspect ratios. The propulsive performance of the robotic ribbon fin was based on the propulsive force generated and power consumption. A series of kinematic experiments were performed using a high-speed camera. Based on the fin kinematics, the natural frequencies of the ribbon fin with different stiffness were determined. We found that the flexible rays would improve or worsen the propulsive performance compared to a rigid counterpart depending on the actuation parameters. For the aspect ratios considered, the propulsive efficiency improves with increase in the fin height. Our data suggest that, the ribbon fin can yield best propulsive behavior close to its natural frequency.
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Date Issued
2015
PURL
http://purl.flvc.org/fau/fd/FA00005881
Format
Document (PDF)