Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 260-265). Also available in electronic format on the Internet.

Thesis (M.S.)--Rochester Institute of Technology, 1995. / Typescript. Bibliography: leaves 72-74

Approved for public release; distribution is unlimited / A detailed experimental study has been carried out on the heat transfer and pressure drop characteristics of a compact heat exchanger with pin fins. A modular wind-tunnel with a rectangular cross-section duct-flow area was constructed that would accommodate the heat exchanger test section with varying pin designs. The flow in the tunnel was achieved through a suction-type blower, and a leading entrance length section was added to achieve predictable flow conditions into the heat exchanger test section. The rig was comprehensively instrumented to provide all desired thermal and flow data. The results from this study provide useful empirical data to validate ongoing numerical studies of such heat exchanger designs. / Lieutenant, United States Navy

Typescript, etc.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. / This project is a part of a research programme by Eskom to develop power station rotary regenerative air heaters that are more compatible with South African coal properties. Large costs are involved in the replacement of air heater surfaces due to the erosion caused by the abrasive South African coal ash. The performance of an air heater L governed by numerous parameters, some of which (such as erosion) are unpredictable. A laborar: 'v testing facility which can produce a real-situation environment for air heater research is not only impractical but also expensive. Hence it has been decided to generate a computer simulation model of a power station air heater. The various alternatives for the improvement of existing air heaters will be assessed using this computer model. Extensive information regarding the influence of various parameters such as thermal performance, erosion, flow resistance, corrosion, etc. is necessary as input to the simulation model. Various test facilities have been commissioned to obtain this information. This project is an experimental study on the thermal performance of the regenerative air heater heating elements using a thermal test facility situated at the Eskom Technology Research and Investigations centre in Johannesburg. The facility uses the single-blow transient technique to establish the heat transfer coefficients of various air heater heating elements. Ten different types of heating elements were tested and the results were analysed .. These test results and recommendations give useful indications for power station application even before the final simulation model is available. The primary objective of this project was to find the heat transfer coefficient and also to make correlations between Colburn j factor, Fanning friction factor and Reynolds number. Packs were tested for various air tlow rates, ranging from Reynolds number 1200 to 6000. The test results were analysed and the correlations were made. A detailed uncertainty analysis was done and found that the results are showing less than 7 % error which is acceptable. The consistency of the test results was tested by a repeatability test and the results were quite satisfactory. The single blow method used in this project considered the longitudinal conduction within the material and it can accommodate any arbitrary inlet fluid temperature history. A comparative study of the various packs was done and traced certain trends. The high density packs gave better heat transfer and high pressure drop. The packs with alternate corrugated and flat plates had lower heat transfer performance, due to the fact that the tlat plates do not create such turbulence to the flow to reduce the boundary layer thickness to enhance the heat transfer. In short the flat plates only add weight to the pack, making it heavier than other packs. Based on the correlations and trends obtained from the analysis, some recommendations are also made. A further modification of the test facility was recommended to include a wider range of flow from very low Reynolds number to very high. This is necessary to find whether the packs with flat plates really perform better for highly turbulent tlow. The non - adiabatic nature of the side wall has to be considered for better reliability of the results. Some other recommendations are made to make the testing of packs more convenient. / Andrew Chakane 2018

