Finned-tube heat exchangers are predominantly used in space conditioning systems, as well as other applications requiring heat exchange between two fluids. One important widespread use is in residential air conditioning systems. These residential cooling systems influence the peak demand on the U.S. national electrical system, which occurs on the hot summer afternoons, and thereby sets the requirement for the expensive infrastructure requirement of the nations power plant and electrical distribution system. In addition to this peak demand, these residential air conditioners are major energy users that dominate residential electrical costs and environmental impact. The design of finned-tube heat exchangers requires the selection of over a dozen design parameters by the designer. The refrigerant side flow and heat transfer characteristics inside the tubes have been thoroughly studied. However, the air side flow around the tube bundle and through the fin gaps is much more complex and depends on over a dozen design parameters. Therefore, experimental measurement of the air side performance is needed. First this study built an experimental system and developed methodology for measuring the air side heat transfer and pressure drop characteristics of fin tube heat exchangers. This capability was then used to continue the goal of expanding and clarifying the present knowledge and understanding of air side performance to enable the air conditioner system designer in verifying an optimum fin tube condenser design. In this study eight fin tube heat exchangers were tested over an air flow face velocity range of 5 ?? ft/s (675-1600cfm). The raw data were reduced to the desired heat transfer and friction data, j and f factors. This reduced heat transfer and friction data was plotted versus Reynolds number and compared. The effect of fin spacing, the number of rows and fin enhancement were all investigated. The heat transfer and friction data were also plotted and compared with various correlations available from open literature. The overall accuracy of each correlation to predict experimental data was calculated. Correlations by C.C. Wang (1998b, 1999) showed the best agreement with the data. Wangs correlations (1998b, 1999) were modified to fit the current studys data.

Gas turbine components for cooling purposes including other unique and complex three-dimensional designs could be made explicitly possible through additive manufacturing using SLM technology in contrary to the conventional machining processes. Nevertheless, the surface roughness and subsequently the friction factor governs thepressure drop in these components implicitly, thus, influencing the secondary air flow system of a gas turbine. Research studies to understand and predict flow behaviours through especially AM parts are still in a budding stage, and thus, in this scope of thesis, the same has been attempted through experimentation to quantifypressure losses in additively manufactured rectangular orices. With the purpose of a brief analogy, a set of aluminium circular samples were also tested which were manufactured by the conventional process of machining. A total of 9 rectangular MA247 samples of different lengths and hydraulic diameters were tested as continuation to the ongoing research at Siemens Industrial Turbomachinery AB and further on to that, 5 Aluminium Alloy- AW-6082 T6 material samples of circular geometry with varying lengths were tested. The on-going research focuses on the additively manufactured geometries for both rectangular and circular, and hence, the data for circular orifices were used to draw a comparison with its Aluminium counterpart. Pressure losses here were described using the coefficient of discharge and the investigations on roughness were by calculating Darcy frictional factor and Colebrooks equation. Classical theories such as the boundary layer theory, Hagen's power law, Ward-Smith's theory for vena contracta and other works by previous researchers were used to validate the results. The coefficient of discharge could be deployed to restrict and measure the mass flow in the secondary air systems, whereas the results from the calculated frictional factors could be held to simulate the flow distribution in cooling geometries. / <p>E-presentation via Zoom due to the pandemic.</p> / Part of the on-going research on pressure loss study for Gas Turbine cooling purposes by Siemens Energy