A dissertation presented in fulfilment of the requirements for the Degree of Master of Science in Engineering DECEMBER 1982 / Although transpiration cooling has been demonstrated to keep the metal surface temperatures, in a gar turbine, below that at which oxidation occurs even though the hot gas temperatures are in excess of the metals melting temperature, few experimental studies have been conducted on the heat transfer aspects of transpiration cooling. Especially the effect blowing has on a turbulent boundary layer that has developed over a porous surface that is heated by the mainstream. Many studies have involved the blowing or suction oi the boundary layer through heated porous plates. Trans. an cooling was exper cntally investigated by making use of an existing wind tunnel which was modified so as to simulate the heat transfer phenomenon resulting from blowing coolant through a porous wall into a heated mainstream. The existing wind tunnel was designed and commissioned by Krieg (13) who considered the momentum transfer aspects of transpiration cooling. The solution of the momentum equation by Krieg forms the basis from which this investigation was developed, the original solution procedure being put forward by Cebeci and Smith (7). Krieg developed a generalised two-dimensional finite-differunce compute* program to solve the incompressible momentum equations describing a blown boundary layer. This program was further developed as part of this effort to solve the compressible momentum and neigy equations so as to account for the heat transfer in the blown boundary layer. The program is used to predict the experimental results obtained from the literature as well is those ottained during the nine experimental runs on the wind tunnel. Freestream flow velocities varied from 4,^5 m/s to 14,95 m/s with correspoi ;.ng temperatures of 44,95°C and 33,00eC respectively. The blowing fr tion F, was varied from 0,0059 to a maximum of , temperature of 40°C. The numerically calculated profiles and tho: » obi lined expurim ntally, as well as one set presented by another researcher, compared well. Finally, recommendations for future studies have been suggested.

The continuation of conductive temperature fields is being considered. The continuation of a field involves the extrapolation of a field known over a limited domain to an adjacent domain in such a way that it satisfies the heat conduction differential equation and other imposed constraints. Continuations forward in time and toward the interior of the space from the constraining initial and boundary conditions are expressed analytically as convolution integrals. Solutions are approximated using linear filter methods in real and transform spaces. The inverse problems of continuation toward the constraining conditions are expressed in real space as power series of derivatives. Solutions are approximated as convolution filtering operations. Variational methods are also used to solve problems which do not yield to convolution filtering operations. The suitability of these approximation methods is shown in two ways: (1) the frequency response of the derived convolution coefficients are compared with the analytic transfer functions; and (2) the methods are applied to artificial test cases. These field continuation methods provide a tool for the interpretation of observational temperature data. Several examples of field data are treated using these techniques; (1) A case of the temperature inversion observed in a geothermal borehole is explained by a transient flow of thermal water along a narrow horizontal fracture; (2) Soil temperature data are treated to determine the in situ thermal diffusivity and show that departures from conductive conditions are accounted for by evaporative effects; (3) Shallow borehole temperature data which exhibit the nonstationary effects of the annual cycle are shown to be influenced by convective effects in the soil. / Graduation date: 1976

No description available.

Thermal spray coating processes have been employed in the current study to deposit well-adhered, dense skins onto the surfaces of open-cell metal foams. The result is a channel that consists of a metal foam core and a thermal sprayed skin wall that can be used as a compact heat-exchanger by directing the coolant flow through the foam. To study the feasibility of the metallic foam heat-exchangers, hydraulic and heat-transfer characteristics were investigated experimentally. The local wall and fluid temperature distribution and the pressure drop along the length of the heat exchanger were measured for different coolant flow velocities. The Dupuit-Forchheimer modification is employed with the experimental results to determine flow characteristics. To measure the heat transfer performance, a length average Nusselt number is derived from a volumetric heat transfer coefficient based on the local wall and fluid temperatures. Heat transfer was shown to have increased nearly 7 times compared to that of a channel without a foam core.

Thermal spray coating processes have been employed in the current study to deposit well-adhered, dense skins onto the surfaces of open-cell metal foams. The result is a channel that consists of a metal foam core and a thermal sprayed skin wall that can be used as a compact heat-exchanger by directing the coolant flow through the foam. To study the feasibility of the metallic foam heat-exchangers, hydraulic and heat-transfer characteristics were investigated experimentally. The local wall and fluid temperature distribution and the pressure drop along the length of the heat exchanger were measured for different coolant flow velocities. The Dupuit-Forchheimer modification is employed with the experimental results to determine flow characteristics. To measure the heat transfer performance, a length average Nusselt number is derived from a volumetric heat transfer coefficient based on the local wall and fluid temperatures. Heat transfer was shown to have increased nearly 7 times compared to that of a channel without a foam core.